From: Kirill Tkhai <ktkhai@virtuozzo.com>
To: Yang Shi <shy828301@gmail.com>,
guro@fb.com, shakeelb@google.com, david@fromorbit.com,
hannes@cmpxchg.org, mhocko@suse.com, akpm@linux-foundation.org
Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [v4 PATCH 04/11] mm: vmscan: remove memcg_shrinker_map_size
Date: Mon, 25 Jan 2021 11:35:58 +0300 [thread overview]
Message-ID: <af9204cb-2298-ee7c-5307-295d33befd8a@virtuozzo.com> (raw)
In-Reply-To: <20210121230621.654304-5-shy828301@gmail.com>
On 22.01.2021 02:06, Yang Shi wrote:
> Both memcg_shrinker_map_size and shrinker_nr_max is maintained, but actually the
> map size can be calculated via shrinker_nr_max, so it seems unnecessary to keep both.
> Remove memcg_shrinker_map_size since shrinker_nr_max is also used by iterating the
> bit map.
>
> Signed-off-by: Yang Shi <shy828301@gmail.com>
> ---
> mm/vmscan.c | 16 +++++++---------
> 1 file changed, 7 insertions(+), 9 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index d3f3701dfcd2..40e7751ef961 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -185,8 +185,7 @@ static LIST_HEAD(shrinker_list);
> static DECLARE_RWSEM(shrinker_rwsem);
>
> #ifdef CONFIG_MEMCG
> -
> -static int memcg_shrinker_map_size;
> +static int shrinker_nr_max;
>
> static void free_shrinker_map_rcu(struct rcu_head *head)
> {
> @@ -248,7 +247,7 @@ int alloc_shrinker_maps(struct mem_cgroup *memcg)
> return 0;
>
> down_write(&shrinker_rwsem);
> - size = memcg_shrinker_map_size;
> + size = (shrinker_nr_max / BITS_PER_LONG + 1) * sizeof(unsigned long);
> for_each_node(nid) {
> map = kvzalloc_node(sizeof(*map) + size, GFP_KERNEL, nid);
> if (!map) {
> @@ -266,10 +265,11 @@ int alloc_shrinker_maps(struct mem_cgroup *memcg)
> static int expand_shrinker_maps(int new_id)
> {
> int size, old_size, ret = 0;
> + int new_nr_max = new_id + 1;
> struct mem_cgroup *memcg;
>
> - size = DIV_ROUND_UP(new_id + 1, BITS_PER_LONG) * sizeof(unsigned long);
> - old_size = memcg_shrinker_map_size;
> + size = (new_nr_max / BITS_PER_LONG + 1) * sizeof(unsigned long);
> + old_size = (shrinker_nr_max / BITS_PER_LONG + 1) * sizeof(unsigned long);
>
> if (size <= old_size)
> return 0;
This looks a BUG:
expand_shrinker_maps(id == 1)
{
old_size = 64;
size = 64;
===>return 0 and shrinker_nr_max remains 0.
}
Then shrink_slab_memcg() misses this shrinker since shrinker_nr_max == 0.
>
> @@ -286,9 +286,10 @@ static int expand_shrinker_maps(int new_id)
> goto out;
> }
> } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL);
> +
> out:
> if (!ret)
> - memcg_shrinker_map_size = size;
> + shrinker_nr_max = new_nr_max;
>
> return ret;
> }
> @@ -321,7 +322,6 @@ void set_shrinker_bit(struct mem_cgroup *memcg, int nid, int shrinker_id)
> #define SHRINKER_REGISTERING ((struct shrinker *)~0UL)
>
> static DEFINE_IDR(shrinker_idr);
> -static int shrinker_nr_max;
>
> static int prealloc_memcg_shrinker(struct shrinker *shrinker)
> {
> @@ -338,8 +338,6 @@ static int prealloc_memcg_shrinker(struct shrinker *shrinker)
> idr_remove(&shrinker_idr, id);
> goto unlock;
> }
> -
> - shrinker_nr_max = id + 1;
> }
> shrinker->id = id;
> ret = 0;
>
next prev parent reply other threads:[~2021-01-25 8:36 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-21 23:06 [v4 PATCH 0/11] Make shrinker's nr_deferred memcg aware Yang Shi
2021-01-21 23:06 ` [v4 PATCH 01/11] mm: vmscan: use nid from shrink_control for tracepoint Yang Shi
2021-01-21 23:06 ` [v4 PATCH 02/11] mm: vmscan: consolidate shrinker_maps handling code Yang Shi
2021-01-21 23:06 ` [v4 PATCH 03/11] mm: vmscan: use shrinker_rwsem to protect shrinker_maps allocation Yang Shi
2021-01-21 23:06 ` [v4 PATCH 04/11] mm: vmscan: remove memcg_shrinker_map_size Yang Shi
2021-01-25 8:35 ` Kirill Tkhai [this message]
2021-01-25 21:06 ` Yang Shi
2021-01-21 23:06 ` [v4 PATCH 05/11] mm: memcontrol: rename shrinker_map to shrinker_info Yang Shi
2021-01-21 23:06 ` [v4 PATCH 06/11] mm: vmscan: use a new flag to indicate shrinker is registered Yang Shi
2021-01-21 23:06 ` [v4 PATCH 07/11] mm: vmscan: add per memcg shrinker nr_deferred Yang Shi
2021-01-25 9:31 ` Kirill Tkhai
2021-01-25 21:08 ` Yang Shi
2021-01-21 23:06 ` [v4 PATCH 08/11] mm: vmscan: use per memcg nr_deferred of shrinker Yang Shi
2021-01-25 9:35 ` Kirill Tkhai
2021-01-25 21:16 ` Yang Shi
2021-01-21 23:06 ` [v4 PATCH 09/11] mm: vmscan: don't need allocate shrinker->nr_deferred for memcg aware shrinkers Yang Shi
2021-01-21 23:06 ` [v4 PATCH 10/11] mm: memcontrol: reparent nr_deferred when memcg offline Yang Shi
2021-01-21 23:06 ` [v4 PATCH 11/11] mm: vmscan: shrink deferred objects proportional to priority Yang Shi
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