From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 BCAD16D1D7; Tue, 11 Jun 2024 18:59:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718132352; cv=none; b=PIA/akYppPVUEgKbu+w7IDvr3ITl8icnvnr9wuT6RGjs5YBfc+4S2fSMNGtXjBqsutmgC8LkS5NUDQ/bfiYJdwHmQDLQsGoxjka4AQxUANryl9rH3yhIxy/Z99Ie2y+SfdyZJWZhkUJkORvTU+bacCQDDnsbrGfeVECivZZLXlE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718132352; c=relaxed/simple; bh=2ko4AZAQjHKkQKP0cOLbkW/lgcK+uu590PSvOaZZPYQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=RLgwDxAVMhtACJH9IrtRXOG6y+eajC13RZnxGnVYE5MHkbFhs9i1PVjPIWYR6ILoOmeiB80gDQtJHTML3Y8Q4+kiCkx/O6DAotIp2mjLGA7+0tMsVM3hNZCXWQH79NVdnyKSeQkClnw3e4mvuFEmwsX497VSbgaml/I6iZSRiQg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=r3fAqW6w; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="r3fAqW6w" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=5/Z2xlBkH/IkjDKgK+u4Kdw+HNECNgtpfjVhYfN2IyE=; b=r3fAqW6wR3TOHT5LMXNw6yql1i p8FMBVIc+dLcNEkS64fwz/4q6hNFANw15RdbDXVRsu16KMrI8mxbh2z2hbyWIAN5FkeS7rNXnvzvE 4VCdj9k3kH0dmVdw9FQo1Krb7JjbMmFbYHnSjkwYzF/6+uvGzy+uVmWeHEktgi/AMpLnj68v9syd0 P69xwyXZrrtQQN4xaBdEezV29h0CBsVfk9CzgwHeGk+TR5rqwte/+ipDj+G1Nlxq8qRi084CxvRG1 FDhxRJ7z/tM0qIhgF5a7FZqFcdjPmD9s2iP43LtyLnk/tXFzpyaQek9psB3/OQVbDV4fh3PmFQMPz qEiAoPfg==; Received: from mcgrof by bombadil.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1sH6i5-00000009vLn-1bJw; Tue, 11 Jun 2024 18:59:09 +0000 Date: Tue, 11 Jun 2024 11:59:09 -0700 From: Luis Chamberlain To: "Darrick J. Wong" Cc: patches@lists.linux.dev, fstests@vger.kernel.org, linux-xfs@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, akpm@linux-foundation.org, ziy@nvidia.com, vbabka@suse.cz, seanjc@google.com, willy@infradead.org, david@redhat.com, hughd@google.com, linmiaohe@huawei.com, muchun.song@linux.dev, osalvador@suse.de, p.raghav@samsung.com, da.gomez@samsung.com, hare@suse.de, john.g.garry@oracle.com Subject: Re: [PATCH 5/5] fstests: add stress truncation + writeback test Message-ID: References: <20240611030203.1719072-1-mcgrof@kernel.org> <20240611030203.1719072-6-mcgrof@kernel.org> <20240611144503.GI52977@frogsfrogsfrogs> <20240611182959.GZ52987@frogsfrogsfrogs> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240611182959.GZ52987@frogsfrogsfrogs> Sender: Luis Chamberlain On Tue, Jun 11, 2024 at 11:29:59AM -0700, Darrick J. Wong wrote: > On Tue, Jun 11, 2024 at 11:15:52AM -0700, Luis Chamberlain wrote: > > On Tue, Jun 11, 2024 at 07:45:03AM -0700, Darrick J. Wong wrote: > > > On Mon, Jun 10, 2024 at 08:02:02PM -0700, Luis Chamberlain wrote: > > > > +# Requires CONFIG_DEBUGFS and truncation knobs > > > > +_require_split_debugfs() > > > > > > Er... I thought "split" referred to debugfs itself. > > > > > > _require_split_huge_pages_knob? > > > > Much better, thanks. > > > > > > +# This aims at trying to reproduce a difficult to reproduce bug found with > > > > +# min order. The issue was root caused to an xarray bug when we split folios > > > > +# to another order other than 0. This functionality is used to support min > > > > +# order. The crash: > > > > +# > > > > +# https://gist.github.com/mcgrof/d12f586ec6ebe32b2472b5d634c397df > > > > > > You might want to paste the stacktrace in here directly, in case the > > > gist ever goes away. > > > > Its not a simple crash trace, it is pretty enourmous considering I > > decoded it, and it has all locking candidates. Even including it after > > the "---" lines of the patch might make someone go: TLDR. Thoughts? > > I'd paste it in, even if it's quite lengthy. I don't even think it's all that > much if you remove some of the less useful bits of the unwind: > > "Crash excerpt is as follows: > > "BUG: kernel NULL pointer dereference, address: 0000000000000036 > #PF: supervisor read access in kernel mode > #PF: error_code(0x0000) - not-present page > PGD 0 P4D 0 > Oops: 0000 [#1] PREEMPT SMP NOPTI > CPU: 7 PID: 2190 Comm: kworker/u38:5 Not tainted 6.9.0-rc5+ #14 > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 > Workqueue: writeback wb_workfn (flush-7:5) > RIP: 0010:filemap_get_folios_tag+0xa9/0x200 > Call Trace: > > writeback_iter+0x17d/0x310 > write_cache_pages+0x42/0xa0 > iomap_writepages+0x33/0x50 > xfs_vm_writepages+0x63/0x90 [xfs] > do_writepages+0xcc/0x260 > __writeback_single_inode+0x3d/0x340 > writeback_sb_inodes+0x1ed/0x4b0 > __writeback_inodes_wb+0x4c/0xe0 > wb_writeback+0x267/0x2d0 > wb_workfn+0x2a4/0x440 > process_one_work+0x189/0x3b0 > worker_thread+0x273/0x390 > kthread+0xda/0x110 > ret_from_fork+0x2d/0x50 > ret_from_fork_asm+0x1a/0x30 > " Ah, sorry yes, this crash dump is small, the other one is the one that was I thinking, which we still deadlock on and have only a lockdep hint about likely what is going on. I'll include this dump on v2. Luis