Re: scsi/qla2xxx: BUG_ON(blk_queued_rq(req) is triggered in blk_finish_request
From: jianchao.wang
Date: Mon May 28 2018 - 21:11:54 EST
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_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
>>
>>
>>
>