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[73.93.239.127]) by smtp.gmail.com with ESMTPSA id 124sm3498648pfd.59.2021.01.27.15.34.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 Jan 2021 15:34:03 -0800 (PST) From: Yang Shi To: guro@fb.com, ktkhai@virtuozzo.com, shakeelb@google.com, david@fromorbit.com, hannes@cmpxchg.org, mhocko@suse.com, akpm@linux-foundation.org Cc: shy828301@gmail.com, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [v5 PATCH 06/11] mm: vmscan: use a new flag to indicate shrinker is registered Date: Wed, 27 Jan 2021 15:33:40 -0800 Message-Id: <20210127233345.339910-7-shy828301@gmail.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20210127233345.339910-1-shy828301@gmail.com> References: <20210127233345.339910-1-shy828301@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Currently registered shrinker is indicated by non-NULL shrinker->nr_defer= red. This approach is fine with nr_deferred at the shrinker level, but the fol= lowing patches will move MEMCG_AWARE shrinkers' nr_deferred to memcg level, so t= heir shrinker->nr_deferred would always be NULL. This would prevent the shrin= kers from unregistering correctly. Remove SHRINKER_REGISTERING since we could check if shrinker is registere= d successfully by the new flag. Signed-off-by: Yang Shi --- include/linux/shrinker.h | 7 ++++--- mm/vmscan.c | 27 +++++++++------------------ 2 files changed, 13 insertions(+), 21 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. */ =20 /* 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) =20 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 92e917033797..256896d157d4 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -308,19 +308,6 @@ void set_shrinker_bit(struct mem_cgroup *memcg, int = nid, int shrinker_id) } } =20 -/* - * 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); =20 static int prealloc_memcg_shrinker(struct shrinker *shrinker) @@ -329,7 +316,7 @@ static int prealloc_memcg_shrinker(struct shrinker *s= hrinker) =20 down_write(&shrinker_rwsem); /* This may call shrinker, so it must use down_read_trylock() */ - id =3D idr_alloc(&shrinker_idr, SHRINKER_REGISTERING, 0, 0, GFP_KERNEL)= ; + id =3D idr_alloc(&shrinker_idr, NULL, 0, 0, GFP_KERNEL); if (id < 0) goto unlock; =20 @@ -496,6 +483,7 @@ void register_shrinker_prepared(struct shrinker *shri= nker) if (shrinker->flags & SHRINKER_MEMCG_AWARE) idr_replace(&shrinker_idr, shrinker, shrinker->id); #endif + shrinker->flags |=3D SHRINKER_REGISTERED; up_write(&shrinker_rwsem); } =20 @@ -515,13 +503,16 @@ 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 &=3D ~SHRINKER_REGISTERED; up_write(&shrinker_rwsem); + + if (shrinker->flags & SHRINKER_MEMCG_AWARE) + unregister_memcg_shrinker(shrinker); kfree(shrinker->nr_deferred); shrinker->nr_deferred =3D NULL; } @@ -687,7 +678,7 @@ static unsigned long shrink_slab_memcg(gfp_t gfp_mask= , int nid, struct shrinker *shrinker; =20 shrinker =3D idr_find(&shrinker_idr, i); - if (unlikely(!shrinker || shrinker =3D=3D SHRINKER_REGISTERING)) { + if (unlikely(!shrinker || !(shrinker->flags & SHRINKER_REGISTERED))) { if (!shrinker) clear_bit(i, info->map); continue; --=20 2.26.2