Re: [PATCH v2] mm/page_alloc: call check_new_pages() while zone spinlock is not held

[Mel Gorman]

On Fri, Mar 04, 2022 at 09:02:15AM -0800, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@xxxxxxxxxx>
> 
> For high order pages not using pcp, rmqueue() is currently calling
> the costly check_new_pages() while zone spinlock is held,
> and hard irqs masked.
> 
> This is not needed, we can release the spinlock sooner to reduce
> zone spinlock contention.
> 
> Note that after this patch, we call __mod_zone_freepage_state()
> before deciding to leak the page because it is in bad state.
> 
> v2: We need to keep interrupts disabled to call __mod_zone_freepage_state()
> 
> Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
> Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
> Cc: Vlastimil Babka <vbabka@xxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxxxx>
> Cc: Shakeel Butt <shakeelb@xxxxxxxxxx>
> Cc: Wei Xu <weixugc@xxxxxxxxxx>
> Cc: Greg Thelen <gthelen@xxxxxxxxxx>
> Cc: Hugh Dickins <hughd@xxxxxxxxxx>
> Cc: David Rientjes <rientjes@xxxxxxxxxx>

Ok, this is only more expensive in the event pages on the free list have
been corrupted whch is already very unlikely so thanks!

Acked-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>

-- 
Mel Gorman
SUSE Labs