From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-qv1-f42.google.com (mail-qv1-f42.google.com [209.85.219.42]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 508688F59; Wed, 20 Dec 2023 03:53:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Y7WSjxZB" Received: by mail-qv1-f42.google.com with SMTP id 6a1803df08f44-67f0cfd3650so38539536d6.3; Tue, 19 Dec 2023 19:53:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1703044430; x=1703649230; darn=vger.kernel.org; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=3XkPfiEhvxa8YlHOcqWd+fwFu91GxNXEY4eP9sBc5VQ=; b=Y7WSjxZBhVcGp33zrgjzc6jd/+dKdv3Go9RxqRqcVa0+v4x9PqzVUhlg06wyHe9zG/ Oaz6HBgRhbpeXZHF3VQ3q+2GHx3xBL2aMHhipq6Br3OEB6mOv9vyfyMEaol1xDz0+weZ tiZrTd6HddqWoFszdp+jM8IVJ1eyMuedzBTYLOKJ5qM5l9H7nA61xODRZcl3FJQjWKDe AiuUCgfoXYg32vHvBFdN0TqAsmNrBr3V9WEtexH/LSC16PfCLs8zWYvp+W96atPPMGoI H5oelkR0ykLmfSxBKhO7pxaCZABg8wyfASOoLFfCrgsDJtoVOXfAyYYIeebtQNReq9l5 AYvA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1703044430; x=1703649230; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=3XkPfiEhvxa8YlHOcqWd+fwFu91GxNXEY4eP9sBc5VQ=; b=Pe0YacC3vVkyh+4qEWKhBhJDiZ05mjQAZQZiNSjtz/6VmVAh/e/5ydQC+Xpmmdesva n3BptQw52qSU7wTbz57gtZGDkdZIkZ54WJsEoHH1R4peG2Elo+1KksEy/1b4Yw1PUqXP XzECg29pnDSuN9w+I5UORP+UU7cCW3Lytx5i/IYc8IFgaf9zMBELEhXVCqvxBo+Wl+fO ikN3IcO9pAvJxpIPLvP6UxXJsbBNZVpuBuvARlJR+s8eGhn3aPF028ieLSk70cpK5+zI CXTZEF5n9Mf1wdrj5D5YxKkwxq8s618P09C2tTiZQihxyxVcW65SVzHNmtthU1dD7hjZ pvLA== X-Gm-Message-State: AOJu0Yw3XyU31+itpL6nhAG9Q3/bkK6E3Do/8z00fBuzwm7mGJNh0yrr VuUDJruhrfdPdGF8mIUHQrqzWgNTTi1m1w+Gylg= X-Google-Smtp-Source: AGHT+IHAJPflP2ZKvyugtw3WMtAMIunzuTW7V+ADzkbLOcp2OMVpjNq9E4VI8GdfRLLz1F9Z4GIvG3y6T0LVFy7ndQ0= X-Received: by 2002:a05:6214:48c:b0:67f:4bd6:ccdd with SMTP id pt12-20020a056214048c00b0067f4bd6ccddmr4825261qvb.64.1703044430124; Tue, 19 Dec 2023 19:53:50 -0800 (PST) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <000000000000e171200600d6d8bd@google.com> <000000000000847160060ce61580@google.com> In-Reply-To: <000000000000847160060ce61580@google.com> From: Amir Goldstein Date: Wed, 20 Dec 2023 05:53:38 +0200 Message-ID: Subject: Re: [syzbot] [overlayfs?] possible deadlock in seq_read_iter (2) To: syzbot Cc: axboe@kernel.dk, hch@lst.de, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-unionfs@vger.kernel.org, miklos@szeredi.hu, rafael@kernel.org, syzkaller-bugs@googlegroups.com, Christian Brauner , David Howells Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, Dec 20, 2023 at 2:30=E2=80=AFAM syzbot wrote: > > syzbot has bisected this issue to: > > commit 1e8c813b083c4122dfeaa5c3b11028331026e85d > Author: Christoph Hellwig > Date: Wed May 31 12:55:32 2023 +0000 > > PM: hibernate: don't use early_lookup_bdev in resume_store > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=3D14b15592e8= 0000 > start commit: 2cf4f94d8e86 Merge tag 'scsi-fixes' of git://git.kernel.o= r.. > git tree: upstream > final oops: https://syzkaller.appspot.com/x/report.txt?x=3D16b15592e8= 0000 > console output: https://syzkaller.appspot.com/x/log.txt?x=3D12b15592e8000= 0 > kernel config: https://syzkaller.appspot.com/x/.config?x=3De5751b3a22261= 35d > dashboard link: https://syzkaller.appspot.com/bug?extid=3Dda4f9f61f96525c= 62cc7 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=3D176a4f49e80= 000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=3D154aa8d6e8000= 0 > > Reported-by: syzbot+da4f9f61f96525c62cc7@syzkaller.appspotmail.com > Fixes: 1e8c813b083c ("PM: hibernate: don't use early_lookup_bdev in resum= e_store") > I'm not sure this bisection is reliable, so I wouldn't use this Fixes tag. The reproducer may be a little flakey. Anyway, this is just one of many problems, real or false positives, related to the unholy dependency which sendfile() creates between locks on two different filesystems. I think those changes that are queued for 6.8 are going so fix this class of problems: #syz test: https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git vfs.= rw Thanks, Amir.