Bug 215562 - BUG: unable to handle page fault in cache_reap (fwd from bugzilla)

[Thorsten Leemhuis <regressions@leemhuis.info>]

Hi, this is your Linux kernel regression tracker speaking.

There is a regression in bugzilla.kernel.org I'd like to add to the
tracking:

#regzbot introduced: v5.10.80..v5.10.90
#regzbot from: Patrick Schaaf <kernelorg@bof.de>
#regzbot title: mm: unable to handle page fault in cache_reap
#regzbot link: https://bugzilla.kernel.org/show_bug.cgi?id=215562

Quote:

> We've been running self-built 5.10.x kernels on DL380 hosts for quite a while, also inside the VMs there.
> 
> With I think 5.10.90 three weeks or so back, we experienced a lockup upon umounting a larger, dirty filesystem on the host side, unfortunately without capturing a backtrace back then.
> 
> Today something feeling similar, happened again, on a machine running 5.10.93 both on the host and inside its 10 various VMs.
> 
> Problem showed shortly (minutes) after shutting down one of the VMs (few hundred GB memory / dataset, VM shutdown was complete already; direct I/O), and then some LVM volume renames, a quick short outside ext4 mount followed by an umount (8 GB volume, probably a few hundred megabyte only to write). Actually monitoring suggests that disk writes were already done about a minute before the onset.
> 
> What we then experienced, was the following BUG:, followed by one after the other CPU saying goodbye with soft lockup messages over the course of a few minutes; meanwhile there was no more pinging the box, logging in on console, etc. We hard powercycled and it recovered fully.
> 
> here's the BUG that was logged; if it is useful for someone to see the followup soft lockup messages, tell me + I'll add them.
> 
> Feb 02 15:22:27 kvm3j kernel: BUG: unable to handle page fault for address: ffffebde00000008
> Feb 02 15:22:27 kvm3j kernel: #PF: supervisor read access in kernel mode
> Feb 02 15:22:27 kvm3j kernel: #PF: error_code(0x0000) - not-present page
> Feb 02 15:22:27 kvm3j kernel: Oops: 0000 [#1] SMP PTI
> Feb 02 15:22:27 kvm3j kernel: CPU: 7 PID: 39833 Comm: kworker/7:0 Tainted: G          I       5.10.93-kvm #1
> Feb 02 15:22:27 kvm3j kernel: Hardware name: HP ProLiant DL380p Gen8, BIOS P70 12/20/2013
> Feb 02 15:22:27 kvm3j kernel: Workqueue: events cache_reap
> Feb 02 15:22:27 kvm3j kernel: RIP: 0010:free_block.constprop.0+0xc0/0x1f0
> Feb 02 15:22:27 kvm3j kernel: Code: 4c 8b 16 4c 89 d0 48 01 e8 0f 82 32 01 00 00 4c 89 f2 48 bb 00 00 00 00 00 ea ff ff 48 01 d0 48 c1 e8 0c 48 c1 e0 06 48 01 d8 <48> 8b 50 08 48 8d 4a ff 83 e2 01 48 >
> Feb 02 15:22:27 kvm3j kernel: RSP: 0018:ffffc9000252bdc8 EFLAGS: 00010086
> Feb 02 15:22:27 kvm3j kernel: RAX: ffffebde00000000 RBX: ffffea0000000000 RCX: ffff888889141b00
> Feb 02 15:22:27 kvm3j kernel: RDX: 0000777f80000000 RSI: ffff893d3edf3400 RDI: ffff8881000403c0
> Feb 02 15:22:27 kvm3j kernel: RBP: 0000000080000000 R08: ffff888100041300 R09: 0000000000000003
> Feb 02 15:22:27 kvm3j kernel: R10: 0000000000000000 R11: ffff888100041308 R12: dead000000000122
> Feb 02 15:22:27 kvm3j kernel: R13: dead000000000100 R14: 0000777f80000000 R15: ffff893ed8780d60
> Feb 02 15:22:27 kvm3j kernel: FS:  0000000000000000(0000) GS:ffff893d3edc0000(0000) knlGS:0000000000000000
> Feb 02 15:22:27 kvm3j kernel: CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> Feb 02 15:22:27 kvm3j kernel: CR2: ffffebde00000008 CR3: 000000048c4aa002 CR4: 00000000001726e0
> Feb 02 15:22:27 kvm3j kernel: Call Trace:
> Feb 02 15:22:27 kvm3j kernel:  drain_array_locked.constprop.0+0x2e/0x80
> Feb 02 15:22:27 kvm3j kernel:  drain_array.constprop.0+0x54/0x70
> Feb 02 15:22:27 kvm3j kernel:  cache_reap+0x6c/0x100
> Feb 02 15:22:27 kvm3j kernel:  process_one_work+0x1cf/0x360
> Feb 02 15:22:27 kvm3j kernel:  worker_thread+0x45/0x3a0
> Feb 02 15:22:27 kvm3j kernel:  ? process_one_work+0x360/0x360
> Feb 02 15:22:27 kvm3j kernel:  kthread+0x116/0x130
> Feb 02 15:22:27 kvm3j kernel:  ? kthread_create_worker_on_cpu+0x40/0x40
> Feb 02 15:22:27 kvm3j kernel:  ret_from_fork+0x22/0x30
> Feb 02 15:22:27 kvm3j kernel: Modules linked in: hpilo
> Feb 02 15:22:27 kvm3j kernel: CR2: ffffebde00000008
> Feb 02 15:22:27 kvm3j kernel: ---[ end trace ded3153d86a92898 ]---
> Feb 02 15:22:27 kvm3j kernel: RIP: 0010:free_block.constprop.0+0xc0/0x1f0
> Feb 02 15:22:27 kvm3j kernel: Code: 4c 8b 16 4c 89 d0 48 01 e8 0f 82 32 01 00 00 4c 89 f2 48 bb 00 00 00 00 00 ea ff ff 48 01 d0 48 c1 e8 0c 48 c1 e0 06 48 01 d8 <48> 8b 50 08 48 8d 4a ff 83 e2 01 48 >
> Feb 02 15:22:27 kvm3j kernel: RSP: 0018:ffffc9000252bdc8 EFLAGS: 00010086
> Feb 02 15:22:27 kvm3j kernel: RAX: ffffebde00000000 RBX: ffffea0000000000 RCX: ffff888889141b00
> Feb 02 15:22:27 kvm3j kernel: RDX: 0000777f80000000 RSI: ffff893d3edf3400 RDI: ffff8881000403c0
> Feb 02 15:22:27 kvm3j kernel: RBP: 0000000080000000 R08: ffff888100041300 R09: 0000000000000003
> Feb 02 15:22:27 kvm3j kernel: R10: 0000000000000000 R11: ffff888100041308 R12: dead000000000122
> Feb 02 15:22:27 kvm3j kernel: R13: dead000000000100 R14: 0000777f80000000 R15: ffff893ed8780d60
> Feb 02 15:22:27 kvm3j kernel: FS:  0000000000000000(0000) GS:ffff893d3edc0000(0000) knlGS:0000000000000000
> Feb 02 15:22:27 kvm3j kernel: CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> Feb 02 15:22:27 kvm3j kernel: CR2: ffffebde00000008 CR3: 000000048c4aa002 CR4: 00000000001726e0

Ciao, Thorsten (wearing his 'Linux kernel regression tracker' hat)

P.S.: As a Linux kernel regression tracker I'm getting a lot of reports
on my table. I can only look briefly into most of them. Unfortunately
therefore I sometimes will get things wrong or miss something important.
I hope that's not the case here; if you think it is, don't hesitate to
tell me about it in a public reply, that's in everyone's interest.

BTW, I have no personal interest in this issue, which is tracked using
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(https://linux-regtracking.leemhuis.info/regzbot/). I'm only posting
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all further activities wrt to this regression.

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