The patch titled
Subject: mm: pvmw: check possible huge PMD map by transhuge_vma_suitable()
has been added to the -mm mm-unstable branch. Its filename is
mm-pvmw-check-possible-huge-pmd-map-by-transhuge_vma_suitable.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-pvmw-check-possible-huge-pmd-map-by-transhuge_vma_suitable.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Yang Shi <shy828301@xxxxxxxxx>
Subject: mm: pvmw: check possible huge PMD map by transhuge_vma_suitable()
IIUC PVMW checks if the vma is possibly huge PMD mapped by
transparent_hugepage_active() and "pvmw->nr_pages >= HPAGE_PMD_NR".
Actually pvmw->nr_pages is returned by compound_nr() or folio_nr_pages(),
so the page should be THP as long as "pvmw->nr_pages >= HPAGE_PMD_NR".
And it is guaranteed THP is allocated for valid VMA in the first place.
But it may be not PMD mapped if the VMA is file VMA and it is not properly
aligned. The transhuge_vma_suitable() is used to do such check, so
replace transparent_hugepage_active() to it, which is too heavy and
overkilling.
Link: https://lkml.kernel.org/r/20220512174551.81279-2-shy828301@xxxxxxxxx
Fixes: 2aff7a4755be ("mm: Convert page_vma_mapped_walk to work on PFNs")
Signed-off-by: Yang Shi <shy828301@xxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_vma_mapped.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/mm/page_vma_mapped.c~mm-pvmw-check-possible-huge-pmd-map-by-transhuge_vma_suitable
+++ a/mm/page_vma_mapped.c
@@ -237,13 +237,14 @@ restart:
spin_unlock(pvmw->ptl);
pvmw->ptl = NULL;
} else if (!pmd_present(pmde)) {
+ unsigned long haddr = pvmw->address & HPAGE_PMD_MASK;
/*
* If PVMW_SYNC, take and drop THP pmd lock so that we
* cannot return prematurely, while zap_huge_pmd() has
* cleared *pmd but not decremented compound_mapcount().
*/
if ((pvmw->flags & PVMW_SYNC) &&
- transparent_hugepage_active(vma) &&
+ transhuge_vma_suitable(vma, haddr) &&
(pvmw->nr_pages >= HPAGE_PMD_NR)) {
spinlock_t *ptl = pmd_lock(mm, pvmw->pmd);
_
Patches currently in -mm which might be from shy828301@xxxxxxxxx are
sched-coredumph-clarify-the-use-of-mmf_vm_hugepage.patch
mm-khugepaged-remove-redundant-check-for-vm_no_khugepaged.patch
mm-khugepaged-skip-dax-vma.patch
mm-thp-only-regular-file-could-be-thp-eligible.patch
mm-khugepaged-make-khugepaged_enter-void-function.patch
mm-khugepaged-make-hugepage_vma_check-non-static.patch
mm-khugepaged-introduce-khugepaged_enter_vma-helper.patch
mm-mmap-register-suitable-readonly-file-vmas-for-khugepaged.patch
mm-rmap-use-the-correct-parameter-name-for-define_page_vma_walk.patch
mm-pvmw-check-possible-huge-pmd-map-by-transhuge_vma_suitable.patch
