From 5af10dfd0afc559bb4b0f7e3e8227a1578333995 Mon Sep 17 00:00:00 2001 From: Andrea Arcangeli Date: Thu, 10 Aug 2017 15:23:38 -0700 Subject: [PATCH] userfaultfd: hugetlbfs: remove superfluous page unlock in VM_SHARED case huge_add_to_page_cache->add_to_page_cache implicitly unlocks the page before returning in case of errors. The error returned was -EEXIST by running UFFDIO_COPY on a non-hole offset of a VM_SHARED hugetlbfs mapping. It was an userland bug that triggered it and the kernel must cope with it returning -EEXIST from ioctl(UFFDIO_COPY) as expected. page dumped because: VM_BUG_ON_PAGE(!PageLocked(page)) kernel BUG at mm/filemap.c:964! invalid opcode: 0000 [#1] SMP CPU: 1 PID: 22582 Comm: qemu-system-x86 Not tainted 4.11.11-300.fc26.x86_64 #1 RIP: unlock_page+0x4a/0x50 Call Trace: hugetlb_mcopy_atomic_pte+0xc0/0x320 mcopy_atomic+0x96f/0xbe0 userfaultfd_ioctl+0x218/0xe90 do_vfs_ioctl+0xa5/0x600 SyS_ioctl+0x79/0x90 entry_SYSCALL_64_fastpath+0x1a/0xa9 Link: http://lkml.kernel.org/r/20170802165145.22628-2-aarcange@redhat.com Signed-off-by: Andrea Arcangeli Tested-by: Maxime Coquelin Reviewed-by: Mike Kravetz Cc: "Dr. David Alan Gilbert" Cc: Mike Rapoport Cc: Alexey Perevalov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/hugetlb.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index a1a0ac0ad6f6..31e207cb399b 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -4062,9 +4062,9 @@ out: return ret; out_release_unlock: spin_unlock(ptl); -out_release_nounlock: if (vm_shared) unlock_page(page); +out_release_nounlock: put_page(page); goto out; }