From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pdx-out-006.esa.us-west-2.outbound.mail-perimeter.amazon.com (pdx-out-006.esa.us-west-2.outbound.mail-perimeter.amazon.com [52.26.1.71]) (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 BC22725A655; Mon, 16 Mar 2026 07:04:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=52.26.1.71 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773644653; cv=none; b=SAOFua3zZUkw1S9tlJoPNieTW9CGIWlocBfATXb6fOREocovPfjVhPfm4LX+b3wjpYXoHiCZQwqWWkwBH3+dn789pEd8AIzKb8EMCBi6xbIGvPLW5xpg/xLxu4PPU29jImiixqXoYQhOcegA42wsJcyIn1DLy1Hfuw0pHm2T+gk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773644653; c=relaxed/simple; bh=Nk+SdV3EmwkPKY+kSJeGHIkhg1w689CrkeY+31Dn7JI=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=nJTpZVUTeOQ1U5N5ca7vTQ05rjatvOKvzCgDDasLO1WVckv26jKQ+thuTYzLqklCr9nYS5yTchmtRkN0S2SJ7RSygEltT+VZ6BN2i8idEz7vv1rHbfZ/GnqDuMv23PXazJ3KhcWtXSXCCPrtDu1Liq2P1JDMZHKL4Y5OcMRlC9E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com; spf=pass smtp.mailfrom=amazon.com; dkim=pass (2048-bit key) header.d=amazon.com header.i=@amazon.com header.b=FTx/HVqC; arc=none smtp.client-ip=52.26.1.71 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=amazon.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=amazon.com header.i=@amazon.com header.b="FTx/HVqC" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazoncorp2; t=1773644652; x=1805180652; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=wcaWTWB9jH4dvndQPVa+EJIrVfjs3M40llDrFeP1Fqw=; b=FTx/HVqCcPDawZr+E/KyljyexIepaPKfb1pt3q7nZqlLwpCzGb9RxTBc /aOxPT1AbGwTvGUbZy8cx1u/59fzDpoGpE6uSeOzKKEID0IYMaLPw2Rnj D6WO5G+yKGC7dmFs624AeAvEVT133Zgn7oU5RvvUUeZ2G3w+9UX9OrbVH CgsHzhcFzent/3/j3UYPTp4AEmtx1gFYytxQlB/s+ioZv9PtQJTqYGFV1 fpyfhjzQxMYHJp4nrOAsiUjCUpTWy1jKzlZtoac8ctwPTQNPKatXxW39H SiTZ0jzMnABwwd54m6UqO2wx5gxulFbqYSNW4lIiCELq2MzposYpAkzJP w==; X-CSE-ConnectionGUID: dajelrIlQxOBEqrcPkfHPQ== X-CSE-MsgGUID: UHzGCNTVQhqNDwv8djZADA== X-IronPort-AV: E=Sophos;i="6.23,123,1770595200"; d="scan'208";a="15105575" Received: from ip-10-5-9-48.us-west-2.compute.internal (HELO smtpout.naws.us-west-2.prod.farcaster.email.amazon.dev) ([10.5.9.48]) by internal-pdx-out-006.esa.us-west-2.outbound.mail-perimeter.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Mar 2026 07:04:09 +0000 Received: from EX19MTAUWB001.ant.amazon.com [205.251.233.51:17362] by smtpin.naws.us-west-2.prod.farcaster.email.amazon.dev [10.0.2.226:2525] with esmtp (Farcaster) id 306cfb32-9b41-47db-ab42-3f47477815ac; Mon, 16 Mar 2026 07:04:09 +0000 (UTC) X-Farcaster-Flow-ID: 306cfb32-9b41-47db-ab42-3f47477815ac Received: from EX19D001UWA001.ant.amazon.com (10.13.138.214) by EX19MTAUWB001.ant.amazon.com (10.250.64.248) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.37; Mon, 16 Mar 2026 07:04:09 +0000 Received: from c889f3b07a0a.amazon.com (10.106.82.26) by EX19D001UWA001.ant.amazon.com (10.13.138.214) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.37; Mon, 16 Mar 2026 07:04:07 +0000 From: Yuto Ohnuki To: Jens Axboe CC: Yu Kuai , Nilay Shroff , Ming Lei , , , Yuto Ohnuki , Subject: [PATCH v2] blk-wbt: remove WARN_ON_ONCE from wbt_init_enable_default() Date: Mon, 16 Mar 2026 07:03:59 +0000 Message-ID: <20260316070358.65225-2-ytohnuki@amazon.com> X-Mailer: git-send-email 2.50.0 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: EX19D040UWA003.ant.amazon.com (10.13.139.6) To EX19D001UWA001.ant.amazon.com (10.13.138.214) Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit wbt_init_enable_default() uses WARN_ON_ONCE to check for failures from wbt_alloc() and wbt_init(). However, both are expected failure paths: - wbt_alloc() can return NULL under memory pressure (-ENOMEM) - wbt_init() can fail with -EBUSY if wbt is already registered syzbot triggers this by injecting memory allocation failures during MTD partition creation via ioctl(BLKPG), causing a spurious warning. wbt_init_enable_default() is a best-effort initialization called from blk_register_queue() with a void return type. Failure simply means the disk operates without writeback throttling, which is harmless. Replace WARN_ON_ONCE with plain if-checks, consistent with how wbt_set_lat() in the same file already handles these failures. Add a pr_warn() for the wbt_init() failure to retain diagnostic information without triggering a full stack trace. Reported-by: syzbot+71fcf20f7c1e5043d78c@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=71fcf20f7c1e5043d78c Fixes: 41afaeeda509 ("blk-wbt: fix possible deadlock to nest pcpu_alloc_mutex under q_usage_counter") Signed-off-by: Yuto Ohnuki --- Changes in v2: - Add pr_warn() for wbt_init() failure as suggested by Yu Kuai - Link to v1: https://lore.kernel.org/all/20260315143137.13547-2-ytohnuki@amazon.com/ --- block/blk-wbt.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/block/blk-wbt.c b/block/blk-wbt.c index 33006edfccd4..dcc2438ca16d 100644 --- a/block/blk-wbt.c +++ b/block/blk-wbt.c @@ -782,10 +782,11 @@ void wbt_init_enable_default(struct gendisk *disk) return; rwb = wbt_alloc(); - if (WARN_ON_ONCE(!rwb)) + if (!rwb) return; - if (WARN_ON_ONCE(wbt_init(disk, rwb))) { + if (wbt_init(disk, rwb)) { + pr_warn("%s: failed to enable wbt\n", disk->disk_name); wbt_free(rwb); return; } -- 2.50.1 Amazon Web Services EMEA SARL, 38 avenue John F. Kennedy, L-1855 Luxembourg, R.C.S. Luxembourg B186284 Amazon Web Services EMEA SARL, Irish Branch, One Burlington Plaza, Burlington Road, Dublin 4, Ireland, branch registration number 908705