Re: raid5 lockups post ca64cae96037de16e4af92678814f5d4bf0c1c65

[Jes Sorensen <Jes.Sorensen@redhat.com>]

NeilBrown <neilb@suse.de> writes:
> On Tue, 12 Mar 2013 14:45:44 +0100 Jes Sorensen <Jes.Sorensen@redhat.com>
> wrote:
>
>> NeilBrown <neilb@suse.de> writes:
>> > On Tue, 12 Mar 2013 09:32:31 +1100 NeilBrown <neilb@suse.de> wrote:
>> >
>> >> On Wed, 06 Mar 2013 10:31:55 +0100 Jes Sorensen <Jes.Sorensen@redhat.com>
>> >> wrote:
>> >> 
>> >
>> >> > 
>> >> > I am attaching the test script I am running too. It was written by Eryu
>> >> > Guan.
>> >> 
>> >> Thanks for that.  I've tried using it but haven't managed to trigger a BUG
>> >> yet.  What size are the loop files?  I mostly use fairly small ones, but
>> >> maybe it needs to be bigger to trigger the problem.
>> >
>> > Shortly after I wrote that I got a bug-on!  It hasn't happened again though.
>> >
>> > This was using code without that latest patch I sent.  The bug was
>> > 		BUG_ON(s->uptodate != disks);
>> >
>> > in the check_state_compute_result case of handle_parity_checks5() which is
>> > probably the same cause as your most recent BUG.
>> >
>> > I've revised my thinking a bit and am now running with this patch which I
>> > think should fix a problem that probably caused the symptoms we have seen.
>> >
>> > If you could run your tests for a while too and is whether it will
>> > still crash
>> > for you, I'd really appreciate it.
>> 
>> Hi Neil,
>> 
>> Sorry I can't verify the line numbers of my old test since I managed to
>> mess up my git tree in the process :(
>> 
>> However running with this new patch I have just hit another but
>> different case. Looks like a deadlock.
>
> You test setup is clearly different from mine.  I've been running all night
> without a single hiccup.
>
>> 
>> This is basically running ca64cae96037de16e4af92678814f5d4bf0c1c65 with
>> your patch applied on top, and nothing else.
>> 
>> If you want me to try a more uptodate Linus tree, please let me know.
>> 
>> Cheers,
>> Jes
>> 
>> 
>> [17635.205927] INFO: task mkfs.ext4:20060 blocked for more than 120 seconds.
>> [17635.213543] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs"
>> disables this message.
>> [17635.222291] mkfs.ext4 D ffff880236814100 0 20060 20026 0x00000080
>> [17635.230199] ffff8801bc8bbb98 0000000000000082 ffff88022f0be540
>> ffff8801bc8bbfd8
>> [17635.238518] ffff8801bc8bbfd8 ffff8801bc8bbfd8 ffff88022d47b2a0
>> ffff88022f0be540
>> [17635.246837] ffff8801cea1f430 000000000001d5f0 ffff8801c7f4f430
>> ffff88022169a400
>> [17635.255161] Call Trace:
>> [17635.257891]  [<ffffffff81614f79>] schedule+0x29/0x70
>> [17635.263433]  [<ffffffffa0386ada>] make_request+0x6da/0x6f0 [raid456]
>> [17635.270525]  [<ffffffff81084210>] ? wake_up_bit+0x40/0x40
>> [17635.276560]  [<ffffffff814a6633>] md_make_request+0xc3/0x200
>> [17635.282884]  [<ffffffff81134655>] ? mempool_alloc_slab+0x15/0x20
>> [17635.289586]  [<ffffffff812c70d2>] generic_make_request+0xc2/0x110
>> [17635.296393]  [<ffffffff812c7199>] submit_bio+0x79/0x160
>> [17635.302232]  [<ffffffff811ca625>] ? bio_alloc_bioset+0x65/0x120
>> [17635.308844]  [<ffffffff812ce234>] blkdev_issue_discard+0x184/0x240
>> [17635.315748]  [<ffffffff812cef76>] blkdev_ioctl+0x3b6/0x810
>> [17635.321877]  [<ffffffff811cb971>] block_ioctl+0x41/0x50
>> [17635.327714]  [<ffffffff811a6aa9>] do_vfs_ioctl+0x99/0x580
>> [17635.333745] [<ffffffff8128a19a>] ?
>> inode_has_perm.isra.30.constprop.60+0x2a/0x30
>> [17635.342103]  [<ffffffff8128b6d7>] ? file_has_perm+0x97/0xb0
>> [17635.348329]  [<ffffffff811a7021>] sys_ioctl+0x91/0xb0
>> [17635.353972]  [<ffffffff810de9dc>] ? __audit_syscall_exit+0x3ec/0x450
>> [17635.361070]  [<ffffffff8161e759>] system_call_fastpath+0x16/0x1b
>
> There is a small race in the exclusion between discard and recovery.
> This patch on top should fix it (I hope).
> Thanks for testing.

Ok I spent most of yesterday running tests on this. With this additional
patch applied I haven't been able to reproduce the hang so far - without
it I could do it in about an hour, so I suspect it solves the problem.

Thanks!
Jes