memory unplug: isolate_lru_page fix
release_pages() in mm/swap.c changes page_count() to be 0 without removing PageLRU flag... This means isolate_lru_page() can see a page, PageLRU() && page_count(page)==0.. This is BUG. (get_page() will be called against count=0 page.) Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -49,9 +49,8 @@ int isolate_lru_page(struct page *page, struct list_head *pagelist)
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struct zone *zone = page_zone(page);
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spin_lock_irq(&zone->lru_lock);
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if (PageLRU(page)) {
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if (PageLRU(page) && get_page_unless_zero(page)) {
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ret = 0;
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get_page(page);
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ClearPageLRU(page);
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if (PageActive(page))
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del_page_from_active_list(zone, page);
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