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mm: fix mm_take_all_locks() locking order
author
Peter Zijlstra
<a.p.zijlstra@chello.nl>
Mon, 11 Aug 2008 07:30:25 +0000
(09:30 +0200)
committer
Ingo Molnar
<mingo@elte.hu>
Mon, 11 Aug 2008 07:30:25 +0000
(09:30 +0200)
Lockdep spotted:
=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.27-rc1 #270
-------------------------------------------------------
qemu-kvm/2033 is trying to acquire lock:
(&inode->i_data.i_mmap_lock){----}, at: [<
ffffffff802996cc
>] mm_take_all_locks+0xc2/0xea
but task is already holding lock:
(&anon_vma->lock){----}, at: [<
ffffffff8029967a
>] mm_take_all_locks+0x70/0xea
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&anon_vma->lock){----}:
[<
ffffffff8025cd37
>] __lock_acquire+0x11be/0x14d2
[<
ffffffff8025d0a9
>] lock_acquire+0x5e/0x7a
[<
ffffffff804c655b
>] _spin_lock+0x3b/0x47
[<
ffffffff8029a2ef
>] vma_adjust+0x200/0x444
[<
ffffffff8029a662
>] split_vma+0x12f/0x146
[<
ffffffff8029bc60
>] mprotect_fixup+0x13c/0x536
[<
ffffffff8029c203
>] sys_mprotect+0x1a9/0x21e
[<
ffffffff8020c0db
>] system_call_fastpath+0x16/0x1b
[<
ffffffffffffffff
>] 0xffffffffffffffff
-> #0 (&inode->i_data.i_mmap_lock){----}:
[<
ffffffff8025ca54
>] __lock_acquire+0xedb/0x14d2
[<
ffffffff8025d397
>] lock_release_non_nested+0x1c2/0x219
[<
ffffffff8025d515
>] lock_release+0x127/0x14a
[<
ffffffff804c6403
>] _spin_unlock+0x1e/0x50
[<
ffffffff802995d9
>] mm_drop_all_locks+0x7f/0xb0
[<
ffffffff802a965d
>] do_mmu_notifier_register+0xe2/0x112
[<
ffffffff802a96a8
>] mmu_notifier_register+0xe/0x10
[<
ffffffffa0043b6b
>] kvm_dev_ioctl+0x11e/0x287 [kvm]
[<
ffffffff802bd0ca
>] vfs_ioctl+0x2a/0x78
[<
ffffffff802bd36f
>] do_vfs_ioctl+0x257/0x274
[<
ffffffff802bd3e1
>] sys_ioctl+0x55/0x78
[<
ffffffff8020c0db
>] system_call_fastpath+0x16/0x1b
[<
ffffffffffffffff
>] 0xffffffffffffffff
other info that might help us debug this:
5 locks held by qemu-kvm/2033:
#0: (&mm->mmap_sem){----}, at: [<
ffffffff802a95d0
>] do_mmu_notifier_register+0x55/0x112
#1: (mm_all_locks_mutex){--..}, at: [<
ffffffff8029963e
>] mm_take_all_locks+0x34/0xea
#2: (&anon_vma->lock){----}, at: [<
ffffffff8029967a
>] mm_take_all_locks+0x70/0xea
#3: (&anon_vma->lock){----}, at: [<
ffffffff8029967a
>] mm_take_all_locks+0x70/0xea
#4: (&anon_vma->lock){----}, at: [<
ffffffff8029967a
>] mm_take_all_locks+0x70/0xea
stack backtrace:
Pid: 2033, comm: qemu-kvm Not tainted 2.6.27-rc1 #270
Call Trace:
[<
ffffffff8025b7c7
>] print_circular_bug_tail+0xb8/0xc3
[<
ffffffff8025ca54
>] __lock_acquire+0xedb/0x14d2
[<
ffffffff80259bb1
>] ? add_lock_to_list+0x7e/0xad
[<
ffffffff8029967a
>] ? mm_take_all_locks+0x70/0xea
[<
ffffffff8029967a
>] ? mm_take_all_locks+0x70/0xea
[<
ffffffff8025d397
>] lock_release_non_nested+0x1c2/0x219
[<
ffffffff802996cc
>] ? mm_take_all_locks+0xc2/0xea
[<
ffffffff802996cc
>] ? mm_take_all_locks+0xc2/0xea
[<
ffffffff8025b202
>] ? trace_hardirqs_on_caller+0x4d/0x115
[<
ffffffff802995d9
>] ? mm_drop_all_locks+0x7f/0xb0
[<
ffffffff8025d515
>] lock_release+0x127/0x14a
[<
ffffffff804c6403
>] _spin_unlock+0x1e/0x50
[<
ffffffff802995d9
>] mm_drop_all_locks+0x7f/0xb0
[<
ffffffff802a965d
>] do_mmu_notifier_register+0xe2/0x112
[<
ffffffff802a96a8
>] mmu_notifier_register+0xe/0x10
[<
ffffffffa0043b6b
>] kvm_dev_ioctl+0x11e/0x287 [kvm]
[<
ffffffff8033f9f2
>] ? file_has_perm+0x83/0x8e
[<
ffffffff802bd0ca
>] vfs_ioctl+0x2a/0x78
[<
ffffffff802bd36f
>] do_vfs_ioctl+0x257/0x274
[<
ffffffff802bd3e1
>] sys_ioctl+0x55/0x78
[<
ffffffff8020c0db
>] system_call_fastpath+0x16/0x1b
Which the locking hierarchy in mm/rmap.c confirms as valid.
Fix this by first taking all the mapping->i_mmap_lock instances and then
take all anon_vma->lock instances.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
mm/mmap.c
patch
|
blob
|
history
diff --git
a/mm/mmap.c
b/mm/mmap.c
index
5d09d08
..
32a287b
100644
(file)
--- a/
mm/mmap.c
+++ b/
mm/mmap.c
@@
-2358,11
+2358,17
@@
int mm_take_all_locks(struct mm_struct *mm)
for (vma = mm->mmap; vma; vma = vma->vm_next) {
if (signal_pending(current))
goto out_unlock;
- if (vma->anon_vma)
- vm_lock_anon_vma(mm, vma->anon_vma);
if (vma->vm_file && vma->vm_file->f_mapping)
vm_lock_mapping(mm, vma->vm_file->f_mapping);
}
+
+ for (vma = mm->mmap; vma; vma = vma->vm_next) {
+ if (signal_pending(current))
+ goto out_unlock;
+ if (vma->anon_vma)
+ vm_lock_anon_vma(mm, vma->anon_vma);
+ }
+
ret = 0;
out_unlock: