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Author SHA1 Message Date
Charan Teja Kalla
9a79443ddc mm/cma_debug: show complete cma name in debugfs directories 
Currently only 12 characters of the cma name is being used as the debug
directories where as the cma name can be of length CMA_MAX_NAME(=64)
characters.  One side problem with this is having 2 cma's with first
common 12 characters would end up in trying to create directories with
same name and fails with -EEXIST thus can limit cma debug functionality.

The 'cma-' prefix is used initially where cma areas don't have any names
and are represented by simple integer values.  Since now each cma would be
having its own name, drop 'cma-' prefix for the cma debug directories as
they are clearly evident that they are for cma debug through creating them
in /sys/kernel/debug/cma/ path.

Link: https://lkml.kernel.org/r/1660223729-22461-1-git-send-email-quic_charante@quicinc.com
Signed-off-by: Charan Teja Kalla <quic_charante@quicinc.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Pavan Kondeti <quic_pkondeti@quicinc.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-09-11 20:25:50 -07:00
Christoph Hellwig
cf1e3fe497 mm/swap: remove the end_write_func argument to __swap_writepage 
The argument is always set to end_swap_bio_write, so remove the argument
and mark end_swap_bio_write static.

Link: https://lkml.kernel.org/r/20220811141741.660214-1-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-09-11 20:25:50 -07:00
Alexey Romanov
f24263a5a0 zsmalloc: remove unnecessary size_class NULL check 
pool->size_class array elements can't be NULL, so this check
is not needed.

In the whole code, we assign pool->size_class[i] values that are
not NULL. Releasing memory for these values occurs in the
zs_destroy_pool() function, which also releases and destroys the pool.

In addition, in the zs_stats_size_show() and async_free_zspage(),
with similar iterations over the array, we don't check it for NULL
pointer.

Link: https://lkml.kernel.org/r/20220811153755.16102-3-avromanov@sberdevices.ru
Signed-off-by: Alexey Romanov <avromanov@sberdevices.ru>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-09-11 20:25:50 -07:00
Alexey Romanov
050a388b7f zsmalloc: zs_object_copy: add clarifying comment 
Patch series "tidy up zsmalloc implementation"

This patchset remove some unnecessary checks and adds a clarifying
comment.  While analysing zs_object_copy() function code, I spent some
time to understand what the call kunmap_atomic(d_addr) is for.  It seems
that this point is not trivial and it is worth adding a comment.


This patch (of 2):

It's not obvious why kunmap_atomic(d_addr) call is needed.

[akpm@linux-foundation.org: tweak comment layout]
Link: https://lkml.kernel.org/r/20220811153755.16102-1-avromanov@sberdevices.ru
Link: https://lkml.kernel.org/r/20220811153755.16102-2-avromanov@sberdevices.ru
Signed-off-by: Alexey Romanov <avromanov@sberdevices.ru>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-09-11 20:25:49 -07:00
Yang Yang
e9c2dbc8bf mm/vmscan: define macros for refaults in struct lruvec 
The magic number 0 and 1 are used in several places in vmscan.c.
Define macros for them to improve code readability.

Link: https://lkml.kernel.org/r/20220808005644.1721066-1-yang.yang29@zte.com.cn
Signed-off-by: Yang Yang <yang.yang29@zte.com.cn>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-09-11 20:25:49 -07:00
Kenneth Lee
b2d4c646d5 mm/damon/dbgfs: use kmalloc for allocating only one element 
Use kmalloc(...) rather than kmalloc_array(1, ...) because the number of
elements we are specifying in this case is 1, kmalloc would accomplish the
same thing and we can simplify.

Link: https://lkml.kernel.org/r/20220808220019.1680469-1-klee33@uw.edu
Signed-off-by: Kenneth Lee <klee33@uw.edu>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-09-11 20:25:48 -07:00
Shaoqin Huang
223ce4910b mm/filemap.c: convert page_endio() to use a folio 
Replace three calls to compound_head() with one.

Link: https://lkml.kernel.org/r/20220809023256.178194-1-shaoqin.huang@intel.com
Signed-off-by: Shaoqin Huang <shaoqin.huang@intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-09-11 20:25:48 -07:00
Kefeng Wang
2ace36f0f5 mm: memory-failure: cleanup try_to_split_thp_page() 
Since commit 5d1fd5dc877b ("mm,hwpoison: introduce MF_MSG_UNSPLIT_THP"),
the action_result(,MF_MSG_UNSPLIT_THP,) called to show memory error event
in memory_failure(), so the pr_info() in try_to_split_thp_page() is only
needed in soft_offline_in_use_page().

Meanwhile this could also fix the unexpected prefix for "thp split failed"
due to commit 96f96763de26 ("mm: memory-failure: convert to pr_fmt()").

Link: https://lkml.kernel.org/r/20220809111813.139690-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-09-11 20:25:48 -07:00
Rik van Riel
f35b5d7d67 mm: align larger anonymous mappings on THP boundaries 
Align larger anonymous memory mappings on THP boundaries by going through
thp_get_unmapped_area if THPs are enabled for the current process.

With this patch, larger anonymous mappings are now THP aligned.  When a
malloc library allocates a 2MB or larger arena, that arena can now be
mapped with THPs right from the start, which can result in better TLB hit
rates and execution time.

Link: https://lkml.kernel.org/r/20220809142457.4751229f@imladris.surriel.com
Signed-off-by: Rik van Riel <riel@surriel.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-09-11 20:25:47 -07:00
Charan Teja Kalla
7b5a0b664e mm/page_ext: remove unused variable in offline_page_ext 
Remove unused variable 'nid' in offline_page_ext().  This is not used
since the page_ext code inception.

Link: https://lkml.kernel.org/r/1659330397-11817-1-git-send-email-quic_charante@quicinc.com
Signed-off-by: Charan Teja Kalla <quic_charante@quicinc.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Pavan Kondeti <quic_pkondeti@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-09-11 20:25:47 -07:00
Zach O'Keefe
876b4a1896 mm/madvise: add MADV_COLLAPSE to process_madvise() 
Allow MADV_COLLAPSE behavior for process_madvise(2) if caller has
CAP_SYS_ADMIN or is requesting collapse of it's own memory.

This is useful for the development of userspace agents that seek to
optimize THP utilization system-wide by using userspace signals to
prioritize what memory is most deserving of being THP-backed.

[zokeefe@google.com: remove CAP_SYS_ADMIN requirement for process_madvise(MADV_COLLAPSE)]
  Link: https://lkml.kernel.org/r/20220801210946.3069083-1-zokeefe@google.com
Link: https://lkml.kernel.org/r/20220706235936.2197195-13-zokeefe@google.com
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-09-11 20:25:46 -07:00
Zach O'Keefe
7d2c4385c3 mm/khugepaged: rename prefix of shared collapse functions 
The following functions are shared between khugepaged and madvise collapse
contexts.  Replace the "khugepaged_" prefix with generic "hpage_collapse_"
prefix in such cases:

khugepaged_test_exit() -> hpage_collapse_test_exit()
khugepaged_scan_abort() -> hpage_collapse_scan_abort()
khugepaged_scan_pmd() -> hpage_collapse_scan_pmd()
khugepaged_find_target_node() -> hpage_collapse_find_target_node()
khugepaged_alloc_page() -> hpage_collapse_alloc_page()

The kerenel ABI (e.g.  huge_memory:mm_khugepaged_scan_pmd tracepoint) is
unaltered.

Link: https://lkml.kernel.org/r/20220706235936.2197195-11-zokeefe@google.com
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-09-11 20:25:46 -07:00
Zach O'Keefe
7d8faaf155 mm/madvise: introduce MADV_COLLAPSE sync hugepage collapse 
This idea was introduced by David Rientjes[1].

Introduce a new madvise mode, MADV_COLLAPSE, that allows users to request
a synchronous collapse of memory at their own expense.

The benefits of this approach are:

* CPU is charged to the process that wants to spend the cycles for the
  THP
* Avoid unpredictable timing of khugepaged collapse

Semantics

This call is independent of the system-wide THP sysfs settings, but will
fail for memory marked VM_NOHUGEPAGE.  If the ranges provided span
multiple VMAs, the semantics of the collapse over each VMA is independent
from the others.  This implies a hugepage cannot cross a VMA boundary.  If
collapse of a given hugepage-aligned/sized region fails, the operation may
continue to attempt collapsing the remainder of memory specified.

The memory ranges provided must be page-aligned, but are not required to
be hugepage-aligned.  If the memory ranges are not hugepage-aligned, the
start/end of the range will be clamped to the first/last hugepage-aligned
address covered by said range.  The memory ranges must span at least one
hugepage-sized region.

All non-resident pages covered by the range will first be
swapped/faulted-in, before being internally copied onto a freshly
allocated hugepage.  Unmapped pages will have their data directly
initialized to 0 in the new hugepage.  However, for every eligible
hugepage aligned/sized region to-be collapsed, at least one page must
currently be backed by memory (a PMD covering the address range must
already exist).

Allocation for the new hugepage may enter direct reclaim and/or
compaction, regardless of VMA flags.  When the system has multiple NUMA
nodes, the hugepage will be allocated from the node providing the most
native pages.  This operation operates on the current state of the
specified process and makes no persistent changes or guarantees on how
pages will be mapped, constructed, or faulted in the future

Return Value

If all hugepage-sized/aligned regions covered by the provided range were
either successfully collapsed, or were already PMD-mapped THPs, this
operation will be deemed successful.  On success, process_madvise(2)
returns the number of bytes advised, and madvise(2) returns 0.  Else, -1
is returned and errno is set to indicate the error for the most-recently
attempted hugepage collapse.  Note that many failures might have occurred,
since the operation may continue to collapse in the event a single
hugepage-sized/aligned region fails.

	ENOMEM	Memory allocation failed or VMA not found
	EBUSY	Memcg charging failed
	EAGAIN	Required resource temporarily unavailable.  Try again
		might succeed.
	EINVAL	Other error: No PMD found, subpage doesn't have Present
		bit set, "Special" page no backed by struct page, VMA
		incorrectly sized, address not page-aligned, ...

Most notable here is ENOMEM and EBUSY (new to madvise) which are intended
to provide the caller with actionable feedback so they may take an
appropriate fallback measure.

Use Cases

An immediate user of this new functionality are malloc() implementations
that manage memory in hugepage-sized chunks, but sometimes subrelease
memory back to the system in native-sized chunks via MADV_DONTNEED;
zapping the pmd.  Later, when the memory is hot, the implementation could
madvise(MADV_COLLAPSE) to re-back the memory by THPs to regain hugepage
coverage and dTLB performance.  TCMalloc is such an implementation that
could benefit from this[2].

Only privately-mapped anon memory is supported for now, but additional
support for file, shmem, and HugeTLB high-granularity mappings[2] is
expected.  File and tmpfs/shmem support would permit:

* Backing executable text by THPs.  Current support provided by
  CONFIG_READ_ONLY_THP_FOR_FS may take a long time on a large system which
  might impair services from serving at their full rated load after
  (re)starting.  Tricks like mremap(2)'ing text onto anonymous memory to
  immediately realize iTLB performance prevents page sharing and demand
  paging, both of which increase steady state memory footprint.  With
  MADV_COLLAPSE, we get the best of both worlds: Peak upfront performance
  and lower RAM footprints.
* Backing guest memory by hugapages after the memory contents have been
  migrated in native-page-sized chunks to a new host, in a
  userfaultfd-based live-migration stack.

[1] https://lore.kernel.org/linux-mm/d098c392-273a-36a4-1a29-59731cdf5d3d@google.com/
[2] https://github.com/google/tcmalloc/tree/master/tcmalloc

[jrdr.linux@gmail.com: avoid possible memory leak in failure path]
  Link: https://lkml.kernel.org/r/20220713024109.62810-1-jrdr.linux@gmail.com
[zokeefe@google.com add missing kfree() to madvise_collapse()]
  Link: https://lore.kernel.org/linux-mm/20220713024109.62810-1-jrdr.linux@gmail.com/
  Link: https://lkml.kernel.org/r/20220713161851.1879439-1-zokeefe@google.com
[zokeefe@google.com: delay computation of hpage boundaries until use]]
  Link: https://lkml.kernel.org/r/20220720140603.1958773-4-zokeefe@google.com
Link: https://lkml.kernel.org/r/20220706235936.2197195-10-zokeefe@google.com
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com>
Suggested-by: David Rientjes <rientjes@google.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-09-11 20:25:46 -07:00
Zach O'Keefe
5072280442 mm/khugepaged: record SCAN_PMD_MAPPED when scan_pmd() finds hugepage 
When scanning an anon pmd to see if it's eligible for collapse, return
SCAN_PMD_MAPPED if the pmd already maps a hugepage.  Note that
SCAN_PMD_MAPPED is different from SCAN_PAGE_COMPOUND used in the
file-collapse path, since the latter might identify pte-mapped compound
pages.  This is required by MADV_COLLAPSE which necessarily needs to know
what hugepage-aligned/sized regions are already pmd-mapped.

In order to determine if a pmd already maps a hugepage, refactor
mm_find_pmd():

Return mm_find_pmd() to it's pre-commit f72e7dcdd252 ("mm: let mm_find_pmd
fix buggy race with THP fault") behavior.  ksm was the only caller that
explicitly wanted a pte-mapping pmd, so open code the pte-mapping logic
there (pmd_present() and pmd_trans_huge() checks).

Undo revert change in commit f72e7dcdd252 ("mm: let mm_find_pmd fix buggy
race with THP fault") that open-coded split_huge_pmd_address() pmd lookup
and use mm_find_pmd() instead.

Link: https://lkml.kernel.org/r/20220706235936.2197195-9-zokeefe@google.com
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-09-11 20:25:46 -07:00
Zach O'Keefe
a7f4e6e4c4 mm/thp: add flag to enforce sysfs THP in hugepage_vma_check() 
MADV_COLLAPSE is not coupled to the kernel-oriented sysfs THP settings[1].

hugepage_vma_check() is the authority on determining if a VMA is eligible
for THP allocation/collapse, and currently enforces the sysfs THP
settings.  Add a flag to disable these checks.  For now, only apply this
arg to anon and file, which use /sys/kernel/transparent_hugepage/enabled. 
We can expand this to shmem, which uses
/sys/kernel/transparent_hugepage/shmem_enabled, later.

Use this flag in collapse_pte_mapped_thp() where previously the VMA flags
passed to hugepage_vma_check() were OR'd with VM_HUGEPAGE to elide the
VM_HUGEPAGE check in "madvise" THP mode.  Prior to "mm: khugepaged: check
THP flag in hugepage_vma_check()", this check also didn't check "never"
THP mode.  As such, this restores the previous behavior of
collapse_pte_mapped_thp() where sysfs THP settings are ignored.  See
comment in code for justification why this is OK.

[1] https://lore.kernel.org/linux-mm/CAAa6QmQxay1_=Pmt8oCX2-Va18t44FV-Vs-WsQt_6+qBks4nZA@mail.gmail.com/

Link: https://lkml.kernel.org/r/20220706235936.2197195-8-zokeefe@google.com
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-09-11 20:25:45 -07:00
Zach O'Keefe
d8ea7cc854 mm/khugepaged: add flag to predicate khugepaged-only behavior 
Add .is_khugepaged flag to struct collapse_control so khugepaged-specific
behavior can be elided by MADV_COLLAPSE context.

Start by protecting khugepaged-specific heuristics by this flag.  In
MADV_COLLAPSE, the user presumably has reason to believe the collapse will
be beneficial and khugepaged heuristics shouldn't prevent the user from
doing so:

1) sysfs-controlled knobs khugepaged_max_ptes_[none|swap|shared]

2) requirement that some pages in region being collapsed be young or
   referenced

[zokeefe@google.com: consistently order cc->is_khugepaged and pte_* checks]
  Link: https://lkml.kernel.org/r/20220720140603.1958773-3-zokeefe@google.com
  Link: https://lore.kernel.org/linux-mm/Ys2qJm6FaOQcxkha@google.com/
Link: https://lkml.kernel.org/r/20220706235936.2197195-7-zokeefe@google.com
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-09-11 20:25:45 -07:00
Zach O'Keefe
50ad2f24b3 mm/khugepaged: propagate enum scan_result codes back to callers 
Propagate enum scan_result codes back through return values of
functions downstream of khugepaged_scan_file() and
khugepaged_scan_pmd() to inform callers if the operation was
successful, and if not, why.

Since khugepaged_scan_pmd()'s return value already has a specific meaning
(whether mmap_lock was unlocked or not), add a bool* argument to
khugepaged_scan_pmd() to retrieve this information.

Change khugepaged to take action based on the return values of
khugepaged_scan_file() and khugepaged_scan_pmd() instead of acting deep
within the collapsing functions themselves.

hugepage_vma_revalidate() now returns SCAN_SUCCEED on success to be more
consistent with enum scan_result propagation.

Remove dependency on error pointers to communicate to khugepaged that
allocation failed and it should sleep; instead just use the result of the
scan (SCAN_ALLOC_HUGE_PAGE_FAIL if allocation fails).

Link: https://lkml.kernel.org/r/20220706235936.2197195-6-zokeefe@google.com
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-09-11 20:25:45 -07:00
Zach O'Keefe
9710a78ab2 mm/khugepaged: dedup and simplify hugepage alloc and charging 
The following code is duplicated in collapse_huge_page() and
collapse_file():

        gfp = alloc_hugepage_khugepaged_gfpmask() | __GFP_THISNODE;

	new_page = khugepaged_alloc_page(hpage, gfp, node);
        if (!new_page) {
                result = SCAN_ALLOC_HUGE_PAGE_FAIL;
                goto out;
        }

        if (unlikely(mem_cgroup_charge(page_folio(new_page), mm, gfp))) {
                result = SCAN_CGROUP_CHARGE_FAIL;
                goto out;
        }
        count_memcg_page_event(new_page, THP_COLLAPSE_ALLOC);

Also, "node" is passed as an argument to both collapse_huge_page() and
collapse_file() and obtained the same way, via
khugepaged_find_target_node().

Move all this into a new helper, alloc_charge_hpage(), and remove the
duplicate code from collapse_huge_page() and collapse_file().  Also,
simplify khugepaged_alloc_page() by returning a bool indicating allocation
success instead of a copy of the allocated struct page *.

Link: https://lkml.kernel.org/r/20220706235936.2197195-5-zokeefe@google.com
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Suggested-by: Peter Xu <peterx@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-09-11 20:25:45 -07:00
Zach O'Keefe
34d6b470ab mm/khugepaged: add struct collapse_control 
Modularize hugepage collapse by introducing struct collapse_control.  This
structure serves to describe the properties of the requested collapse, as
well as serve as a local scratch pad to use during the collapse itself.

Start by moving global per-node khugepaged statistics into this new
structure.  Note that this structure is still statically allocated since
CONFIG_NODES_SHIFT might be arbitrary large, and stack-allocating a
MAX_NUMNODES-sized array could cause -Wframe-large-than= errors.

[zokeefe@google.com: use minimal bits to store num page < HPAGE_PMD_NR]
  Link: https://lkml.kernel.org/r/20220720140603.1958773-2-zokeefe@google.com
  Link: https://lore.kernel.org/linux-mm/Ys2CeIm%2FQmQwWh9a@google.com/
[sfr@canb.auug.org.au: fix build]
  Link: https://lkml.kernel.org/r/20220721195508.15f1e07a@canb.auug.org.au
[zokeefe@google.com: fix struct collapse_control load_node definition]
  Link: https://lore.kernel.org/linux-mm/202209021349.F73i5d6X-lkp@intel.com/
  Link: https://lkml.kernel.org/r/20220903021221.1130021-1-zokeefe@google.com
Link: https://lkml.kernel.org/r/20220706235936.2197195-4-zokeefe@google.com
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-09-11 20:25:45 -07:00
Yang Shi
c6a7f445a2 mm: khugepaged: don't carry huge page to the next loop for !CONFIG_NUMA 
Patch series "mm: userspace hugepage collapse", v7.

Introduction
--------------------------------

This series provides a mechanism for userspace to induce a collapse of
eligible ranges of memory into transparent hugepages in process context,
thus permitting users to more tightly control their own hugepage
utilization policy at their own expense.

This idea was introduced by David Rientjes[5].

Interface
--------------------------------

The proposed interface adds a new madvise(2) mode, MADV_COLLAPSE, and
leverages the new process_madvise(2) call.

process_madvise(2)

	Performs a synchronous collapse of the native pages
	mapped by the list of iovecs into transparent hugepages.

	This operation is independent of the system THP sysfs settings,
	but attempts to collapse VMAs marked VM_NOHUGEPAGE will still fail.

	THP allocation may enter direct reclaim and/or compaction.

	When a range spans multiple VMAs, the semantics of the collapse
	over of each VMA is independent from the others.

	Caller must have CAP_SYS_ADMIN if not acting on self.

	Return value follows existing process_madvise(2) conventions.  A
	“success” indicates that all hugepage-sized/aligned regions
	covered by the provided range were either successfully
	collapsed, or were already pmd-mapped THPs.

madvise(2)

	Equivalent to process_madvise(2) on self, with 0 returned on
	“success”.

Current Use-Cases
--------------------------------

(1)	Immediately back executable text by THPs.  Current support provided
	by CONFIG_READ_ONLY_THP_FOR_FS may take a long time on a large
	system which might impair services from serving at their full rated
	load after (re)starting.  Tricks like mremap(2)'ing text onto
	anonymous memory to immediately realize iTLB performance prevents
	page sharing and demand paging, both of which increase steady state
	memory footprint.  With MADV_COLLAPSE, we get the best of both
	worlds: Peak upfront performance and lower RAM footprints.  Note
	that subsequent support for file-backed memory is required here.

(2)	malloc() implementations that manage memory in hugepage-sized
	chunks, but sometimes subrelease memory back to the system in
	native-sized chunks via MADV_DONTNEED; zapping the pmd.  Later,
	when the memory is hot, the implementation could
	madvise(MADV_COLLAPSE) to re-back the memory by THPs to regain
	hugepage coverage and dTLB performance.  TCMalloc is such an
	implementation that could benefit from this[6].  A prior study of
	Google internal workloads during evaluation of Temeraire, a
	hugepage-aware enhancement to TCMalloc, showed that nearly 20% of
	all cpu cycles were spent in dTLB stalls, and that increasing
	hugepage coverage by even small amount can help with that[7].

(3)	userfaultfd-based live migration of virtual machines satisfy UFFD
	faults by fetching native-sized pages over the network (to avoid
	latency of transferring an entire hugepage).  However, after guest
	memory has been fully copied to the new host, MADV_COLLAPSE can
	be used to immediately increase guest performance.  Note that
	subsequent support for file/shmem-backed memory is required here.

(4)	HugeTLB high-granularity mapping allows HugeTLB a HugeTLB page to
	be mapped at different levels in the page tables[8].  As it's not
	"transparent" like THP, HugeTLB high-granularity mappings require
	an explicit user API. It is intended that MADV_COLLAPSE be co-opted
	for this use case[9].  Note that subsequent support for HugeTLB
	memory is required here.

Future work
--------------------------------

Only private anonymous memory is supported by this series. File and
shmem memory support will be added later.

One possible user of this functionality is a userspace agent that
attempts to optimize THP utilization system-wide by allocating THPs
based on, for example, task priority, task performance requirements, or
heatmaps.  For the latter, one idea that has already surfaced is using
DAMON to identify hot regions, and driving THP collapse through a new
DAMOS_COLLAPSE scheme[10].


This patch (of 17):

The khugepaged has optimization to reduce huge page allocation calls for
!CONFIG_NUMA by carrying the allocated but failed to collapse huge page to
the next loop.  CONFIG_NUMA doesn't do so since the next loop may try to
collapse huge page from a different node, so it doesn't make too much
sense to carry it.

But when NUMA=n, the huge page is allocated by khugepaged_prealloc_page()
before scanning the address space, so it means huge page may be allocated
even though there is no suitable range for collapsing.  Then the page
would be just freed if khugepaged already made enough progress.  This
could make NUMA=n run have 5 times as much thp_collapse_alloc as NUMA=y
run.  This problem actually makes things worse due to the way more
pointless THP allocations and makes the optimization pointless.

This could be fixed by carrying the huge page across scans, but it will
complicate the code further and the huge page may be carried indefinitely.
But if we take one step back, the optimization itself seems not worth
keeping nowadays since:

  * Not too many users build NUMA=n kernel nowadays even though the kernel is
    actually running on a non-NUMA machine. Some small devices may run NUMA=n
    kernel, but I don't think they actually use THP.
  * Since commit 44042b449872 ("mm/page_alloc: allow high-order pages to be
    stored on the per-cpu lists"), THP could be cached by pcp.  This actually
    somehow does the job done by the optimization.

Link: https://lkml.kernel.org/r/20220706235936.2197195-1-zokeefe@google.com
Link: https://lkml.kernel.org/r/20220706235936.2197195-3-zokeefe@google.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Co-developed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-09-11 20:25:44 -07:00
Peter Xu
3d2f78f08c mm/mprotect: only reference swap pfn page if type match 
Yu Zhao reported a bug after the commit "mm/swap: Add swp_offset_pfn() to
fetch PFN from swap entry" added a check in swp_offset_pfn() for swap type [1]:

  kernel BUG at include/linux/swapops.h:117!
  CPU: 46 PID: 5245 Comm: EventManager_De Tainted: G S         O L 6.0.0-dbg-DEV #2
  RIP: 0010:pfn_swap_entry_to_page+0x72/0xf0
  Code: c6 48 8b 36 48 83 fe ff 74 53 48 01 d1 48 83 c1 08 48 8b 09 f6
  c1 01 75 7b 66 90 48 89 c1 48 8b 09 f6 c1 01 74 74 5d c3 eb 9e <0f> 0b
  48 ba ff ff ff ff 03 00 00 00 eb ae a9 ff 0f 00 00 75 13 48
  RSP: 0018:ffffa59e73fabb80 EFLAGS: 00010282
  RAX: 00000000ffffffe8 RBX: 0c00000000000000 RCX: ffffcd5440000000
  RDX: 1ffffffffff7a80a RSI: 0000000000000000 RDI: 0c0000000000042b
  RBP: ffffa59e73fabb80 R08: ffff9965ca6e8bb8 R09: 0000000000000000
  R10: ffffffffa5a2f62d R11: 0000030b372e9fff R12: ffff997b79db5738
  R13: 000000000000042b R14: 0c0000000000042b R15: 1ffffffffff7a80a
  FS:  00007f549d1bb700(0000) GS:ffff99d3cf680000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000440d035b3180 CR3: 0000002243176004 CR4: 00000000003706e0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  Call Trace:
   <TASK>
   change_pte_range+0x36e/0x880
   change_p4d_range+0x2e8/0x670
   change_protection_range+0x14e/0x2c0
   mprotect_fixup+0x1ee/0x330
   do_mprotect_pkey+0x34c/0x440
   __x64_sys_mprotect+0x1d/0x30

It triggers because pfn_swap_entry_to_page() could be called upon e.g. a
genuine swap entry.

Fix it by only calling it when it's a write migration entry where the page*
is used.

[1] https://lore.kernel.org/lkml/CAOUHufaVC2Za-p8m0aiHw6YkheDcrO-C3wRGixwDS32VTS+k1w@mail.gmail.com/

Link: https://lkml.kernel.org/r/20220823221138.45602-1-peterx@redhat.com
Fixes: 6c287605fd56 ("mm: remember exclusively mapped anonymous pages with PG_anon_exclusive")
Signed-off-by: Peter Xu <peterx@redhat.com>
Reported-by: Yu Zhao <yuzhao@google.com>
Tested-by: Yu Zhao <yuzhao@google.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-08-28 14:02:46 -07:00
Badari Pulavarty
d26f607036 mm/damon/dbgfs: avoid duplicate context directory creation 
When user tries to create a DAMON context via the DAMON debugfs interface
with a name of an already existing context, the context directory creation
fails but a new context is created and added in the internal data
structure, due to absence of the directory creation success check.  As a
result, memory could leak and DAMON cannot be turned on.  An example test
case is as below:

    # cd /sys/kernel/debug/damon/
    # echo "off" >  monitor_on
    # echo paddr > target_ids
    # echo "abc" > mk_context
    # echo "abc" > mk_context
    # echo $$ > abc/target_ids
    # echo "on" > monitor_on  <<< fails

Return value of 'debugfs_create_dir()' is expected to be ignored in
general, but this is an exceptional case as DAMON feature is depending
on the debugfs functionality and it has the potential duplicate name
issue.  This commit therefore fixes the issue by checking the directory
creation failure and immediately return the error in the case.

Link: https://lkml.kernel.org/r/20220821180853.2400-1-sj@kernel.org
Fixes: 75c1c2b53c78 ("mm/damon/dbgfs: support multiple contexts")
Signed-off-by: Badari Pulavarty <badari.pulavarty@intel.com>
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org>	[ 5.15.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-08-28 14:02:45 -07:00
Liu Shixin
dd0ff4d12d bootmem: remove the vmemmap pages from kmemleak in put_page_bootmem 
The vmemmap pages is marked by kmemleak when allocated from memblock. 
Remove it from kmemleak when freeing the page.  Otherwise, when we reuse
the page, kmemleak may report such an error and then stop working.

 kmemleak: Cannot insert 0xffff98fb6eab3d40 into the object search tree (overlaps existing)
 kmemleak: Kernel memory leak detector disabled
 kmemleak: Object 0xffff98fb6be00000 (size 335544320):
 kmemleak:   comm "swapper", pid 0, jiffies 4294892296
 kmemleak:   min_count = 0
 kmemleak:   count = 0
 kmemleak:   flags = 0x1
 kmemleak:   checksum = 0
 kmemleak:   backtrace:

Link: https://lkml.kernel.org/r/20220819094005.2928241-1-liushixin2@huawei.com
Fixes: f41f2ed43ca5 (mm: hugetlb: free the vmemmap pages associated with each HugeTLB page)
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-08-28 14:02:45 -07:00
Sergey Senozhatsky
a5d2172180 mm/zsmalloc: do not attempt to free IS_ERR handle 
zsmalloc() now returns ERR_PTR values as handles, which zram accidentally
can pass to zs_free().  Another bad scenario is when zcomp_compress()
fails - handle has default -ENOMEM value, and zs_free() will try to free
that "pointer value".

Add the missing check and make sure that zs_free() bails out when
ERR_PTR() is passed to it.

Link: https://lkml.kernel.org/r/20220816050906.2583956-1-senozhatsky@chromium.org
Fixes: c7e6f17b52e9 ("zsmalloc: zs_malloc: return ERR_PTR on failure")
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>,
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-08-28 14:02:44 -07:00
Khazhismel Kumykov
f87904c075 writeback: avoid use-after-free after removing device 
When a disk is removed, bdi_unregister gets called to stop further
writeback and wait for associated delayed work to complete.  However,
wb_inode_writeback_end() may schedule bandwidth estimation dwork after
this has completed, which can result in the timer attempting to access the
just freed bdi_writeback.

Fix this by checking if the bdi_writeback is alive, similar to when
scheduling writeback work.

Since this requires wb->work_lock, and wb_inode_writeback_end() may get
called from interrupt, switch wb->work_lock to an irqsafe lock.

Link: https://lkml.kernel.org/r/20220801155034.3772543-1-khazhy@google.com
Fixes: 45a2966fd641 ("writeback: fix bandwidth estimate for spiky workload")
Signed-off-by: Khazhismel Kumykov <khazhy@google.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Michael Stapelberg <stapelberg+linux@google.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-08-28 14:02:43 -07:00
Matthew Wilcox (Oracle)
9dfb3b8d65 shmem: update folio if shmem_replace_page() updates the page 
If we allocate a new page, we need to make sure that our folio matches
that new page.

If we do end up in this code path, we store the wrong page in the shmem
inode's page cache, and I would rather imagine that data corruption
ensues.

This will be solved by changing shmem_replace_page() to
shmem_replace_folio(), but this is the minimal fix.

Link: https://lkml.kernel.org/r/20220730042518.1264767-1-willy@infradead.org
Fixes: da08e9b79323 ("mm/shmem: convert shmem_swapin_page() to shmem_swapin_folio()")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-08-28 14:02:43 -07:00
Miaohe Lin
ab74ef708d mm/hugetlb: avoid corrupting page->mapping in hugetlb_mcopy_atomic_pte 
In MCOPY_ATOMIC_CONTINUE case with a non-shared VMA, pages in the page
cache are installed in the ptes.  But hugepage_add_new_anon_rmap is called
for them mistakenly because they're not vm_shared.  This will corrupt the
page->mapping used by page cache code.

Link: https://lkml.kernel.org/r/20220712130542.18836-1-linmiaohe@huawei.com
Fixes: f619147104c8 ("userfaultfd: add UFFDIO_CONTINUE ioctl")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-08-28 14:02:43 -07:00
Hugh Dickins
76d36dea02 mm/shmem: shmem_replace_page() remember NR_SHMEM 
Elsewhere, NR_SHMEM is updated at the same time as shmem NR_FILE_PAGES;
but shmem_replace_page() was forgetting to do that - so NR_SHMEM stats
could grow too big or too small, in those unusual cases when it's used.

Link: https://lkml.kernel.org/r/cec7c09d-5874-e160-ada6-6e10ee48784@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Radoslaw Burny <rburny@google.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-08-20 15:17:45 -07:00
Hugh Dickins
15f242bb65 mm/shmem: tmpfs fallocate use file_modified() 
5.18 fixed the btrfs and ext4 fallocates to use file_modified(), as xfs
was already doing, to drop privileges: and fstests generic/{683,684,688}
expect this.  There's no need to argue over keep-size allocation (which
could just update ctime): fix shmem_fallocate() to behave the same way.

Link: https://lkml.kernel.org/r/39c5e62-4896-7795-c0a0-f79c50d4909@google.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Radoslaw Burny <rburny@google.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-08-20 15:17:45 -07:00
Hugh Dickins
cb241339b9 mm/shmem: fix chattr fsflags support in tmpfs 
ext[234] have always allowed unimplemented chattr flags to be set, but
other filesystems have tended to be stricter.  Follow the stricter
approach for tmpfs: I don't want to have to explain why csu attributes
don't actually work, and we won't need to update the chattr(1) manpage;
and it's never wrong to start off strict, relaxing later if persuaded. 
Allow only a (append only) i (immutable) A (no atime) and d (no dump).

Although lsattr showed 'A' inherited, the NOATIME behavior was not being
inherited: because nothing sync'ed FS_NOATIME_FL to S_NOATIME.  Add
shmem_set_inode_flags() to sync the flags, using inode_set_flags() to
avoid that instant of lost immutablility during fileattr_set().

But that change switched generic/079 from passing to failing: because
FS_IMMUTABLE_FL and FS_APPEND_FL had been unconventionally included in the
INHERITED fsflags: remove them and generic/079 is back to passing.

Link: https://lkml.kernel.org/r/2961dcb0-ddf3-b9f0-3268-12a4ff996856@google.com
Fixes: e408e695f5f1 ("mm/shmem: support FS_IOC_[SG]ETFLAGS in tmpfs")
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Radoslaw Burny <rburny@google.com>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-08-20 15:17:45 -07:00
David Hildenbrand
1d8d14641f mm/hugetlb: support write-faults in shared mappings 
If we ever get a write-fault on a write-protected page in a shared
mapping, we'd be in trouble (again).  Instead, we can simply map the page
writable.

And in fact, there is even a way right now to trigger that code via
uffd-wp ever since we stared to support it for shmem in 5.19:

--------------------------------------------------------------------------
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <fcntl.h>
 #include <unistd.h>
 #include <errno.h>
 #include <sys/mman.h>
 #include <sys/syscall.h>
 #include <sys/ioctl.h>
 #include <linux/userfaultfd.h>

 #define HUGETLB_SIZE (2 * 1024 * 1024u)

 static char *map;
 int uffd;

 static int temp_setup_uffd(void)
 {
 	struct uffdio_api uffdio_api;
 	struct uffdio_register uffdio_register;
 	struct uffdio_writeprotect uffd_writeprotect;
 	struct uffdio_range uffd_range;

 	uffd = syscall(__NR_userfaultfd,
 		       O_CLOEXEC | O_NONBLOCK | UFFD_USER_MODE_ONLY);
 	if (uffd < 0) {
 		fprintf(stderr, "syscall() failed: %d\n", errno);
 		return -errno;
 	}

 	uffdio_api.api = UFFD_API;
 	uffdio_api.features = UFFD_FEATURE_PAGEFAULT_FLAG_WP;
 	if (ioctl(uffd, UFFDIO_API, &uffdio_api) < 0) {
 		fprintf(stderr, "UFFDIO_API failed: %d\n", errno);
 		return -errno;
 	}

 	if (!(uffdio_api.features & UFFD_FEATURE_PAGEFAULT_FLAG_WP)) {
 		fprintf(stderr, "UFFD_FEATURE_WRITEPROTECT missing\n");
 		return -ENOSYS;
 	}

 	/* Register UFFD-WP */
 	uffdio_register.range.start = (unsigned long) map;
 	uffdio_register.range.len = HUGETLB_SIZE;
 	uffdio_register.mode = UFFDIO_REGISTER_MODE_WP;
 	if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register) < 0) {
 		fprintf(stderr, "UFFDIO_REGISTER failed: %d\n", errno);
 		return -errno;
 	}

 	/* Writeprotect a single page. */
 	uffd_writeprotect.range.start = (unsigned long) map;
 	uffd_writeprotect.range.len = HUGETLB_SIZE;
 	uffd_writeprotect.mode = UFFDIO_WRITEPROTECT_MODE_WP;
 	if (ioctl(uffd, UFFDIO_WRITEPROTECT, &uffd_writeprotect)) {
 		fprintf(stderr, "UFFDIO_WRITEPROTECT failed: %d\n", errno);
 		return -errno;
 	}

 	/* Unregister UFFD-WP without prior writeunprotection. */
 	uffd_range.start = (unsigned long) map;
 	uffd_range.len = HUGETLB_SIZE;
 	if (ioctl(uffd, UFFDIO_UNREGISTER, &uffd_range)) {
 		fprintf(stderr, "UFFDIO_UNREGISTER failed: %d\n", errno);
 		return -errno;
 	}

 	return 0;
 }

 int main(int argc, char **argv)
 {
 	int fd;

 	fd = open("/dev/hugepages/tmp", O_RDWR | O_CREAT);
 	if (!fd) {
 		fprintf(stderr, "open() failed\n");
 		return -errno;
 	}
 	if (ftruncate(fd, HUGETLB_SIZE)) {
 		fprintf(stderr, "ftruncate() failed\n");
 		return -errno;
 	}

 	map = mmap(NULL, HUGETLB_SIZE, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
 	if (map == MAP_FAILED) {
 		fprintf(stderr, "mmap() failed\n");
 		return -errno;
 	}

 	*map = 0;

 	if (temp_setup_uffd())
 		return 1;

 	*map = 0;

 	return 0;
 }
--------------------------------------------------------------------------

Above test fails with SIGBUS when there is only a single free hugetlb page.
 # echo 1 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages
 # ./test
 Bus error (core dumped)

And worse, with sufficient free hugetlb pages it will map an anonymous page
into a shared mapping, for example, messing up accounting during unmap
and breaking MAP_SHARED semantics:
 # echo 2 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages
 # ./test
 # cat /proc/meminfo | grep HugePages_
 HugePages_Total:       2
 HugePages_Free:        1
 HugePages_Rsvd:    18446744073709551615
 HugePages_Surp:        0

Reason is that uffd-wp doesn't clear the uffd-wp PTE bit when
unregistering and consequently keeps the PTE writeprotected.  Reason for
this is to avoid the additional overhead when unregistering.  Note that
this is the case also for !hugetlb and that we will end up with writable
PTEs that still have the uffd-wp PTE bit set once we return from
hugetlb_wp().  I'm not touching the uffd-wp PTE bit for now, because it
seems to be a generic thing -- wp_page_reuse() also doesn't clear it.

VM_MAYSHARE handling in hugetlb_fault() for FAULT_FLAG_WRITE indicates
that MAP_SHARED handling was at least envisioned, but could never have
worked as expected.

While at it, make sure that we never end up in hugetlb_wp() on write
faults without VM_WRITE, because we don't support maybe_mkwrite()
semantics as commonly used in the !hugetlb case -- for example, in
wp_page_reuse().

Note that there is no need to do any kind of reservation in
hugetlb_fault() in this case ...  because we already have a hugetlb page
mapped R/O that we will simply map writable and we are not dealing with
COW/unsharing.

Link: https://lkml.kernel.org/r/20220811103435.188481-3-david@redhat.com
Fixes: b1f9e876862d ("mm/uffd: enable write protection for shmem & hugetlbfs")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jamie Liu <jamieliu@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Peter Feiner <pfeiner@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: <stable@vger.kernel.org>	[5.19]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-08-20 15:17:45 -07:00
David Hildenbrand
f96f7a4087 mm/hugetlb: fix hugetlb not supporting softdirty tracking 
Patch series "mm/hugetlb: fix write-fault handling for shared mappings", v2.

I observed that hugetlb does not support/expect write-faults in shared
mappings that would have to map the R/O-mapped page writable -- and I
found two case where we could currently get such faults and would
erroneously map an anon page into a shared mapping.

Reproducers part of the patches.

I propose to backport both fixes to stable trees.  The first fix needs a
small adjustment.


This patch (of 2):

Staring at hugetlb_wp(), one might wonder where all the logic for shared
mappings is when stumbling over a write-protected page in a shared
mapping.  In fact, there is none, and so far we thought we could get away
with that because e.g., mprotect() should always do the right thing and
map all pages directly writable.

Looks like we were wrong:

--------------------------------------------------------------------------
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <fcntl.h>
 #include <unistd.h>
 #include <errno.h>
 #include <sys/mman.h>

 #define HUGETLB_SIZE (2 * 1024 * 1024u)

 static void clear_softdirty(void)
 {
         int fd = open("/proc/self/clear_refs", O_WRONLY);
         const char *ctrl = "4";
         int ret;

         if (fd < 0) {
                 fprintf(stderr, "open(clear_refs) failed\n");
                 exit(1);
         }
         ret = write(fd, ctrl, strlen(ctrl));
         if (ret != strlen(ctrl)) {
                 fprintf(stderr, "write(clear_refs) failed\n");
                 exit(1);
         }
         close(fd);
 }

 int main(int argc, char **argv)
 {
         char *map;
         int fd;

         fd = open("/dev/hugepages/tmp", O_RDWR | O_CREAT);
         if (!fd) {
                 fprintf(stderr, "open() failed\n");
                 return -errno;
         }
         if (ftruncate(fd, HUGETLB_SIZE)) {
                 fprintf(stderr, "ftruncate() failed\n");
                 return -errno;
         }

         map = mmap(NULL, HUGETLB_SIZE, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
         if (map == MAP_FAILED) {
                 fprintf(stderr, "mmap() failed\n");
                 return -errno;
         }

         *map = 0;

         if (mprotect(map, HUGETLB_SIZE, PROT_READ)) {
                 fprintf(stderr, "mmprotect() failed\n");
                 return -errno;
         }

         clear_softdirty();

         if (mprotect(map, HUGETLB_SIZE, PROT_READ|PROT_WRITE)) {
                 fprintf(stderr, "mmprotect() failed\n");
                 return -errno;
         }

         *map = 0;

         return 0;
 }
--------------------------------------------------------------------------

Above test fails with SIGBUS when there is only a single free hugetlb page.
 # echo 1 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages
 # ./test
 Bus error (core dumped)

And worse, with sufficient free hugetlb pages it will map an anonymous page
into a shared mapping, for example, messing up accounting during unmap
and breaking MAP_SHARED semantics:
 # echo 2 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages
 # ./test
 # cat /proc/meminfo | grep HugePages_
 HugePages_Total:       2
 HugePages_Free:        1
 HugePages_Rsvd:    18446744073709551615
 HugePages_Surp:        0

Reason in this particular case is that vma_wants_writenotify() will
return "true", removing VM_SHARED in vma_set_page_prot() to map pages
write-protected. Let's teach vma_wants_writenotify() that hugetlb does not
support softdirty tracking.

Link: https://lkml.kernel.org/r/20220811103435.188481-1-david@redhat.com
Link: https://lkml.kernel.org/r/20220811103435.188481-2-david@redhat.com
Fixes: 64e455079e1b ("mm: softdirty: enable write notifications on VMAs after VM_SOFTDIRTY cleared")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Peter Feiner <pfeiner@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Jamie Liu <jamieliu@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: <stable@vger.kernel.org>	[3.18+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-08-20 15:17:45 -07:00
Peter Xu
f369b07c86 mm/uffd: reset write protection when unregister with wp-mode 
The motivation of this patch comes from a recent report and patchfix from
David Hildenbrand on hugetlb shared handling of wr-protected page [1].

With the reproducer provided in commit message of [1], one can leverage
the uffd-wp lazy-reset of ptes to trigger a hugetlb issue which can affect
not only the attacker process, but also the whole system.

The lazy-reset mechanism of uffd-wp was used to make unregister faster,
meanwhile it has an assumption that any leftover pgtable entries should
only affect the process on its own, so not only the user should be aware
of anything it does, but also it should not affect outside of the process.

But it seems that this is not true, and it can also be utilized to make
some exploit easier.

So far there's no clue showing that the lazy-reset is important to any
userfaultfd users because normally the unregister will only happen once
for a specific range of memory of the lifecycle of the process.

Considering all above, what this patch proposes is to do explicit pte
resets when unregister an uffd region with wr-protect mode enabled.

It should be the same as calling ioctl(UFFDIO_WRITEPROTECT, wp=false)
right before ioctl(UFFDIO_UNREGISTER) for the user.  So potentially it'll
make the unregister slower.  From that pov it's a very slight abi change,
but hopefully nothing should break with this change either.

Regarding to the change itself - core of uffd write [un]protect operation
is moved into a separate function (uffd_wp_range()) and it is reused in
the unregister code path.

Note that the new function will not check for anything, e.g.  ranges or
memory types, because they should have been checked during the previous
UFFDIO_REGISTER or it should have failed already.  It also doesn't check
mmap_changing because we're with mmap write lock held anyway.

I added a Fixes upon introducing of uffd-wp shmem+hugetlbfs because that's
the only issue reported so far and that's the commit David's reproducer
will start working (v5.19+).  But the whole idea actually applies to not
only file memories but also anonymous.  It's just that we don't need to
fix anonymous prior to v5.19- because there's no known way to exploit.

IOW, this patch can also fix the issue reported in [1] as the patch 2 does.

[1] https://lore.kernel.org/all/20220811103435.188481-3-david@redhat.com/

Link: https://lkml.kernel.org/r/20220811201340.39342-1-peterx@redhat.com
Fixes: b1f9e876862d ("mm/uffd: enable write protection for shmem & hugetlbfs")
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-08-20 15:17:45 -07:00
Hao Lee
a39c5d3ce0 mm: add DEVICE_ZONE to FOR_ALL_ZONES 
FOR_ALL_ZONES should be consistent with enum zone_type.  Otherwise,
__count_zid_vm_events have the potential to add count to wrong item when
zid is ZONE_DEVICE.

Link: https://lkml.kernel.org/r/20220807154442.GA18167@haolee.io
Signed-off-by: Hao Lee <haolee.swjtu@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-08-20 15:17:45 -07:00
David Hildenbrand
5535be3099 mm/gup: fix FOLL_FORCE COW security issue and remove FOLL_COW 
Ever since the Dirty COW (CVE-2016-5195) security issue happened, we know
that FOLL_FORCE can be possibly dangerous, especially if there are races
that can be exploited by user space.

Right now, it would be sufficient to have some code that sets a PTE of a
R/O-mapped shared page dirty, in order for it to erroneously become
writable by FOLL_FORCE.  The implications of setting a write-protected PTE
dirty might not be immediately obvious to everyone.

And in fact ever since commit 9ae0f87d009c ("mm/shmem: unconditionally set
pte dirty in mfill_atomic_install_pte"), we can use UFFDIO_CONTINUE to map
a shmem page R/O while marking the pte dirty.  This can be used by
unprivileged user space to modify tmpfs/shmem file content even if the
user does not have write permissions to the file, and to bypass memfd
write sealing -- Dirty COW restricted to tmpfs/shmem (CVE-2022-2590).

To fix such security issues for good, the insight is that we really only
need that fancy retry logic (FOLL_COW) for COW mappings that are not
writable (!VM_WRITE).  And in a COW mapping, we really only broke COW if
we have an exclusive anonymous page mapped.  If we have something else
mapped, or the mapped anonymous page might be shared (!PageAnonExclusive),
we have to trigger a write fault to break COW.  If we don't find an
exclusive anonymous page when we retry, we have to trigger COW breaking
once again because something intervened.

Let's move away from this mandatory-retry + dirty handling and rely on our
PageAnonExclusive() flag for making a similar decision, to use the same
COW logic as in other kernel parts here as well.  In case we stumble over
a PTE in a COW mapping that does not map an exclusive anonymous page, COW
was not properly broken and we have to trigger a fake write-fault to break
COW.

Just like we do in can_change_pte_writable() added via commit 64fe24a3e05e
("mm/mprotect: try avoiding write faults for exclusive anonymous pages
when changing protection") and commit 76aefad628aa ("mm/mprotect: fix
soft-dirty check in can_change_pte_writable()"), take care of softdirty
and uffd-wp manually.

For example, a write() via /proc/self/mem to a uffd-wp-protected range has
to fail instead of silently granting write access and bypassing the
userspace fault handler.  Note that FOLL_FORCE is not only used for debug
access, but also triggered by applications without debug intentions, for
example, when pinning pages via RDMA.

This fixes CVE-2022-2590. Note that only x86_64 and aarch64 are
affected, because only those support CONFIG_HAVE_ARCH_USERFAULTFD_MINOR.

Fortunately, FOLL_COW is no longer required to handle FOLL_FORCE. So
let's just get rid of it.

Thanks to Nadav Amit for pointing out that the pte_dirty() check in
FOLL_FORCE code is problematic and might be exploitable.

Note 1: We don't check for the PTE being dirty because it doesn't matter
	for making a "was COWed" decision anymore, and whoever modifies the
	page has to set the page dirty either way.

Note 2: Kernels before extended uffd-wp support and before
	PageAnonExclusive (< 5.19) can simply revert the problematic
	commit instead and be safe regarding UFFDIO_CONTINUE. A backport to
	v5.19 requires minor adjustments due to lack of
	vma_soft_dirty_enabled().

Link: https://lkml.kernel.org/r/20220809205640.70916-1-david@redhat.com
Fixes: 9ae0f87d009c ("mm/shmem: unconditionally set pte dirty in mfill_atomic_install_pte")
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: <stable@vger.kernel.org>	[5.16]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-08-20 15:17:44 -07:00
Linus Torvalds
b1701d5e29 - hugetlb_vmemmap cleanups from Muchun Song 
- hardware poisoning support for 1GB hugepages, from Naoya Horiguchi
 
 - highmem documentation fixups from Fabio De Francesco
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Merge tag 'mm-stable-2022-08-09' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull remaining MM updates from Andrew Morton:
 "Three patch series - two that perform cleanups and one feature:

   - hugetlb_vmemmap cleanups from Muchun Song

   - hardware poisoning support for 1GB hugepages, from Naoya Horiguchi

   - highmem documentation fixups from Fabio De Francesco"

* tag 'mm-stable-2022-08-09' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (23 commits)
  Documentation/mm: add details about kmap_local_page() and preemption
  highmem: delete a sentence from kmap_local_page() kdocs
  Documentation/mm: rrefer kmap_local_page() and avoid kmap()
  Documentation/mm: avoid invalid use of addresses from kmap_local_page()
  Documentation/mm: don't kmap*() pages which can't come from HIGHMEM
  highmem: specify that kmap_local_page() is callable from interrupts
  highmem: remove unneeded spaces in kmap_local_page() kdocs
  mm, hwpoison: enable memory error handling on 1GB hugepage
  mm, hwpoison: skip raw hwpoison page in freeing 1GB hugepage
  mm, hwpoison: make __page_handle_poison returns int
  mm, hwpoison: set PG_hwpoison for busy hugetlb pages
  mm, hwpoison: make unpoison aware of raw error info in hwpoisoned hugepage
  mm, hwpoison, hugetlb: support saving mechanism of raw error pages
  mm/hugetlb: make pud_huge() and follow_huge_pud() aware of non-present pud entry
  mm/hugetlb: check gigantic_page_runtime_supported() in return_unused_surplus_pages()
  mm: hugetlb_vmemmap: use PTRS_PER_PTE instead of PMD_SIZE / PAGE_SIZE
  mm: hugetlb_vmemmap: move code comments to vmemmap_dedup.rst
  mm: hugetlb_vmemmap: improve hugetlb_vmemmap code readability
  mm: hugetlb_vmemmap: replace early_param() with core_param()
  mm: hugetlb_vmemmap: move vmemmap code related to HugeTLB to hugetlb_vmemmap.c
  ...
 2022-08-10 11:18:00 -07:00
Linus Torvalds
c235698355 cxl for 6.0 
- Introduce a 'struct cxl_region' object with support for provisioning
   and assembling persistent memory regions.
 
 - Introduce alloc_free_mem_region() to accompany the existing
   request_free_mem_region() as a method to allocate physical memory
   capacity out of an existing resource.
 
 - Export insert_resource_expand_to_fit() for the CXL subsystem to
   late-publish CXL platform windows in iomem_resource.
 
 - Add a polled mode PCI DOE (Data Object Exchange) driver service and
   use it in cxl_pci to retrieve the CDAT (Coherent Device Attribute
   Table).
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Merge tag 'cxl-for-6.0' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl

Pull cxl updates from Dan Williams:
 "Compute Express Link (CXL) updates for 6.0:

   - Introduce a 'struct cxl_region' object with support for
     provisioning and assembling persistent memory regions.

   - Introduce alloc_free_mem_region() to accompany the existing
     request_free_mem_region() as a method to allocate physical memory
     capacity out of an existing resource.

   - Export insert_resource_expand_to_fit() for the CXL subsystem to
     late-publish CXL platform windows in iomem_resource.

   - Add a polled mode PCI DOE (Data Object Exchange) driver service and
     use it in cxl_pci to retrieve the CDAT (Coherent Device Attribute
     Table)"

* tag 'cxl-for-6.0' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl: (74 commits)
  cxl/hdm: Fix skip allocations vs multiple pmem allocations
  cxl/region: Disallow region granularity != window granularity
  cxl/region: Fix x1 interleave to greater than x1 interleave routing
  cxl/region: Move HPA setup to cxl_region_attach()
  cxl/region: Fix decoder interleave programming
  Documentation: cxl: remove dangling kernel-doc reference
  cxl/region: describe targets and nr_targets members of cxl_region_params
  cxl/regions: add padding for cxl_rr_ep_add nested lists
  cxl/region: Fix IS_ERR() vs NULL check
  cxl/region: Fix region reference target accounting
  cxl/region: Fix region commit uninitialized variable warning
  cxl/region: Fix port setup uninitialized variable warnings
  cxl/region: Stop initializing interleave granularity
  cxl/hdm: Fix DPA reservation vs cxl_endpoint_decoder lifetime
  cxl/acpi: Minimize granularity for x1 interleaves
  cxl/region: Delete 'region' attribute from root decoders
  cxl/acpi: Autoload driver for 'cxl_acpi' test devices
  cxl/region: decrement ->nr_targets on error in cxl_region_attach()
  cxl/region: prevent underflow in ways_to_cxl()
  cxl/region: uninitialized variable in alloc_hpa()
  ...
 2022-08-10 11:07:26 -07:00
Linus Torvalds
b8dcef877a memblock updates for v5.20 
* An optimization in memblock_add_range() to reduce array traversals
 * Improvements to the memblock test suite
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Merge tag 'memblock-v5.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock

Pull memblock updates from Mike Rapoport:

 - An optimization in memblock_add_range() to reduce array traversals

 - Improvements to the memblock test suite

* tag 'memblock-v5.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock:
  memblock test: Modify the obsolete description in README
  memblock tests: fix compilation errors
  memblock tests: change build options to run-time options
  memblock tests: remove completed TODO items
  memblock tests: set memblock_debug to enable memblock_dbg() messages
  memblock tests: add verbose output to memblock tests
  memblock tests: Makefile: add arguments to control verbosity
  memblock: avoid some repeat when add new range
 2022-08-09 09:48:30 -07:00
Linus Torvalds
f30adc0d33 iov_iter stuff, part 2, rebased 
* more new_sync_{read,write}() speedups - ITER_UBUF introduction
 * ITER_PIPE cleanups
 * unification of iov_iter_get_pages/iov_iter_get_pages_alloc and
   switching them to advancing semantics
 * making ITER_PIPE take high-order pages without splitting them
 * handling copy_page_from_iter() for high-order pages properly
 
 Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Merge tag 'pull-work.iov_iter-rebased' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull more iov_iter updates from Al Viro:

 - more new_sync_{read,write}() speedups - ITER_UBUF introduction

 - ITER_PIPE cleanups

 - unification of iov_iter_get_pages/iov_iter_get_pages_alloc and
   switching them to advancing semantics

 - making ITER_PIPE take high-order pages without splitting them

 - handling copy_page_from_iter() for high-order pages properly

* tag 'pull-work.iov_iter-rebased' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (32 commits)
  fix copy_page_from_iter() for compound destinations
  hugetlbfs: copy_page_to_iter() can deal with compound pages
  copy_page_to_iter(): don't split high-order page in case of ITER_PIPE
  expand those iov_iter_advance()...
  pipe_get_pages(): switch to append_pipe()
  get rid of non-advancing variants
  ceph: switch the last caller of iov_iter_get_pages_alloc()
  9p: convert to advancing variant of iov_iter_get_pages_alloc()
  af_alg_make_sg(): switch to advancing variant of iov_iter_get_pages()
  iter_to_pipe(): switch to advancing variant of iov_iter_get_pages()
  block: convert to advancing variants of iov_iter_get_pages{,_alloc}()
  iov_iter: advancing variants of iov_iter_get_pages{,_alloc}()
  iov_iter: saner helper for page array allocation
  fold __pipe_get_pages() into pipe_get_pages()
  ITER_XARRAY: don't open-code DIV_ROUND_UP()
  unify the rest of iov_iter_get_pages()/iov_iter_get_pages_alloc() guts
  unify xarray_get_pages() and xarray_get_pages_alloc()
  unify pipe_get_pages() and pipe_get_pages_alloc()
  iov_iter_get_pages(): sanity-check arguments
  iov_iter_get_pages_alloc(): lift freeing pages array on failure exits into wrapper
  ...
 2022-08-08 20:04:35 -07:00
Al Viro
fcb14cb1bd new iov_iter flavour - ITER_UBUF 
Equivalent of single-segment iovec.  Initialized by iov_iter_ubuf(),
checked for by iter_is_ubuf(), otherwise behaves like ITER_IOVEC
ones.

We are going to expose the things like ->write_iter() et.al. to those
in subsequent commits.

New predicate (user_backed_iter()) that is true for ITER_IOVEC and
ITER_UBUF; places like direct-IO handling should use that for
checking that pages we modify after getting them from iov_iter_get_pages()
would need to be dirtied.

DO NOT assume that replacing iter_is_iovec() with user_backed_iter()
will solve all problems - there's code that uses iter_is_iovec() to
decide how to poke around in iov_iter guts and for that the predicate
replacement obviously won't suffice.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
 2022-08-08 22:37:15 -04:00
Naoya Horiguchi
6f4614886b mm, hwpoison: enable memory error handling on 1GB hugepage 
Now error handling code is prepared, so remove the blocking code and
enable memory error handling on 1GB hugepage.

Link: https://lkml.kernel.org/r/20220714042420.1847125-9-naoya.horiguchi@linux.dev
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-08-08 18:06:44 -07:00
Naoya Horiguchi
ceaf8fbea7 mm, hwpoison: skip raw hwpoison page in freeing 1GB hugepage 
Currently if memory_failure() (modified to remove blocking code with
subsequent patch) is called on a page in some 1GB hugepage, memory error
handling fails and the raw error page gets into leaked state.  The impact
is small in production systems (just leaked single 4kB page), but this
limits the testability because unpoison doesn't work for it.  We can no
longer create 1GB hugepage on the 1GB physical address range with such
leaked pages, that's not useful when testing on small systems.

When a hwpoison page in a 1GB hugepage is handled, it's caught by the
PageHWPoison check in free_pages_prepare() because the 1GB hugepage is
broken down into raw error pages before coming to this point:

        if (unlikely(PageHWPoison(page)) && !order) {
                ...
                return false;
        }

Then, the page is not sent to buddy and the page refcount is left 0.

Originally this check is supposed to work when the error page is freed
from page_handle_poison() (that is called from soft-offline), but now we
are opening another path to call it, so the callers of
__page_handle_poison() need to handle the case by considering the return
value 0 as success.  Then page refcount for hwpoison is properly
incremented so unpoison works.

Link: https://lkml.kernel.org/r/20220714042420.1847125-8-naoya.horiguchi@linux.dev
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-08-08 18:06:44 -07:00
Naoya Horiguchi
7453bf621c mm, hwpoison: make __page_handle_poison returns int 
__page_handle_poison() returns bool that shows whether
take_page_off_buddy() has passed or not now.  But we will want to
distinguish another case of "dissolve has passed but taking off failed" by
its return value.  So change the type of the return value.  No functional
change.

Link: https://lkml.kernel.org/r/20220714042420.1847125-7-naoya.horiguchi@linux.dev
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-08-08 18:06:44 -07:00
Naoya Horiguchi
38f6d29397 mm, hwpoison: set PG_hwpoison for busy hugetlb pages 
If memory_failure() fails to grab page refcount on a hugetlb page because
it's busy, it returns without setting PG_hwpoison on it.  This not only
loses a chance of error containment, but breaks the rule that
action_result() should be called only when memory_failure() do any of
handling work (even if that's just setting PG_hwpoison).  This
inconsistency could harm code maintainability.

So set PG_hwpoison and call hugetlb_set_page_hwpoison() for such a case.

Link: https://lkml.kernel.org/r/20220714042420.1847125-6-naoya.horiguchi@linux.dev
Fixes: 405ce051236c ("mm/hwpoison: fix race between hugetlb free/demotion and memory_failure_hugetlb()")
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-08-08 18:06:44 -07:00
Naoya Horiguchi
ac5fcde0a9 mm, hwpoison: make unpoison aware of raw error info in hwpoisoned hugepage 
Raw error info list needs to be removed when hwpoisoned hugetlb is
unpoisoned.  And unpoison handler needs to know how many errors there are
in the target hugepage.  So add them.

HPageVmemmapOptimized(hpage) and HPageRawHwpUnreliable(hpage)) sometimes
can't be unpoisoned, so skip them.

Link: https://lkml.kernel.org/r/20220714042420.1847125-5-naoya.horiguchi@linux.dev
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-08-08 18:06:44 -07:00
Naoya Horiguchi
161df60e9e mm, hwpoison, hugetlb: support saving mechanism of raw error pages 
When handling memory error on a hugetlb page, the error handler tries to
dissolve and turn it into 4kB pages.  If it's successfully dissolved,
PageHWPoison flag is moved to the raw error page, so that's all right. 
However, dissolve sometimes fails, then the error page is left as
hwpoisoned hugepage.  It's useful if we can retry to dissolve it to save
healthy pages, but that's not possible now because the information about
where the raw error pages is lost.

Use the private field of a few tail pages to keep that information.  The
code path of shrinking hugepage pool uses this info to try delayed
dissolve.  In order to remember multiple errors in a hugepage, a
singly-linked list originated from SUBPAGE_INDEX_HWPOISON-th tail page is
constructed.  Only simple operations (adding an entry or clearing all) are
required and the list is assumed not to be very long, so this simple data
structure should be enough.

If we failed to save raw error info, the hwpoison hugepage has errors on
unknown subpage, then this new saving mechanism does not work any more, so
disable saving new raw error info and freeing hwpoison hugepages.

Link: https://lkml.kernel.org/r/20220714042420.1847125-4-naoya.horiguchi@linux.dev
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-08-08 18:06:44 -07:00
Naoya Horiguchi
3a194f3f8a mm/hugetlb: make pud_huge() and follow_huge_pud() aware of non-present pud entry 
follow_pud_mask() does not support non-present pud entry now.  As long as
I tested on x86_64 server, follow_pud_mask() still simply returns
no_page_table() for non-present_pud_entry() due to pud_bad(), so no severe
user-visible effect should happen.  But generally we should call
follow_huge_pud() for non-present pud entry for 1GB hugetlb page.

Update pud_huge() and follow_huge_pud() to handle non-present pud entries.
The changes are similar to previous works for pud entries commit
e66f17ff7177 ("mm/hugetlb: take page table lock in follow_huge_pmd()") and
commit cbef8478bee5 ("mm/hugetlb: pmd_huge() returns true for non-present
hugepage").

Link: https://lkml.kernel.org/r/20220714042420.1847125-3-naoya.horiguchi@linux.dev
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-08-08 18:06:43 -07:00
Naoya Horiguchi
c0531714d6 mm/hugetlb: check gigantic_page_runtime_supported() in return_unused_surplus_pages() 
Patch series "mm, hwpoison: enable 1GB hugepage support", v7.


This patch (of 8):

I found a weird state of 1GB hugepage pool, caused by the following
procedure:

  - run a process reserving all free 1GB hugepages,
  - shrink free 1GB hugepage pool to zero (i.e. writing 0 to
    /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages), then
  - kill the reserving process.

, then all the hugepages are free *and* surplus at the same time.

  $ cat /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages
  3
  $ cat /sys/kernel/mm/hugepages/hugepages-1048576kB/free_hugepages
  3
  $ cat /sys/kernel/mm/hugepages/hugepages-1048576kB/resv_hugepages
  0
  $ cat /sys/kernel/mm/hugepages/hugepages-1048576kB/surplus_hugepages
  3

This state is resolved by reserving and allocating the pages then freeing
them again, so this seems not to result in serious problem.  But it's a
little surprising (shrinking pool suddenly fails).

This behavior is caused by hstate_is_gigantic() check in
return_unused_surplus_pages().  This was introduced so long ago in 2008 by
commit aa888a74977a ("hugetlb: support larger than MAX_ORDER"), and at
that time the gigantic pages were not supposed to be allocated/freed at
run-time.  Now kernel can support runtime allocation/free, so let's check
gigantic_page_runtime_supported() together.

Link: https://lkml.kernel.org/r/20220714042420.1847125-1-naoya.horiguchi@linux.dev
Link: https://lkml.kernel.org/r/20220714042420.1847125-2-naoya.horiguchi@linux.dev
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Liu Shixin <liushixin2@huawei.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: kernel test robot <lkp@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-08-08 18:06:43 -07:00
Muchun Song
e38f055d6d mm: hugetlb_vmemmap: use PTRS_PER_PTE instead of PMD_SIZE / PAGE_SIZE 
There is already a macro PTRS_PER_PTE to represent the number of page
table entries, just use it.

Link: https://lkml.kernel.org/r/20220628092235.91270-9-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Will Deacon <will@kernel.org>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-08-08 18:06:43 -07:00
Muchun Song
6213834c10 mm: hugetlb_vmemmap: improve hugetlb_vmemmap code readability 
There is a discussion about the name of hugetlb_vmemmap_alloc/free in
thread [1].  The suggestion suggested by David is rename "alloc/free" to
"optimize/restore" to make functionalities clearer to users, "optimize"
means the function will optimize vmemmap pages, while "restore" means
restoring its vmemmap pages discared before.  This commit does this.

Another discussion is the confusion RESERVE_VMEMMAP_NR isn't used
explicitly for vmemmap_addr but implicitly for vmemmap_end in
hugetlb_vmemmap_alloc/free.  David suggested we can compute what
hugetlb_vmemmap_init() does now at runtime.  We do not need to worry for
the overhead of computing at runtime since the calculation is simple
enough and those functions are not in a hot path.  This commit has the
following improvements:

  1) The function suffixed name ("optimize/restore") is more expressive.
  2) The logic becomes less weird in hugetlb_vmemmap_optimize/restore().
  3) The hugetlb_vmemmap_init() does not need to be exported anymore.
  4) A ->optimize_vmemmap_pages field in struct hstate is killed.
  5) There is only one place where checks is_power_of_2(sizeof(struct
     page)) instead of two places.
  6) Add more comments for hugetlb_vmemmap_optimize/restore().
  7) For external users, hugetlb_optimize_vmemmap_pages() is used for
     detecting if the HugeTLB's vmemmap pages is optimizable originally.
     In this commit, it is killed and we introduce a new helper
     hugetlb_vmemmap_optimizable() to replace it.  The name is more
     expressive.

Link: https://lore.kernel.org/all/20220404074652.68024-2-songmuchun@bytedance.com/ [1]
Link: https://lkml.kernel.org/r/20220628092235.91270-7-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Will Deacon <will@kernel.org>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
 2022-08-08 18:06:43 -07:00