From 0017c869ddcb73069905d09f9e98e68627466237 Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj@kernel.org>
Date: Mon, 22 Jun 2009 11:56:24 +0900
Subject: [PATCH] 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>
---
arch/x86/kernel/setup_percpu.c | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c
index 165ebd5ba83bc6..29a3eef7cf4aff 100644
--- a/arch/x86/kernel/setup_percpu.c
+++ b/arch/x86/kernel/setup_percpu.c
@@ -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) {
--
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