[to-be-updated] smaps-fix-the-abnormal-memory-statistics-obtained-through-proc-pid-smaps.patch removed from -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

The quilt patch titled
     Subject: smaps: fix the abnormal memory statistics obtained through /proc/pid/smaps
has been removed from the -mm tree.  Its filename was
     smaps-fix-the-abnormal-memory-statistics-obtained-through-proc-pid-smaps.patch

This patch was dropped because an updated version will be merged

------------------------------------------------------
From: liubo <liubo254@huawei.com>
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.

[akpm@linux-foundation.org: tweak comment and code layout]
Link: https://lkml.kernel.org/r/20230726073409.631838-1-liubo254@huawei.com
Signed-off-by: liubo <liubo254@huawei.com>
Fixes: 474098edac26 ("mm/gup: replace FOLL_NUMA by gup_can_follow_protnone()")
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/proc/task_mmu.c |    8 ++++++--
 1 file changed, 6 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 +587,12 @@ 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: 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@huawei.com are