Re: [PATCH] mm: alloc_contig: re-allow CMA to compact FS pages

[Michal Hocko <mhocko@suse.com>]

On Fri 13-01-17 12:51:55, Lucas Stach wrote:
> Commit 73e64c51afc5 (mm, compaction: allow compaction for GFP_NOFS requests)
> changed compation to skip FS pages if not explicitly allowed to touch them,
> but missed to update the CMA compact_control.
> 
> This leads to a very high isolation failure rate, crippling performance of
> CMA even on a lightly loaded system. Re-allow CMA to compact FS pages by
> setting the correct GFP flags, restoring CMA behavior and performance to
> the kernel 4.9 level.
> 
> Fixes: 73e64c51afc5 (mm, compaction: allow compaction for GFP_NOFS requests)
> Signed-off-by: Lucas Stach <l.stach@pengutronix.de>

Acked-by: Michal Hocko <mhocko@suse.com>

Thanks for catching that.

> ---
>  mm/page_alloc.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 8d5d82c8a85a..eced9fee582b 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -7255,6 +7255,7 @@ int alloc_contig_range(unsigned long start, unsigned long end,
>  		.zone = page_zone(pfn_to_page(start)),
>  		.mode = MIGRATE_SYNC,
>  		.ignore_skip_hint = true,
> +		.gfp_mask = GFP_KERNEL,
>  	};
>  	INIT_LIST_HEAD(&cc.migratepages);
>  
> -- 
> 2.11.0
> 

-- 
Michal Hocko
SUSE Labs

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