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Thu, 15 Apr 2021 04:56:25 -0700 (PDT) Received: from abel.fritz.box ([2a02:908:1252:fb60:3ba1:ccd9:cd93:a8ed]) by smtp.gmail.com with ESMTPSA id s9sm2182461edd.16.2021.04.15.04.56.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 15 Apr 2021 04:56:25 -0700 (PDT) From: "=?UTF-8?q?Christian=20K=C3=B6nig?=" X-Google-Original-From: =?UTF-8?q?Christian=20K=C3=B6nig?= To: linux-mm@kvack.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org Cc: vbabka@suse.cz, daniel@ffwll.ch, ray.huang@amd.com, akpm@linux-foundation.org Subject: [PATCH 1/2] mm/vmscan: add sync_shrinkers function Date: Thu, 15 Apr 2021 13:56:23 +0200 Message-Id: <20210415115624.2904-1-christian.koenig@amd.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Stat-Signature: d4mkuuro7xbqihxwp85i6qx5bnibjfk3 X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 964B580192F1 Received-SPF: none (gmail.com>: No applicable sender policy available) receiver=imf08; identity=mailfrom; envelope-from=""; helo=mail-ej1-f51.google.com; client-ip=209.85.218.51 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1618487772-577202 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: To be able to switch to a spinlock and reduce lock contention in the TTM shrinker we don't want to hold a mutex while unmapping and freeing pages from the pool. But then we somehow need to prevent a race between (for example) the shri= nker trying to free pages and hotplug trying to remove the device which those = pages belong to. Taking and releasing the shrinker semaphore on the write side after unmapping and freeing all pages should make sure that no shrinker is runn= ing in paralell any more. Signed-off-by: Christian K=C3=B6nig --- include/linux/shrinker.h | 1 + mm/vmscan.c | 10 ++++++++++ 2 files changed, 11 insertions(+) diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h index 0f80123650e2..6b75dc372fce 100644 --- a/include/linux/shrinker.h +++ b/include/linux/shrinker.h @@ -92,4 +92,5 @@ extern void register_shrinker_prepared(struct shrinker = *shrinker); extern int register_shrinker(struct shrinker *shrinker); extern void unregister_shrinker(struct shrinker *shrinker); extern void free_prealloced_shrinker(struct shrinker *shrinker); +extern void sync_shrinkers(void); #endif diff --git a/mm/vmscan.c b/mm/vmscan.c index 562e87cbd7a1..46cd9c215d73 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -408,6 +408,16 @@ void unregister_shrinker(struct shrinker *shrinker) } EXPORT_SYMBOL(unregister_shrinker); =20 +/** + * sync_shrinker - Wait for all running shrinkers to complete. + */ +void sync_shrinkers(void) +{ + down_write(&shrinker_rwsem); + up_write(&shrinker_rwsem); +} +EXPORT_SYMBOL(sync_shrinkers); + #define SHRINK_BATCH 128 =20 static unsigned long do_shrink_slab(struct shrink_control *shrinkctl, --=20 2.25.1