Re: [PATCH RFC v2 2/7] mm: memory_failure: Allow truncate_error_folio to return MF_DELAYED

Miaohe Lin
2026-03-30T07:02:13Z

On 2026/3/20 7:30, Lisa Wang wrote:
> The .error_remove_folio a_ops is used by different filesystems to handle
> folio truncation upon discovery of a memory failure in the memory
> associated with the given folio.
>
> Currently, MF_DELAYED is treated as an error, causing "Failed to punch
> page" to be written to the console. MF_DELAYED is then relayed to the
> caller of truncate_error_folio() as MF_FAILED. This further causes
> memory_failure() to return -EBUSY, which then always causes a SIGBUS.
>
> This is also implies that regardless of whether the thread's memory
> corruption kill policy is PR_MCE_KILL_EARLY or PR_MCE_KILL_LATE, a
> memory failure with MF_DELAYED will always cause a SIGBUS.
>
> Update truncate_error_folio() to return MF_DELAYED to the caller if the
> .error_remove_folio() callback reports MF_DELAYED.
>
> Signed-off-by: Lisa Wang <wyihan@google.com>
> ---
> mm/memory-failure.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 4f143334d5a1..57f7762e7418 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -941,6 +941,8 @@ static int truncate_error_folio(struct folio *folio, unsigned long pfn,
> if (mapping->a_ops->error_remove_folio) {
> int err = mapping->a_ops->error_remove_folio(mapping, folio);
>
> + if (err == MF_DELAYED)
> + return err;

Will it be better to add a pr_info here to provide some information for users?

Thanks.
.