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 EF69E425872; Thu, 1 Oct 2026 18:43:42 +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=1790880225; cv=none; b=UQMQRL9MzKBB0BV70Yb9O4l677yvgub7jCT2xv0ElOywH2eQSYnDNARfgUROg7qEY5l8YklEG7eYIUQdSurq6M0rLnIPezWiXnWp9hmMHkVbIKzp6C4mafNgqVUs/gBcP37brjduygBxGAS2p0h79/2uPZ4u+9fnvgex1EgRDSI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790880225; c=relaxed/simple; bh=fQh5POTK+q9BTx7WT1J4poQSlvm3gOoIRiWfRW/aGc0=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=r90pLUMN9wX2ni/7Y7bCCR1dNm5OzYenUasUfXdA6rjECg4toaGwwP8HXp3dfTsZ5sfKotj1NPqxMtzIxzpEpxqAMGqhu6rUYLyreV6KN3j4g4PnIZtqcIwba+W6bhGfDK3bbMdIy63nOKrQvglocT0afilSjqKJ4n7Hyismx2M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZXHKEJiH; 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="ZXHKEJiH" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A06981F000FF; Thu, 1 Oct 2026 18:43:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790880221; bh=Nf7k3kUZJ8lq1fxACTFvD6heNgFRBaaOnt6+P+Ou9hM=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=ZXHKEJiHam3Z2xUpQMDGRKdXcZRxWTOI/dwRFHVYOszxIyjzXh/2KukXPW5tcl6+v 5qXOQIL9wrwUJHtf5jzaTWLy2Z83KOGJeqqy6Buv03l9TZqulFqoiLscBARN4GZGzX Fr3btU8qMBKAe5LomhIa2cKvT2m8V8Cka5j4wJgcTBrUwd/lWbXW73ScaIkA1yLcn3 a0u65q04EujCObMXKy8nWmY1Jz/aCW7m+k+LDlbgTOkkFX2Cs/H3xlwLiBZ2cAejsf tY3qJke5nvl+aDB0xe9MuWUD5j1YJvx470DP3iuL4299Zxj3vJSTktKdKzQ/pNadu+ oq8pn8LPrT5FA== Date: Thu, 01 Oct 2026 08:43:41 -1000 Message-ID: From: Tejun Heo To: Liz Fong-Jones Cc: Christian Brauner , Jan Kara , Alexander Viro , Jens Axboe , Andrew Morton , Johannes Weiner , Roman Gushchin , Shakeel Butt , Xin Yin , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, ian@honeycomb.io Subject: Re: [PATCH v4 1/2] writeback: let foreign flushes reach dying cgwbs In-Reply-To: <20260930-wb-dying-cgwb-flush-v4-1-bde637803a96@honeycomb.io> References: <20260930-wb-dying-cgwb-flush-v4-0-bde637803a96@honeycomb.io> <20260930-wb-dying-cgwb-flush-v4-1-bde637803a96@honeycomb.io> 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-Transfer-Encoding: 7bit Hello, Liz. On Wed, Sep 30, 2026 at 07:35:37PM +0000, Liz Fong-Jones wrote: > if (test_bit(WB_registered, &bdi->wb.state) && > - blkcg_cgwb_list->next && memcg_cgwb_list->next) { > + blkcg_cgwb_list->next && memcg_cgwb_list->next && > + !css_is_dying(memcg_css)) { With patch 2 switching a replaced wb's inodes to its successor instead of flushing them in place, this doesn't matter anymore. If a removed memcg's wb gets replaced, the successor takes over the inodes and stays in the tree until released, so foreign flushes still reach them. I asked for it against v3, where patch 2 only kicked writeback on the old wb. Can you drop it and the description sentence about it? Thanks. -- tejun