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Filename Latest commit message Latest commit date
Mike Kravetz 6d86b4ceb0 mm: hugetlb: proc: check for hugetlb shared PMD in /proc/PID/smaps
commit 3489dbb696d25602aea8c3e669a6d43b76bd5358 upstream.

Patch series "Fixes for hugetlb mapcount at most 1 for shared PMDs".

This issue of mapcount in hugetlb pages referenced by shared PMDs was
discussed in [1].  The following two patches address user visible behavior
caused by this issue.

[1] https://lore.kernel.org/linux-mm/Y9BF+OCdWnCSilEu@monkey/


This patch (of 2):

A hugetlb page will have a mapcount of 1 if mapped by multiple processes
via a shared PMD.  This is because only the first process increases the
map count, and subsequent processes just add the shared PMD page to their
page table.

page_mapcount is being used to decide if a hugetlb page is shared or
private in /proc/PID/smaps.  Pages referenced via a shared PMD were
incorrectly being counted as private.

To fix, check for a shared PMD if mapcount is 1.  If a shared PMD is found
count the hugetlb page as shared.  A new helper to check for a shared PMD
is added.

[akpm@linux-foundation.org: simplification, per David]
[akpm@linux-foundation.org: hugetlb.h: include page_ref.h for page_count()]
Link: https://lkml.kernel.org/r/20230126222721.222195-2-mike.kravetz@oracle.com
Fixes: 25ee01a2fc ("mm: hugetlb: proc: add hugetlb-related fields to /proc/PID/smaps")
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Peter Xu <peterx@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: James Houghton <jthoughton@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-02-22 12:50:28 +01:00
arch riscv: disable generation of unwind tables 2023-02-22 12:50:28 +01:00
block
certs
crypto
Documentation
drivers iio:adc:twl6030: Enable measurements of VUSB, VBAT and others 2023-02-22 12:50:27 +01:00
fs mm: hugetlb: proc: check for hugetlb shared PMD in /proc/PID/smaps 2023-02-22 12:50:28 +01:00
include mm: hugetlb: proc: check for hugetlb shared PMD in /proc/PID/smaps 2023-02-22 12:50:28 +01:00
init
ipc
kernel
lib
LICENSES
mm
net net/x25: Fix to not accept on connected socket 2023-02-22 12:50:26 +01:00
samples
scripts
security
sound ALSA: hda/via: Avoid potential array out-of-bound in add_secret_dac_path() 2023-02-22 12:50:23 +01:00
tools selftests: net: udpgso_bench_tx: Cater for pending datagrams zerocopy benchmarking 2023-02-22 12:50:25 +01:00
usr
virt
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.cocciconfig
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Makefile Linux 5.4.231 2023-02-06 07:52:51 +01:00
README

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

There are several guides for kernel developers and users. These guides can
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In order to build the documentation, use ``make htmldocs`` or
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    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.