Re: bcache patch for kernel version 3.0

Hi Matthew,

I have bcache patch for 3.7 kernel. But I was trying to use bcache in
an android device which has a 3.0 kernel. So, I tried to back port
bcache patch to 3.0. But the bio handling in case of 3.0 is having
issues. Tried the git, but was not able to get a 3.0 compatible patch.

Regards
Ashim

On Tue, Aug 6, 2013 at 2:29 PM, Ashim Saikia [off-list ref] wrote:

Hi,

I am new to bcache and I am looking for a bcache patch for linux kernel
version 3.0.

Initially, form a 3.7 kernel, I prepared a patch and applied to 3.0 kernel.
But in this case, I encounter "null pointer dereference".

I am trying to use ramdisk as cache device and mmc partiton as backing
device.


Unable to handle kernel NULL pointer dereference at virtual address 00000000
kernel BUG at fs/bio.c:424!
Unable to handle kernel NULL pointer dereference at virtual address 00000000
pgd = c0004000
[00000000] *pgd=00000000
Internal error: Oops: 817 [#1] PREEMPT
Modules linked in:
CPU: 0    Not tainted  (3.0.8-00054-gece392b-dirty #5)
PC is at __bug+0x1c/0x24
LR is at __bug+0x18/0x24
pc : [<c003c584>]    lr : [<c003c580>]    psr: 60000193
sp : f0bf7d88  ip : f0bf7cc0  fp : 00000000
r10: f02f3000  r9 : e2b70400  r8 : e2b70400
r7 : 00000000  r6 : 00000800  r5 : 00000000  r4 : 00000000
r3 : 00000000  r2 : 00000001  r1 : 00000002  r0 : 00000022
Flags: nZCv  IRQs off  FIQs on  Mode SVC_32  ISA ARM  Segment kernel
Control: 10c5387d  Table: 4da00019  DAC: 00000015

PC: 0xc003c504:

So, I am trying to debug this issue. My guess is back porting bcache from
3.7 kernel may not be the right way.
I am looking for help in getting a bcache 3.0 patch. If anybody can give me
some pointers in order to get that patch, that will be really helpful to me.

Regards
Ashim