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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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240611182959.GZ52987@frogsfrogsfrogs> X-Rspam-User: X-Rspamd-Queue-Id: 2D84C40009 X-Rspamd-Server: rspam01 X-Stat-Signature: 8an3jxfoyp3boghzxsxqbusrbhhy7kr6 X-HE-Tag: 1718132351-705573 X-HE-Meta: U2FsdGVkX1+hQyewBPcROOb5CpDcElAEQn54EZu0kRc1UdarC3j+pDQ4Va4z25GXQdGJ0aymG3Ms6wSRtfLWBOjX6ddZc8vEOJRDenIHAVWFvnutGRXnjLfpMTDwjT9R/lyQEzMQtrZ9PF8o1e6rDJfHnIL8IXHj7Bc7r+NWtpJk8XllPcdMfaRjOPvdDsWpOIeDbU46svNyEzkAzhAhR/Mgu84c7dVWagVW0Z8MDKcV7Rx+ky9WhbwVjDugOmpARps1WE/flCUQuCN4oFOPpGVLJhnlKnDwENULlkWYD6TZDBICOhs6tq11ADuA1mBXnmSRPqYCsFF7iIPIFFOUqJDU+4i5k16jPRrppauSqp5f1pnxDdOkOtVs3zUJrXhL3UuxRmnaEJoNwLPcIbiVnkLSLptyrHqGHPuRxrb2v+UQIc/AjxoOEYSu4+fwGlJ3hj5ABhf3QThl3ksJweKLwxGcYL5e/eZCoxX6ykbHEVaRCMaRTFGRJpytHYhppCoHpsmQYmNivKRHyd/f5SRSXyeN7wLNP7qtLcoqSE1kI+CPFjEfca+zTPvEHBINgPrU9ZX9EgV01paJBrivDkfB1SebpSBXWJ7uYjgjgCpbJOVcfjAa1pMCKZMv5MH24mnTXRDjfEiBbnQaMJxwS0Vn9bogF1nPajVpCM44vBGR+ZbaFuDs1XtWNUnW2p1qdXN+Hzvso0f6Kvbwh+9sz3lhEwZF844KSHX2ZmVEV/4o4QsJbefNms+G9t1HRF7al5EwWjkmmI+t2saBA+g2BWWv+CE6s/ditvaL1S+B102S1tkYeL5PappJHfFqKoy3FwK7IWxebxNqUBuroI73YJYvYINnFR6sPjS8l6T9/VWhztWasQ2JseU3y3vujPRfk302WnFH5rzNEczd4ZPujyqgTUxaE0MYI7gRwjfSjRTqPFO4JI3G8i8IepIOH3VzdQAPw9niK6EfiS4On9jR92b 0NOKktfg J1xqwO5Qhyz77cBMCn/UqW/M5SlEQQCjFoxyBFHdAtzsLa9P6d4QpI3We668vibNnjUcFgribqYJj0gg5KPksQ08OjufwEFuEVhIeqIWuAvbPboFBm0Pw1Xfe33D9imZVcl2326fjCUMEvu7dEe1SKZYbEBuURB8hFIu9CL4ij66lGFtW/4rf1nIfRgr6QLhi2CpS+xzYxhgcA4k8rNnhKqhPtBk0oxeb31PXCY5IYxuQ7m2COnv9WusIox/DRiMQ0hWJlG7kXVDrrQX7LtAr9tpn562ogFyrV7A/F+YQg/d2FfN5XUCBoZ8r+pHrufPlg5yzjQvskkEOeNs= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000901, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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