linux-kernel - Re: [linux] [5.19.0] task hung for indefinite time with call traces when rebooted with Kexec

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Date:   Thu, 18 Aug 2022 15:13:56 +0530
From:   Tasmiya Nalatwad <tasmiya@...ux.vnet.ibm.com>
To:     Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     abdhalee@...ux.vnet.ibm.com, mputtash@...ux.vnet.com,
        sachinp@...ux.vnet.com
Subject: Re: [linux] [5.19.0] task hung for indefinite time with call traces
 when rebooted with Kexec

Greetings,


Please find the location in source code from where i am seeing the call 
traces generating

File : kernel/hung_task.c

         /*
          * Ok, the task did not get scheduled for more than 2 minutes,
          * complain:
          */
         if (sysctl_hung_task_warnings) {
                 if (sysctl_hung_task_warnings > 0)
                         sysctl_hung_task_warnings--;
                 pr_err("INFO: task %s:%d blocked for more than %ld 
seconds.\n",
                        t->comm, t->pid, (jiffies - t->last_switch_time) 
/ HZ);
                 pr_err("      %s %s %.*s\n",
                         print_tainted(), init_utsname()->release,
                         (int)strcspn(init_utsname()->version, " "),
                         init_utsname()->version);
                 pr_err("\"echo 0 > 
/proc/sys/kernel/hung_task_timeout_secs\""
                         " disables this message.\n");
                 sched_show_task(t);
                 hung_task_show_lock = true;

                 if (sysctl_hung_task_all_cpu_backtrace)
                         hung_task_show_all_bt = true;
         }

         touch_nmi_watchdog();
}


On 8/6/22 15:30, Tetsuo Handa wrote:
> On 2022/08/05 15:54, Tasmiya Nalatwad wrote:
>> Greetings,
>>
>> [linux] [5.19.0] task hung for indefinite time with call traces when rebooted with Kexec, A restart is required to recover the machine.
> 
> kexec is waiting for workqueues ("kworker/3:1" and "kworker/3:0") to complete.
> If this problem happens only when rebooting with kexec, something in kexec path
> might be preventing these workqueues from completing.
> 
> Anyway, please repost with locations in source code like syzbot report does.
> 
> [ 1104.673153] task:kworker/3:1     state:D stack:    0 pid:  221 ppid:     2 flags:0x00000800
> [ 1104.673160] Workqueue: fc_wq_0 fc_rport_final_delete [scsi_transport_fc]
> [ 1104.673170] Call Trace:
> [ 1104.673173] [c0000000060eb860] [0000000000000004] 0x4 (unreliable)
> [ 1104.673178] [c0000000060eba50] [c00000000001e378] __switch_to+0x288/0x4a0
> [ 1104.673185] [c0000000060ebab0] [c000000000d23e84] __schedule+0x2c4/0x8c0
> [ 1104.673190] [c0000000060ebb80] [c000000000d244e8] schedule+0x68/0x130
> [ 1104.673196] [c0000000060ebbb0] [c0000000008d4574] scsi_remove_target+0x314/0x390
> 
> [ 1104.673233] task:kworker/3:0     state:D stack:    0 pid:227332 ppid:     2 flags:0x00000880
> [ 1104.673237] Workqueue: fc_wq_0 fc_rport_final_delete [scsi_transport_fc]
> [ 1104.673243] Call Trace:
> [ 1104.673244] [c0000000726bb860] [c0000000001b9cb4] enqueue_entity+0x184/0x4f0 (unreliable)
> [ 1104.673250] [c0000000726bba50] [c00000000001e378] __switch_to+0x288/0x4a0
> [ 1104.673254] [c0000000726bbab0] [c000000000d23e84] __schedule+0x2c4/0x8c0
> [ 1104.673258] [c0000000726bbb80] [c000000000d244e8] schedule+0x68/0x130
> [ 1104.673262] [c0000000726bbbb0] [c0000000008d4574] scsi_remove_target+0x314/0x390
> [
> [ 1104.673295] task:kexec           state:D stack:    0 pid:228289 ppid:     1 flags:0x00040080
> [ 1104.673299] Call Trace:
> [ 1104.673301] [c000000069147510] [c00000000001e378] __switch_to+0x288/0x4a0
> [ 1104.673305] [c000000069147570] [c000000000d23e84] __schedule+0x2c4/0x8c0
> [ 1104.673309] [c000000069147640] [c000000000d244e8] schedule+0x68/0x130
> [ 1104.673313] [c000000069147670] [c000000000d2e028] schedule_timeout+0x348/0x3f0
> [ 1104.673317] [c000000069147750] [c000000000d2554c] wait_for_completion+0xcc/0x2b0
> [ 1104.673321] [c0000000691477d0] [c00000000017cbe8] flush_workqueue+0x158/0x520
> [ 1104.673325] [c000000069147870] [c00000000017d068] drain_workqueue+0xb8/0x240
> [ 1104.673329] [c000000069147930] [c0000000001825e0] destroy_workqueue+0x60/0x420
> [ 1104.673333] [c0000000691479c0] [c0080000009291e4] fc_remove_host+0x21c/0x280 [scsi_transport_fc]
> 
> 

-- 
Regards,
Tasmiya Nalatwad
IBM Linux Technology Center