x86: cpu_init(): fix memory leak when using CPU hotplug (b55793f7) · Commits · 戴 / test

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:

Andreas Herrmann <andreas.herrmann3@amd.com> Cc: akpm@linux-foundation.org Signed-off-by:

Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/cpu/common_64.c

+13 −10

Original line number	Diff line number	Diff line
		@@ -606,19 +606,22 @@ 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);

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