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Subjectkernel hangs in 118th call to vmalloc
I'm writing a driver for the 2.4.2 kernel.  I need to use this kernel 
because this driver needs to be compatible with a stock Red Hat system.
Patches to the kernel are not an option.

The purpose of the driver is to locate a device that exists on a
specific memory chip. To help find it, I've written this routine:

#define CLEAR_BLOCK_SIZE 1048576UL // must be a multiple of 1MB
#define CLEAR_BLOCK_COUNT ((PHYSICAL_HOP * 2) / CLEAR_BLOCK_SIZE)

void clear_out_memory(void)
{
void *p[CLEAR_BLOCK_COUNT];
unsigned i;
unsigned long size = 0;

for (i=0; i<CLEAR_BLOCK_COUNT; i++)
{
p[i] = vmalloc(CLEAR_BLOCK_SIZE);
if (!p[i])
break;
size += CLEAR_BLOCK_SIZE;
}

while (--i)
vfree(p[i]);

printk("Paged %luMB of memory\n", size / 1048576UL);
}

What this routine does is call vmalloc() repeatedly for a number of 1MB
chunks until it fails or until it's allocated 128MB (CLEAR_BLOCK_COUNT
is equal to 128 in this case). Then, it starts freeing them.

The side-effect of this routine is to page-out up to 128MB of RAM.
Unfortunately, on a 128MB machine, the 118th call to vmalloc() hangs the
system. I was expecting it to return NULL instead.

Is this a bug in vmalloc()? If so, is there a work-around that I can use?

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