"include/asm-<arch>" was replaced by "arch/<arch>/include/asm" a long time
ago. All assembler header files are now included using "#include
<asm/*>", so there is no longer a need to rewrite paths.
Link: https://lkml.kernel.org/r/19fb5b49396239d28020015ba2640d77dacdb6c2.1733404444.git.geert+renesas@glider.be
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dwaipayan Ray <dwaipayanray1@gmail.com>
Cc: Joe Perches <joe@perches.com>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nicolas Schier <nicolas@fjasle.eu>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "Update reference to include/asm-<arch>".
Despite "include/asm-<arch>" having been replaced by
"arch/<arch>/include/asm" 15 years ago, there are still several
references left.
This patch series updates the most visible ones.
This patch (of 3):
"include/asm-<arch>" was replaced by "arch/<arch>/include/asm" a long
time ago.
Link: https://lkml.kernel.org/r/cover.1733404444.git.geert+renesas@glider.be
Link: https://lkml.kernel.org/r/2c4a75726a976d117055055b68a31c40dcab044e.1733404444.git.geert+renesas@glider.be
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dwaipayan Ray <dwaipayanray1@gmail.com>
Cc: Joe Perches <joe@perches.com>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nicolas Schier <nicolas@fjasle.eu>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The logfile option was documented but not working. Add it and optimized
the while loop.
Link: https://lkml.kernel.org/r/20241203020550.3145-1-zhangjiao2@cmss.chinamobile.com
Signed-off-by: zhang jiao <zhangjiao2@cmss.chinamobile.com>
Reviewed-by: Dr. Thomas Orgis <thomas.orgis@uni-hamburg.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Update delay-accounting.rst to include the 'delay max' in the output of
getdelays, and fix some spelling errors before.
Link: https://lkml.kernel.org/r/20241213192700771XKZ8H30OtHSeziGqRVMs0@zte.com.cn
Signed-off-by: Yaxin Wang <wang.yaxin@zte.com.cn>
Signed-off-by: Jiang Kun <jiang.kun2@zte.com.cn>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Fan Yu <fan.yu9@zte.com.cn>
Cc: Peilin He <he.peilin@zte.com.cn>
Cc: tuqiang <tu.qiang35@zte.com.cn>
Cc: Wang Yong <wang.yong12@zte.com.cn>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: ye xingchen <ye.xingchen@zte.com.cn>
Cc: Yunkai Zhang <zhang.yunkai@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Introduce the use cases of delay max, which can help quickly detect
potential abnormal delays in the system and record the types and specific
details of delay spikes.
Problem
========
Delay accounting can track the average delay of processes to show
system workload. However, when a process experiences a significant
delay, maybe a delay spike, which adversely affects performance,
getdelays can only display the average system delay over a period
of time. Yet, average delay is unhelpful for diagnosing delay peak.
It is not even possible to determine which type of delay has spiked,
as this information might be masked by the average delay.
Solution
=========
the 'delay max' can display delay peak since the system's startup,
which can record potential abnormal delays over time, including
the type of delay and the maximum delay. This is helpful for
quickly identifying crash caused by delay.
Use case
=========
bash# ./getdelays -d -p 244
print delayacct stats ON
PID 244
CPU count real total virtual total delay total delay average delay max
68 192000000 213676651 705643 0.010ms 0.306381ms
IO count delay total delay average delay max
0 0 0.000ms 0.000000ms
SWAP count delay total delay average delay max
0 0 0.000ms 0.000000ms
RECLAIM count delay total delay average delay max
0 0 0.000ms 0.000000ms
THRASHING count delay total delay average delay max
0 0 0.000ms 0.000000ms
COMPACT count delay total delay average delay max
0 0 0.000ms 0.000000ms
WPCOPY count delay total delay average delay max
235 15648284 0.067ms 0.263842ms
IRQ count delay total delay average delay max
0 0 0.000ms 0.000000ms
Link: https://lkml.kernel.org/r/20241203164848805CS62CQPQWG9GLdQj2_BxS@zte.com.cn
Co-developed-by: Wang Yong <wang.yong12@zte.com.cn>
Signed-off-by: Wang Yong <wang.yong12@zte.com.cn>
Co-developed-by: xu xin <xu.xin16@zte.com.cn>
Signed-off-by: xu xin <xu.xin16@zte.com.cn>
Co-developed-by: Wang Yaxin <wang.yaxin@zte.com.cn>
Signed-off-by: Wang Yaxin <wang.yaxin@zte.com.cn>
Signed-off-by: Kun Jiang <jiang.kun2@zte.com.cn>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Fan Yu <fan.yu9@zte.com.cn>
Cc: Peilin He <he.peilin@zte.com.cn>
Cc: tuqiang <tu.qiang35@zte.com.cn>
Cc: Yang Yang <yang.yang29@zte.com.cn>
Cc: ye xingchen <ye.xingchen@zte.com.cn>
Cc: Yunkai Zhang <zhang.yunkai@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Simplify __devm_release_region() implementation by dedicated API
devres_release() which have below advantages than current
__release_region() + devres_destroy():
It is simpler if __devm_release_region() is undoing what
__devm_request_region() did, otherwise, it can avoid wrong and undesired
__release_region().
Link: https://lkml.kernel.org/r/20241017-release_region_fix-v1-1-84a3e8441284@quicinc.com
Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reduce code duplication by extracting a static inline function. This
function is identical to __xa_cmpxchg with the exception that it does not
coerce zero entries to null on the return path.
Link: https://lkml.kernel.org/r/20241112-xarray-insert-cmpxchg-v1-2-dc2bdd8c4136@gmail.com
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andreas Hindborg <a.hindborg@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "xarray: extract __xa_cmpxchg_raw".
This series reduces duplication between __xa_cmpxchg and __xa_insert by
extracting a new function that does not coerce zero entries to null on the
return path.
The new function may be used by the upcoming Rust xarray abstraction in
its reservation API where it is useful to tell the difference between zero
entries and null slots.
This patch (of 2):
Reduce code duplication by extracting a static inline function that
returns its argument if it is non-zero and NULL otherwise.
This changes xas_result to check for errors before checking for zero but
this cannot change the behavior of existing callers:
- __xa_erase: passes the result of xas_store(_, NULL) which cannot fail.
- __xa_store: passes the result of xas_store(_, entry) which may fail.
xas_store calls xas_create when entry is not NULL which returns NULL
on error, which is immediately checked. This should not change
observable behavior.
- __xa_cmpxchg: passes the result of xas_load(_) which might be zero.
This would previously return NULL regardless of the outcome of
xas_store but xas_store cannot fail if xas_load returns zero
because there is no need to allocate memory.
- xa_store_range: same as __xa_erase.
Link: https://lkml.kernel.org/r/20241112-xarray-insert-cmpxchg-v1-0-dc2bdd8c4136@gmail.com
Link: https://lkml.kernel.org/r/20241112-xarray-insert-cmpxchg-v1-1-dc2bdd8c4136@gmail.com
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andreas Hindborg <a.hindborg@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Add some of the more common spelling mistakes and typos that I've found
while fixing up spelling mistakes in the kernel over the past year.
Link: https://lkml.kernel.org/r/20241113102106.1163050-1-colin.i.king@gmail.com
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
As with other documentation files, author information is added to
min_heap.rst, providing contact details for any questions regarding the
Min Heap API or the document itself.
Link: https://lkml.kernel.org/r/20241129181222.646855-5-visitorckw@gmail.com
Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
Cc: Ching-Chun (Jim) Huang <jserv@ccns.ncku.edu.tw>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
A short description of the Min Heap API is added to the min_heap.h,
explaining its purpose for managing min-heaps and emphasizing the use of
macro wrappers instead of direct function calls. For more details, users
are directed to the documentation at Documentation/core-api/min_heap.rst.
Link: https://lkml.kernel.org/r/20241129181222.646855-4-visitorckw@gmail.com
Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
Cc: Ching-Chun (Jim) Huang <jserv@ccns.ncku.edu.tw>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
To address concerns about increasing the attack vector, remove the select
MIN_HEAP dependency from TEST_MIN_HEAP in Kconfig.debug.
Additionally, all min heap test function calls in lib/test_min_heap.c are
replaced with their inline variants. By exclusively using inline
variants, we eliminate the need to enable CONFIG_MIN_HEAP for testing
purposes.
Link: https://lore.kernel.org/lkml/CAMuHMdVO5DPuD9HYWBFqKDHphx7+0BEhreUxtVC40A=8p6VAhQ@mail.gmail.com
Link: https://lkml.kernel.org/r/20241129181222.646855-3-visitorckw@gmail.com
Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
Suggested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ching-Chun (Jim) Huang <jserv@ccns.ncku.edu.tw>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "lib min_heap: Improve min_heap safety, testing, and
documentation".
Improve the min heap implementation by enhancing type safety with
container_of, reducing the attack vector by replacing test function calls
with inline variants, and adding a brief API introduction in min_heap.h.
It also includes author information in
Documentation/core-api/min_heap.rst.
This patch (of 4):
The current implementation of min_heap macros uses explicit casting to
min_heap_char *, which prevents the compiler from detecting incorrect
pointer types. This can lead to errors if non-min_heap pointers are
passed inadvertently.
To enhance safety, replace all explicit casts to min_heap_char * with the
use of container_of(&(_heap)->nr, min_heap_char, nr). This approach
ensures that the _heap parameter is indeed a min_heap_char-compatible
structure, allowing the compiler to catch improper usages.
Link: https://lkml.kernel.org/r/20241129181222.646855-1-visitorckw@gmail.com
Link: https://lore.kernel.org/lkml/CAMuHMdVO5DPuD9HYWBFqKDHphx7+0BEhreUxtVC40A=8p6VAhQ@mail.gmail.com
Link: https://lkml.kernel.org/r/20241129181222.646855-2-visitorckw@gmail.com
Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
Suggested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ching-Chun (Jim) Huang <jserv@ccns.ncku.edu.tw>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The bodies of __signed_type_use() and __unsigned_type_use() are much the
same size as their names - so put the bodies in the only line that expands
them.
Similarly __signed_type() is defined separately for 64bit and then used
exactly once just below.
Change the test for __signed_type from CONFIG_64BIT to one based on gcc
defined macros so that the code is valid if it gets used outside of a
kernel build.
Link: https://lkml.kernel.org/r/9386d1ebb8974fbabbed2635160c3975@AcuMS.aculab.com
Signed-off-by: David Laight <david.laight@aculab.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Arnd Bergmann <arnd@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Always pass a 'type' through to __clamp_once(), pass '__auto_type' from
clamp() itself.
The expansion of __types_ok3() is reasonable so it isn't worth the added
complexity of avoiding it when a fixed type is used for all three values.
Link: https://lkml.kernel.org/r/8f69f4deac014f558bab186444bac2e8@AcuMS.aculab.com
Signed-off-by: David Laight <david.laight@aculab.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Arnd Bergmann <arnd@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
At some point the definitions for clamp() got added in the middle of the
ones for min() and max(). Re-order the definitions so they are more
sensibly grouped.
Link: https://lkml.kernel.org/r/8bb285818e4846469121c8abc3dfb6e2@AcuMS.aculab.com
Signed-off-by: David Laight <david.laight@aculab.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Arnd Bergmann <arnd@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Use BUILD_BUG_ON_MSG(statically_true(ulo > uhi), ...) for the sanity check
of the bounds in clamp(). Gives better error coverage and one less
expansion of the arguments.
Link: https://lkml.kernel.org/r/34d53778977747f19cce2abb287bb3e6@AcuMS.aculab.com
Signed-off-by: David Laight <david.laight@aculab.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Arnd Bergmann <arnd@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Since the test for signed values being non-negative only relies on
__builtion_constant_p() (not is_constexpr()) it can use the 'ux' variable
instead of the caller supplied expression. This means that the #define
parameters are only expanded twice. Once in the code and once quoted in
the error message.
Link: https://lkml.kernel.org/r/051afc171806425da991908ed8688a98@AcuMS.aculab.com
Signed-off-by: David Laight <david.laight@aculab.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Arnd Bergmann <arnd@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
- Change three to several.
- Remove the comment about retaining constant expressions, no longer true.
- Realign to nearer 80 columns and break on major punctiation.
- Add a leading comment to the block before __signed_type() and __is_nonneg()
Otherwise the block explaining the cast is a bit 'floating'.
Reword the rest of that comment to improve readability.
Link: https://lkml.kernel.org/r/85b050c81c1d4076aeb91a6cded45fee@AcuMS.aculab.com
Signed-off-by: David Laight <david.laight@aculab.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Arnd Bergmann <arnd@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "minmax.h: Cleanups and minor optimisations".
Some tidyups and minor changes to minmax.h.
This patch (of 7):
Link: https://lkml.kernel.org/r/c50365d214e04f9ba256d417c8bebbc0@AcuMS.aculab.com
Link: https://lkml.kernel.org/r/f04b2e1310244f62826267346fde0553@AcuMS.aculab.com
Signed-off-by: David Laight <david.laight@aculab.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Arnd Bergmann <arnd@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
simple_strtol() ignores overflows and has an awkward interface for error
checking. Replace with the recommended kstrtol function leads to clearer
error checking and safer conversions.
Link: https://lkml.kernel.org/r/20241115080018.5372-1-danielyangkang@gmail.com
Signed-off-by: Daniel Yang <danielyangkang@gmail.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Correct spelling here and there as suggested by codespell.
Link: https://lkml.kernel.org/r/20241115151013.1404929-1-dmantipov@yandex.ru
Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Acked-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
simple_strtoul() is deprecated due to ignoring overflows and also requires
clunkier error checking. Replacing with kstrtoul() leads to safer code
and cleaner error checking.
Link: https://lkml.kernel.org/r/20241117215219.4012-1-danielyangkang@gmail.com
Signed-off-by: Daniel Yang <danielyangkang@gmail.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Same thing as 8ac5dc6659 ("get_task_mm: check PF_KTHREAD lockless")
Nowadays PF_KTHREAD is sticky and it was never protected by ->alloc_lock.
Move the PF_KTHREAD check outside of task_lock() section to make this code
more understandable.
Link: https://lkml.kernel.org/r/20241119143526.704986-1-mjguzik@gmail.com
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
My machine has 4 NUMA nodes, each equipped with 32GB of memory. I have
configured each NUMA node with 16GB of CMA and 16GB of in-use hugetlb
pages. The allocation of contiguous memory via cma_alloc() can fail
probabilistically.
cma_alloc() may fail if it sees an in-use hugetlb page within the
allocation range, even if that page has already been migrated. When
in-use hugetlb pages are migrated, they may simply be released back into
the free hugepage pool instead of being returned to the buddy system.
This can cause test_pages_isolated() check to fail, ultimately leading to
the failure of cma_alloc():
cma_alloc()
__alloc_contig_migrate_range() // migrate in-use hugepage
test_pages_isolated()
__test_page_isolated_in_pageblock()
PageBuddy(page) // check if the page is in buddy
To address this issue, we add a function named
replace_free_hugepage_folios(). This function will replace the hugepage
in the free hugepage pool with a new one and release the old one to the
buddy system. After the migration of in-use hugetlb pages is completed,
we will invoke replace_free_hugepage_folios() to ensure that these
hugepages are properly released to the buddy system. Following this step,
when test_pages_isolated() is executed for inspection, it will
successfully pass.
Link: https://lkml.kernel.org/r/1734503588-16254-1-git-send-email-yangge1116@126.com
Signed-off-by: yangge <yangge1116@126.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
zram writeback is a costly operation, because every target slot (unless
ZRAM_HUGE) is decompressed before it gets written to a backing device.
The writeback to a backing device uses submit_bio_wait() which may look
like a rescheduling point. However, if the backing device has
BD_HAS_SUBMIT_BIO bit set __submit_bio() calls directly
disk->fops->submit_bio(bio) on the backing device and so when
submit_bio_wait() calls blk_wait_io() the I/O is already done. On such
systems we effective end up in a loop
for_each (target slot) {
decompress(slot)
__submit_bio()
disk->fops->submit_bio(bio)
}
Which on PREEMPT_NONE systems triggers watchdogs (since there are no
explicit rescheduling points). Add cond_resched() to the zram writeback
loop.
Link: https://lkml.kernel.org/r/20241218063513.297475-8-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
We only can read pages from zspool in writeback, zram_read_page() is not
really right in that context not only because it's a more generic function
that handles ZRAM_WB pages, but also because it requires us to unlock slot
between slot flag check and actual page read. Use zram_read_from_zspool()
instead and do slot flags check and page read under the same slot lock.
Link: https://lkml.kernel.org/r/20241218063513.297475-7-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Similarly to write, split the page read code into ZRAM_HUGE read,
ZRAM_SAME read and compressed page read to simplify the code.
Link: https://lkml.kernel.org/r/20241218063513.297475-6-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
zram_write_page() handles: ZRAM_SAME pages (which was already factored
out) stores, regular page stores and ZRAM_HUGE pages stores.
ZRAM_HUGE handling adds a significant amount of complexity. Instead, we
can handle ZRAM_HUGE in a separate function. This allows us to simplify
zs_handle allocations slow-path, as it now does not handle ZRAM_HUGE case.
ZRAM_HUGE zs_handle allocation, on the other hand, can now drop
__GFP_KSWAPD_RECLAIM because we handle ZRAM_HUGE in preemptible context
(outside of local-lock scope).
Link: https://lkml.kernel.org/r/20241218063513.297475-5-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Handling of ZRAM_SAME now uses a goto to the final stages of
zram_write_page() plus it introduces a branch and flags variable, which is
not making the code any simpler. In reality, we can handle ZRAM_SAME
immediately when we detect such pages and remove a goto and a branch.
Factor out ZRAM_SAME handling into a separate routine to simplify
zram_write_page().
Link: https://lkml.kernel.org/r/20241218063513.297475-4-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Element is in the same anon union as handle and hence holds the same
value, which makes code below sort of confusing
handle = zram_get_handle()
if (!handle)
element = zram_get_element()
Element doesn't really simplify the code, let's just remove it. We
already re-purpose handle to store the block id a written back page.
Link: https://lkml.kernel.org/r/20241218063513.297475-3-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "zram: split page type read/write handling", v2.
This is a subset of [1] series which contains only fixes and improvements
(no new features, as ZRAM_HUGE split is still under consideration).
The motivation for factoring out is that zram_write_page() gets more and
more complex all the time, because it tries to handle too many scenarios:
ZRAM_SAME store, ZRAM_HUGE store, compress page store with zs_malloc
allocation slowpath and conditional recompression, etc. Factor those out
and make things easier to handle.
Addition of cond_resched() is simply a fix, I can trigger watchdog from
zram writeback(). And early slot free is just a reasonable thing to do.
[1] https://lore.kernel.org/linux-kernel/20241119072057.3440039-1-senozhatsky@chromium.org
This patch (of 7):
In the current implementation entry's previously allocated memory is
released in the very last moment, when we already have allocated a new
memory for new data. This, basically, temporarily increases memory usage
for no good reason. For example, consider the case when both old (stale)
and new entry data are incompressible so such entry will temporarily use
two physical pages - one for stale (old) data and one for new data. We
can release old memory as soon as we get a write request for entry.
Link: https://lkml.kernel.org/r/20241218063513.297475-1-senozhatsky@chromium.org
Link: https://lkml.kernel.org/r/20241218063513.297475-2-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The current implementation of swap cgroup tracking is a bit complex and
fragile:
On charging path, swap_cgroup_record always records an actual memcg id,
and it depends on the caller to make sure all entries passed in must
belong to one single folio. As folios are always charged or uncharged as
a whole, and always charged and uncharged in order, swap_cgroup doesn't
need an extra lock.
On uncharging path, swap_cgroup_record always sets the record to zero.
These entries won't be charged again until uncharging is done. So there
is no extra lock needed either. Worth noting that swap cgroup clearing
may happen without folio involved, eg. exiting processes will zap its
page table without swapin.
The xchg/cmpxchg provides atomic operations and barriers to ensure no
tearing or synchronization issue of these swap cgroup records.
It works but quite error-prone. Things can be much clear and robust by
decoupling recording and clearing into two helpers. Recording takes the
actual folio being charged as argument, and clearing always set the record
to zero, and refine the debug sanity checks to better reflect their usage
Benchmark even showed a very slight improvement as it saved some
extra arguments and lookups:
make -j96 with defconfig on tmpfs in 1.5G memory cgroup using 4k folios:
Before: sys 9617.23 (stdev 37.764062)
After : sys 9541.54 (stdev 42.973976)
make -j96 with defconfig on tmpfs in 2G memory cgroup using 64k folios:
Before: sys 7358.98 (stdev 54.927593)
After : sys 7337.82 (stdev 39.398956)
Link: https://lkml.kernel.org/r/20241218114633.85196-5-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Suggested-by: Chris Li <chrisl@kernel.org>
Cc: Barry Song <baohua@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
commit e9e58a4ec3 ("memcg: avoid use cmpxchg in swap cgroup
maintainance") replaced the cmpxchg/xchg with a global irq spinlock
because some archs doesn't support 2 bytes cmpxchg/xchg. Clearly this
won't scale well.
And as commented in swap_cgroup.c, this lock is not needed for map
synchronization.
Emulation of 2 bytes xchg with atomic cmpxchg isn't hard, so implement it
to get rid of this lock. Introduced two helpers for doing so and they can
be easily dropped if a generic 2 byte xchg is support.
Testing using 64G brd and build with build kernel with make -j96 in 1.5G
memory cgroup using 4k folios showed below improvement (6 test run):
Before this series:
Sys time: 10782.29 (stdev 42.353886)
Real time: 171.49 (stdev 0.595541)
After this commit:
Sys time: 9617.23 (stdev 37.764062), -10.81%
Real time: 159.65 (stdev 0.587388), -6.90%
With 64k folios and 2G memcg:
Before this series:
Sys time: 8176.94 (stdev 26.414712)
Real time: 141.98 (stdev 0.797382)
After this commit:
Sys time: 7358.98 (stdev 54.927593), -10.00%
Real time: 134.07 (stdev 0.757463), -5.57%
Sequential swapout of 8G 64k zero folios with madvise (24 test run):
Before this series:
5461409.12 us (stdev 183957.827084)
After this commit:
5420447.26 us (stdev 196419.240317)
Sequential swapin of 8G 4k zero folios (24 test run):
Before this series:
19736958.916667 us (stdev 189027.246676)
After this commit:
19662182.629630 us (stdev 172717.640614)
Performance is better or at least not worse for all tests above.
Link: https://lkml.kernel.org/r/20241218114633.85196-4-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Barry Song <baohua@kernel.org>
Cc: Chris Li <chrisl@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This function is never used after commit 6b611388b6 ("memcg-v1: remove
charge move code").
Link: https://lkml.kernel.org/r/20241218114633.85196-3-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Chris Li <chrisl@kernel.org>
Cc: Barry Song <baohua@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "mm/swap_cgroup: remove global swap cgroup lock", v3.
This series removes the global swap cgroup lock. The critical section of
this lock is very short but it's still a bottle neck for mass parallel
swap workloads.
Up to 10% performance gain for tmpfs build kernel test on a 48c96t system
under memory pressure, and no regression for other cases:
This patch (of 3):
mem_cgroup_uncharge_swap() includes a mem_cgroup_disabled() check,
so the caller doesn't need to check that.
Link: https://lkml.kernel.org/r/20241218114633.85196-1-ryncsn@gmail.com
Link: https://lkml.kernel.org/r/20241218114633.85196-2-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Chris Li <chrisl@kernel.org>
Cc: Barry Song <baohua@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
When the upper bound of the search is exhausted, the maple state may be
returned in an error state of -EBUSY. This means maple state needs to be
reset before the second search in mas_alloc_cylic() to ensure the search
happens. This test ensures the issue is not recreated.
Link: https://lkml.kernel.org/r/20241216190113.1226145-3-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: Yang Erkun <yangerkun@huawei.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Chuck Lever <chuck.lever@oracle.com> says:
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The sysfs core now allows instances of 'struct bin_attribute' to be moved
into read-only memory. Make use of that to protect them against
accidental or malicious modifications.
Link: https://lkml.kernel.org/r/20241216-sysfs-const-bin_attr-page_idle-v1-1-cc01ecc55196@weissschuh.net
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
split_huge_pages_write() has a lccal `buf' which shadows incoming arg
`buf'. Reviewer confusion resulted. Rename the inner local to `tok_buf'.
Cc: Leo Stone <leocstone@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Introduce demonstrative, basic, __mmap_region() test upon which we can
base further work upon moving forwards.
This simply asserts that mappings can be made and merges occur as
expected.
As part of this change, fix the security_vm_enough_memory_mm() stub which
was previously incorrectly implemented.
Link: https://lkml.kernel.org/r/20241213162409.41498-1-lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Jann Horn <jannh@google.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
In the current FUSE writeback design (see commit 3be5a52b30 ("fuse:
support writable mmap")), a temp page is allocated for every dirty page to
be written back, the contents of the dirty page are copied over to the
temp page, and the temp page gets handed to the server to write back.
This is done so that writeback may be immediately cleared on the dirty page,
and this in turn is done for two reasons:
a) in order to mitigate the following deadlock scenario that may arise
if reclaim waits on writeback on the dirty page to complete:
* single-threaded FUSE server is in the middle of handling a request
that needs a memory allocation
* memory allocation triggers direct reclaim
* direct reclaim waits on a folio under writeback
* the FUSE server can't write back the folio since it's stuck in
direct reclaim
b) in order to unblock internal (eg sync, page compaction) waits on
writeback without needing the server to complete writing back to disk,
which may take an indeterminate amount of time.
With a recent change that added AS_WRITEBACK_INDETERMINATE and mitigates
the situations described above, FUSE writeback does not need to use temp
pages if it sets AS_WRITEBACK_INDETERMINATE on its inode mappings.
This commit sets AS_WRITEBACK_INDETERMINATE on the inode mappings and
removes the temporary pages + extra copying and the internal rb tree.
fio benchmarks --
(using averages observed from 10 runs, throwing away outliers)
Setup:
sudo mount -t tmpfs -o size=30G tmpfs ~/tmp_mount
./libfuse/build/example/passthrough_ll -o writeback -o max_threads=4 -o source=~/tmp_mount ~/fuse_mount
fio --name=writeback --ioengine=sync --rw=write --bs={1k,4k,1M} --size=2G
--numjobs=2 --ramp_time=30 --group_reporting=1 --directory=/root/fuse_mount
bs = 1k 4k 1M
Before 351 MiB/s 1818 MiB/s 1851 MiB/s
After 341 MiB/s 2246 MiB/s 2685 MiB/s
% diff -3% 23% 45%
Link: https://lkml.kernel.org/r/20241122232359.429647-6-joannelkoong@gmail.com
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: Bernd Schubert <bernd.schubert@fastmail.fm>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
For migrations called in MIGRATE_SYNC mode, skip migrating the folio if it
is under writeback and has the AS_WRITEBACK_INDETERMINATE flag set on its
mapping. If the AS_WRITEBACK_INDETERMINATE flag is set on the mapping,
the writeback may take an indeterminate amount of time to complete, and
waits may get stuck.
Link: https://lkml.kernel.org/r/20241122232359.429647-5-joannelkoong@gmail.com
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: Bernd Schubert <bernd.schubert@fastmail.fm>
Cc: Jingbo Xu <jefflexu@linux.alibaba.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
For filesystems with the AS_WRITEBACK_INDETERMINATE flag set, writeback
operations may take an indeterminate time to complete. For example,
writing data back to disk in FUSE filesystems depends on the userspace
server successfully completing writeback.
In this commit, wait_sb_inodes() skips waiting on writeback if the inode's
mapping has AS_WRITEBACK_INDETERMINATE set, else sync(2) may take an
indeterminate amount of time to complete.
If the caller wishes to ensure the data for a mapping with the
AS_WRITEBACK_INDETERMINATE flag set has actually been written back to
disk, they should use fsync(2)/fdatasync(2) instead.
Link: https://lkml.kernel.org/r/20241122232359.429647-4-joannelkoong@gmail.com
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: Bernd Schubert <bernd.schubert@fastmail.fm>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Currently in shrink_folio_list(), reclaim for folios under writeback falls
into 3 different cases:
1) Reclaim is encountering an excessive number of folios under
writeback and this folio has both the writeback and reclaim flags
set
2) Dirty throttling is enabled (this happens if reclaim through cgroup
is not enabled, if reclaim through cgroupv2 memcg is enabled, or
if reclaim is on the root cgroup), or if the folio is not marked for
immediate reclaim, or if the caller does not have __GFP_FS (or
__GFP_IO if it's going to swap) set
3) Legacy cgroupv1 encounters a folio that already has the reclaim flag
set and the caller did not have __GFP_FS (or __GFP_IO if swap) set
In cases 1) and 2), we activate the folio and skip reclaiming it while in
case 3), we wait for writeback to finish on the folio and then try to
reclaim the folio again. In case 3, we wait on writeback because cgroupv1
does not have dirty folio throttling, as such this is a mitigation against
the case where there are too many folios in writeback with nothing else to
reclaim.
For filesystems where writeback may take an indeterminate amount of time
to write to disk, this has the possibility of stalling reclaim.
In this commit, if legacy memcg encounters a folio with the reclaim flag
set (eg case 3) and the folio belongs to a mapping that has the
AS_WRITEBACK_INDETERMINATE flag set, the folio will be activated and skip
reclaim (eg default to behavior in case 2) instead.
Link: https://lkml.kernel.org/r/20241122232359.429647-3-joannelkoong@gmail.com
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: Bernd Schubert <bernd.schubert@fastmail.fm>
Cc: Jingbo Xu <jefflexu@linux.alibaba.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "fuse: remove temp page copies in writeback", v6.
The purpose of this patchset is to help make writeback-cache write
performance in FUSE filesystems as fast as possible.
In the current FUSE writeback design (see commit 3be5a52b30 ("fuse:
support writable mmap"))), a temp page is allocated for every dirty page
to be written back, the contents of the dirty page are copied over to the
temp page, and the temp page gets handed to the server to write back.
This is done so that writeback may be immediately cleared on the dirty
page, and this in turn is done for two reasons:
a) in order to mitigate the following deadlock scenario that may arise
if reclaim waits on writeback on the dirty page to complete (more
details can be found in this thread [1]):
* single-threaded FUSE server is in the middle of handling a request
that needs a memory allocation
* memory allocation triggers direct reclaim
* direct reclaim waits on a folio under writeback
* the FUSE server can't write back the folio since it's stuck in
direct reclaim
b) in order to unblock internal (eg sync, page compaction) waits on
writeback without needing the server to complete writing back to disk,
which may take an indeterminate amount of time.
Allocating and copying dirty pages to temp pages is the biggest
performance bottleneck for FUSE writeback. This patchset aims to get rid
of the temp page altogether (which will also allow us to get rid of the
internal FUSE rb tree that is needed to keep track of writeback status on
the temp pages). Benchmarks show approximately a 20% improvement in
throughput for 4k block-size writes and a 45% improvement for 1M
block-size writes.
With removing the temp page, writeback state is now only cleared on the
dirty page after the server has written it back to disk. This may take an
indeterminate amount of time. As well, there is also the possibility of
malicious or well-intentioned but buggy servers where writeback may in the
worst case scenario, never complete. This means that any
folio_wait_writeback() on a dirty page belonging to a FUSE filesystem
needs to be carefully audited.
In particular, these are the cases that need to be accounted for:
* potentially deadlocking in reclaim, as mentioned above
* potentially stalling sync(2)
* potentially stalling page migration / compaction
This patchset adds a new mapping flag, AS_WRITEBACK_INDETERMINATE, which
filesystems may set on its inode mappings to indicate that writeback
operations may take an indeterminate amount of time to complete. FUSE
will set this flag on its mappings. This patchset adds checks to the
critical parts of reclaim, sync, and page migration logic where writeback
may be waited on.
Please note the following:
* For sync(2), waiting on writeback will be skipped for FUSE, but this has no
effect on existing behavior. Dirty FUSE pages are already not guaranteed to
be written to disk by the time sync(2) returns (eg writeback is cleared on
the dirty page but the server may not have written out the temp page to disk
yet). If the caller wishes to ensure the data has actually been synced to
disk, they should use fsync(2)/fdatasync(2) instead.
* AS_WRITEBACK_INDETERMINATE does not indicate that the folios should never be
waited on when in writeback. There are some cases where the wait is
desirable. For example, for the sync_file_range() syscall, it is fine to
wait on the writeback since the caller passes in a fd for the operation.
[1] https://lore.kernel.org/linux-kernel/495d2400-1d96-4924-99d3-8b2952e05fc3@linux.alibaba.com/
This patch (of 5):
Add a new mapping flag AS_WRITEBACK_INDETERMINATE which filesystems may
set to indicate that writing back to disk may take an indeterminate amount
of time to complete. Extra caution should be taken when waiting on
writeback for folios belonging to mappings where this flag is set.
Link: https://lkml.kernel.org/r/20241122232359.429647-1-joannelkoong@gmail.com
Link: https://lkml.kernel.org/r/20241122232359.429647-2-joannelkoong@gmail.com
Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: Bernd Schubert <bernd.schubert@fastmail.fm>
Cc: Jingbo Xu <jefflexu@linux.alibaba.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
