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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B2EA3CA0FE7 for ; Mon, 25 Aug 2025 18:53:12 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D91728E0064; Mon, 25 Aug 2025 14:53:11 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D42198E0038; Mon, 25 Aug 2025 14:53:11 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C57D98E0064; Mon, 25 Aug 2025 14:53:11 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id B41F98E0038 for ; Mon, 25 Aug 2025 14:53:11 -0400 (EDT) Received: from smtpin04.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 604F81604F4 for ; Mon, 25 Aug 2025 18:53:11 +0000 (UTC) X-FDA: 83816177382.04.5C919CF Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf12.hostedemail.com (Postfix) with ESMTP id B3CBD40002 for ; Mon, 25 Aug 2025 18:53:09 +0000 (UTC) Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=lb2uYPi3; spf=pass (imf12.hostedemail.com: domain of tj@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=tj@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1756147989; 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=x3rjkwd+yp81du5a0+5OxVddHSkCngCSEH8LmT8UTGg=; b=6EVJ/KJ4adm3vsHErip2y0jbsApnudBXjfAECCAgnJSRKK/2WZl39TGKZ/JVoXM3Ck6opE emlnObhhDXZx21yX4qk6whXzSJoCcNysfG556UPdJFya70X17+K9cQRlajOY/spEdZx1ZH sBrxUCm4qeTKrq9VGbsC6jhMoEHEwIg= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=lb2uYPi3; spf=pass (imf12.hostedemail.com: domain of tj@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=tj@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1756147989; a=rsa-sha256; cv=none; b=iLkUgmTJ3pREvo93umearPG4DibyoKuP3nzntVwe1iHyQO8jgI66DxblyzuPf1LAYM5ICi WaUANppAegnaFR0rtgjVstSGSI0TV3xrBqqawJKQqd1SlRi52M1AsL44x5Yciy0+D4yIqt P8K6CCRYGvmL8CtFKrGpZoWQxEwgmF8= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 6F1F6446BD; Mon, 25 Aug 2025 18:53:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2D076C4CEED; Mon, 25 Aug 2025 18:53:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1756147988; bh=LEW9gsFvgQr17Q8Hvz8WKHs69INOEWZ5Ig+Zk2KyLtE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=lb2uYPi3eOLm4CsBv3EOgir97hD2gec70fzgc/UUC8EgEShwvOdx+TqoWoH5I+vSU 7J0r+U27tSe46fwR7OShP/BtBT5nwybHwJX2RupZSUSKL7xhLmcSuOA+A+mmzkeXtT J+Crq080KBH41tinXIe+SgBIsDfgokYByiFlW2K14TxcyDtVulXENi9UoRR717CSN0 FlpLQ9TYYTcCPQLkLkzaRL2crTdOmVlP4mhzusombwS4zUE2sAWfin7EqyrsHqHV6w Nn7Qv0yfJezlb8xsRFvxlsR5QH9MNTob2gXIN61wUZzNxBeWCfl0f5ahcWY9fdFF53 5VaWFk2ISjhvA== Date: Mon, 25 Aug 2025 08:53:07 -1000 From: Tejun Heo To: Julian Sun Cc: linux-fsdevel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.cz, hannes@cmpxchg.org, mhocko@kernel.org, roman.gushchin@linux.dev, shakeel.butt@linux.dev, muchun.song@linux.dev, axboe@kernel.dk Subject: Re: [External] Re: [PATCH] memcg: Don't wait writeback completion when release memcg. Message-ID: References: <20250820111940.4105766-1-sunjunchao@bytedance.com> <20250820111940.4105766-4-sunjunchao@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Stat-Signature: 89cz1s8fdyuhgkr96k7b3ckioijfk1c5 X-Rspam-User: X-Rspamd-Queue-Id: B3CBD40002 X-Rspamd-Server: rspam01 X-HE-Tag: 1756147989-412867 X-HE-Meta: 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 nwb2324H 9vzSZg9nKvk2PQrQn8vXXQ+sabV2Ntd+3xX+u9LRiY1v9trvHwnqovetah5eRl1pd5LkWR7KM4JyfTnh4BqffeIovEERbz3Xm5Rp0LPFyZCyD7A9lcD/A3xOZsj/0Rf4zk7wDlryOAjIuWqCcYJATSsCds8ibEVRb7UIxKm/Zc8GIST60WHWmtC7KEcNVGvkN7n+HYYvh5850cVPCt6q5U2TjpTp6frDc/6XUnGojOLGDBpk= 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: List-Subscribe: List-Unsubscribe: Hello, On Tue, Aug 26, 2025 at 01:45:44AM +0800, Julian Sun wrote: ... > Sorry for having misunderstood what you meant before. I’m afraid that > init_wait_func() cannot work the same way. Because calling > init_wait_func() presupposes that we are preparing to wait for an > event(like wb_wait_completion()), but waiting for such an event might > lead to a hung task. > > Please correct me if I'm wrong. Using init_wait_func() does not require someone waiting for it. AFAICS, you should be able to do the same thing that you did - allocating the done entries individually and freeing them when the done count reaches zero without anyone waiting for it. waitq doesn't really make many assumptions about how it's used - when you call wake_up() on it, it just walks the queued entries and invoke the callbacks there. Thanks. -- tejun