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userfaultfd: shmem: lock the page before adding it to pagecache

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A VM_BUG_ON triggered on the shmem selftest.

Link: http://lkml.kernel.org/r/20161216144821.5183-36-aarcange@redhat.com
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrea Arcangeli 2017-02-22 15:43:49 -08:00 committed by Linus Torvalds
parent 419624daf0
commit 9cc90c664a
1 changed files with 5 additions and 0 deletions
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5
mm/shmem.c
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@ -2245,6 +2245,10 @@ int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm,
*pagep = NULL;
}
VM_BUG_ON(PageLocked(page) || PageSwapBacked(page));
__SetPageLocked(page);
__SetPageSwapBacked(page);
ret = mem_cgroup_try_charge(page, dst_mm, gfp, &memcg, false);
if (ret)
goto out_release;
@ -2294,6 +2298,7 @@ out_release_uncharge_unlock:
out_release_uncharge:
mem_cgroup_cancel_charge(page, memcg, false);
out_release:
unlock_page(page);
put_page(page);
out_dec_used_blocks:
if (sbinfo->max_blocks)