Re: [PATCH V5 2/2] mm/khugepaged: retry with sync writeback for MADV_COLLAPSE

[David Hildenbrand (Red Hat)]

On 1/18/26 20:09, Shivank Garg wrote:
> When MADV_COLLAPSE is called on file-backed mappings (e.g., executable
> text sections), the pages may still be dirty from recent writes.
> collapse_file() will trigger async writeback and fail with
> SCAN_PAGE_DIRTY_OR_WRITEBACK (-EAGAIN).
>
> MADV_COLLAPSE is a synchronous operation where userspace expects
> immediate results. If the collapse fails due to dirty pages, perform
> synchronous writeback on the specific range and retry once.
>
> This avoids spurious failures for freshly written executables while
> avoiding unnecessary synchronous I/O for mappings that are already clean.
>
> Reported-by: Branden Moore <Branden.Moore@xxxxxxx>
> Closes: https://lore.kernel.org/all/4e26fe5e-7374-467c-a333-9dd48f85d7cc@xxxxxxx
> Fixes: 34488399fa08 ("mm/madvise: add file and shmem support to MADV_COLLAPSE")
> Suggested-by: David Hildenbrand <david@xxxxxxxxxx>
> Tested-by: Lance Yang <lance.yang@xxxxxxxxx>
> Signed-off-by: Shivank Garg <shivankg@xxxxxxx>
> ---

Looks good to me now, thanks Shivank!

Acked-by: David Hildenbrand (Red Hat) <david@xxxxxxxxxx>

--
Cheers

David