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Commit 0017c869 authored by Tejun Heo's avatar Tejun Heo
Browse files

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: default avatarTejun Heo <tj@kernel.org>
Reported-by: default avatarJan Beulich <JBeulich@novell.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ingo Molnar <mingo@elte.hu>
parent fa8a7094

arch/x86/kernel/setup_percpu.c

+15 −3
Original line number Diff line number Diff line
@@ -163,9 +163,21 @@ static ssize_t __init setup_pcpu_lpage(size_t static_size, bool chosen) 
	int i, j;

	ssize_t ret;



	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 (!chosen && !pcpu_need_numa())

		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) {