Re: scsi/qla2xxx: BUG_ON(blk_queued_rq(req) is triggered in blk_finish_request

From: jianchao.wang
Date: Fri May 25 2018 - 07:59:50 EST

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Hi Himanshu

I'm afraid I cannot provide you the vmcore file, it is from our customer.
If any information needed in the vmcore, I could provide with you.

In this scene, there are two contexts:
1. the irq context, scsi_done() from qla2x00_sp_compl()
2. the kworker context, scmd_eh_abort_handler which invokes the
qla2xxx_eh_abort()

Let's see the irq context.
scsi_done() will invoke the blk_complete_request().
In common case, the REQ_ATOM_COMPLETEãshould have been set by
blk_rq_check_expired() when the request was confirmed timeout. So
__blk_complete_request() will not be invoked.

On the other hand, in the kworker context, scmd_eh_abort_handler() will do some
other things on this aborted request.

rtn = scsi_try_to_abort_cmd(sdev->host->hostt, scmd);
if (rtn == SUCCESS) {
set_host_byte(scmd, DID_TIME_OUT)
if (scsi_host_eh_past_deadline(sdev->host)) {
>>>>
} else if (!scsi_noretry_cmd(scmd) &&
(++scmd->retries <= scmd->allowed)) {
scsi_queue_insert(scmd, SCSI_MLQUEUE_EH_RETRY)
}>>>>
>>>>
}
The host type of the result will set to DID_TIME_OUT. scsi_noretry_cmd() will
return false and scsi_queue_insert() will be invoked, finally the
blk_requeue_request().

blk_requeue_request() will clear the REQ_ATOM_COMPLETE and queue the request on
request_queue->queue_head.

There could be a race between these two contexts:
what if the blk_clear_rq_complete() in kworker context is invoked before the
blk_mark_rq_complete() in irq context ?

BLK_SOFTIRQ will be raised by __blk_complete_request() in irq context. Then the
scsi_softirq_done() will be invoked. At the moment, the request has been
requeued by kworker context and scsi_cmnd->result is set 0. On the cpu of the
irq context, the blk_finish_request() will be invoked finally, and panic comes
up due to BUG_ON(blk_queued_rq(req)

Here is the dmesg log.
[4937745.180213] qla2xxx [0000:92:00.1]-801c:4: Abort command issued nexus=4:5:5 -- 1 2002.
[4937745.180655] qla2xxx [0000:92:00.1]-801c:4: Abort command issued nexus=4:4:73 -- 0 2002.
[4937745.181059] qla2xxx [0000:92:00.1]-801c:4: Abort command issued nexus=4:5:5 -- 1 2002.
[4937745.181514] qla2xxx [0000:92:00.1]-801c:4: Abort command issued nexus=4:4:73 -- 0 2002.
[4937745.181636] ------------[ cut here ]------------
[4937745.181900] kernel BUG at block/blk-core.c:2601!
[4937745.182095] qla2xxx [0000:92:00.1]-801c:4: Abort command issued nexus=4:5:5 -- 1 2002.
[4937745.182338] qla2xxx [0000:92:00.1]-801c:4: Abort command issued nexus=4:4:73 -- 1 2002.
[4937745.183046] qla2xxx [0000:92:00.1]-801c:4: Abort command issued nexus=4:5:5 -- 1 2002.
[4937745.183213] qla2xxx [0000:92:00.1]-801c:4: Abort command issued nexus=4:4:73 -- 1 2002.
[4937745.183844] qla2xxx [0000:92:00.1]-801c:4: Abort command issued nexus=4:5:5 -- 1 2002.
[4937745.184038] qla2xxx [0000:92:00.1]-801c:4: Abort command issued nexus=4:4:73 -- 1 2002.
[4937745.184919] invalid opcode: 0000 [#1] SMP
[4937745.185173] Modules linked in: ...
[4937745.188237] CPU: 18 PID: 0 Comm: swapper/18 Not tainted 4.1.12-61.1.9.el6uek.x86_64 #2
[4937745.188691] Hardware name: Oracle Corporation SUN BLADE X4-2B /BD,ASSY,PCB,X4-2B , BIOS 28010200 01/16/2014
[4937745.189157] task: ffff880227fa9c00 ti: ffff880227fc0000 task.ti: ffff880227fc0000
[4937745.189607] RIP: e030:[<ffffffff812ed130>] [<ffffffff812ed130>] blk_finish_request+0xd0/0xe0
[4937745.190104] RSP: e02b:ffff88022d483d78 EFLAGS: 00010083
[4937745.190339] RAX: 0000000000000280 RBX: ffff8801c4508730 RCX: 0000000000000280
[4937745.190791] RDX: 0000000000008b5a RSI: 0000000000000000 RDI: ffff8801c4508730
[4937745.191246] RBP: ffff88022d483d88 R08: 0000000000000000 R09: 0000000000004000
[4937745.191694] R10: 000000000000000b R11: 0000000000007ffe R12: 0000000000000000
[4937745.192153] R13: ffff88022374d000 R14: ffff880184cb88c0 R15: ffff8800536ccc90
[4937745.197930] FS: 0000000000000000(0000) GS:ffff88022d480000(0000) knlGS:ffff88022d480000
[4937745.198389] CS: e033 DS: 002b ES: 002b CR0: 0000000080050033
[4937745.198627] CR2: 00000000016e1f18 CR3: 000000010caed000 CR4: 0000000000042660
[4937745.199080] Stack:
[4937745.199309] ffff8801c4508730 0000000000000000 ffff88022d483dd8 ffffffff814ac82f
[4937745.199790] ffff88022d483da8 0000000000000280 ffff88022d483dd8 ffff880184cb88c0
[4937745.200290] ffff8801c4508730 0000000000000000 0000000000000000 0000000000000000
[4937745.200745] Call Trace:
[4937745.200968] <IRQ>
[4937745.200986] [<ffffffff814ac82f>] scsi_end_request+0x11f/0x1e0
[4937745.201422] [<ffffffff814accfc>] scsi_io_completion+0xac/0x500
[4937745.201651] [<ffffffff814a3bb0>] scsi_finish_command+0xf0/0x150
[4937745.201875] [<ffffffff814ad2ba>] scsi_softirq_done+0x14a/0x160
[4937745.202103] [<ffffffff812f3c66>] blk_done_softirq+0x86/0xa0
[4937745.202333] [<ffffffff8108879a>] __do_softirq+0x10a/0x350
[4937745.202558] [<ffffffff81088b55>] irq_exit+0x125/0x130
[4937745.202787] [<ffffffff813e5a89>] xen_evtchn_do_upcall+0x39/0x50
[4937745.203020] [<ffffffff816cce5e>] xen_do_hypervisor_callback+0x1e/0x40
[4937745.203247] <EOI>
[4937745.203263] [<ffffffff810013aa>] ? xen_hypercall_sched_op+0xa/0x20
[4937745.203703] [<ffffffff810013aa>] ? xen_hypercall_sched_op+0xa/0x20
[4937745.203930] [<ffffffff8100baf0>] ? xen_safe_halt+0x10/0x20
[4937745.204160] [<ffffffff81022abe>] ? default_idle+0x1e/0x100
[4937745.204387] [<ffffffff8102210f>] ? arch_cpu_idle+0xf/0x20
[4937745.204614] [<ffffffff810c8f25>] ? cpuidle_idle_call+0x135/0x1e0
[4937745.204841] [<ffffffff810c91c5>] ? cpu_idle_loop+0x1f5/0x220
[4937745.205070] [<ffffffff810c920b>] ? cpu_startup_entry+0x1b/0x70
[4937745.205294] [<ffffffff810c924f>] ? cpu_startup_entry+0x5f/0x70
[4937745.205524] [<ffffffff81013a5a>] ? cpu_bringup_and_idle+0x2a/0x40
[4937745.205749] Code: 89 de e8 a4 14 00 00 e9 6b ff ff ff 83 7b 48 01 0f 85
78 ff ff ff 48 8b 7b 30 48 81 c7 98 01 00 00 e8 75 6b ea ff e9 63 ff ff ff
<0f> 0b eb fe 66 66 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 48
[4937745.206811] RIP [<ffffffff812ed130>] blk_finish_request+0xd0/0xe0
[4937745.207046] RSP <ffff88022d483d78>
[4937745.207687] ---[ end trace 0b43a57bdab9464f ]---
[4937745.207693] ------------[ cut here ]------------

On 05/25/2018 02:30 PM, Madhani, Himanshu wrote:
> Hi Jianchao,
>
> Do you have any debug logs collected for us to look at this in details.
>
> Can you provide me crash/vmlinux/modules for details analysis.
>
> Thanks,
> himanshu
>
> ïOn 5/24/18, 6:49 AM, "Madhani, Himanshu" <Himanshu.Madhani@xxxxxxxxxx> wrote:
>
>
> > On May 24, 2018, at 2:09 AM, jianchao.wang <jianchao.w.wang@xxxxxxxxxx> wrote:
> >
> > Hi Himanshu
> >
> > Thanks god get response from your side finally :)
> > I get qla2xxx-upstream@xxxxxxxxxx from the maintainer information of driver/scsi/qla2xxx
> > Looks like it should be modified.
> >
> Sorry for delay. I do try to respond quickly to any emails received on that ID as well.
>
> Weâll keep it for now and Iâll look into updating it, if needed.
>
> > Thanks
> > Jianchao
> >
> > On 05/24/2018 12:21 PM, Madhani, Himanshu wrote:
> >> Hi,
> >>
> >> Yes. We'll look at this issue.
> >>
> >> Thanks,
> >> Himanshu
> >>
> >>> -----Original Message-----
> >>> From: jianchao.wang [mailto:jianchao.w.wang@xxxxxxxxxx]
> >>> Sent: Wednesday, May 23, 2018 6:51 PM
> >>> To: Dept-Eng QLA2xxx Upstream <qla2xxx-upstream@xxxxxxxxxx>; Madhani,
> >>> Himanshu <Himanshu.Madhani@xxxxxxxxxx>; jthumshirn@xxxxxxx
> >>> Cc: linux-scsi@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> >>> jejb@xxxxxxxxxxxxxxxxxx; Martin K. Petersen <martin.petersen@xxxxxxxxxx>;
> >>> Junxiao Bi <junxiao.bi@xxxxxxxxxx>
> >>> Subject: Re: BUG: scsi/qla2xxx: BUG_ON(blk_queued_rq(req) is triggered in
> >>> blk_finish_request
> >>>
> >>> Would anyone please take a look at this ?
> >>>
> >>> Thanks in advance
> >>> Jianchao
> >>>
> >>> On 05/23/2018 11:55 AM, jianchao.wang wrote:
> >>>>
> >>>>
> >>>> Hi all
> >>>>
> >>>> Our customer met a panic triggered by BUG_ON in blk_finish_request.
> >>>>> From the dmesg log, the BUG_ON was triggered after command abort
> >>> occurred many times.
> >>>> There is a race condition in the following scenario.
> >>>>
> >>>> cpu A cpu B
> >>>> kworker interrupt
> >>>>
> >>>> scmd_eh_abort_handler()
> >>>> -> scsi_try_to_abort_cmd()
> >>>> -> qla2xxx_eh_abort()
> >>>> -> qla2x00_eh_wait_on_command() qla2x00_status_entry()
> >>>> -> qla2x00_sp_compl()
> >>>> -> qla2x00_sp_free_dma()
> >>>> -> scsi_queue_insert()
> >>>> -> __scsi_queue_insert()
> >>>> -> blk_requeue_request()
> >>>> -> blk_clear_rq_complete()
> >>>> -> scsi_done
> >>>> -> blk_complete_request
> >>>> -> blk_mark_rq_complete
> >>>> -> elv_requeue_request() -> __blk_complete_request()
> >>>> -> __elv_add_request()
> >>>> // req will be queued here
> >>>> BLK_SOFTIRQ
> >>>> scsi_softirq_done()
> >>>> -> scsi_finish_command()
> >>>> -> scsi_io_completion()
> >>>> -> scsi_end_request()
> >>>> -> blk_finish_request() //
> >>> BUG_ON(blk_queued_rq(req)) !!!
> >>>>
> >>>> The issue will not be triggered most of time, because the request is marked as
> >>> complete by timeout path.
> >>>> So the scsi_done from qla2x00_sp_compl does nothing.
> >>>> But as the scenario above, if the complete state has been cleaned by
> >>> blk_requeue_request, we will get
> >>>> the request both requeued and completed, and then
> >>> BUG_ON(blk_queued_rq(req)) in blk_finish_request comes up.
> >>>>
> >>>> Is there any solution for this in qla2xxx driver side ?
> >>>>
> >>>> Thanks
> >>>> Jianchao
> >>>>
> >>>>
>
> Thanks,
> - Himanshu
>
>
>

Next message: Joe Perches: "Re: [PATCH] gpu: Consistently use octal not symbolic permissions"
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