linux-kernel - Re: [PATCH] mm, slub: Consider rest of partial list if acquire

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Message-ID: <CAAmzW4P9OQTh0TYfKUc6Q6z1j0-ewfmOD3c18b9tHPNy0T45hQ@mail.gmail.com>
Date:   Tue, 29 Dec 2020 10:10:34 +0900
From:   Joonsoo Kim <js1304@...il.com>
To:     Jann Horn <jannh@...gle.com>
Cc:     Christoph Lameter <cl@...ux.com>,
        Pekka Enberg <penberg@...nel.org>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mm, slub: Consider rest of partial list if acquire_slab() fails

2020년 12월 28일 (월) 오후 10:10, Jann Horn <jannh@...gle.com>님이 작성:
>
> acquire_slab() fails if there is contention on the freelist of the page
> (probably because some other CPU is concurrently freeing an object from the
> page). In that case, it might make sense to look for a different page
> (since there might be more remote frees to the page from other CPUs, and we
> don't want contention on struct page).
>
> However, the current code accidentally stops looking at the partial list
> completely in that case. Especially on kernels without CONFIG_NUMA set,
> this means that get_partial() fails and new_slab_objects() falls back to
> new_slab(), allocating new pages. This could lead to an unnecessary
> increase in memory fragmentation.
>
> Fixes: 7ced37197196 ("slub: Acquire_slab() avoid loop")
> Signed-off-by: Jann Horn <jannh@...gle.com>

Acked-by: Joonsoo Kim <iamjoonsoo.kim@....com>

Thanks.