[PATCH] md: avoid deadlock when md_set_badblocks.

From: ycbzzjlby
Date: Mon Oct 21 2013 - 12:35:54 EST

From: Bian Yu <bianyu@xxxxxxxxxxx>

When operate harddisk and hit errors, md_set_badblocks is called after
scsi_restart_operations which already disabled the irq. but md_set_badblocks
will call write_sequnlock_irq and enable irq. so softirq can preempt the
current thread and that may cause a deadlock. I think this situation should
use write_sequnlock_irqsave/irqrestore instead.

I met the situation and the call trace is below:
[ 638.919974] BUG: spinlock recursion on CPU#0, scsi_eh_13/1010
[ 638.921923] lock: 0xffff8800d4d51fc8, .magic: dead4ead, .owner: scsi_eh_13/1010, .owner_cpu: 0
[ 638.923890] CPU: 0 PID: 1010 Comm: scsi_eh_13 Not tainted 3.12.0-rc5+ #37
[ 638.925844] Hardware name: To be filled by O.E.M. To be filled by O.E.M./MAHOBAY, BIOS 4.6.5 03/05/2013
[ 638.927816] ffff880037ad4640 ffff880118c03d50 ffffffff8172ff85 0000000000000007
[ 638.929829] ffff8800d4d51fc8 ffff880118c03d70 ffffffff81730030 ffff8800d4d51fc8
[ 638.931848] ffffffff81a72eb0 ffff880118c03d90 ffffffff81730056 ffff8800d4d51fc8
[ 638.933884] Call Trace:
[ 638.935867] <IRQ> [<ffffffff8172ff85>] dump_stack+0x55/0x76
[ 638.937878] [<ffffffff81730030>] spin_dump+0x8a/0x8f
[ 638.939861] [<ffffffff81730056>] spin_bug+0x21/0x26
[ 638.941836] [<ffffffff81336de4>] do_raw_spin_lock+0xa4/0xc0
[ 638.943801] [<ffffffff8173f036>] _raw_spin_lock+0x66/0x80
[ 638.945747] [<ffffffff814a73ed>] ? scsi_device_unbusy+0x9d/0xd0
[ 638.947672] [<ffffffff8173fb1b>] ? _raw_spin_unlock+0x2b/0x50
[ 638.949595] [<ffffffff814a73ed>] scsi_device_unbusy+0x9d/0xd0
[ 638.951504] [<ffffffff8149ec47>] scsi_finish_command+0x37/0xe0
[ 638.953388] [<ffffffff814a75e8>] scsi_softirq_done+0xa8/0x140
[ 638.955248] [<ffffffff8130e32b>] blk_done_softirq+0x7b/0x90
[ 638.957116] [<ffffffff8104fddd>] __do_softirq+0xfd/0x330
[ 638.958987] [<ffffffff810b964f>] ? __lock_release+0x6f/0x100
[ 638.960861] [<ffffffff8174a5cc>] call_softirq+0x1c/0x30
[ 638.962724] [<ffffffff81004c7d>] do_softirq+0x8d/0xc0
[ 638.964565] [<ffffffff8105024e>] irq_exit+0x10e/0x150
[ 638.966390] [<ffffffff8174ad4a>] smp_apic_timer_interrupt+0x4a/0x60
[ 638.968223] [<ffffffff817499af>] apic_timer_interrupt+0x6f/0x80
[ 638.970079] <EOI> [<ffffffff810b964f>] ? __lock_release+0x6f/0x100
[ 638.971899] [<ffffffff8173fa6a>] ? _raw_spin_unlock_irq+0x3a/0x50
[ 638.973691] [<ffffffff8173fa60>] ? _raw_spin_unlock_irq+0x30/0x50
[ 638.975475] [<ffffffff81562393>] md_set_badblocks+0x1f3/0x4a0
[ 638.977243] [<ffffffff81566e07>] rdev_set_badblocks+0x27/0x80
[ 638.978988] [<ffffffffa00d97bb>] raid5_end_read_request+0x36b/0x4e0 [raid456]
[ 638.980723] [<ffffffff811b5a1d>] bio_endio+0x1d/0x40
[ 638.982463] [<ffffffff81304ff3>] req_bio_endio.isra.65+0x83/0xa0
[ 638.984214] [<ffffffff81306b9f>] blk_update_request+0x7f/0x350
[ 638.985967] [<ffffffff81306ea1>] blk_update_bidi_request+0x31/0x90
[ 638.987710] [<ffffffff813085e0>] __blk_end_bidi_request+0x20/0x50
[ 638.989439] [<ffffffff8130862f>] __blk_end_request_all+0x1f/0x30
[ 638.991149] [<ffffffff81308746>] blk_peek_request+0x106/0x250
[ 638.992861] [<ffffffff814a62a9>] ? scsi_kill_request.isra.32+0xe9/0x130
[ 638.994561] [<ffffffff814a633a>] scsi_request_fn+0x4a/0x3d0
[ 638.996251] [<ffffffff813040a7>] __blk_run_queue+0x37/0x50
[ 638.997900] [<ffffffff813045af>] blk_run_queue+0x2f/0x50
[ 638.999553] [<ffffffff814a5750>] scsi_run_queue+0xe0/0x1c0
[ 639.001185] [<ffffffff814a7721>] scsi_run_host_queues+0x21/0x40
[ 639.002798] [<ffffffff814a2e87>] scsi_restart_operations+0x177/0x200
[ 639.004391] [<ffffffff814a4fe9>] scsi_error_handler+0xc9/0xe0
[ 639.005996] [<ffffffff814a4f20>] ? scsi_unjam_host+0xd0/0xd0
[ 639.007600] [<ffffffff81072f6b>] kthread+0xdb/0xe0
[ 639.009205] [<ffffffff81072e90>] ? flush_kthread_worker+0x170/0x170
[ 639.010821] [<ffffffff81748cac>] ret_from_fork+0x7c/0xb0
[ 639.012437] [<ffffffff81072e90>] ? flush_kthread_worker+0x170/0x170

Signed-off-by: Bian Yu <bianyu@xxxxxxxxxxx>
Reviewed-by: Jianpeng Ma <majianpeng@xxxxxxxxx>
---
drivers/md/md.c | 5 +++--
1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 8a0d762..2445fec 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -8111,6 +8111,7 @@ static int md_set_badblocks(struct badblocks *bb, sector_t s, int sectors,
u64 *p;
int lo, hi;
int rv = 1;
+ unsigned long flags;

if (bb->shift < 0)
/* badblocks are disabled */
@@ -8125,7 +8126,7 @@ static int md_set_badblocks(struct badblocks *bb, sector_t s, int sectors,
sectors = next - s;
}

- write_seqlock_irq(&bb->lock);
+ write_seqlock_irqsave(&bb->lock, flags);

p = bb->page;
lo = 0;
@@ -8241,7 +8242,7 @@ static int md_set_badblocks(struct badblocks *bb, sector_t s, int sectors,
bb->changed = 1;
if (!acknowledged)
bb->unacked_exist = 1;
- write_sequnlock_irq(&bb->lock);
+ write_sequnlock_irqrestore(&bb->lock, flags);

return rv;
}
--
1.7.1

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