From: Andrea Arcangeli <aarcange@xxxxxxxxxx> Subject: userfaultfd: shmem: lock the page before adding it to pagecache A VM_BUG_ON triggered on the shmem selftest. Link: http://lkml.kernel.org/r/20161216144821.5183-36-aarcange@xxxxxxxxxx Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx> Cc: "Dr. David Alan Gilbert" <dgilbert@xxxxxxxxxx> Cc: Hillf Danton <hillf.zj@xxxxxxxxxxxxxxx> Cc: Michael Rapoport <RAPOPORT@xxxxxxxxxx> Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Cc: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx> Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/shmem.c | 5 +++++ 1 file changed, 5 insertions(+) diff -puN mm/shmem.c~userfaultfd-shmem-lock-the-page-before-adding-it-to-pagecache mm/shmem.c --- a/mm/shmem.c~userfaultfd-shmem-lock-the-page-before-adding-it-to-pagecache +++ a/mm/shmem.c @@ -2245,6 +2245,10 @@ int shmem_mcopy_atomic_pte(struct mm_str *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) _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
