From: liubo liubo254@huawei.com
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 the traversal In the page table, 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.
Signed-off-by: liubo liubo254@huawei.com Cc: stable@vger.kernel.org Fixes: 474098edac26 ("mm/gup: replace FOLL_NUMA by gup_can_follow_protnone()") Signed-off-by: David Hildenbrand david@redhat.com # AKPM fixups, cc stable Signed-off-by: David Hildenbrand david@redhat.com --- fs/proc/task_mmu.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index c1e6531cb02a..7075ce11dc7d 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -571,8 +571,12 @@ static void smaps_pmd_entry(pmd_t *pmd, unsigned long addr, 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);