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Danilo Krummrich 590b9d576c mm: kvmalloc: align kvrealloc() with krealloc()
Besides the obvious (and desired) difference between krealloc() and
kvrealloc(), there is some inconsistency in their function signatures and
behavior:

 - krealloc() frees the memory when the requested size is zero, whereas
   kvrealloc() simply returns a pointer to the existing allocation.

 - krealloc() behaves like kmalloc() if a NULL pointer is passed, whereas
   kvrealloc() does not accept a NULL pointer at all and, if passed,
   would fault instead.

 - krealloc() is self-contained, whereas kvrealloc() relies on the caller
   to provide the size of the previous allocation.

Inconsistent behavior throughout allocation APIs is error prone, hence
make kvrealloc() behave like krealloc(), which seems superior in all
mentioned aspects.

Besides that, implementing kvrealloc() by making use of krealloc() and
vrealloc() provides oppertunities to grow (and shrink) allocations more
efficiently.  For instance, vrealloc() can be optimized to allocate and
map additional pages to grow the allocation or unmap and free unused pages
to shrink the allocation.

[dakr@kernel.org: document concurrency restrictions]
  Link: https://lkml.kernel.org/r/20240725125442.4957-1-dakr@kernel.org
[dakr@kernel.org: disable KASAN when switching to vmalloc]
  Link: https://lkml.kernel.org/r/20240730185049.6244-2-dakr@kernel.org
[dakr@kernel.org: properly document __GFP_ZERO behavior]
  Link: https://lkml.kernel.org/r/20240730185049.6244-5-dakr@kernel.org
Link: https://lkml.kernel.org/r/20240722163111.4766-3-dakr@kernel.org
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Chandan Babu R <chandan.babu@oracle.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Oliver Upton <oliver.upton@linux.dev>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Uladzislau Rezki <urezki@gmail.com>
Cc: Wedson Almeida Filho <wedsonaf@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-09-01 20:25:44 -07:00
arch mm: kvmalloc: align kvrealloc() with krealloc() 2024-09-01 20:25:44 -07:00
block block: fix detection of unsupported WRITE SAME in blkdev_issue_write_zeroes 2024-08-28 08:49:25 -06:00
certs kbuild: use $(src) instead of $(srctree)/$(src) for source directory 2024-05-10 04:34:52 +09:00
crypto crypto: testmgr - generate power-of-2 lengths more often 2024-07-13 11:50:28 +12:00
Documentation USB fixes for 6.11-rc6 2024-09-01 07:06:28 +12:00
drivers mm: kvmalloc: align kvrealloc() with krealloc() 2024-09-01 20:25:44 -07:00
fs mm: kvmalloc: align kvrealloc() with krealloc() 2024-09-01 20:25:44 -07:00
include mm: kvmalloc: align kvrealloc() with krealloc() 2024-09-01 20:25:44 -07:00
init Rust fixes for v6.11 2024-08-16 11:24:06 -07:00
io_uring io_uring/kbuf: return correct iovec count from classic buffer peek 2024-08-30 10:45:54 -06:00
ipc sysctl: treewide: constify the ctl_table argument of proc_handlers 2024-07-24 20:59:29 +02:00
kernel mm: kvmalloc: align kvrealloc() with krealloc() 2024-09-01 20:25:44 -07:00
lib mm: kvmalloc: align kvrealloc() with krealloc() 2024-09-01 20:25:44 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm: kvmalloc: align kvrealloc() with krealloc() 2024-09-01 20:25:44 -07:00
net Including fixes from bluetooth, wireless and netfilter. 2024-08-30 06:14:39 +12:00
rust Rust fixes for v6.11 2024-08-16 11:24:06 -07:00
samples treewide: remove unnecessary <linux/version.h> inclusion 2024-08-12 18:36:44 +09:00
scripts net: drop special comment style 2024-08-23 10:21:02 +01:00
security Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging 2024-09-01 09:18:48 +12:00
sound sound fixes for 6.11-rc6 2024-08-28 06:24:22 +12:00
tools IOMMU Fixes for Linux v6.11-rc5 2024-08-31 06:11:34 +12:00
usr initramfs: shorten cmd_initfs in usr/Makefile 2024-07-16 01:07:52 +09:00
virt KVM: x86: Disallow read-only memslots for SEV-ES and SEV-SNP (and TDX) 2024-08-14 12:28:24 -04:00
.clang-format Docs: Move clang-format from process/ to dev-tools/ 2024-06-26 16:36:00 -06:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: add script and target to generate pacman package 2024-07-22 01:24:22 +09:00
.mailmap ARM: SoC fixes for 6.11, part 2 2024-09-01 06:42:13 +12:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS tracing: Update of MAINTAINERS and CREDITS file 2024-07-18 14:08:42 -07:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS USB fixes for 6.11-rc6 2024-09-01 07:06:28 +12:00
Makefile Linux 6.11-rc6 2024-09-01 19:46:02 +12:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.