Bug#664088: mdadm fails to initialize components for bitmap

[Michael Tokarev]

On 31.03.2012 01:28, Markus Hochholdinger wrote:
> Package: mdadm
> Version: 3.2.3-2
> Followup-For: Bug #664088
> 
> Dear Maintainer,
> 
> seems I've been stumbled over this bug. I'm running wheezy and can reproduce a crash:
> mdadm --grow /dev/md0 --bitmap=none
> mdadm --grow /dev/md0 --bitmap=internal
> 
> A few seconds after this, the system is still alive, I see the newly created bitmap in /proc/mdstat, and then the system crashes:
> [  342.437949] md0: bitmap file is out of date (0 < 322) -- forcing full recovery
> [  342.437967] created bitmap (1 pages) for device md0
> [  347.949946] BUG: unable to handle kernel NULL pointer dereference at 00000008
> [  347.949969] IP: [<eda5edbd>] bitmap_endwrite+0x138/0x199 [md_mod]
> [  347.949991] *pdpt = 0000000002660007 *pde = 0000000000000000 
> [  347.950010] Oops: 0000 [#1] SMP 

Oh.  This is a kernel bug, kernel should not crash like this even if
incorrect bitmap is created.

Marcus, what's your kernel version?

Thank you!

/mjt