Jeremy Fitzhardinge
2011-Mar-25 12:28 UTC
[Xen-devel] WARNING: at kernel/timer.c:1012 del_timer_sync+0x39/0x4e()
In today''s linux-2.6.38+ I''m seeing this in my Xen domains:
------------[ cut here ]------------
WARNING: at /home/jeremy/git/upstream/kernel/timer.c:1012
del_timer_sync+0x39/0x4e()
Modules linked in: sunrpc microcode [last unloaded: scsi_wait_scan]
Pid: 0, comm: swapper Tainted: G W 2.6.38+ #349
Call Trace:
<IRQ> [<ffffffff8104c283>] ? del_timer_sync+0x39/0x4e
[<ffffffff8103f080>] warn_slowpath_common+0x85/0x9d
[<ffffffff8103f0b2>] warn_slowpath_null+0x1a/0x1c
[<ffffffff8104c283>] del_timer_sync+0x39/0x4e
[<ffffffff81206d4e>] blk_stop_queue+0x1d/0x6d
[<ffffffff812e82f6>] do_blkif_request+0x35d/0x3ba
[<ffffffff8120560f>] __blk_run_queue+0x7d/0xd7
[<ffffffff81205880>] blk_start_queue+0x78/0x7d
[<ffffffff812e837b>] kick_pending_request_queues+0x28/0x38
[<ffffffff812e85d5>] blkif_interrupt+0x1f8/0x21c
[<ffffffff8108e866>] handle_irq_event_percpu+0x61/0x1a5
[<ffffffff8108e9fa>] handle_irq_event+0x50/0x74
[<ffffffff81090c87>] handle_fasteoi_irq+0x7e/0xaa
[<ffffffff812853aa>] __xen_evtchn_do_upcall+0x166/0x206
[<ffffffff81286d32>] xen_evtchn_do_upcall+0x2f/0x42
[<ffffffff8150148e>] xen_do_hypervisor_callback+0x1e/0x30
<EOI> [<ffffffff810013aa>] ? hypercall_page+0x3aa/0x1000
[<ffffffff810013aa>] ? hypercall_page+0x3aa/0x1000
[<ffffffff81006c34>] ? xen_safe_halt+0x10/0x18
[<ffffffff81010251>] ? default_idle+0x6a/0xc3
[<ffffffff810091af>] ? cpu_idle+0x6b/0x8a
[<ffffffff814e1b2e>] ? rest_init+0x72/0x74
[<ffffffff81b04b70>] ? start_kernel+0x39b/0x3a6
[<ffffffff81b042cb>] ? x86_64_start_reservations+0xb6/0xba
[<ffffffff81b07d6f>] ? xen_start_kernel+0x5dc/0x5e3
---[ end trace 1605d7ec4cdfe9eb ]---
Which is the result of this call to blk_stop_queue() in
drivers/block/xen-blkfront.c:
static void do_blkif_request(struct request_queue *rq)
{
[...]
if (blkif_queue_request(req)) {
blk_requeue_request(rq, req);
wait:
/* Avoid pointless unplugs. */
blk_stop_queue(rq);
break;
}
How should this be fixed? Is this call to blk_stop_queue() bogus, or is
it OK to call it in a handler like this? If so, is the warning itself
wrong?
Does this relate to 7eaceaccab5f4 "block: remove per-queue plugging"?
Thanks,
J
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Jens Axboe
2011-Mar-25 12:52 UTC
[Xen-devel] Re: WARNING: at kernel/timer.c:1012 del_timer_sync+0x39/0x4e()
On 2011-03-25 13:28, Jeremy Fitzhardinge wrote:> In today''s linux-2.6.38+ I''m seeing this in my Xen domains: > > ------------[ cut here ]------------ > WARNING: at /home/jeremy/git/upstream/kernel/timer.c:1012 del_timer_sync+0x39/0x4e() > Modules linked in: sunrpc microcode [last unloaded: scsi_wait_scan] > Pid: 0, comm: swapper Tainted: G W 2.6.38+ #349 > Call Trace: > <IRQ> [<ffffffff8104c283>] ? del_timer_sync+0x39/0x4e > [<ffffffff8103f080>] warn_slowpath_common+0x85/0x9d > [<ffffffff8103f0b2>] warn_slowpath_null+0x1a/0x1c > [<ffffffff8104c283>] del_timer_sync+0x39/0x4e > [<ffffffff81206d4e>] blk_stop_queue+0x1d/0x6d > [<ffffffff812e82f6>] do_blkif_request+0x35d/0x3ba > [<ffffffff8120560f>] __blk_run_queue+0x7d/0xd7 > [<ffffffff81205880>] blk_start_queue+0x78/0x7d > [<ffffffff812e837b>] kick_pending_request_queues+0x28/0x38 > [<ffffffff812e85d5>] blkif_interrupt+0x1f8/0x21c > [<ffffffff8108e866>] handle_irq_event_percpu+0x61/0x1a5 > [<ffffffff8108e9fa>] handle_irq_event+0x50/0x74 > [<ffffffff81090c87>] handle_fasteoi_irq+0x7e/0xaa > [<ffffffff812853aa>] __xen_evtchn_do_upcall+0x166/0x206 > [<ffffffff81286d32>] xen_evtchn_do_upcall+0x2f/0x42 > [<ffffffff8150148e>] xen_do_hypervisor_callback+0x1e/0x30 > <EOI> [<ffffffff810013aa>] ? hypercall_page+0x3aa/0x1000 > [<ffffffff810013aa>] ? hypercall_page+0x3aa/0x1000 > [<ffffffff81006c34>] ? xen_safe_halt+0x10/0x18 > [<ffffffff81010251>] ? default_idle+0x6a/0xc3 > [<ffffffff810091af>] ? cpu_idle+0x6b/0x8a > [<ffffffff814e1b2e>] ? rest_init+0x72/0x74 > [<ffffffff81b04b70>] ? start_kernel+0x39b/0x3a6 > [<ffffffff81b042cb>] ? x86_64_start_reservations+0xb6/0xba > [<ffffffff81b07d6f>] ? xen_start_kernel+0x5dc/0x5e3 > ---[ end trace 1605d7ec4cdfe9eb ]--- > > Which is the result of this call to blk_stop_queue() in drivers/block/xen-blkfront.c: > > static void do_blkif_request(struct request_queue *rq) > { > [...] > if (blkif_queue_request(req)) { > blk_requeue_request(rq, req); > wait: > /* Avoid pointless unplugs. */ > blk_stop_queue(rq); > break; > } > > > > How should this be fixed? Is this call to blk_stop_queue() bogus, or is > it OK to call it in a handler like this? If so, is the warning itself > wrong?Calling it in there should be fine, the problem is that the work cancel turns into a sync timer delete. That is not needed. Can you try the below?> Does this relate to 7eaceaccab5f4 "block: remove per-queue plugging"?No diff --git a/block/blk-core.c b/block/blk-core.c index 59b5c00..f97c088 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -271,7 +271,7 @@ EXPORT_SYMBOL(blk_start_queue); **/ void blk_stop_queue(struct request_queue *q) { - cancel_delayed_work(&q->delay_work); + __cancel_delayed_work(&q->delay_work); queue_flag_set(QUEUE_FLAG_STOPPED, q); } EXPORT_SYMBOL(blk_stop_queue); -- Jens Axboe _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Jeremy Fitzhardinge
2011-Mar-25 14:01 UTC
[Xen-devel] Re: WARNING: at kernel/timer.c:1012 del_timer_sync+0x39/0x4e()
On 03/25/2011 12:52 PM, Jens Axboe wrote:>> How should this be fixed? Is this call to blk_stop_queue() bogus, or is >> it OK to call it in a handler like this? If so, is the warning itself >> wrong? > Calling it in there should be fine, the problem is that the work cancel > turns into a sync timer delete. That is not needed. Can you try the > below?Yep, that works. Tested-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>>> Does this relate to 7eaceaccab5f4 "block: remove per-queue plugging"? > NoOK. Is the correct fix for that change to just remove all the plug/unplug code? We have some still out-of-tree code that stopped compiling. Thanks, J _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel