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[PATCH mmotm 3/5] huge tmpfs recovery: tweak shmem_getpage_gfp to fill team fix

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Please add this fix after my 27/31, your
huge-tmpfs-recovery-tweak-shmem_getpage_gfp-to-fill-team.patch
for later merging into it.  Great catch by Mika Penttila, a bug which
prevented some unusual cases from being recovered into huge pages as
intended: an initially sparse head would be set PageTeam only after
this check.  But the check is guarding against a racing disband, which
cannot happen before the head is published as PageTeam, plus we have
an additional reference on the head which keeps it safe throughout:
so very easily fixed.

Reported-by: Mika Penttila <mika.penttila@nextfour.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
---
 mm/shmem.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2938,7 +2938,7 @@ repeat:
 			page = *pagep;
 			lock_page(page);
 			head = page - (index & (HPAGE_PMD_NR-1));
-			if (!PageTeam(head)) {
+			if (!PageTeam(head) && page != head) {
 				error = -ENOENT;
 				goto decused;
 			}

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[PATCH mmotm 1/5] huge tmpfs: try to allocate huge pages split into  a team fix Hugh Dickins <hughd@google.com> - 2016-04-17 01:30 +0200
  [PATCH mmotm 2/5] huge tmpfs: fix mlocked meminfo track huge unhuge  mlocks fix Hugh Dickins <hughd@google.com> - 2016-04-17 01:40 +0200
    Re: [PATCH mmotm 2/5] huge tmpfs: fix mlocked meminfo track huge  unhuge mlocks fix Stephen Rothwell <sfr@canb.auug.org.au> - 2016-04-21 01:50 +0200
  [PATCH mmotm 4/5] huge tmpfs: avoid premature exposure of new  pagetable revert Hugh Dickins <hughd@google.com> - 2016-04-17 01:40 +0200
    Re: [PATCH mmotm 4/5] huge tmpfs: avoid premature exposure of new  pagetable revert Stephen Rothwell <sfr@canb.auug.org.au> - 2016-04-21 02:00 +0200
  [PATCH mmotm 3/5] huge tmpfs recovery: tweak shmem_getpage_gfp to  fill team fix Hugh Dickins <hughd@google.com> - 2016-04-17 01:40 +0200
    Re: [PATCH mmotm 3/5] huge tmpfs recovery: tweak shmem_getpage_gfp  to fill team fix Stephen Rothwell <sfr@canb.auug.org.au> - 2016-04-21 02:00 +0200
  [PATCH mmotm 5/5] huge tmpfs: add shmem_pmd_fault() Hugh Dickins <hughd@google.com> - 2016-04-17 01:50 +0200
    Re: [PATCH mmotm 5/5] huge tmpfs: add shmem_pmd_fault() "Kirill A. Shutemov" <kirill@shutemov.name> - 2016-04-17 02:50 +0200
      Re: [PATCH mmotm 5/5] huge tmpfs: add shmem_pmd_fault() Hugh Dickins <hughd@google.com> - 2016-04-17 03:30 +0200
    Re: [PATCH mmotm 5/5] huge tmpfs: add shmem_pmd_fault() Stephen Rothwell <sfr@canb.auug.org.au> - 2016-04-21 02:00 +0200
  Re: [PATCH mmotm 1/5] huge tmpfs: try to allocate huge pages split  into a team fix Stephen Rothwell <sfr@canb.auug.org.au> - 2016-04-21 01:50 +0200

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