From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from submarine.notk.org (submarine.notk.org [62.210.214.84]) by smtp.subspace.kernel.org (Postfix) with ESMTP id E105CA2D; Tue, 25 Mar 2025 14:59:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=62.210.214.84 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742914762; cv=none; b=DnpF4+qCt+jfw2Kw/Lp0vxEvSe4qkw1+3mkaH6P9rhCSCb7z8jqHfquAB0Ecevvowk1kioMmOwE2XuGXRJRY4ax64T3tjCgkPHKDfV8Wt0Q+3XWckSMASLXK1/VRCnvXUPojlTDzXv6i/NqpY1PHbtxljNW+jY+Lf8GcEglSezk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742914762; c=relaxed/simple; bh=jFKEhjNjq9tWLi1tufH12YoYuLncNqbR/nzyYY8yoFc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=NGLFVkiCOiHzA4Bsg/ZvvgR2Euwg2WGw9qdKsoC1JT58k99EEkANMUcw/iX6RYlenJLUqpO/jeK2czJ5Y1uSLaSakP5FDcp7CxyvrfY2v5gozSnUlywpjUNPe85e0OcLCLo1pT0+Yot1GxHyKJQIdPY/xYVnvdMsnWOzakxGvCk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=codewreck.org; spf=pass smtp.mailfrom=codewreck.org; dkim=pass (2048-bit key) header.d=codewreck.org header.i=@codewreck.org header.b=W3/5436i; arc=none smtp.client-ip=62.210.214.84 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=codewreck.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=codewreck.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=codewreck.org header.i=@codewreck.org header.b="W3/5436i" Received: from gaia.codewreck.org (localhost [127.0.0.1]) by submarine.notk.org (Postfix) with ESMTPS id 494BD14C2D3; Tue, 25 Mar 2025 15:59:13 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=codewreck.org; s=2; t=1742914758; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=LA2ZWfipp543V5Octm+YivgRf31pm38h6sG4nFoFVL4=; b=W3/5436ielp+x8Mg+ylaT1KwQLXmybgWQDRFANia1QIR5etK8+gW7Dk4fWWTQlCrj6Tkad vgLy5gZ/5N8CvbH+NS29LwIEi23qDuWlaxtwdi8nV8zNAN8L0Ztf0cUYdpEIPrYOvKrtL0 nKtHroMZM9HTu/lCxJ7sBGryNeMS1iRjuWs2kl7o1BM6Pg1FkZkhBBAwWCpBVnvNcGzq3s rVAXnUzgy8K1U3e/Qn6FeFY4w8hcycOuxZKajjueOVaqnN0z4ieDQOQEqh70519uT/MjvE cWZOqiDjql//4x7MeXIQ9UiRxAtbG0VD4DWlRRn0JeRy5uelCkgZgtw/6cgWlg== Received: from localhost (gaia.codewreck.org [local]) by gaia.codewreck.org (OpenSMTPD) with ESMTPA id ad07f38a; Tue, 25 Mar 2025 14:59:11 +0000 (UTC) Date: Tue, 25 Mar 2025 23:58:56 +0900 From: Dominique Martinet To: K Prateek Nayak Cc: Oleg Nesterov , Eric Van Hensbergen , Latchesar Ionkov , Christian Schoenebeck , Mateusz Guzik , syzbot , brauner@kernel.org, dhowells@redhat.com, jack@suse.cz, jlayton@kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, netfs@lists.linux.dev, swapnil.sapkal@amd.com, syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk, v9fs@lists.linux.dev Subject: Re: [syzbot] [netfs?] INFO: task hung in netfs_unbuffered_write_iter Message-ID: References: <20250323210251.GD14883@redhat.com> <7e377feb-a78b-4055-88cc-2c20f924bf82@amd.com> <20250325121526.GA7904@redhat.com> <20250325130410.GA10828@redhat.com> Precedence: bulk X-Mailing-List: v9fs@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Thanks for the traces. w/ revert K Prateek Nayak wrote on Tue, Mar 25, 2025 at 08:19:26PM +0530: > kworker/100:1-1803 [100] ..... 286.618822: p9_fd_poll: p9_fd_poll rd poll > kworker/100:1-1803 [100] ..... 286.618822: p9_fd_poll: p9_fd_request wr poll > kworker/100:1-1803 [100] ..... 286.618823: p9_read_work: Data read wait 7 new behavior > repro-4076 [031] ..... 95.011394: p9_fd_poll: p9_fd_poll rd poll > repro-4076 [031] ..... 95.011394: p9_fd_poll: p9_fd_request wr poll > repro-4076 [031] ..... 99.731970: p9_client_rpc: Wait event killable (-512) For me the problem isn't so much that this gets ERESTARTSYS but that it nevers gets to read the 7 bytes that are available? If the repro has already written the bytes in both cases then there's no reason to wait 5 seconds here... OTOH syzbot 9p code is silly and might have been depending on something that's not supposed to work e.g. they might be missing a flush or equivalent for all I know (I still haven't looked at the repro) -- Dominique