Hi, this is your Linux kernel regression tracker speaking. Top-posting for once, to make this easy accessible to everyone.

Below issue that started to happen between v5.10.80..v5.10.90 was recently reported to bugzilla, but the reporter didn't even get a single reply afaics. Could somebody maybe take a look? Bisection is likely no easy in this case, so a few tips to narrow down the area to search might help a lot here.

https://bugzilla.kernel.org/show_bug.cgi?id=215562

Ciao, Thorsten

On 03.02.22 16:03, Thorsten Leemhuis wrote:

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 regzbot, my Linux kernel regression tracking bot (https://linux-regtracking.leemhuis.info/regzbot/). I'm only posting this mail to get things rolling again and hence don't need to be CC on all further activities wrt to this regression.

---

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Hint for reporters: when reporting a regression it's in your interest to tell #regzbot about it in the report, as that will ensure the regression gets on the radar of regzbot and the regression tracker. That's in your interest, as they will make sure the report won't fall through the cracks unnoticed.

Hint for developers: you normally don't need to care about regzbot once it's involved. Fix the issue as you normally would, just remember to include a 'Link:' tag to the report in the commit message, as explained in Documentation/process/submitting-patches.rst That aspect was recently was made more explicit in commit 1f57bd42b77c: https://git.kernel.org/linus/1f57bd42b77c