Messages in this thread | | | Date | Fri, 27 Jan 2023 17:23:39 +0100 | Subject | Re: [PATCH 1/2] mm: hugetlb: proc: check for hugetlb shared PMD in /proc/PID/smaps | From | David Hildenbrand <> |
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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@vger.kernel.org > Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> > --- > 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
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