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| author | Nadav Amit <namit@vmware.com> | 2021-11-21 12:40:07 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-12-08 08:44:06 +0100 |
| commit | 8a8ae093b52ba76b650b493848d67e7b526c8751 (patch) | |
| tree | 1edcbc6df3d00e781de8d443ea7622afde82cc6a /mm/hugetlb.c | |
| parent | cad2eb4159d42ef590ff2c9c0d4045cdd05c9425 (diff) | |
| download | linux-stable-8a8ae093b52ba76b650b493848d67e7b526c8751.tar.gz linux-stable-8a8ae093b52ba76b650b493848d67e7b526c8751.tar.bz2 linux-stable-8a8ae093b52ba76b650b493848d67e7b526c8751.zip | |
hugetlbfs: flush TLBs correctly after huge_pmd_unshare
commit a4a118f2eead1d6c49e00765de89878288d4b890 upstream.
When __unmap_hugepage_range() calls to huge_pmd_unshare() succeed, a TLB
flush is missing. This TLB flush must be performed before releasing the
i_mmap_rwsem, in order to prevent an unshared PMDs page from being
released and reused before the TLB flush took place.
Arguably, a comprehensive solution would use mmu_gather interface to
batch the TLB flushes and the PMDs page release, however it is not an
easy solution: (1) try_to_unmap_one() and try_to_migrate_one() also call
huge_pmd_unshare() and they cannot use the mmu_gather interface; and (2)
deferring the release of the page reference for the PMDs page until
after i_mmap_rwsem is dropeed can confuse huge_pmd_unshare() into
thinking PMDs are shared when they are not.
Fix __unmap_hugepage_range() by adding the missing TLB flush, and
forcing a flush when unshare is successful.
Fixes: 24669e58477e ("hugetlb: use mmu_gather instead of a temporary linked list for accumulating pages)" # 3.6
Signed-off-by: Nadav Amit <namit@vmware.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm/hugetlb.c')
| -rw-r--r-- | mm/hugetlb.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 86a5c9852acf..4387fa138bd2 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -3290,8 +3290,11 @@ again: continue; ptl = huge_pte_lock(h, mm, ptep); - if (huge_pmd_unshare(mm, &address, ptep)) + if (huge_pmd_unshare(mm, &address, ptep)) { + tlb_flush_pmd_range(tlb, address & PUD_MASK, PUD_SIZE); + force_flush = 1; goto unlock; + } pte = huge_ptep_get(ptep); if (huge_pte_none(pte)) |