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Pavel Tatashin 83c02c23d0 mm/gup: check every subpage of a compound page during isolation 
When pages are isolated in check_and_migrate_movable_pages() we skip
compound number of pages at a time.  However, as Jason noted, it is not
necessary correct that pages[i] corresponds to the pages that we
skipped.  This is because it is possible that the addresses in this
range had split_huge_pmd()/split_huge_pud(), and these functions do not
update the compound page metadata.

The problem can be reproduced if something like this occurs:

1. User faulted huge pages.
2. split_huge_pmd() was called for some reason
3. User has unmapped some sub-pages in the range
4. User tries to longterm pin the addresses.

The resulting pages[i] might end-up having pages which are not compound
size page aligned.

Link: https://lkml.kernel.org/r/20210215161349.246722-3-pasha.tatashin@soleen.com
Fixes: aa712399c1 ("mm/gup: speed up check_and_migrate_cma_pages() on huge page")
Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Reported-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: James Morris <jmorris@namei.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sasha Levin <sashal@kernel.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Tyler Hicks <tyhicks@linux.microsoft.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 11:27:26 -07:00
arch mm: drop redundant HAVE_ARCH_TRANSPARENT_HUGEPAGE 2021-05-05 11:27:25 -07:00
block cgroup: rstat: punt root-level optimization to individual controllers 2021-04-30 11:20:37 -07:00
certs certs: add 'x509_revocation_list' to gitignore 2021-04-26 10:48:07 -07:00
crypto for-5.13/drivers-2021-04-27 2021-04-28 14:39:37 -07:00
Documentation mm: cma: support sysfs 2021-05-05 11:27:24 -07:00
drivers mm/vmalloc: remove unmap_kernel_range 2021-04-30 11:20:40 -07:00
fs mm: generalize SYS_SUPPORTS_HUGETLBFS (rename as ARCH_SUPPORTS_HUGETLBFS) 2021-05-05 11:27:25 -07:00
include x86/mm: track linear mapping split events 2021-05-05 11:27:25 -07:00
init userfaultfd: add minor fault registration mode 2021-05-05 11:27:22 -07:00
ipc fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
kernel mm/compaction: remove unused variable sysctl_compact_memory 2021-05-05 11:27:24 -07:00
lib kasan: detect false-positives in tests 2021-04-30 11:20:42 -07:00
LICENSES LICENSES: Add the CC-BY-4.0 license 2020-12-08 10:33:27 -07:00
mm mm/gup: check every subpage of a compound page during isolation 2021-05-05 11:27:26 -07:00
net net: page_pool: use alloc_pages_bulk in refill code path 2021-04-30 11:20:43 -07:00
samples samples/vfio-mdev/mdpy: use remap_vmalloc_range 2021-04-30 11:20:39 -07:00
scripts scripts: a new script for checking duplicate struct declaration 2021-04-30 11:20:35 -07:00
security Networking changes for 5.13. 2021-04-29 11:57:23 -07:00
sound - Core Frameworks 2021-04-28 15:59:13 -07:00
tools userfaultfd/selftests: add test exercising minor fault handling 2021-05-05 11:27:23 -07:00
usr Kbuild updates for v5.12 2021-02-25 10:17:31 -08:00
virt KVM: x86/mmu: Consider the hva in mmu_notifier retry 2021-02-22 13:16:53 -05:00
.clang-format cxl for 5.12 2021-02-24 09:38:36 -08:00
.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 kbuild: generate Module.symvers only when vmlinux exists 2021-04-25 05:17:02 +09:00
.mailmap It's been a relatively busy cycle in docsland, though more than usually 2021-04-26 13:22:43 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS - Core Frameworks 2021-04-28 15:59:13 -07:00
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 MAINTAINERS: assign pagewalk.h to MEMORY MANAGEMENT 2021-04-30 11:20:41 -07:00
Makefile Kconfig updates for v5.13 2021-04-29 14:32:00 -07:00
README

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.