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SubjectRe: [BUG REPORT] kernel BUG in ext4_write_inline_data_end or ext4_writepages
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On 2022/12/5 16:54, Jun Nie wrote:
> Hi,
> syzbot find a new bug[1] in ext4 that's similar with bug[0], that
> leads to reboot.
> While the bug[0] can be fixed with patch[2] from Bin. This new bug is still
> triggered with the patch[2], and log[3] is collected. Both log[1] and
> log[3] are
> collected when testing bug[4] on the mainline.
>
> [0] https://syzkaller.appspot.com/bug?id=5bafe4554067100b70f58a81268aa06ea3f9c345
> [1] https://syzkaller.appspot.com/text?tag=CrashLog&x=16325fc3880000
> [2] https://lore.kernel.org/lkml/CABymUCN+NSzkunRqFs8LgqjT6vXz-gyyZYn0hQWf8V9kmcO0Hw@mail.gmail.com/T/
> [3] https://syzkaller.appspot.com/text?tag=CrashLog&x=155abe7b880000
> [4] https://syzkaller.appspot.com/bug?id=899b37f20ce4072bcdfecfe1647b39602e956e36
>
>
> [ 38.932317][ T494] Call Trace:
> [ 38.935437][ T494] <TASK>
> [ 38.938393][ T494] ext4_write_inline_data_end+0xa39/0xdf0
> [ 38.943946][ T494] ? put_page+0xa0/0xa0
> [ 38.947936][ T494] ? ext4_da_write_begin+0x6f0/0x8d0
> [ 38.953055][ T494] ? pipe_zero+0x240/0x240
> [ 38.957308][ T494] ext4_da_write_end+0x1e2/0x950
> [ 38.962082][ T494] ? ext4_da_write_begin+0x8d0/0x8d0
> [ 38.967204][ T494] generic_perform_write+0x401/0x5f0
> [ 38.972326][ T494] ? generic_file_direct_write+0x6c0/0x6c0
> [ 38.977994][ T494] ? generic_write_checks_count+0x4b0/0x4b0
> [ 38.983694][ T494] ext4_buffered_write_iter+0x35f/0x640
> [ 38.989074][ T494] ext4_file_write_iter+0x198/0x1cd0
> [ 38.994194][ T494] ? futex_unqueue+0x156/0x180
> [ 38.998795][ T494] ? futex_wait+0x4c5/0x5c0
> [ 39.003307][ T494] ? futex_wait_setup+0x320/0x320
> [ 39.008168][ T494] ? avc_policy_seqno+0x1b/0x70
> [ 39.012862][ T494] ? ext4_file_read_iter+0x470/0x470
> [ 39.017976][ T494] vfs_write+0x8b5/0xef0
> [ 39.022056][ T494] ? file_end_write+0x1b0/0x1b0
> [ 39.026739][ T494] ? mutex_lock+0xb6/0x130
> [ 39.030994][ T494] ? bit_wait_io_timeout+0x110/0x110
> [ 39.036117][ T494] ? __fget_files+0x2d9/0x330
> [ 39.040630][ T494] ? __fdget_pos+0x268/0x300
> [ 39.045054][ T494] ? ksys_write+0x77/0x2c0
> [ 39.049307][ T494] ksys_write+0x198/0x2c0
> [ 39.053472][ T494] ? save_fpregs_to_fpstate+0x210/0x210
> [ 39.058855][ T494] ? __ia32_sys_read+0x90/0x90
> [ 39.063465][ T494] ? __kasan_check_write+0x14/0x20
> [ 39.068403][ T494] ? switch_fpu_return+0x129/0x270
> [ 39.073348][ T494] __x64_sys_write+0x7b/0x90
> [ 39.077783][ T494] do_syscall_64+0x2f/0x50
> [ 39.082030][ T494] entry_SYSCALL_64_after_hwframe+0x63/0xcd
>
> Regards,
> Jun
> .

I analyze that the above issue should be caused by the concurrency
of inline data conversion and buffer write.
At present, I haven't thought of any good solution.


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