linux-kernel - Re: [PATCH -mm 1/2] mm: vmscan: account slab pages on memcg reclaim

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 12 Jan 2015 17:18:39 -0500
From:	Johannes Weiner <hannes@...xchg.org>
To:	Vladimir Davydov <vdavydov@...allels.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Michal Hocko <mhocko@...e.cz>,
	Vlastimil Babka <vbabka@...e.cz>, Mel Gorman <mgorman@...e.de>,
	Rik van Riel <riel@...hat.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH -mm 1/2] mm: vmscan: account slab pages on memcg reclaim

On Mon, Jan 12, 2015 at 12:30:37PM +0300, Vladimir Davydov wrote:
> Since try_to_free_mem_cgroup_pages() can now call slab shrinkers, we
> should initialize reclaim_state and account reclaimed slab pages in
> scan_control->nr_reclaimed.
> 
> Signed-off-by: Vladimir Davydov <vdavydov@...allels.com>
> ---
>  mm/vmscan.c |   33 ++++++++++++++++++++++-----------
>  1 file changed, 22 insertions(+), 11 deletions(-)
> 
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 16f3e45742d6..b2c041139a51 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -367,13 +367,16 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl,
>   * the ->seeks setting of the shrink function, which indicates the
>   * cost to recreate an object relative to that of an LRU page.
>   *
> - * Returns the number of reclaimed slab objects.
> + * Returns the number of reclaimed slab objects. The number of reclaimed
> + * pages is added to *@..._nr_reclaimed.
>
>  static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
>  				 struct mem_cgroup *memcg,
>  				 unsigned long nr_scanned,
> -				 unsigned long nr_eligible)
> +				 unsigned long nr_eligible,
> +				 unsigned long *ret_nr_reclaimed)

Can't we just return the number of pages directly from this function?

> @@ -426,7 +434,7 @@ void drop_slab_node(int nid)
>  		freed = 0;
>  		do {
>  			freed += shrink_slab(GFP_KERNEL, nid, memcg,
> -					     1000, 1000);
> +					     1000, 1000, &nr_reclaimed);
>  		} while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL);
>  	} while (freed > 10);

This is the only caller that cares about the return value, and it's a
magic number that could probably be changed to comparing with a magic
number of pages instead.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/