linux/fs/proc
Mike Kravetz 3489dbb696 mm: hugetlb: proc: check for hugetlb shared PMD in /proc/PID/smaps
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>
2023-01-31 16:44:09 -08:00
..
array.c ucounts: Split rlimit and ucount values and max values 2022-10-09 16:24:05 -07:00
base.c - Yu Zhao's Multi-Gen LRU patches are here. They've been under test in 2022-10-10 17:53:04 -07:00
bootconfig.c proc: bootconfig: Add null pointer check 2022-04-02 08:40:09 -04:00
cmdline.c proc: give /proc/cmdline size 2022-11-18 13:55:07 -08:00
consoles.c proc: consoles: use console_list_lock for list iteration 2022-12-02 11:25:02 +01:00
cpuinfo.c x86/aperfmperf: Replace aperfmperf_get_khz() 2022-04-27 20:22:19 +02:00
devices.c proc: mark more files as permanent 2022-10-03 14:21:45 -07:00
fd.c proc: report open files as size in stat() for /proc/pid/fd 2022-11-18 13:55:07 -08:00
fd.h fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
generic.c proc: fix dentry/inode overinstantiating under /proc/${pid}/net 2022-05-09 18:29:19 -07:00
inode.c take care to handle NULL ->proc_lseek() 2022-08-14 15:16:18 -04:00
internal.h - hfs and hfsplus kmap API modernization from Fabio Francesco 2022-10-12 11:00:22 -07:00
interrupts.c
Kconfig proc: make config PROC_CHILDREN depend on PROC_FS 2022-10-03 14:21:43 -07:00
kcore.c mm: remove kern_addr_valid() completely 2022-11-08 17:37:18 -08:00
kmsg.c printk changes for 6.1 2022-10-10 11:24:19 -07:00
loadavg.c proc: mark more files as permanent 2022-10-03 14:21:45 -07:00
Makefile proc: bootconfig: Add /proc/bootconfig to show boot config list 2020-01-13 13:19:39 -05:00
meminfo.c proc/meminfo: fix spacing in SecPageTables 2022-11-22 18:50:44 -08:00
namespaces.c Merge branch 'work.openat2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-01-29 11:20:24 -08:00
nommu.c proc: delete unused <linux/uaccess.h> includes 2022-07-17 17:31:39 -07:00
page.c mm: Add PG_arch_3 page flag 2022-11-29 09:26:07 +00:00
proc_net.c proc: add some (hopefully) insightful comments 2022-07-29 18:12:35 -07:00
proc_sysctl.c kernel/sysctl.c: move sysctl_vals and sysctl_long_vals to sysctl.c 2022-09-08 16:56:45 -07:00
proc_tty.c proc: delete unused <linux/uaccess.h> includes 2022-07-17 17:31:39 -07:00
root.c proc: add some (hopefully) insightful comments 2022-07-29 18:12:35 -07:00
self.c Revert "proc: don't allow async path resolution of /proc/self components" 2021-02-23 20:32:11 -07:00
softirqs.c proc: mark more files as permanent 2022-10-03 14:21:45 -07:00
stat.c fs/proc/uptime.c: Fix idle time reporting in /proc/uptime 2021-10-05 15:51:35 +02:00
task_mmu.c mm: hugetlb: proc: check for hugetlb shared PMD in /proc/PID/smaps 2023-01-31 16:44:09 -08:00
task_nommu.c proc: remove VMA rbtree use from nommu 2022-09-26 19:46:16 -07:00
thread_self.c Revert "proc: don't allow async path resolution of /proc/thread-self components" 2021-02-23 20:32:11 -07:00
uptime.c proc: mark more files as permanent 2022-10-03 14:21:45 -07:00
util.c fs/proc/util.c: include fs/proc/internal.h for name_to_int() 2019-01-04 13:13:45 -08:00
version.c proc: mark more files as permanent 2022-10-03 14:21:45 -07:00
vmcore.c iov_iter work; most of that is about getting rid of 2022-12-12 18:29:54 -08:00