mm/slab: ppc: ubi: kmalloc_slab WARNING / PPC + UBI driver

[Christoph Lameter]

On Wed, 31 Jul 2013, Wladislav Wiebe wrote:

> on a PPC 32-Bit board with a Linux Kernel v3.10.0 I see trouble with kmalloc_slab.
> Basically at system startup, something request a size of 8388608 b,
> but KMALLOC_MAX_SIZE has 4194304 b in our case. It points a WARNING at:

> ..
> NIP [c0099fec] kmalloc_slab+0x60/0xe8
> LR [c0099fd4] kmalloc_slab+0x48/0xe8
> Call Trace:
> [ccd3be60] [c0099fd4] kmalloc_slab+0x48/0xe8 (unreliable)
> [ccd3be70] [c00ae650] __kmalloc+0x20/0x1b4
> [ccd3be90] [c00d46f4] seq_read+0x2a4/0x540
> [ccd3bee0] [c00fe09c] proc_reg_read+0x5c/0x90
> [ccd3bef0] [c00b4e1c] vfs_read+0xa4/0x150
> [ccd3bf10] [c00b500c] SyS_read+0x4c/0x84
> [ccd3bf40] [c000be80] ret_from_syscall+0x0/0x3c
> ..
>
> Do you have any idea how I can analyze where these 8388608 b coming from?

It comes from the kmalloc in seq_read(). And 8M read from the proc
filesystem? Wow. Maybe switch the kmalloc to vmalloc()?