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Steven Price c235c4fc52 mm: pagewalk: Fix race between unmap and page walker 
[ Upstream commit 8782fb61cc ]

The mmap lock protects the page walker from changes to the page tables
during the walk.  However a read lock is insufficient to protect those
areas which don't have a VMA as munmap() detaches the VMAs before
downgrading to a read lock and actually tearing down PTEs/page tables.

For users of walk_page_range() the solution is to simply call pte_hole()
immediately without checking the actual page tables when a VMA is not
present. We now never call __walk_page_range() without a valid vma.

For walk_page_range_novma() the locking requirements are tightened to
require the mmap write lock to be taken, and then walking the pgd
directly with 'no_vma' set.

This in turn means that all page walkers either have a valid vma, or
it's that special 'novma' case for page table debugging.  As a result,
all the odd '(!walk->vma && !walk->no_vma)' tests can be removed.

Fixes: dd2283f260 ("mm: mmap: zap pages with read mmap_sem in munmap")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
 		2022-09-08 12:28:05 +02:00
Documentation arm64: errata: Add Cortex-A510 to the repeat tlbi list 2022-09-05 10:30:04 +02:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
arch mm: pagewalk: Fix race between unmap and page walker 2022-09-08 12:28:05 +02:00
block blk-mq: fix io hung due to missing commit_rqs 2022-08-31 17:16:50 +02:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:22:01 +02:00
crypto KEYS: asymmetric: enforce SM2 signature use pkey algo 2022-08-17 14:24:28 +02:00
drivers xen/grants: prevent integer overflow in gnttab_dma_alloc_pages() 2022-09-08 12:28:05 +02:00
fs cifs: fix small mempool leak in SMB2_negotiate() 2022-09-08 12:28:04 +02:00
include platform/x86: pmc_atom: Fix SLP_TYPx bitfield mask 2022-09-08 12:28:01 +02:00
init stack: Declare {randomize_,}kstack_offset to fix Sparse warnings 2022-08-17 14:23:10 +02:00
ipc ipc/mqueue: use get_tree_nodev() in mqueue_get_tree() 2022-06-09 10:23:10 +02:00
kernel bpf, cgroup: Fix kernel BUG in purge_effective_progs 2022-09-08 12:28:01 +02:00
lib crypto: lib - remove unneeded selection of XOR_BLOCKS 2022-09-05 10:30:03 +02:00
mm mm: pagewalk: Fix race between unmap and page walker 2022-09-08 12:28:05 +02:00
net net/smc: Remove redundant refcount increase 2022-09-08 12:28:03 +02:00
samples samples/landlock: Format with clang-format 2022-06-09 10:23:23 +02:00
scripts kbuild: Fix include path in scripts/Makefile.modpost 2022-09-05 10:30:06 +02:00
security apparmor: Fix memleak in aa_simple_write_to_buffer() 2022-08-25 11:40:01 +02:00
sound ALSA: hda: intel-nhlt: Correct the handling of fmt_config flexible array 2022-09-08 12:28:02 +02:00
tools testing: selftests: nft_flowtable.sh: use random netns names 2022-09-05 10:30:12 +02:00
usr usr/include/Makefile: add linux/nfc.h to the compile-test coverage 2022-02-01 17:27:15 +01:00
virt KVM: Unconditionally get a ref to /dev/kvm module when creating a VM 2022-08-25 11:39:53 +02:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig
…
.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: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: add Andrej Shadura 2021-10-18 20:22:03 -10:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
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 Input: goodix - add a goodix.h header file 2022-07-12 16:34:51 +02:00
Makefile Linux 5.15.65 2022-09-05 10:30:13 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

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.