From: Andrea Arcangeli <aarcange@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>,
Maxime Coquelin <maxime.coquelin@redhat.com>,
Mike Rapoport <rppt@linux.vnet.ibm.com>,
Mike Kravetz <mike.kravetz@oracle.com>,
Alexey Perevalov <a.perevalov@samsung.com>
Subject: [PATCH 1/6] userfaultfd: hugetlbfs: remove superfluous page unlock in VM_SHARED case
Date: Wed, 2 Aug 2017 18:51:40 +0200 [thread overview]
Message-ID: <20170802165145.22628-2-aarcange@redhat.com> (raw)
In-Reply-To: <20170802165145.22628-1-aarcange@redhat.com>
huge_add_to_page_cache->add_to_page_cache implicitly unlock 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))
------------[ cut here ]------------
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
task: ffff973131ab2600 task.stack: ffffacc0cba78000
RIP: 0010:unlock_page+0x4a/0x50
RSP: 0018:ffffacc0cba7bca0 EFLAGS: 00010246
RAX: 0000000000000036 RBX: fffff99d09f38000 RCX: 0000000000000006
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff97326148e0c0
RBP: ffffacc0cba7bca0 R08: 00000000000006be R09: 0000000000000004
R10: 00000000000007ae R11: ffffffffb622cbed R12: 0000000000000008
R13: ffff972f9a265240 R14: ffff972de2919740 R15: ffffffffb62da820
FS: 00007f122efff700(0000) GS:ffff973261480000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd52f788ea8 CR3: 000000036d022000 CR4: 00000000003426e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
hugetlb_mcopy_atomic_pte+0xc0/0x320
mcopy_atomic+0x96f/0xbe0
userfaultfd_ioctl+0x218/0xe90
? __schedule+0x23c/0x8d0
? hrtimer_start_range_ns+0x1bd/0x330
do_vfs_ioctl+0xa5/0x600
? do_vfs_ioctl+0xa5/0x600
SyS_ioctl+0x79/0x90
entry_SYSCALL_64_fastpath+0x1a/0xa9
Tested-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
---
mm/hugetlb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index bc48ee783dd9..5a240c72c3b6 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -4062,9 +4062,9 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
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;
}
--
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next prev parent reply other threads:[~2017-08-02 16:52 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-02 16:51 [PATCH 0/6] userfaultfd updates for v4.13-rc3 Andrea Arcangeli
2017-08-02 16:51 ` Andrea Arcangeli [this message]
2017-08-02 17:12 ` [PATCH 1/6] userfaultfd: hugetlbfs: remove superfluous page unlock in VM_SHARED case Mike Kravetz
2017-08-02 16:51 ` [PATCH 2/6] userfaultfd: selftest: exercise UFFDIO_COPY/ZEROPAGE -EEXIST Andrea Arcangeli
2017-08-02 21:33 ` Mike Kravetz
2017-08-02 16:51 ` [PATCH 3/6] userfaultfd: selftest: explicit failure if the SIGBUS test failed Andrea Arcangeli
2017-08-02 16:51 ` [PATCH 4/6] userfaultfd: call userfaultfd_unmap_prep only if __split_vma succeeds Andrea Arcangeli
2017-08-02 16:51 ` [PATCH 5/6] userfaultfd: provide pid in userfault msg Andrea Arcangeli
2017-08-02 16:51 ` [PATCH 6/6] userfaultfd: provide pid in userfault msg - add feat union Andrea Arcangeli
2017-08-02 21:29 ` [PATCH 0/6] userfaultfd updates for v4.13-rc3 Andrew Morton
2017-08-02 22:27 ` Andrea Arcangeli
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