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Date: Tue, 5 Jun 2018 09:11:18 +0800
From: "jianchao.wang" <jianchao.w.wang@...cle.com>
To: "Madhani, Himanshu" <Himanshu.Madhani@...ium.com>
Cc: Dept-Eng QLA2xxx Upstream <qla2xxx-upstream@...ium.com>,
"jthumshirn@...e.de" <jthumshirn@...e.de>,
"linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"jejb@...ux.vnet.ibm.com" <jejb@...ux.vnet.ibm.com>,
"Martin K. Petersen" <martin.petersen@...cle.com>,
Junxiao Bi <junxiao.bi@...cle.com>
Subject: Re: scsi/qla2xxx: BUG_ON(blk_queued_rq(req) is triggered in
blk_finish_request
Hi Himanshu
Would you please give some comment here?
Thanks
Jianchao
On 05/30/2018 11:28 AM, jianchao.wang wrote:
> Hi Himanshu
>
> Thanks for your kindly response.
>
> On 05/30/2018 01:44 AM, Madhani, Himanshu wrote:
>> Thanks for the information. I was out for couple days. Still working through my emails.
>>
>> Without core dump shared with us, things become hard to debug. We'll take a look at this data.
>>
>> Also, if you have any reproducer test case, Can you share that with us so that we can try to trigger It internally and see if we have better luck debugging that.
>
> This issue occurred in customer's environment twice till now, there is no reproduce steps.
>
> If you have time, would you please look at our analysis to see whether it is reasonable ?
> The kernel is not newest, but there should be the same issue in mainline with scsi + block legacy
> The key point here is:
> when the aborted command returns in irq context, it will invoke scsi_done, then blk_complete_request.
> however, the scsi recovery context could clear the ATOM_COMPLETE and requeue the request before irq
> context get it.
>
> Thanks
> Jianchao
>
>>
>> On 5/28/18, 6:11 PM, "jianchao.wang" <jianchao.w.wang@...cle.com> wrote:
>>
>> Hi Himanshu
>>
>> do you need any other information ?
>>
>> Thanks
>> Jianchao
>>
>> On 05/25/2018 02:48 PM, jianchao.wang wrote:
>> > 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_COMPLETE should 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
>> >>
>> >> On 5/24/18, 6:49 AM, "Madhani, Himanshu" <Himanshu.Madhani@...ium.com> wrote:
>> >>
>> >>
>> >> > On May 24, 2018, at 2:09 AM, jianchao.wang <jianchao.w.wang@...cle.com> wrote:
>> >> >
>> >> > Hi Himanshu
>> >> >
>> >> > Thanks god get response from your side finally :)
>> >> > I get qla2xxx-upstream@...gic.com 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.
>> >>
>> >> We’ll keep it for now and I’ll 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@...cle.com]
>> >> >>> Sent: Wednesday, May 23, 2018 6:51 PM
>> >> >>> To: Dept-Eng QLA2xxx Upstream <qla2xxx-upstream@...ium.com>; Madhani,
>> >> >>> Himanshu <Himanshu.Madhani@...ium.com>; jthumshirn@...e.de
>> >> >>> Cc: linux-scsi@...r.kernel.org; linux-kernel@...r.kernel.org;
>> >> >>> jejb@...ux.vnet.ibm.com; Martin K. Petersen <martin.petersen@...cle.com>;
>> >> >>> Junxiao Bi <junxiao.bi@...cle.com>
>> >> >>> 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
>> >>
>> >>
>> >>
>> >
>>
>>
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