Hi, Thank you. I have found the main reason for my problem. alloc_bootmem() must use after init_bootmem_node() and before free_all_bootmem(), but profile_init() is executed after free_all_bootmem(), so it could not alloc the memory what I want.

2011/4/15 Dave Hylands <dhylands@gmail.com>
Hi,

On Thu, Apr 14, 2011 at 10:49 PM, javaweb zhang <javawebzwp@gmail.com> wrote:
> Hello, everyone. I use alloc_bootmem() in profile.c to allocate a big memory
> at function profile_init(), how I know whether it is success? The following
> is my code:
> // at kernel/profile.c
> ctxsw_A = (struct ctxsw_rec *)alloc_bootmem(sizeof(struct ctxsw_rec)*CTXSW);
> ctxsw_rec is a struct which declared in include/linux/profile.h,  CTXSW =
> 4>>10

Looking at the source code for alloc_bootmem, it returns a NULL
pointer (which is what most allocators do when the allocation fails).
It appears that it will hit a panic first though, so you may never get
to the receiving the NULL.

--
Dave Hylands
Shuswap, BC, Canada
http://www.davehylands.com