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block: initialize the bounce pool if high memory may be added later

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init_emergency_pool() does not create the page pool for bouncing block
requests if the current count of high pages is zero.  If high memory
may be added later (either via memory hotplug or a balloon driver in a
virtualized system) then a oops occurs if a request with a high page
need bouncing because the pool does not exist.

So, always create the pool if memory hotplug is enabled and change the
test so it's valid even if all high pages are currently in the balloon
(the balloon drivers adjust totalhigh_pages but not max_pfn).

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
David Vrabel 2011-10-20 21:24:30 +02:00 committed by Jens Axboe
parent c9a929dde3
commit 3bcfeaf93f
1 changed files with 4 additions and 5 deletions
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9
mm/bounce.c
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@ -14,6 +14,7 @@
#include <linux/init.h>
#include <linux/hash.h>
#include <linux/highmem.h>
#include <linux/bootmem.h>
#include <asm/tlbflush.h>
#include <trace/events/block.h>
@ -26,12 +27,10 @@ static mempool_t *page_pool, *isa_page_pool;
#ifdef CONFIG_HIGHMEM
static __init int init_emergency_pool(void)
{
struct sysinfo i;
si_meminfo(&i);
si_swapinfo(&i);
if (!i.totalhigh)
#ifndef CONFIG_MEMORY_HOTPLUG
if (max_pfn <= max_low_pfn)
return 0;
#endif
page_pool = mempool_create_page_pool(POOL_SIZE, 0);
BUG_ON(!page_pool);