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Message-ID: <x49vb9bducp.fsf@segfault.boston.devel.redhat.com> Date: Mon, 09 Nov 2015 11:13:10 -0500 From: Jeff Moyer <jmoyer@...hat.com> To: Jan Kara <jack@...e.cz> Cc: Richard Weinberger <richard@....at>, "linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org>, linux-fsdevel <linux-fsdevel@...r.kernel.org>, "Theodore Ts'o" <tytso@....edu>, octavian.purdila@...el.com, Al Viro <viro@...iv.linux.org.uk>, Jens Axboe <axboe@...nel.dk> Subject: Re: WARNING: CPU: 0 PID: 1 at fs/block_dev.c:58 __blkdev_put+0x16f/0x1b0() Jan Kara <jack@...e.cz> writes: > Hi! > > On Sat 07-11-15 13:07:30, Richard Weinberger wrote: >> While playing with the Linux kernel library I run into this warning. >> Root cause of the warning is that the backing file on the host >> side is locked an therefore all IO on it results into -EIO. >> >> The question is whether ext4/jbd2 should abort earlier or not. >> The WARN_ON_ONCE in bdev_write_inode() triggers as jbd2's do_one_pass() >> sets up a dirty buffer_head and fails later. >> Then ext4 gives up, calls blkdev_put() and we reach bdev_write_inode() >> with a dirty ->bd_inode. >> >> What do you think? > > So I think the right question is what we should do when we cannot writeback > dirty data. Currently we WARN_ON in some places (bdev_write_inode() is one > of them) and print errors in others. Although loosing data is nasty, people > seem to remove devices or do similar stuff too often for WARN_ON to be really > an adequate answer... So I think we should just print error message and go > on without spewing stack traces. Thoughts? There's a patch from Vivek to do just that: https://lkml.org/lkml/2015/10/30/419 Cheers, Jeff >> [ 0.128000] blk_update_request: I/O error, dev vda, sector 0 >> [ 0.128000] Buffer I/O error on dev vda, logical block 0, lost async page write >> [ 0.128000] blk_update_request: I/O error, dev vda, sector 8 >> [ 0.128000] Buffer I/O error on dev vda, logical block 1, lost async page write >> [ 0.128000] blk_update_request: I/O error, dev vda, sector 528 >> [ 0.128000] Buffer I/O error on dev vda, logical block 66, lost async page write >> [ 0.128000] blk_update_request: I/O error, dev vda, sector 1824 >> [ 0.128000] Buffer I/O error on dev vda, logical block 228, lost async page write >> [ 0.128000] blk_update_request: I/O error, dev vda, sector 1864 >> [ 0.128000] Buffer I/O error on dev vda, logical block 233, lost async page write >> [ 0.128000] blk_update_request: I/O error, dev vda, sector 41840 >> [ 0.128000] Buffer I/O error on dev vda, logical block 5230, lost async page write >> [ 0.128000] blk_update_request: I/O error, dev vda, sector 262672 >> [ 0.128000] Buffer I/O error on dev vda, logical block 32834, lost async page write >> [ 0.128000] blk_update_request: I/O error, dev vda, sector 262680 >> [ 0.128000] Buffer I/O error on dev vda, logical block 32835, lost async page write >> [ 0.128000] blk_update_request: I/O error, dev vda, sector 262752 >> [ 0.128000] Buffer I/O error on dev vda, logical block 32844, lost async page write >> [ 0.128000] blk_update_request: I/O error, dev vda, sector 262792 >> [ 0.128000] Buffer I/O error on dev vda, logical block 32849, lost async page write >> [ 0.132000] JBD2: recovery failed >> [ 0.132000] EXT4-fs (vda): error loading journal >> [ 0.132000] ------------[ cut here ]------------ >> [ 0.132000] WARNING: CPU: 0 PID: 1 at fs/block_dev.c:58 __blkdev_put+0x16f/0x1b0() >> [ 0.132000] Call Trace: >> [ 0.132000] 00007fd99262db68: [<0040673d>] warn_slowpath_common+0x7d/0xb0 >> [ 0.132000] 00007fd99262dba8: [<004068d5>] warn_slowpath_null+0x15/0x20 >> [ 0.132000] 00007fd99262dbb8: [<0048efbf>] __blkdev_put+0x16f/0x1b0 >> [ 0.132000] 00007fd99262dbf8: [<0048fcd2>] blkdev_put+0x92/0x110 >> [ 0.132000] 00007fd99262dc28: [<00462faf>] kill_block_super+0x3f/0x70 >> [ 0.132000] 00007fd99262dc48: [<00461bf2>] deactivate_locked_super+0x52/0xb0 >> [ 0.132000] 00007fd99262dc78: [<00462f51>] mount_bdev+0x1b1/0x1d0 >> [ 0.132000] 00007fd99262dc80: [<004c5c40>] ext4_fill_super+0x0/0x32f0 >> [ 0.132000] 00007fd99262dce8: [<004c16f0>] ext4_mount+0x10/0x20 >> [ 0.132000] 00007fd99262dcf8: [<00463164>] mount_fs+0x14/0xc0 >> [ 0.132000] 00007fd99262dd28: [<0047a38e>] vfs_kern_mount+0x5e/0x120 >> [ 0.132000] 00007fd99262dd78: [<0047baa8>] do_mount+0x208/0xd90 >> [ 0.132000] 00007fd99262dd88: [<0045d7db>] __kmalloc_track_caller+0x18b/0x1c0 >> [ 0.132000] 00007fd99262dd98: [<00450618>] strndup_user+0x48/0x60 >> [ 0.132000] 00007fd99262de08: [<00450618>] strndup_user+0x48/0x60 >> [ 0.132000] 00007fd99262de48: [<0047c99a>] SyS_mount+0x6a/0xb0 >> [ 0.132000] 00007fd99262de98: [<00403b89>] run_syscalls+0xd9/0x1c0 >> [ 0.132000] 00007fd99262deb0: [<00425970>] autoremove_wake_function+0x0/0x40 >> [ 0.132000] 00007fd99262dec8: [<005535f0>] kernel_init+0x0/0xf0 >> [ 0.132000] 00007fd99262dee8: [<005535f0>] kernel_init+0x0/0xf0 >> [ 0.132000] 00007fd99262df08: [<00402f2d>] run_init_process+0x1d/0x40 >> [ 0.132000] 00007fd99262df18: [<00553626>] kernel_init+0x36/0xf0 >> [ 0.132000] 00007fd99262df28: [<00403158>] thread_bootstrap+0x48/0x50 >> [ 0.132000] >> [ 0.132000] ---[ end trace 0b886a9a044a4995 ]--- >> >> Thanks, >> //richard -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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