The patch titled
Subject: smaps: fix the abnormal memory statistics obtained through /proc/pid/smaps
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
smaps-fix-the-abnormal-memory-statistics-obtained-through-proc-pid-smaps.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/smaps-fix-the-abnormal-memory-statistics-obtained-through-proc-pid-smaps.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: liubo <liubo254@xxxxxxxxxx>
Subject: smaps: fix the abnormal memory statistics obtained through /proc/pid/smaps
Date: Wed, 26 Jul 2023 15:34:09 +0800
In commit 474098edac26 ("mm/gup: replace FOLL_NUMA by
gup_can_follow_protnone()"), FOLL_NUMA was removed and replaced by the
gup_can_follow_protnone interface.
However, for the case where the user-mode process uses transparent huge
pages, when analyzing the memory usage through /proc/pid/smaps_rollup, the
obtained memory usage is not consistent with the RSS in /proc/pid/status.
Related examples are as follows:
cat /proc/15427/status
VmRSS: 20973024 kB
RssAnon: 20971616 kB
RssFile: 1408 kB
RssShmem: 0 kB
cat /proc/15427/smaps_rollup
00400000-7ffcc372d000 ---p 00000000 00:00 0 [rollup]
Rss: 14419432 kB
Pss: 14418079 kB
Pss_Dirty: 14418016 kB
Pss_Anon: 14418016 kB
Pss_File: 63 kB
Pss_Shmem: 0 kB
Anonymous: 14418016 kB
LazyFree: 0 kB
AnonHugePages: 14417920 kB
The root cause is that in the traversal of the page tables, the number of
pages obtained by smaps_pmd_entry does not include the pages corresponding
to PROTNONE, resulting in a different situation.
Therefore, when obtaining pages through the follow_trans_huge_pmd
interface, add the FOLL_FORCE flag to count the pages corresponding to
PROTNONE to solve the above problem.
Link: https://lkml.kernel.org/r/20230726073409.631838-1-liubo254@xxxxxxxxxx
Signed-off-by: liubo <liubo254@xxxxxxxxxx>
Fixes: 474098edac26 ("mm/gup: replace FOLL_NUMA by gup_can_follow_protnone()")
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/task_mmu.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
--- a/fs/proc/task_mmu.c~smaps-fix-the-abnormal-memory-statistics-obtained-through-proc-pid-smaps
+++ a/fs/proc/task_mmu.c
@@ -587,8 +587,10 @@ static void smaps_pmd_entry(pmd_t *pmd,
bool migration = false;
if (pmd_present(*pmd)) {
- /* FOLL_DUMP will return -EFAULT on huge zero page */
- page = follow_trans_huge_pmd(vma, addr, pmd, FOLL_DUMP);
+ /* FOLL_DUMP will return -EFAULT on huge zero page
+ * FOLL_FORCE follow a PROT_NONE mapped page
+ */
+ page = follow_trans_huge_pmd(vma, addr, pmd, FOLL_DUMP | FOLL_FORCE);
} else if (unlikely(thp_migration_supported() && is_swap_pmd(*pmd))) {
swp_entry_t entry = pmd_to_swp_entry(*pmd);
_
Patches currently in -mm which might be from liubo254@xxxxxxxxxx are
smaps-fix-the-abnormal-memory-statistics-obtained-through-proc-pid-smaps.patch
