Re: [PATCH 0/3] selftests/mm: add memory failure selftests

["David Hildenbrand (Red Hat)" <david@kernel.org>]

On 1/12/26 13:44, Miaohe Lin wrote:
> On 2026/1/12 19:33, Miaohe Lin wrote:
>> On 2026/1/12 17:40, David Hildenbrand (Red Hat) wrote:
>>> On 1/12/26 10:19, Miaohe Lin wrote:
>>>> On 2026/1/9 21:45, David Hildenbrand (Red Hat) wrote:
>>>>> On 1/7/26 10:37, Miaohe Lin wrote:
>>>>>> Introduce selftests to validate the functionality of memory failure.
>>>>>> These tests help ensure that memory failure handling for anonymous
>>>>>> pages, pagecaches pages works correctly, including proper SIGBUS
>>>>>> delivery to user processes, page isolation, and recovery paths.
>>>>>>
>>>>>> Currently madvise syscall is used to inject memory failures. And only
>>>>>> anonymous pages and pagecaches are tested. More test scenarios, e.g.
>>>>>> hugetlb, shmem, thp, will be added. Also more memory failure injecting
>>>>>> methods will be supported, e.g. APEI Error INJection, if required.
>>>>>
>>>>
>>>> Thanks for test and report. :)
>>>>
>>>>> 0day reports that these tests fail:
>>>>>
>>>>> # # ------------------------
>>>>> # # running ./memory-failure
>>>>> # # ------------------------
>>>>> # # TAP version 13
>>>>> # # 1..6
>>>>> # # # Starting 6 tests from 2 test cases.
>>>>> # # #  RUN           memory_failure.madv_hard.anon ...
>>>>> # # #            OK  memory_failure.madv_hard.anon
>>>>> # # ok 1 memory_failure.madv_hard.anon
>>>>> # # #  RUN           memory_failure.madv_hard.clean_pagecache ...
>>>>> # # # memory-failure.c:166:clean_pagecache:Expected setjmp (1) == 0 (0)
>>>>> # # # clean_pagecache: Test terminated by assertion
>>>>> # # #          FAIL  memory_failure.madv_hard.clean_pagecache
>>>>> # # not ok 2 memory_failure.madv_hard.clean_pagecache
>>>>> # # #  RUN           memory_failure.madv_hard.dirty_pagecache ...
>>>>> # # # memory-failure.c:207:dirty_pagecache:Expected unpoison_memory(self->pfn) (-16) == 0 (0)
>>>>> # # # dirty_pagecache: Test terminated by assertion
>>>>> # # #          FAIL  memory_failure.madv_hard.dirty_pagecache
>>>>> # # not ok 3 memory_failure.madv_hard.dirty_pagecache
>>>>> # # #  RUN           memory_failure.madv_soft.anon ...
>>>>> # # #            OK  memory_failure.madv_soft.anon
>>>>> # # ok 4 memory_failure.madv_soft.anon
>>>>> # # #  RUN           memory_failure.madv_soft.clean_pagecache ...
>>>>> # # # memory-failure.c:282:clean_pagecache:Expected variant->inject(self, addr) (-1) == 0 (0)
>>>>> # # # clean_pagecache: Test terminated by assertion
>>>>> # # #          FAIL  memory_failure.madv_soft.clean_pagecache
>>>>> # # not ok 5 memory_failure.madv_soft.clean_pagecache
>>>>> # # #  RUN           memory_failure.madv_soft.dirty_pagecache ...
>>>>> # # # memory-failure.c:319:dirty_pagecache:Expected variant->inject(self, addr) (-1) == 0 (0)
>>>>> # # # dirty_pagecache: Test terminated by assertion
>>>>> # # #          FAIL  memory_failure.madv_soft.dirty_pagecache
>>>>> # # not ok 6 memory_failure.madv_soft.dirty_pagecache
>>>>> # # # FAILED: 2 / 6 tests passed.
>>>>> # # # Totals: pass:2 fail:4 xfail:0 xpass:0 skip:0 error:0
>>>>> # # [FAIL]
>>>>> # not ok 71 memory-failure # exit=1
>>>>>
>>>>>
>>>>> Can the test maybe not deal with running in certain environments (config options etc)?
>>>>
>>>> To run the test, I think there should be:
>>>>     1.CONFIG_MEMORY_FAILURE and CONFIG_HWPOISON_INJECT should be enabled.
>>>>     2.Root privilege is required.
>>>>     3.For dirty/clean pagecache testcases, the test file "./clean-page-cache-test-file" and
>>>>       "./dirty-page-cache-test-file" are assumed to be created on non-memory file systems
>>>>       such as xfs, ext4, etc.
>>>>
>>>> Does your test environment break any of the above rules?
>>>
>>> It is 0day environment, so very likely yes. I suspect 1).
> 
> Hi David,
> 
> After taking a more close look, I think CONFIG_MEMORY_FAILURE and CONFIG_HWPOISON_INJECT should have been
> enabled in 0day environment or testcase memory_failure.madv_hard.anon should fail. memory_failure.madv_hard.anon
> will inject memory failure and expects seeing a SIGBUG signal.

Good point.

> 
>>>
>>>> Am I expected to add some code to
>>>> guard against this?
>>>
>>> Yes, at least some.
>>>
>>> Checking for root privileges is not required. The tests are commonly run from non-memory file systems, but, in theory, could be run from nfs etc.
>>>
>>> If you require special file systems, take a look at gup_longterm.o where we test for some fileystsem types.
> 
> And I think the cause of failures of testcases memory_failure.madv_hard.clean_pagecache and memory_failure.madv_hard.dirty_pagecache
> is they running on memory filesystems. The error pages are kept in page cache in that case while memory_failure.madv_hard.clean_pagecache
> expects to see the error page truncated.

Maybe they are run on shmem? Good question. (@Phil?)

> 
> But I have no idea why memory_failure.madv_soft.dirty_pagecache and memory_failure.madv_soft.clean_pagecache return -1(-EPERM?) when try
> to inject memory error through madvise syscall. It could be really helpful if more information can be provided.

Here is more information:

https://download.01.org/0day-ci/archive/20260110/202601100241.326d7cce-lkp@intel.com

Unfortunately no config yet. (@Phil, could we provide that one as well 
as part of that bundle?)

-- 
Cheers

David