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

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Date:   Mon, 7 Mar 2022 09:15:41 +0000
From:   Mel Gorman <mgorman@...hsingularity.net>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-mm <linux-mm@...ck.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Michal Hocko <mhocko@...nel.org>,
        Shakeel Butt <shakeelb@...gle.com>,
        Wei Xu <weixugc@...gle.com>, Greg Thelen <gthelen@...gle.com>,
        Hugh Dickins <hughd@...gle.com>,
        David Rientjes <rientjes@...gle.com>
Subject: Re: [PATCH v2] mm/page_alloc: call check_new_pages() while zone
 spinlock is not held

On Fri, Mar 04, 2022 at 09:02:15AM -0800, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@...gle.com>
> 
> 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@...gle.com>
> Cc: Mel Gorman <mgorman@...hsingularity.net>
> Cc: Vlastimil Babka <vbabka@...e.cz>
> Cc: Michal Hocko <mhocko@...nel.org>
> Cc: Shakeel Butt <shakeelb@...gle.com>
> Cc: Wei Xu <weixugc@...gle.com>
> Cc: Greg Thelen <gthelen@...gle.com>
> Cc: Hugh Dickins <hughd@...gle.com>
> Cc: David Rientjes <rientjes@...gle.com>

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@...hsingularity.net>

-- 
Mel Gorman
SUSE Labs