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>
diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c
index 165ebd5..29a3eef 100644
--- a/arch/x86/kernel/setup_percpu.c
+++ b/arch/x86/kernel/setup_percpu.c
@@ -163,9 +163,21 @@
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) {