Re: xfs/folio splat with v6.14-rc1

[Zi Yan <ziy@nvidia.com>]

On 9 Feb 2025, at 23:02, Qi Zheng wrote:

> Hi Zi,
>
> On 2025/2/10 11:35, Zi Yan wrote:
>> On 7 Feb 2025, at 17:17, Matthew Wilcox wrote:
>>
>>> On Fri, Feb 07, 2025 at 04:29:36PM +0100, Christian Brauner wrote:
>>>> while true; do ./xfs.run.sh "generic/437"; done
>>>>
>>>> allows me to reproduce this fairly quickly.
>>>
>>> on holiday, back monday
>>
>> git bisect points to commit
>> 4817f70c25b6 ("x86: select ARCH_SUPPORTS_PT_RECLAIM if X86_64").
>> Qi is cc'd.
>>
>> After deselect PT_RECLAIM on v6.14-rc1, the issue is gone.
>> At least, no splat after running for more than 300s,
>> whereas the splat is usually triggered after ~20s with
>> PT_RECLAIM set.
>
> The PT_RECLAIM mainly made the following two changes:
>
> 1) try to reclaim page table pages during madvise(MADV_DONTNEED)
> 2) Unconditionally select MMU_GATHER_RCU_TABLE_FREE
>
> Will ./xfs.run.sh "generic/437" perform the madvise(MADV_DONTNEED)?

Yes. See: https://github.com/kdave/xfstests/blob/master/src/t_mmap_cow_race.c#L34

>
> Anyway, I will try to reproduce it locally and troubleshoot it.

You will need xfstests and run "while true; do sudo ./check "generic/437"; done".

The local.config for xfstests is at:
https://lore.kernel.org/linux-mm/20250207-anbot-bankfilialen-acce9d79a2c7@brauner/


--
Best Regards,
Yan, Zi