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Commit bd1ce5f9 authored by Wu Fengguang's avatar Wu Fengguang Committed by Andi Kleen
Browse files

HWPOISON: avoid grabbing the page count multiple times during madvise injection 



If page is double referenced in madvise_hwpoison() and __memory_failure(),
remove_mapping() will fail because it expects page_count=2. Fix it by
not grabbing extra page count in __memory_failure().

Signed-off-by: default avatarWu Fengguang <fengguang.wu@intel.com>
Signed-off-by: default avatarAndi Kleen <ak@linux.intel.com>
parent a7560fc8

mm/madvise.c

+0 −1
Original line number Diff line number Diff line
@@ -238,7 +238,6 @@ static int madvise_hwpoison(unsigned long start, unsigned long end) 
		       page_to_pfn(p), start);

		/* Ignore return value for now */

		__memory_failure(page_to_pfn(p), 0, 1);

		put_page(p);

	}

	return ret;

}

mm/memory-failure.c

+4 −4
Original line number Diff line number Diff line
@@ -627,7 +627,7 @@ static void action_result(unsigned long pfn, char *msg, int result) 
}



static int page_action(struct page_state *ps, struct page *p,

			unsigned long pfn, int ref)

			unsigned long pfn)

{

	int result;

	int count;
@@ -635,7 +635,7 @@ static int page_action(struct page_state *ps, struct page *p, 
	result = ps->action(p, pfn);

	action_result(pfn, ps->msg, result);



	count = page_count(p) - 1 - ref;

	count = page_count(p) - 1;

	if (count != 0)

		printk(KERN_ERR

		       "MCE %#lx: %s page still referenced by %d users\n",
@@ -773,7 +773,7 @@ int __memory_failure(unsigned long pfn, int trapno, int ref) 
	 * In fact it's dangerous to directly bump up page count from 0,

	 * that may make page_freeze_refs()/page_unfreeze_refs() mismatch.

	 */

	if (!get_page_unless_zero(compound_head(p))) {

	if (!ref && !get_page_unless_zero(compound_head(p))) {

		action_result(pfn, "free or high order kernel", IGNORED);

		return PageBuddy(compound_head(p)) ? 0 : -EBUSY;

	}
@@ -821,7 +821,7 @@ int __memory_failure(unsigned long pfn, int trapno, int ref) 
	res = -EBUSY;

	for (ps = error_states;; ps++) {

		if (((p->flags | lru_flag)& ps->mask) == ps->res) {

			res = page_action(ps, p, pfn, ref);

			res = page_action(ps, p, pfn);

			break;

		}

	}