Re: [PATCH -v2] rmap: make anon_vma_prepare link in all the anon_vmasof a mergeable VMA

From: Rik van Riel
Date: Mon Apr 12 2010 - 12:09:22 EST


On 04/12/2010 12:01 PM, Peter Zijlstra wrote:

@@ -864,15 +889,8 @@ void page_remove_rmap(struct page *page)
__dec_zone_page_state(page, NR_FILE_MAPPED);
mem_cgroup_update_file_mapped(page, -1);
}
- /*
- * It would be tidy to reset the PageAnon mapping here,
- * but that might overwrite a racing page_add_anon_rmap
- * which increments mapcount after us but sets mapping
- * before us: so leave the reset to free_hot_cold_page,
- * and remember that it's only reliable while mapped.
- * Leaving it set also helps swapoff to reinstate ptes
- * faster for those pages still in swapcache.
- */
+
+ page->mapping = NULL;
}

That would be a bug for file pages :)

I could see how it could work for anonymous memory, though.
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