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Matthew Wilcox (Oracle) e320d3012d mm/page_alloc.c: fix freeing non-compound pages
Here is a very rare race which leaks memory:

Page P0 is allocated to the page cache.  Page P1 is free.

Thread A                Thread B                Thread C
find_get_entry():
xas_load() returns P0
						Removes P0 from page cache
						P0 finds its buddy P1
			alloc_pages(GFP_KERNEL, 1) returns P0
			P0 has refcount 1
page_cache_get_speculative(P0)
P0 has refcount 2
			__free_pages(P0)
			P0 has refcount 1
put_page(P0)
P1 is not freed

Fix this by freeing all the pages in __free_pages() that won't be freed
by the call to put_page().  It's usually not a good idea to split a page,
but this is a very unlikely scenario.

Fixes: e286781d5f ("mm: speculative page references")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Nick Piggin <npiggin@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200926213919.26642-1-willy@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-10-13 18:38:33 -07:00
arch mm: account PMD tables like PTE tables 2020-10-13 18:38:31 -07:00
block drivers-5.10-2020-10-12 2020-10-13 13:04:41 -07:00
certs .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
crypto drivers-5.10-2020-10-12 2020-10-13 13:04:41 -07:00
Documentation KASAN: Testing Documentation 2020-10-13 18:38:32 -07:00
drivers virtio-mem: don't special-case ZONE_MOVABLE 2020-10-13 18:38:33 -07:00
fs mm: proc: smaps_rollup: do not stall write attempts on mmap_lock 2020-10-13 18:38:31 -07:00
include mmzone: clean code by removing unused macro parameter 2020-10-13 18:38:33 -07:00
init io_uring-5.10-2020-10-12 2020-10-13 12:36:21 -07:00
ipc ipc: adjust proc_ipc_sem_dointvec definition to match prototype 2020-09-05 12:14:29 -07:00
kernel mm: remove src/dst mm parameter in copy_page_range() 2020-10-13 18:38:32 -07:00
lib mm/page_alloc.c: fix freeing non-compound pages 2020-10-13 18:38:33 -07:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm mm/page_alloc.c: fix freeing non-compound pages 2020-10-13 18:38:33 -07:00
net io_uring-5.10-2020-10-12 2020-10-13 12:36:21 -07:00
samples mm,kmemleak-test.c: move kmemleak-test.c to samples dir 2020-10-13 18:38:27 -07:00
scripts scripts/decodecode: add the capability to supply the program counter 2020-10-13 18:38:26 -07:00
security Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2020-10-13 08:50:16 -07:00
sound sound fixes for 5.9-rc7 2020-09-24 09:00:05 -07:00
tools tools/testing/selftests/vm/hmm-tests.c: use the new SKIP() macro 2020-10-13 18:38:32 -07:00
usr Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 13:29:39 -07:00
virt KVM: fix memory leak in kvm_io_bus_unregister_dev() 2020-09-11 13:15:11 -04:00
.clang-format clang-format: Update with the latest for_each macro list 2020-09-01 12:53:42 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: docs: ignore sphinx_*/ directories 2020-09-10 10:44:31 -06:00
.mailmap As hoped, things calmed down for docs this cycle; fewer changes and almost 2020-10-12 16:21:29 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS CREDITS: Replace HTTP links with HTTPS ones 2020-07-23 14:53:58 -06:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS mm,kmemleak-test.c: move kmemleak-test.c to samples dir 2020-10-13 18:38:27 -07:00
Makefile Revert "kbuild: disable clang's default use of -fmerge-all-constants" 2020-10-13 18:38:26 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -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 Restructured Text 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.