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

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

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).

> 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.

Regarding 1): tools/testing/selftests/mm/config includes the config 
options we expect to be set for running MM tests. Extending that might 
take a while until environments like 0day would pick up such changes. If 
you require something else, make your test SKIP tests if the relevant 
kernel support is not there (e.g., sense support and conditionally skip).

-- 
Cheers

David