[dm-devel] dm-snapshot

[Mikulas Patocka]

On Thu, 29 Jan 2009, sdrb wrote:

> Hi,
> 
> Ok -  is it possible to tell which commits on git.kernel.org are fixing it?


dm snapshot: wait for chunks in destructor
commit 879129d208f725267366296b631aef31409cf304

There is another crashbug in 2.6.27:
dm snapshot: fix primary_pe race
7c5f78b9d7f21937e46c26db82976df4b459c95c
... but this was backported to 2.6.27.x

Mikulas

> Mikulas Patocka wrote:
> > Hi
> > 
> > Upgrade to 2.6.28.* It is already fixed there.
> > 
> > Mikulas
> > 
> > On Tue, 27 Jan 2009, sdrb wrote:
> > 
> > > Hello,
> > > 
> > > I've been using snapshots functionality from DM for some time and
> > > sometimes I
> > > encounter following calltrace:
> > > 
> > > -------------
> > > Pid: 26230, comm: kcopyd Not tainted (2.6.27.6 #36)
> > > EIP: 0060:[<c044d485>] EFLAGS: 00010282 CPU: 1
> > > EIP is at remove_exception+0x5/0x20
> > > EAX: ca3b5908 EBX: ca3b5908 ECX: 00200200 EDX: 00100100
> > > ESI: f7b489f8 EDI: e92ad980 EBP: 00000000 ESP: f29c7ec0
> > > DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068
> > > Process kcopyd (pid: 26230, ti=f29c6000 task=e8512430 task.ti=f29c6000)
> > > Stack: c044e03f 0000000d 00000000 c85948c0 00000000 c044f2e7 0009bc30
> > > 00000000
> > >       0000e705 00000000 e8e41288 e92ad980 00000000 c044e0f0 e8e41288
> > > c7800ec8
> > >       00000000 c0449224 00000000 c7800fb4 00000400 00000000 00000000
> > > f2bdfbb0
> > > Call Trace:
> > > [<c044e03f>] pending_complete+0x9f/0x110
> > > [<c044f2e7>] persistent_commit+0xc7/0x1100x110
> > > [<c044e0f0>] copy_callback+0x30/0x40
> > > [<c0449224>] segment_complete+0x154/0x1d0
> > > [<c0448e55>] run_complete_job+0x45/0x80
> > > [<c04490d0>] segment_complete+0x0/0x1d0
> > > [<c0448e10>] run_complete_job+0x0/0x80
> > > [<c0449014>] process_jobs+0x14/0x70
> > > [<c0449070>] do_work+0x0/0x40
> > > [<c0449086>] do_work+0x16/0x40
> > > [<c013502d>] run_workqueue+0x4d/0xf0
> > > [<c013514d>] worker_thread+0x7d/0xc0
> > > [<c01382e0>] autoremove_wake_function+0x0/0x30
> > > [<c0526583>] __sched_text_start+0x1e3/0x4a0
> > > [<c01382e0>] autoremove_wake_function+0x0/0x30
> > > [<c0121a2b>] complete+0x2b/0x40
> > > [<c01350d0>] worker_thread+0x0/0xc0
> > > [<c0137db4>] kthread+0x44/0x70
> > > [<c0137d70>] kthread+0x0/0x70
> > > [<c0104c57>] kernel_thread_helper+0x7/0x10
> > > =======================
> > > Code: 4b 0c e8 cf ff ff ff 8b 56 08 8d 04 c2 8b 10 89 13 89 18 89 5a 04
> > > 89 43 04 5b 5e c3 8d 76 00 8d bc 27 00 00 00 00 8b 48 04 8b 10 <89> 11
> > > 89 4a 04 c7 00 00 01 10 00 c7 40 04 00 02 20 00 c3 90 8d
> > > EIP: [<c044d485>] remove_exception+0x5/0x20 SS:ESP 0068:f29c7ec0
> > > --------------
> > > 
> > > As I see it occurs because kernel tried to access poisoned element list.
> > > Isn't it because of given element has been deleted from list earlier and
> > > now kernel is trying to delete it second time? I had similar problems,
> > > when
> > > I deleted (by mistake) element from list which was the "head" of list. In
> > > other words
> > > - I had the pointer to the head element of list and I removed this element
> > > from list, so
> > > this pointer points to element outside the list. Then I tried to go
> > > through
> > > this list using
> > > this pointer as a head of list - and then I get similar error. In fact I
> > > lost
> > > contact with this
> > > list because I didn't change pointer to another element in that list
> > > before I
> > > deleted head element.
> > > 
> > > Aren't the both situations (calltrace and mine) similar?
> > > 
> > > p.s. It is probably the same problem as in:
> > > https://www.redhat.com/archives/dm-devel/2008-December/msg00006.html
> > > 
> > > --
> > > dm-devel mailing list
> > > dm-devel at redhat.com
> > > https://www.redhat.com/mailman/listinfo/dm-devel
> > > 
> > 
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> > 
> 
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