Re: [syzbot] [ext4?] kernel panic: EXT4-fs (device loop0): panic forced after error (3)

Theodore Ts'o
2023-08-17T14:45:19Z

On Thu, Aug 17, 2023 at 04:28:33PM +0200, Aleksandr Nogikh wrote:
> The console log has the following line:
>
> [ 60.708717][ T5061] Kernel panic - not syncing: EXT4-fs (device
> loop0): panic forced after error
>
> Can we consider a "panic forced after error" line to be a reliable
> indicator that syzbot must ignore the report?

Yes. And the file system image that generated this bug should be
discarded, because otherwise successive mutations will generate a
large number of crashes that syzbot will then need to ignore, thus
consuming syzbot resources.

Alternatively, you can do the moral equivalent of "tune2fs -e continue
foo.img" on any mutated file system seed, which will clear the "panic
on error".

(The other alternative is "tune2fs -e remount-ro", but given syzbot's
desire to find kernel crashes, "tune2fs -e continue" is more likely
find ways in which the kernel will find itself into trouble. Some
sysadmins will want to chose "remount-ro", however, since that is more
likely to limit file system damage once the file system is discovered
to be corrupted.)

- Ted