Re: [PATCH v5 8/9] mm/collapse: call collapse_file() from collapse_single_pmd()

[Baolin Wang <baolin.wang@linux.alibaba.com>]

On 10/15/26 1:11 AM, Kiryl Shutsemau (Meta) wrote:
> collapse_scan_file() reads the page cache to decide whether a table is
> worth collapsing and, when it is, calls collapse_file() itself.  The
> caller cannot get between the decision and the collapse.
> 
> Move the collapse_file() call up into collapse_single_pmd(), so the scan
> stops at the decision.
> 
> Two things change with it.  The writeback retry re-runs collapse_file()
> alone instead of rescanning first; collapse_file() repeats the scan's
> checks under the page cache lock anyway.  And mm_khugepaged_scan_file
> fires before the collapse, so for an accepted table its status reads
> SCAN_SUCCEED; what the collapse made of the table is for
> mm_khugepaged_collapse_file to report.
> 
> Preparation for splitting a collapse into a scan under mmap_lock and a
> run without it.  The file scan has to stop where the anonymous one will.
> 
> Assisted-by: LLM
> Acked-by: David Hildenbrand (Arm) <david@kernel.org>
> Reviewed-by: Zi Yan <ziy@nvidia.com>
> Signed-off-by: Kiryl Shutsemau (Meta) <kas@kernel.org>
> ---

LGTM.
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>