Re: Stable backport request: skbuff: Proactively round up to kmalloc bucket size

[Daniel Díaz]

Hello!

On Tue, 23 May 2023 at 00:28, Vlastimil Babka <vbabka@xxxxxxx> wrote:
> On 5/22/23 20:23, Daniel Díaz wrote:
> > Hello!
> >
> > Would the stable maintainers please consider backporting the following
> > commit to the 6.1? We are trying to build gki_defconfig (plus a few
> > extras) on Arm64 and test it under Qemu-arm64, but it fails to boot.
> > Bisection has pointed here.
>
> You mean the bisection was done to find the first "good" commit between 6.1
> and e.g. 6.3?
>
> As others said, this commit wasn't expected to be a fix to a known bug.
> Maybe you found one that we didn't know of, or it might be accidentaly
> masking some other bug.

How interesting! Yes, we happened to run a bisection between v6.1 and
v6.3 and we found where it started working with the following
configuration:
  https://storage.tuxsuite.com/public/linaro/daniel/builds/2QA2CHQUpqKe27FyMZrBNILVwXi/config

With that patch on top of v6.1.29 it boots fine under Qemu-arm64; as
v6.1.y stands, it panics with this:
-----8<-----
  Unexpected kernel BRK exception at EL1
  Internal error: BRK handler: 00000000f2000001 [#1] PREEMPT SMP
  Modules linked in:
  CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.1.29 #1
  Hardware name: linux,dummy-virt (DT)
  pstate: 80000005 (Nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
  pc : pskb_expand_head+0x448/0x480
  lr : pskb_expand_head+0x13c/0x480
  sp : ffff80000802b850
  x29: ffff80000802b860 x28: 00000000000002c0 x27: 0000000000000ec0
  x26: ffff0000c02c8ec0 x25: ffff0000c02c8000 x24: 00000000000128c0
  x23: ffff0000c030e800 x22: ffff0000c030e800 x21: 0000000000000240
  x20: 0000000000000000 x19: ffff0000c085e900 x18: ffff800008021068
  x17: 00000000ad6b63b6 x16: 00000000ad6b63b6 x15: 0001001c00070038
  x14: 0000000c00020008 x13: 00882cc00000ffff x12: 0000000000000000
  x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000001
  x8 : ffff0000c030eac0 x7 : 0000000000000000 x6 : 0000000000000000
  x5 : ffff0000c030eaf0 x4 : ffff0000ff7abd10 x3 : 0000000000001740
  x2 : ffff0000c02c8000 x1 : 0000000000000000 x0 : 0000000000000000
  Call trace:
   pskb_expand_head+0x448/0x480
   netlink_trim+0xa0/0xc8
   netlink_broadcast+0x54/0x764
   genl_ctrl_event+0x21c/0x37c
   genl_register_family+0x628/0x708
   thermal_netlink_init+0x28/0x3c
   thermal_init+0x28/0xec
   do_one_initcall+0xfc/0x358
   do_initcall_level+0xd8/0x1b4
   do_initcalls+0x64/0xa8
   do_basic_setup+0x2c/0x3c
   kernel_init_freeable+0x118/0x198
   kernel_init+0x30/0x1c0
   ret_from_fork+0x10/0x20
  Code: f9406679 38776b28 3707eba8 17ffff67 (d4200020)
  ---[ end trace 0000000000000000 ]---
  Kernel panic - not syncing: BRK handler: Fatal exception
  SMP: stopping secondary CPUs
----->8-----

Greetings!

Daniel Díaz
daniel.diaz@xxxxxxxxxx