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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: Andreas Herrmann <andreas.herrmann3@amd.com>
Cc: akpm@linux-foundation.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Andreas Herrmann 2008-08-06 10:29:37 +02:00 committed by Ingo Molnar
parent d04ec773d7
commit 23952a96ae
1 changed files with 13 additions and 10 deletions
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23
arch/x86/kernel/cpu/common_64.c
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@ -640,19 +640,22 @@ void __cpuinit cpu_init(void)
/* /*
* set up and load the per-CPU TSS * 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] = { static const unsigned int order[N_EXCEPTION_STACKS] = {
[0 ... N_EXCEPTION_STACKS - 1] = EXCEPTION_STACK_ORDER, [0 ... N_EXCEPTION_STACKS - 1] = EXCEPTION_STACK_ORDER,
[DEBUG_STACK - 1] = DEBUG_STACK_ORDER [DEBUG_STACK - 1] = DEBUG_STACK_ORDER
}; };
if (cpu) { for (v = 0; v < N_EXCEPTION_STACKS; v++) {
estacks = (char *)__get_free_pages(GFP_ATOMIC, order[v]); if (cpu) {
if (!estacks) estacks = (char *)__get_free_pages(GFP_ATOMIC, order[v]);
panic("Cannot allocate exception stack %ld %d\n", if (!estacks)
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;
} }
estacks += PAGE_SIZE << order[v];
orig_ist->ist[v] = t->x86_tss.ist[v] = (unsigned long)estacks;
} }
t->x86_tss.io_bitmap_base = offsetof(struct tss_struct, io_bitmap); t->x86_tss.io_bitmap_base = offsetof(struct tss_struct, io_bitmap);