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 CCF7A3ED3B2; Tue, 21 Jul 2026 19:22:37 +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=1784661758; cv=none; b=CN7ABmVXTP4XomKPP5pbUtysnMmIy/pdUnjIsaEHarD3ccgTvBnfy5KDT3Lz3IvOlOFEn7Vn1TSNqDxZtH1r9UitgqMUPwPDUZm5f/HhZgiVaAtOdclQ72t06Th/tqbRqI2+XnUs9qUOE8nnTGs4Mcx728PyTPNdJ7oY6+ponkY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784661758; c=relaxed/simple; bh=UFgdakgOc2j6cdVHJsCM0WCv+PqY/R31uDAIEhUEmZg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=W9i0zZCvokOM3mq+xpkBAzThwr4HEy6bIhHETVGhSdapdI82KEOXQnpuC/qPSBu0DGOCvm0Y7gFW40ZGIhvRiBwWpLpeW8ej1mbSaXoL92shLwln7CXDry5wBc5n4tZP+71ZOp5eg6zs5FJ8gWGz8WkM8O17gMvIZGb47C/3KYQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=aghbehD+; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="aghbehD+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3F0821F00A3A; Tue, 21 Jul 2026 19:22:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784661757; bh=MJBsFtK1ApwQ2AaSNI/N++P+R8WW1DeqYisvoUJbmzM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=aghbehD+4XGM7Ynj6IxvDcCqZK5FJ+nF0CvmqV3pID1uI5Dghc0g1XS3TNjLN5Ur4 PQchaAQidkYhQ+X9BuwnC8w8IcOjzsS9ZefW2SGJLkYYak+YN828qyT4mGkUlCZsRq ZiOG8aKoyFHwv38BLBRXm0a0kgHThd/is5FTVLMs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jan Kara , Baokun Li , Tejun Heo , "Christian Brauner (Amutable)" , Sasha Levin Subject: [PATCH 6.12 0144/1276] writeback: drop now-unnecessary rcu_barrier() in cgroup_writeback_umount() Date: Tue, 21 Jul 2026 17:09:47 +0200 Message-ID: <20260721152449.323916487@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152446.065700225@linuxfoundation.org> References: <20260721152446.065700225@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Baokun Li [ Upstream commit e90a6d668e26e00a72df2d09c173b563468f09c9 ] 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 Link: https://patch.msgid.link/20260521095016.2791354-3-libaokun@linux.alibaba.com Acked-by: Tejun Heo Signed-off-by: Christian Brauner (Amutable) Signed-off-by: Sasha Levin --- fs/fs-writeback.c | 5 ----- 1 file changed, 5 deletions(-) diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 57a31bd110c0bf..4e1e0dd16428ba 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -1218,11 +1218,6 @@ void cgroup_writeback_umount(struct super_block *sb) * will then drain it. */ synchronize_rcu(); - /* - * Use rcu_barrier() to wait for all pending callbacks to - * ensure that all in-flight wb switches are in the workqueue. - */ - rcu_barrier(); flush_workqueue(isw_wq); } } -- 2.53.0