Re: BUG_ON() in pfn_swap_entry_to_page()

Ritesh Harjani
2022-03-22T18:53:21Z

On 22/03/22 06:25PM, Sebastian Andrzej Siewior wrote:
> Run into
>
> |kernel BUG at include/linux/swapops.h:258!
> |invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
> |CPU: 10 PID: 1741 Comm: malloc-mem Not tainted 5.17.0-next-20220322 #19
> |Hardware name: Intel Corporation S2600CP/S2600CP, BIOS SE5C600.86B.02.03.0003.041920141333 04/19/2014
> |RIP: 0010:migration_entry_wait_on_locked+0x233/0x2c0
> |Code: 66 90 e9 8a fe ff ff 66 90 e9 3d ff ff ff 48 8b 43 08 a8 01 0f 85 87 00 00 00 66 90 48 89 d8 48 8b 00 a8 01 0f 85 23 fe ff ff <0f> 0b 48 83 e8 01 48 89 c3 e9 29 fe ff ff 65 48 8b 04 25 00 c0 01
> |RSP: 0000:ffffc9000a44bd78 EFLAGS: 00010246
> |RAX: 002fffff80000000 RBX: ffffea0014a20000 RCX: ffffffff5aeffe00
> |RDX: ffff88811b42e200 RSI: 0000000000000000 RDI: 000000000000001f
> |RBP: ffff88811b42e200 R08: 0000000000000001 R09: 0000000000000000
> |R10: 0000000000000000 R11: 0000000000000000 R12: 00007f7131200000
> |R13: 0000000000000c48 R14: 0400000000000000 R15: fff000003fffffff
> |FS: 00007f7145570580(0000) GS:ffff888a2aa80000(0000) knlGS:0000000000000000
> |CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> |CR2: 00007f7131200000 CR3: 00000006f42c4006 CR4: 00000000000606e0
> |Call Trace:
> | <TASK>
> | __handle_mm_fault+0x2bf/0x1810
> | handle_mm_fault+0x136/0x3e0
> | exc_page_fault+0x1d2/0x850
> | asm_exc_page_fault+0x22/0x30

Based on call stack, this looks similar to the issue reported here [1].
I just happen to stumble upon it, but haven't checked any details of why this
can trigger though.

[1]: https://lore.kernel.org/all/20220317080504.GC735@xsang-OptiPlex-9020/

-ritesh

>
> This is the BUG_ON() in pfn_swap_entry_to_page(). The box itself has no
> swapspace configured. Is this something known?
>
> Sebastian
>