From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6AAEE381B02; Thu, 21 May 2026 17:18:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779383915; cv=none; b=GKAni2K180iXIPD7BTI3AScsbsEhjLB8S2BSqkwQLY1DfAWjBaEBq24cZNP1lRp13yZ/y5DcXbG3DtNmeDbDI7iVIwrMU77gX3anhEqdCb1L+i1YsG8zdINIz6t0bl9zxkM66sywNpX15u27Q1taaOzwqKhyCDp8v9sIfoix2Gw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779383915; c=relaxed/simple; bh=R92kWi2yFCLckQIu3dU4u9xw6ybgbdqcKO/vXSuMKB0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=fLqro9TZOSkZMuCzvkTAfbmm49ciJRnPU+mo678a8hDwHyVPr6SplloYNpHk2Q9oOX8nlC0EpiOmL+Xm643NGzHnouFOtAmtVyvZunybGQIiyT9kjmmGvKtIFtC8FQbsABJ8peerg+m5uQl8J/le9eHMdChtcgsT7C+P+0zdE3E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JJ6R66cT; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="JJ6R66cT" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 252401F000E9; Thu, 21 May 2026 17:18:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779383914; bh=XVFbF6HYn2YQk7B8y49fDdDuULfdkYo7a26mwtdbjMA=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=JJ6R66cTus8CjKsExdA12p2npq8HPKv8Yp3wC3KCB1G/q/UgVj4AhP1dXdF0uUgBW LYSmnOeujkt7nOnbbxqOx8yy0zfRIIvr0O+Qv3KdDP6ImC9NLTmk10oFGzQq4XCRGd s3Ih0NBHEXXav+9w3Kv1Uc44ZexZoC6yDnEOWy3pIJ4U8+eHz6xXv26a+ouEPCPYh7 8tVhsHd/JuYtwsgm/v+P6sZHQSC0ESPgUlYp80orwUv0hJWdTVTf0KBeHt+rCjU7Vx cKq8d9+Tc7AntY5ZdaH7uZvDu/knlyiuWXcoskmgpAM90tyGldtO8Nnmlk+9hR3Doy 6GRGvyMlolO3Q== Date: Thu, 21 May 2026 07:18:33 -1000 From: Tejun Heo To: Baokun Li Cc: linux-fsdevel@vger.kernel.org, viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.cz, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 2/3] writeback: drop now-unnecessary rcu_barrier() in cgroup_writeback_umount() Message-ID: References: <20260521095016.2791354-1-libaokun@linux.alibaba.com> <20260521095016.2791354-3-libaokun@linux.alibaba.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260521095016.2791354-3-libaokun@linux.alibaba.com> On Thu, May 21, 2026 at 05:50:15PM +0800, Baokun Li wrote: > Commit e1b849cfa6b6 ("writeback: Avoid contention on wb->list_lock when > switching inodes") replaced the queue_rcu_work() based scheduling of > inode wb switches with a plain queue_work(). Since then no switcher > goes through call_rcu(), so rcu_barrier() in cgroup_writeback_umount() > has no callbacks of its own to wait for. It still drains unrelated > call_rcu() callbacks from other subsystems on busy systems, which > incidentally slows umount down; drop it. > > Fixes: e1b849cfa6b6 ("writeback: Avoid contention on wb->list_lock when switching inodes") > Reviewed-by: Jan Kara > Signed-off-by: Baokun Li Acked-by: Tejun Heo Thanks. -- tejun