From: Vlastimil Babka <vbabka@suse.cz>
To: Vasily Averin <vvs@virtuozzo.com>, Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
Vladimir Davydov <vdavydov.dev@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
cgroups@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, kernel@openvz.org,
Mel Gorman <mgorman@techsingularity.net>,
Uladzislau Rezki <urezki@gmail.com>
Subject: Re: [PATCH memcg] mm/page_alloc.c: avoid statistic update with 0
Date: Fri, 8 Oct 2021 13:47:00 +0200 [thread overview]
Message-ID: <29155011-f884-b0e5-218e-911039568acb@suse.cz> (raw)
In-Reply-To: <b2371951-bb8a-e62e-8d33-10830bbf6275@virtuozzo.com>
On 10/8/21 11:24, Vasily Averin wrote:
> __alloc_pages_bulk can call __count_zid_vm_events and zone_statistics
> with nr_account = 0.
But that's not a bug, right? Just an effective no-op that's not commonly
happening, so is it worth the check?
> Fixes: 3e23060b2d0b ("mm/page_alloc: batch the accounting updates in the bulk allocator")
> Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
> ---
> mm/page_alloc.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 602819a232e5..e67113452ee8 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5364,9 +5364,10 @@ unsigned long __alloc_pages_bulk(gfp_t gfp, int preferred_nid,
> }
>
> local_unlock_irqrestore(&pagesets.lock, flags);
> -
> - __count_zid_vm_events(PGALLOC, zone_idx(zone), nr_account);
> - zone_statistics(ac.preferred_zoneref->zone, zone, nr_account);
> + if (nr_account) {
> + __count_zid_vm_events(PGALLOC, zone_idx(zone), nr_account);
> + zone_statistics(ac.preferred_zoneref->zone, zone, nr_account);
> + }
> if (objcg)
> memcg_bulk_post_charge_hook(objcg, nr_pre_charge - nr_account);
>
>
next prev parent reply other threads:[~2021-10-08 11:47 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-08 9:24 [PATCH memcg] mm/page_alloc.c: avoid statistic update with 0 Vasily Averin
2021-10-08 11:47 ` Vlastimil Babka [this message]
2021-10-12 10:42 ` Vasily Averin
2021-10-12 11:09 ` David Hildenbrand
2021-10-12 11:38 ` Mel Gorman
2021-10-12 12:02 ` Chris Down
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