On 26.01.23 23:27, Mike Kravetz wrote:
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. Fixes: 25ee01a2fca0 ("mm: hugetlb: proc: add hugetlb-related fields to /proc/PID/smaps") Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx> --- fs/proc/task_mmu.c | 10 ++++++++-- include/linux/hugetlb.h | 12 ++++++++++++ 2 files changed, 20 insertions(+), 2 deletions(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index e35a0398db63..cb9539879402 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -749,8 +749,14 @@ static int smaps_hugetlb_range(pte_t *pte, unsigned long hmask,if (mapcount >= 2)mss->shared_hugetlb += huge_page_size(hstate_vma(vma)); - else - mss->private_hugetlb += huge_page_size(hstate_vma(vma)); + else {
Better: if (mapcount >= 2 || hugetlb_pmd_shared(pte)) mss->shared_hugetlb += huge_page_size(hstate_vma(vma)); else mss->private_hugetlb += huge_page_size(hstate_vma(vma)); -- Thanks, David / dhildenb
