From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-171.mta1.migadu.com (out-171.mta1.migadu.com [95.215.58.171]) (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 4183F3BCD3C for ; Sun, 2 Aug 2026 15:18:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.171 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785683915; cv=none; b=hD1E/6qVH/eFnxARa9/Exelkp2GlCFLibaMLmE2bAKVBiYPELp1RbXn0oyX0w3kwWA1ry+ECK/WdUTCM9S9p/SYtwwMUpQ2kF/dEufmB+PwXl3kRlBbT8qGrQaZswy7V5/aJV1vHikOXdwaFt1zFSMYGCo0emYXTrNPS19yVyuw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785683915; c=relaxed/simple; bh=T36/4Ejjiy5odXG4QB3fu/Kf8rd0KzX7NAGBSokqo2A=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=ertA9HoG+MKAeotYxxBkP+JSdD8SCK/4nwOTtHnmG2ADr8OPVzycQYQJtIRyfGxCsHdmilOtSsqivCVZ4YkKN5T9MXnwUj4wM/9aJk5pOcEBcO4e01PVG/65gaFMT+E1rsOWGBoaEZR7EMCkMM0AqFxyXsT8KoABnxyzbY8CEP0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=rg7EgQr5; arc=none smtp.client-ip=95.215.58.171 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="rg7EgQr5" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1785683893; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=h3rFpk5yukQZkFt2SrOCVUimOAtm8ZF/Q+0Pgr/OyYE=; b=rg7EgQr5XndWr9IqCvu+o3O34BdRE/70gcYk+uZP8DTgDP0wL/eDFv3/u9HkhbEFviUOiW jtYe2vENjut00n9DvetEj/N7H223NOMpVwFWk+Wc/WGj+h/Tvee8rM2BWs7ACS57xXLdAs Yp2jcCVP//W/DlYV8uAqgnz2LcZAtA8= From: Tao Cui To: tj@kernel.org, axboe@kernel.dk Cc: josef@toxicpanda.com, cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, cui.tao@linux.dev, Tao Cui Subject: [PATCH] block/blk-iocost: annotate committed flag with READ_ONCE/WRITE_ONCE Date: Sun, 2 Aug 2026 23:17:55 +0800 Message-ID: <20260802151755.35511-1-cui.tao@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT From: Tao Cui The "committed" wait flag is written by iocg_wake_fn() under waitq.lock and read by ioc_rqos_throttle() without the lock, which trips KCSAN. The ordering is already handled by set_current_state()/wake_up() so the race is harmless. Use READ_ONCE()/WRITE_ONCE() to document the intentional lockless access. Signed-off-by: Tao Cui --- block/blk-iocost.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/block/blk-iocost.c b/block/blk-iocost.c index 8b2aeba2e1e3..782bbe2d27b3 100644 --- a/block/blk-iocost.c +++ b/block/blk-iocost.c @@ -1458,7 +1458,7 @@ static int iocg_wake_fn(struct wait_queue_entry *wq_entry, unsigned mode, return -1; iocg_commit_bio(ctx->iocg, wait->bio, wait->abs_cost, cost); - wait->committed = true; + WRITE_ONCE(wait->committed, true); /* * autoremove_wake_function() removes the wait entry only when it @@ -2763,7 +2763,7 @@ static void ioc_rqos_throttle(struct rq_qos *rqos, struct bio *bio) while (true) { set_current_state(TASK_UNINTERRUPTIBLE); - if (wait.committed) + if (READ_ONCE(wait.committed)) break; io_schedule(); } -- 2.43.0