From: Kirill Tkhai <ktkhai@virtuozzo.com>
To: Yang Shi <shy828301@gmail.com>,
guro@fb.com, vbabka@suse.cz, 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: [v6 PATCH 06/11] mm: vmscan: use a new flag to indicate shrinker is registered
Date: Thu, 4 Feb 2021 11:15:32 +0300 [thread overview]
Message-ID: <3343b6a8-c192-9668-68ce-8b2abb7026ba@virtuozzo.com> (raw)
In-Reply-To: <20210203172042.800474-7-shy828301@gmail.com>
On 03.02.2021 20:20, Yang Shi wrote:
> Currently registered shrinker is indicated by non-NULL shrinker->nr_deferred.
> This approach is fine with nr_deferred at the shrinker level, but the following
> patches will move MEMCG_AWARE shrinkers' nr_deferred to memcg level, so their
> shrinker->nr_deferred would always be NULL. This would prevent the shrinkers
> from unregistering correctly.
>
> Remove SHRINKER_REGISTERING since we could check if shrinker is registered
> successfully by the new flag.
>
> Signed-off-by: Yang Shi <shy828301@gmail.com>
Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com>
> ---
> include/linux/shrinker.h | 7 ++++---
> mm/vmscan.c | 31 +++++++++----------------------
> 2 files changed, 13 insertions(+), 25 deletions(-)
>
> diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h
> index 0f80123650e2..1eac79ce57d4 100644
> --- a/include/linux/shrinker.h
> +++ b/include/linux/shrinker.h
> @@ -79,13 +79,14 @@ struct shrinker {
> #define DEFAULT_SEEKS 2 /* A good number if you don't know better. */
>
> /* Flags */
> -#define SHRINKER_NUMA_AWARE (1 << 0)
> -#define SHRINKER_MEMCG_AWARE (1 << 1)
> +#define SHRINKER_REGISTERED (1 << 0)
> +#define SHRINKER_NUMA_AWARE (1 << 1)
> +#define SHRINKER_MEMCG_AWARE (1 << 2)
> /*
> * It just makes sense when the shrinker is also MEMCG_AWARE for now,
> * non-MEMCG_AWARE shrinker should not have this flag set.
> */
> -#define SHRINKER_NONSLAB (1 << 2)
> +#define SHRINKER_NONSLAB (1 << 3)
>
> extern int prealloc_shrinker(struct shrinker *shrinker);
> extern void register_shrinker_prepared(struct shrinker *shrinker);
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 9436f9246d32..dc0d69e081b0 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -309,19 +309,6 @@ void set_shrinker_bit(struct mem_cgroup *memcg, int nid, int shrinker_id)
> }
> }
>
> -/*
> - * We allow subsystems to populate their shrinker-related
> - * LRU lists before register_shrinker_prepared() is called
> - * for the shrinker, since we don't want to impose
> - * restrictions on their internal registration order.
> - * In this case shrink_slab_memcg() may find corresponding
> - * bit is set in the shrinkers map.
> - *
> - * This value is used by the function to detect registering
> - * shrinkers and to skip do_shrink_slab() calls for them.
> - */
> -#define SHRINKER_REGISTERING ((struct shrinker *)~0UL)
> -
> static DEFINE_IDR(shrinker_idr);
>
> static int prealloc_memcg_shrinker(struct shrinker *shrinker)
> @@ -330,7 +317,7 @@ static int prealloc_memcg_shrinker(struct shrinker *shrinker)
>
> down_write(&shrinker_rwsem);
> /* This may call shrinker, so it must use down_read_trylock() */
> - id = idr_alloc(&shrinker_idr, SHRINKER_REGISTERING, 0, 0, GFP_KERNEL);
> + id = idr_alloc(&shrinker_idr, shrinker, 0, 0, GFP_KERNEL);
> if (id < 0)
> goto unlock;
>
> @@ -493,10 +480,7 @@ void register_shrinker_prepared(struct shrinker *shrinker)
> {
> down_write(&shrinker_rwsem);
> list_add_tail(&shrinker->list, &shrinker_list);
> -#ifdef CONFIG_MEMCG
> - if (shrinker->flags & SHRINKER_MEMCG_AWARE)
> - idr_replace(&shrinker_idr, shrinker, shrinker->id);
> -#endif
> + shrinker->flags |= SHRINKER_REGISTERED;
> up_write(&shrinker_rwsem);
> }
>
> @@ -516,13 +500,16 @@ EXPORT_SYMBOL(register_shrinker);
> */
> void unregister_shrinker(struct shrinker *shrinker)
> {
> - if (!shrinker->nr_deferred)
> + if (!(shrinker->flags & SHRINKER_REGISTERED))
> return;
> - if (shrinker->flags & SHRINKER_MEMCG_AWARE)
> - unregister_memcg_shrinker(shrinker);
> +
> down_write(&shrinker_rwsem);
> list_del(&shrinker->list);
> + shrinker->flags &= ~SHRINKER_REGISTERED;
> up_write(&shrinker_rwsem);
> +
> + if (shrinker->flags & SHRINKER_MEMCG_AWARE)
> + unregister_memcg_shrinker(shrinker);
> kfree(shrinker->nr_deferred);
> shrinker->nr_deferred = NULL;
> }
> @@ -688,7 +675,7 @@ static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid,
> struct shrinker *shrinker;
>
> shrinker = idr_find(&shrinker_idr, i);
> - if (unlikely(!shrinker || shrinker == SHRINKER_REGISTERING)) {
> + if (unlikely(!shrinker || !(shrinker->flags & SHRINKER_REGISTERED))) {
> if (!shrinker)
> clear_bit(i, info->map);
> continue;
>
next prev parent reply other threads:[~2021-02-04 8:16 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-03 17:20 [v6 PATCH 0/11] Make shrinker's nr_deferred memcg aware Yang Shi
2021-02-03 17:20 ` [v6 PATCH 01/11] mm: vmscan: use nid from shrink_control for tracepoint Yang Shi
2021-02-04 7:22 ` Kirill Tkhai
2021-02-03 17:20 ` [v6 PATCH 02/11] mm: vmscan: consolidate shrinker_maps handling code Yang Shi
2021-02-04 7:23 ` Kirill Tkhai
2021-02-03 17:20 ` [v6 PATCH 03/11] mm: vmscan: use shrinker_rwsem to protect shrinker_maps allocation Yang Shi
2021-02-04 7:24 ` Kirill Tkhai
2021-02-03 17:20 ` [v6 PATCH 04/11] mm: vmscan: remove memcg_shrinker_map_size Yang Shi
2021-02-04 8:01 ` Kirill Tkhai
2021-02-03 17:20 ` [v6 PATCH 05/11] mm: memcontrol: rename shrinker_map to shrinker_info Yang Shi
2021-02-04 8:03 ` Kirill Tkhai
2021-02-03 17:20 ` [v6 PATCH 06/11] mm: vmscan: use a new flag to indicate shrinker is registered Yang Shi
2021-02-04 8:15 ` Kirill Tkhai [this message]
2021-02-03 17:20 ` [v6 PATCH 07/11] mm: vmscan: add per memcg shrinker nr_deferred Yang Shi
2021-02-04 8:30 ` Kirill Tkhai
2021-02-04 17:17 ` Yang Shi
2021-02-05 14:37 ` Kirill Tkhai
2021-02-05 16:49 ` Yang Shi
2021-02-03 17:20 ` [v6 PATCH 08/11] mm: vmscan: use per memcg nr_deferred of shrinker Yang Shi
2021-02-04 8:41 ` Kirill Tkhai
2021-02-04 17:23 ` Yang Shi
2021-02-05 14:41 ` Kirill Tkhai
2021-02-05 16:40 ` Yang Shi
2021-02-05 3:12 ` [mm] [confidence: ] 3510a44e0e: WARNING:suspicious_RCU_usage kernel test robot
2021-02-03 17:20 ` [v6 PATCH 09/11] mm: vmscan: don't need allocate shrinker->nr_deferred for memcg aware shrinkers Yang Shi
2021-02-04 9:29 ` Kirill Tkhai
2021-02-04 10:14 ` Kirill Tkhai
2021-02-04 17:32 ` Yang Shi
2021-02-05 14:44 ` Kirill Tkhai
2021-02-03 17:20 ` [v6 PATCH 10/11] mm: memcontrol: reparent nr_deferred when memcg offline Yang Shi
2021-02-04 10:15 ` Kirill Tkhai
2021-02-03 17:20 ` [v6 PATCH 11/11] mm: vmscan: shrink deferred objects proportional to priority Yang Shi
2021-02-04 10:23 ` Kirill Tkhai
2021-02-04 17:29 ` Yang Shi
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