From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 75963C678D5 for ; Wed, 8 Mar 2023 22:40:02 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 17477280001; Wed, 8 Mar 2023 17:40:02 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 1244D6B0072; Wed, 8 Mar 2023 17:40:02 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0136B280001; Wed, 8 Mar 2023 17:40:01 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id E79C96B0071 for ; Wed, 8 Mar 2023 17:40:01 -0500 (EST) Received: from smtpin02.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id B553B1C697E for ; Wed, 8 Mar 2023 22:40:01 +0000 (UTC) X-FDA: 80547200202.02.3FEC545 Received: from forward502c.mail.yandex.net (forward502c.mail.yandex.net [178.154.239.210]) by imf11.hostedemail.com (Postfix) with ESMTP id 86C8340004 for ; Wed, 8 Mar 2023 22:39:59 +0000 (UTC) Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=ya.ru header.s=mail header.b=AItsOs1t; spf=pass (imf11.hostedemail.com: domain of tkhai@ya.ru designates 178.154.239.210 as permitted sender) smtp.mailfrom=tkhai@ya.ru; dmarc=pass (policy=none) header.from=ya.ru ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1678315199; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=jtp2l4lNFJPAxiRvDYywOQOC6WaE6pPy91DLgHdQQhI=; b=ZLC8kPhD4xPNN8s6piP6aLMUDgMLQQ5OU0gfURr4jXcPLIzin9oIMrOENQiE1YpDB9qEkL DxouiWfqkCJ31qRYE52i+9gYtWuDgKl5CZOrzdiHFTBJrvwQtl26axHCOvu939EQyZzLV2 0mBv87PFHz7zBlet696kVy7NxObFmvc= ARC-Authentication-Results: i=1; imf11.hostedemail.com; dkim=pass header.d=ya.ru header.s=mail header.b=AItsOs1t; spf=pass (imf11.hostedemail.com: domain of tkhai@ya.ru designates 178.154.239.210 as permitted sender) smtp.mailfrom=tkhai@ya.ru; dmarc=pass (policy=none) header.from=ya.ru ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1678315199; a=rsa-sha256; cv=none; b=fEhfQ1mJarRSkGlnNlup3G5JD+ZD5KprmUOJIETj2CMCxGmGn6pdGziq2nV0GIjfSfpFsp BY+5//A1A24pTqgXOnzVItPFOHDu2gc0MwaHz6gASru989peCZPTCXtTnbJDhcIe8dPZpf Qf7kt+ZsFM++xk0Jt4xQ6yyGiHtWAY8= Received: from sas2-ee8a69bedcfd.qloud-c.yandex.net (sas2-ee8a69bedcfd.qloud-c.yandex.net [IPv6:2a02:6b8:c14:252d:0:640:ee8a:69be]) by forward502c.mail.yandex.net (Yandex) with ESMTP id A5E6C5F425; Thu, 9 Mar 2023 01:39:56 +0300 (MSK) Received: by sas2-ee8a69bedcfd.qloud-c.yandex.net (smtp/Yandex) with ESMTPSA id qdlK4ADc3mI1-YobY5zlJ; Thu, 09 Mar 2023 01:39:55 +0300 X-Yandex-Fwd: 1 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ya.ru; s=mail; t=1678315195; bh=jtp2l4lNFJPAxiRvDYywOQOC6WaE6pPy91DLgHdQQhI=; h=From:In-Reply-To:Cc:Date:References:To:Subject:Message-ID; b=AItsOs1tUQbS7iAuk2AT3NjB2XQBUNKQspE0WlDkhD+jJT1LG0nOLzhGV0oCoyS/A LOTbtus5nWHPWBaW0X3g7s+eLhJCCWUHcE6qAEU6NBRUkM1BZsYWCz/VmZLV9JwWSA a4xjilBcji57Mbv5zrKn1AeWxqphWGgIONs/6HjU= Message-ID: Date: Thu, 9 Mar 2023 01:39:52 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [PATCH v4 7/8] mm: vmscan: remove shrinker_rwsem from synchronize_shrinkers() Content-Language: en-US To: Qi Zheng , akpm@linux-foundation.org, hannes@cmpxchg.org, shakeelb@google.com, mhocko@kernel.org, roman.gushchin@linux.dev, muchun.song@linux.dev, david@redhat.com, shy828301@gmail.com, rppt@kernel.org Cc: sultan@kerneltoast.com, dave@stgolabs.net, penguin-kernel@I-love.SAKURA.ne.jp, paulmck@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20230307065605.58209-1-zhengqi.arch@bytedance.com> <20230307065605.58209-8-zhengqi.arch@bytedance.com> From: Kirill Tkhai In-Reply-To: <20230307065605.58209-8-zhengqi.arch@bytedance.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: 8e1sraj9qdan5oswbdrzjhdr8fr4piko X-Rspam-User: X-Rspamd-Queue-Id: 86C8340004 X-Rspamd-Server: rspam06 X-HE-Tag: 1678315199-5909 X-HE-Meta: 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 0gpIKUrv OweqH842sGZT1Qbook8DQx5vBmF+31tLmn57pcd4AzMnBNgGAT63ZdKMQHjhjjMhoGJ/GP7MrTt1vIy8JD7PfycsyxVXR1xcEJtDPt+Z/x6GWR78Hhwiw6jSx+vciMDSghBCjiuinTe2A0dXYKnTr1QFqE+2VkVfgvPd175xoBLJdeX5uaHcPcvtVis2ajxB/1z3PmGMfNs10mss5w7RoRkllvne7hIZst57OqYuHZUnFeWAdfDJJq0/e0txmO8nkWoYHjWdUWNaPVSbIBeBGWTDa19i9qMMxI8RRviBWshUCuFJXeFH17UoGs9l5KRQD4ZrxU5jPyXPQK0EIqEEb0TkanrUfV/URXWEtxvkIvXyGGLdU/Agc/EL6ePMORVaQzkPnbp3+docBwc0= 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: On 07.03.2023 09:56, Qi Zheng wrote: > Now there are no readers of shrinker_rwsem, so > synchronize_shrinkers() does not need to hold the > writer of shrinker_rwsem to wait for all running > shinkers to complete, synchronize_srcu() is enough. > > Signed-off-by: Qi Zheng > --- > mm/vmscan.c | 8 ++------ > 1 file changed, 2 insertions(+), 6 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 7aaf6f94ac1b..ac7ab4aa344f 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -796,15 +796,11 @@ EXPORT_SYMBOL(unregister_shrinker); > /** > * synchronize_shrinkers - Wait for all running shrinkers to complete. > * > - * This is equivalent to calling unregister_shrink() and register_shrinker(), > - * but atomically and with less overhead. This is useful to guarantee that all > - * shrinker invocations have seen an update, before freeing memory, similar to > - * rcu. > + * This is useful to guarantee that all shrinker invocations have seen an > + * update, before freeing memory. > */ > void synchronize_shrinkers(void) > { > - down_write(&shrinker_rwsem); > - up_write(&shrinker_rwsem); > atomic_inc(&shrinker_srcu_generation); > synchronize_srcu(&shrinker_srcu); > } Just curious, callers of synchronize_shrinkers() don't want to have parallel register_shrinker() and unregister_shrink() are completed? Here we only should wait for parallel shrink_slab(), correct?