The patch titled
Subject: hugetlb: fix nr_pmds accounting with shared page tables
has been added to the -mm tree. Its filename is
hugetlb-fix-nr_pmds-accounting-with-shared-page-tables.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/hugetlb-fix-nr_pmds-accounting-with-shared-page-tables.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/hugetlb-fix-nr_pmds-accounting-with-shared-page-tables.patch
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------------------------------------------------------
From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Subject: hugetlb: fix nr_pmds accounting with shared page tables
We account HugeTLB's shared page table to all processes who share it.
The accounting happens during huge_pmd_share().
If somebody populates pud entry under us, we should decrease pagetable's
refcount and decrease nr_pmds of the process.
By mistake, I increase nr_pmds again in this case. :-/
It will lead to "BUG: non-zero nr_pmds on freeing mm: 2" on process'
exit.
Let's fix this by increasing nr_pmds only when we're sure that the page
table will be used.
Link: http://lkml.kernel.org/r/20160617122506.GC6534@xxxxxxxxxxxxxxxxxx
Fixes: dc6c9a35b66b ("mm: account pmd page tables to the process")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Reported-by: zhongjiang <zhongjiang@xxxxxxxxxx>
Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/hugetlb.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff -puN mm/hugetlb.c~hugetlb-fix-nr_pmds-accounting-with-shared-page-tables mm/hugetlb.c
--- a/mm/hugetlb.c~hugetlb-fix-nr_pmds-accounting-with-shared-page-tables
+++ a/mm/hugetlb.c
@@ -4228,7 +4228,6 @@ pte_t *huge_pmd_share(struct mm_struct *
if (saddr) {
spte = huge_pte_offset(svma->vm_mm, saddr);
if (spte) {
- mm_inc_nr_pmds(mm);
get_page(virt_to_page(spte));
break;
}
@@ -4243,9 +4242,9 @@ pte_t *huge_pmd_share(struct mm_struct *
if (pud_none(*pud)) {
pud_populate(mm, pud,
(pmd_t *)((unsigned long)spte & PAGE_MASK));
+ mm_inc_nr_pmds(mm);
} else {
put_page(virt_to_page(spte));
- mm_inc_nr_pmds(mm);
}
spin_unlock(ptl);
out:
_
Patches currently in -mm which might be from kirill.shutemov@xxxxxxxxxxxxxxx are
revert-mm-make-faultaround-produce-old-ptes.patch
revert-mm-disable-fault-around-on-emulated-access-bit-architecture.patch
hugetlb-fix-nr_pmds-accounting-with-shared-page-tables.patch
mm-make-swapin-readahead-to-improve-thp-collapse-rate-fix.patch
mm-make-swapin-readahead-to-improve-thp-collapse-rate-fix-2.patch
mm-make-swapin-readahead-to-improve-thp-collapse-rate-fix-3.patch
mm-thp-make-swapin-readahead-under-down_read-of-mmap_sem-fix.patch
khugepaged-recheck-pmd-after-mmap_sem-re-acquired.patch
thp-mlock-update-unevictable-lrutxt.patch
mm-do-not-pass-mm_struct-into-handle_mm_fault.patch
mm-introduce-fault_env.patch
mm-postpone-page-table-allocation-until-we-have-page-to-map.patch
rmap-support-file-thp.patch
mm-introduce-do_set_pmd.patch
thp-vmstats-add-counters-for-huge-file-pages.patch
thp-support-file-pages-in-zap_huge_pmd.patch
thp-handle-file-pages-in-split_huge_pmd.patch
thp-handle-file-cow-faults.patch
thp-skip-file-huge-pmd-on-copy_huge_pmd.patch
thp-prepare-change_huge_pmd-for-file-thp.patch
thp-run-vma_adjust_trans_huge-outside-i_mmap_rwsem.patch
thp-file-pages-support-for-split_huge_page.patch
thp-mlock-do-not-mlock-pte-mapped-file-huge-pages.patch
vmscan-split-file-huge-pages-before-paging-them-out.patch
page-flags-relax-policy-for-pg_mappedtodisk-and-pg_reclaim.patch
radix-tree-implement-radix_tree_maybe_preload_order.patch
filemap-prepare-find-and-delete-operations-for-huge-pages.patch
truncate-handle-file-thp.patch
mm-rmap-account-shmem-thp-pages.patch
shmem-prepare-huge=-mount-option-and-sysfs-knob.patch
shmem-add-huge-pages-support.patch
shmem-thp-respect-madv_nohugepage-for-file-mappings.patch
thp-extract-khugepaged-from-mm-huge_memoryc.patch
khugepaged-move-up_readmmap_sem-out-of-khugepaged_alloc_page.patch
shmem-make-shmem_inode_info-lock-irq-safe.patch
khugepaged-add-support-of-collapse-for-tmpfs-shmem-pages.patch
thp-introduce-config_transparent_huge_pagecache.patch
shmem-split-huge-pages-beyond-i_size-under-memory-pressure.patch
thp-update-documentation-vm-transhugefilesystems-proctxt.patch
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