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x86: ensure percpu lpage doesn't consume too much vmalloc space 

On extreme configuration (e.g. 32bit 32-way NUMA machine), lpage
percpu first chunk allocator can consume too much of vmalloc space.
Make it fall back to 4k allocator if the consumption goes over 20%.

[ Impact: add sanity check for lpage percpu first chunk allocator ]

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Jan Beulich <JBeulich@novell.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Tejun Heo 2009-06-22 11:56:24 +09:00
parent fa8a7094ba
commit 0017c869dd
1 changed files with 15 additions and 3 deletions
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18
arch/x86/kernel/setup_percpu.c
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@ -163,9 +163,21 @@ static ssize_t __init setup_pcpu_lpage(size_t static_size, bool chosen)
int i, j;
ssize_t ret;
/* on non-NUMA, embedding is better */
if (!chosen && !pcpu_need_numa())
return -EINVAL;
if (!chosen) {
size_t vm_size = VMALLOC_END - VMALLOC_START;
size_t tot_size = num_possible_cpus() * PMD_SIZE;
/* on non-NUMA, embedding is better */
if (!pcpu_need_numa())
return -EINVAL;
/* don't consume more than 20% of vmalloc area */
if (tot_size > vm_size / 5) {
pr_info("PERCPU: too large chunk size %zuMB for "
"large page remap\n", tot_size >> 20);
return -EINVAL;
}
}
/* need PSE */
if (!cpu_has_pse) {