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Commit 23952a96 authored by Andreas Herrmann's avatar Andreas Herrmann Committed by Ingo Molnar
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x86: cpu_init(): fix memory leak when using CPU hotplug 



Exception stacks are allocated each time a CPU is set online.
But the allocated space is never freed. Thus with one CPU hotplug
offline/online cycle there is a memory leak of 24K (6 pages) for
a CPU.

Fix is to allocate exception stacks only once -- when the CPU is
set online for the first time.

Signed-off-by: default avatarAndreas Herrmann <andreas.herrmann3@amd.com>
Cc: akpm@linux-foundation.org
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent d04ec773

arch/x86/kernel/cpu/common_64.c

+13 −10
Original line number Diff line number Diff line
@@ -640,19 +640,22 @@ void __cpuinit cpu_init(void) 
	/*

	 * set up and load the per-CPU TSS

	 */

	for (v = 0; v < N_EXCEPTION_STACKS; v++) {

	if (!orig_ist->ist[0]) {

		static const unsigned int order[N_EXCEPTION_STACKS] = {

		  [0 ... N_EXCEPTION_STACKS - 1] = EXCEPTION_STACK_ORDER,

		  [DEBUG_STACK - 1] = DEBUG_STACK_ORDER

		};

		for (v = 0; v < N_EXCEPTION_STACKS; v++) {

			if (cpu) {

				estacks = (char *)__get_free_pages(GFP_ATOMIC, order[v]);

				if (!estacks)

				panic("Cannot allocate exception stack %ld %d\n",

				      v, cpu);

					panic("Cannot allocate exception "

					      "stack %ld %d\n", v, cpu);

			}

			estacks += PAGE_SIZE << order[v];

		orig_ist->ist[v] = t->x86_tss.ist[v] = (unsigned long)estacks;

			orig_ist->ist[v] = t->x86_tss.ist[v] =

					(unsigned long)estacks;

		}

	}



	t->x86_tss.io_bitmap_base = offsetof(struct tss_struct, io_bitmap);