Re: [PATCH] mm: page_alloc: dump migrate-failed pages only at -EBUSY

[Minchan Kim]

On Wed, May 19, 2021 at 02:33:41PM -0700, Minchan Kim wrote:
> alloc_contig_dump_pages aims for helping debugging page migration
> failure by page refcount mismatch or something else of page itself
> from migration handler function. However, in -ENOMEM case, there is
> nothing to get clue from page descriptor information so just
> dump pages only when -EBUSY happens.
> 
> Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
> ---
>  mm/page_alloc.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 3100fcb08500..c0a2971dc755 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -8760,7 +8760,8 @@ static int __alloc_contig_migrate_range(struct compact_control *cc,
>  
>  	lru_cache_enable();
>  	if (ret < 0) {
> -		alloc_contig_dump_pages(&cc->migratepages);
> +		if (ret == -EBUSY)
> +			alloc_contig_dump_pages(&cc->migratepages);
>  		putback_movable_pages(&cc->migratepages);
>  		return ret;
>  	}
> -- 
> 2.31.1.751.gd2f1c929bd-goog
> 

Resend with a little modifying description.