From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 74F7227BF79; Tue, 27 May 2025 17:36:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748367385; cv=none; b=jbBz+rrvsjWRsU3SAKpP1UyRsUJywNZll18M44LlE0FmV9poyyPeXkHfehqpfutf3d/xelmBvAwYpgq0Rqnvj4Lc5ZRBjJVCa3Nh7h7Fy31+ekHl9gh8CsLRXQdOUG14blIaIUTLIfrI2bAol77DoROtp8MXpKLq0DMfwC94ff8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748367385; c=relaxed/simple; bh=zF5fyoJiQ2tL1aJIrQzzwBIgslOx6CIeEPJncUzR2n4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=bMfjMiqJCPdpDLQm8MV5/5rLAhXwCZgz6Us9cKCH3ynYGnGNASSLPTyjOWw34EbGUVzLiPpA/XaeAAD1aC54P6PGTvOzcarNBnxxZh68WCMV5pG8LQ6Je5YWDrSevLBXQN6uQAWnGbK78bX8kOhSJYM0hc5vaThb+PpqrOffB88= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=cc9ALVlD; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="cc9ALVlD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 06BC4C4CEE9; Tue, 27 May 2025 17:36:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1748367385; bh=zF5fyoJiQ2tL1aJIrQzzwBIgslOx6CIeEPJncUzR2n4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cc9ALVlDQEPBjhesyytEV+OT/rF6uI/M20ZWZAVjCzhkE+Qu4X1dQmL26nbP+CZkh kPSjRsFCXX9xvm76uX4OutexRRzUwDAc4yr3z6m3cDVsheex8incftL8yD46fVo6m3 qHf/jVXQXO09/zF6dw/jHEvLHqKpQWqgvMWfFwY4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jinliang Zheng , Tianxiang Peng , Hao Peng , Mikulas Patocka , Sasha Levin Subject: [PATCH 6.14 370/783] dm: fix unconditional IO throttle caused by REQ_PREFLUSH Date: Tue, 27 May 2025 18:22:47 +0200 Message-ID: <20250527162528.153450226@linuxfoundation.org> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250527162513.035720581@linuxfoundation.org> References: <20250527162513.035720581@linuxfoundation.org> User-Agent: quilt/0.68 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 6.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jinliang Zheng [ Upstream commit 88f7f56d16f568f19e1a695af34a7f4a6ce537a6 ] When a bio with REQ_PREFLUSH is submitted to dm, __send_empty_flush() generates a flush_bio with REQ_OP_WRITE | REQ_PREFLUSH | REQ_SYNC, which causes the flush_bio to be throttled by wbt_wait(). An example from v5.4, similar problem also exists in upstream: crash> bt 2091206 PID: 2091206 TASK: ffff2050df92a300 CPU: 109 COMMAND: "kworker/u260:0" #0 [ffff800084a2f7f0] __switch_to at ffff80004008aeb8 #1 [ffff800084a2f820] __schedule at ffff800040bfa0c4 #2 [ffff800084a2f880] schedule at ffff800040bfa4b4 #3 [ffff800084a2f8a0] io_schedule at ffff800040bfa9c4 #4 [ffff800084a2f8c0] rq_qos_wait at ffff8000405925bc #5 [ffff800084a2f940] wbt_wait at ffff8000405bb3a0 #6 [ffff800084a2f9a0] __rq_qos_throttle at ffff800040592254 #7 [ffff800084a2f9c0] blk_mq_make_request at ffff80004057cf38 #8 [ffff800084a2fa60] generic_make_request at ffff800040570138 #9 [ffff800084a2fae0] submit_bio at ffff8000405703b4 #10 [ffff800084a2fb50] xlog_write_iclog at ffff800001280834 [xfs] #11 [ffff800084a2fbb0] xlog_sync at ffff800001280c3c [xfs] #12 [ffff800084a2fbf0] xlog_state_release_iclog at ffff800001280df4 [xfs] #13 [ffff800084a2fc10] xlog_write at ffff80000128203c [xfs] #14 [ffff800084a2fcd0] xlog_cil_push at ffff8000012846dc [xfs] #15 [ffff800084a2fda0] xlog_cil_push_work at ffff800001284a2c [xfs] #16 [ffff800084a2fdb0] process_one_work at ffff800040111d08 #17 [ffff800084a2fe00] worker_thread at ffff8000401121cc #18 [ffff800084a2fe70] kthread at ffff800040118de4 After commit 2def2845cc33 ("xfs: don't allow log IO to be throttled"), the metadata submitted by xlog_write_iclog() should not be throttled. But due to the existence of the dm layer, throttling flush_bio indirectly causes the metadata bio to be throttled. Fix this by conditionally adding REQ_IDLE to flush_bio.bi_opf, which makes wbt_should_throttle() return false to avoid wbt_wait(). Signed-off-by: Jinliang Zheng Reviewed-by: Tianxiang Peng Reviewed-by: Hao Peng Signed-off-by: Mikulas Patocka Signed-off-by: Sasha Levin --- drivers/md/dm.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 4d1e42891d246..5ab7574c0c76a 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1540,14 +1540,18 @@ static void __send_empty_flush(struct clone_info *ci) { struct dm_table *t = ci->map; struct bio flush_bio; + blk_opf_t opf = REQ_OP_WRITE | REQ_PREFLUSH | REQ_SYNC; + + if ((ci->io->orig_bio->bi_opf & (REQ_IDLE | REQ_SYNC)) == + (REQ_IDLE | REQ_SYNC)) + opf |= REQ_IDLE; /* * Use an on-stack bio for this, it's safe since we don't * need to reference it after submit. It's just used as * the basis for the clone(s). */ - bio_init(&flush_bio, ci->io->md->disk->part0, NULL, 0, - REQ_OP_WRITE | REQ_PREFLUSH | REQ_SYNC); + bio_init(&flush_bio, ci->io->md->disk->part0, NULL, 0, opf); ci->bio = &flush_bio; ci->sector_count = 0; -- 2.39.5