Commit 9bdedfce authored by Andrew Morton's avatar Andrew Morton Committed by Oleg Drokin

[PATCH] Fix a race between __page_cache_release() and shrink_cache()

__page_cache_release() needs to recheck the page count inside the LRU
lock, because shrink_cache() may have found the page on the LRU and
incremented its refcount again.

Which is carefully documented over __pagevec_release().  Duh.
parent ac31cf70
......@@ -81,14 +81,17 @@ void __page_cache_release(struct page *page)
unsigned long flags;
spin_lock_irqsave(&_pagemap_lru_lock, flags);
if (!TestClearPageLRU(page))
BUG();
if (TestClearPageLRU(page)) {
if (PageActive(page))
del_page_from_active_list(page);
else
del_page_from_inactive_list(page);
}
if (page_count(page) != 0)
page = NULL;
spin_unlock_irqrestore(&_pagemap_lru_lock, flags);
}
if (page)
__free_pages_ok(page, 0);
}
......
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