Re: [PATCH] mm/memory-failure: fix infinite UCE for VM_PFNMAP pfn

[Miaohe Lin <linmiaohe@huawei.com>]

On 2025/8/6 10:05, Jinjiang Tu wrote:
> When memory_failure() is called for a already hwpoisoned pfn,
> kill_accessing_process() will be called to kill current task. However, if

Thanks for your patch.

> the vma of the accessing vaddr is VM_PFNMAP, walk_page_range() will skip
> the vma in walk_page_test() and return 0.
> 
> Before commit aaf99ac2ceb7 ("mm/hwpoison: do not send SIGBUS to processes
> with recovered clean pages"), kill_accessing_process() will return EFAULT.

I'm not sure but pfn_to_online_page should return NULL for VM_PFNMAP pages?
So memory_failure_dev_pagemap should handle these pages?

> For x86, the current task will be killed in kill_me_maybe().
> 
> However, after this commit, kill_accessing_process() simplies return 0,
> that means UCE is handled properly, but it doesn't actually. In such case,
> the user task will trigger UCE infinitely.

Did you ever trigger this loop?

Thanks.
.