[DRBD-user] drbd-9.0.18-1 : BUG: unable to handle kernel NULL pointer dereference at 00000000000000b0

Lars Ellenberg lars.ellenberg at linbit.com
Wed Jun 12 15:43:31 CEST 2019

On Wed, Jun 12, 2019 at 10:39:14AM +0200, Joel Colledge wrote:
> Hi Rob,
> This message indicates that mounting with DAX is failing here:
> https://github.com/openSUSE/kernel/blob/SLE12-SP4/drivers/dax/super.c#L131
> But DRBD performs the corresponding check here:
> https://github.com/LINBIT/drbd-9.0/blob/drbd-9.0.18-1/drbd/drbd_dax_pmem.c#L57

Unfortunately ((unsigned long)-ENOTSUP < 1) is false,
we simply did not notice error returns :-(
Fixed now.

Still, a block device claiming to support it,
but then returning "sorry, not supported"
once you actually try to use it, is ... not very friendly either.

> > [525370.955135] dm-16: error: dax access failed (-95)

: Lars Ellenberg
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