On Sun 13-10-13 22:16:06, Eric Whitney wrote: > Since 3.12-rc1, I've noticed a new warning message in my kernel logs when > running ext4 regression tests with xfstests on both my x86-64 (KVM guest) and > ARM (Pandaboard ES) SUTs. (I'm using xfstests-bld to run xfstests.) It > remains visible in 3.12-rc4. > > The warning appears when running ext4/271 after mounting the test file system > with the dioread_nolock option. > > After running ext4/271, the kernel log contains the following trace repeated > 21 times, apparently once for each write performed by dd in the test: > > EXT4-fs (vdc): mounted filesystem without journal. Opts: dioread_nolock,noload Ah, OK. Unusual combination of mount options about which I didn't think when writing the assertion :) The warning is false positive - in nojournal mode it doesn't make sense to ask for a reserved handle. I'll send a fix to silence the warning. Thanks for report! Honza > ------------[ cut here ]------------ > WARNING: CPU: 1 PID: 1366 at fs/ext4/page-io.c:205 ext4_put_io_end_defer+0xf5/0x100() > Modules linked in: snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_timer psmouse serio_raw snd soundcore virtio_balloon snd_page_alloc i2c_piix4 mac_hid lp parport floppy > CPU: 1 PID: 1366 Comm: dd Not tainted 3.12.0-rc4-ext4testing+ #1 > Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 > 0000000000000009 ffff88003fd03d10 ffffffff816e3b66 0000000000000000 > ffff88003fd03d48 ffffffff8104eb4c ffff88003d1a1168 ffff88003d209c10 > 0000000000000000 0000000000001000 ffff88003bb57490 ffff88003fd03d58 > Call Trace: > <IRQ> [<ffffffff816e3b66>] dump_stack+0x45/0x56 > [<ffffffff8104eb4c>] warn_slowpath_common+0x8c/0xc0 > [<ffffffff8104eb9a>] warn_slowpath_null+0x1a/0x20 > [<ffffffff81245df5>] ext4_put_io_end_defer+0xf5/0x100 > [<ffffffff81245ec6>] ext4_end_bio+0xc6/0xe0 > [<ffffffff811d206d>] bio_endio+0x1d/0x30 > [<ffffffff8133313a>] blk_update_request+0xba/0x450 > [<ffffffff813333e0>] ? blk_update_request+0x360/0x450 > [<ffffffff813334f7>] blk_update_bidi_request+0x27/0xa0 > [<ffffffff81336720>] __blk_end_bidi_request+0x20/0x50 > [<ffffffff8133676f>] __blk_end_request_all+0x1f/0x30 > [<ffffffff81480a20>] virtblk_done+0x100/0x260 > [<ffffffff81412b11>] vring_interrupt+0x31/0x50 > [<ffffffff810a6394>] handle_irq_event_percpu+0x54/0x1f0 > [<ffffffff810a6578>] handle_irq_event+0x48/0x70 > [<ffffffff810a8de7>] handle_edge_irq+0x77/0x110 > [<ffffffff810044de>] handle_irq+0x1e/0x30 > [<ffffffff816f70ba>] do_IRQ+0x5a/0xe0 > [<ffffffff816ecdaf>] common_interrupt+0x6f/0x6f > <EOI> [<ffffffff810be18e>] ? lock_acquire+0x9e/0x100 > [<ffffffff811a76ad>] ? path_init+0x26d/0x4c0 > [<ffffffff8107ca94>] lg_local_lock+0x34/0x70 > [<ffffffff811a76ad>] ? path_init+0x26d/0x4c0 > [<ffffffff811a76ad>] path_init+0x26d/0x4c0 > [<ffffffff81370898>] ? __raw_spin_lock_init+0x38/0x70 > [<ffffffff811abbb1>] path_openat+0x81/0x660 > [<ffffffff81165031>] ? handle_mm_fault+0x2d1/0xaf0 > [<ffffffff816f0638>] ? __do_page_fault+0x148/0x570 > [<ffffffff811ac4b3>] do_filp_open+0x43/0xa0 > [<ffffffff816ec897>] ? _raw_spin_unlock+0x27/0x30 > [<ffffffff811b9876>] ? __alloc_fd+0xd6/0x130 > [<ffffffff8119a62c>] do_sys_open+0x13c/0x230 > [<ffffffff8119a742>] SyS_open+0x22/0x30 > [<ffffffff816f5192>] system_call_fastpath+0x16/0x1b > ---[ end trace bd3f4c22c85fc732 ]--- > > The test itself concludes successfully as written, though it's worth noting > the test does not check the integrity of the data written. > > The same warning can be triggered by the following simple sequence of > commands, extracted from ext4/271: > > mkfs.ext4 /dev/vdc > mount -o dioread_nolock,noload /dev/vdc /vdc > touch /vdc/file > chattr +S /vdc/file > dd if=/dev/zero of=/vdc/file bs=4k count=1 > > (FWIW, if you omit the touch and chattr commands, the warning won't be > triggered unless a second instance of the dd command is issued.) > > The warning bisects cleanly to this patch: > 7b7a8665ed direct-io: Implement generic deferred AIO completions > > Apparently, !io_end->handle is unexpectedly true in this test case. A > WARN_ON for that condition was newly added in the patch. > > It's not yet clear to me how serious this warning is, but the new message is > at least a minor regression. > > Thanks, > Eric > > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
