On Sat, May 15, 2021 at 09:06:07PM +0200, Thorsten Knabe wrote:
> Hello.
>
> Starting with Linux 5.12 bcache triggers a BUG() after a few minutes of
> usage.
>
> Linux up to 5.11.x is not affected by this bug.
>
> Environment:
> - Debian 10 AMD 64
> - Kernel 5.12 - 5.12.4
> - Filesystem ext4
> - Backing device: degraded software RAID-6 (MD) with 3 of 4 disks active
> (unsure if the degraded RAID-6 has an effect or not)
> - Cache device: Single SSD
Sorry I can't immediately help with bcache, but for DRBD, there was a
similar problem with DRBD on degraded md-raid fixed just recently:
https://lists.linbit.com/pipermail/drbd-user/2021-May/025904.html
Although they had silent data corruption AFAICT, not a loud BUG(), and
they stated problems started with kernel 4.3.
For DRBD it had to do with split BIOs and readahead, which degraded
md-raid may or may not fail, and missing a fail on parts of a split-up
readahead BIO.
Matthias
