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Commit 28e4d965 authored by Nick Piggin's avatar Nick Piggin Committed by Linus Torvalds
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[PATCH] mm: remove_mapping() safeness 



Some users of remove_mapping had been unsafe.

Modify the remove_mapping precondition to ensure the caller has locked the
page and obtained the correct mapping.  Modify callers to ensure the
mapping is the correct one.

[hugh@veritas.com: swapper_space fix]
Signed-off-by: default avatarNick Piggin <npiggin@suse.de>
Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent bfa5bf6d

mm/vmscan.c

+3 −3
Original line number Diff line number Diff line
@@ -377,8 +377,8 @@ static pageout_t pageout(struct page *page, struct address_space *mapping) 


int remove_mapping(struct address_space *mapping, struct page *page)

{

	if (!mapping)

		return 0;		/* truncate got there first */

	BUG_ON(!PageLocked(page));

	BUG_ON(mapping != page_mapping(page));



	write_lock_irq(&mapping->tree_lock);
@@ -547,7 +547,7 @@ static unsigned long shrink_page_list(struct list_head *page_list, 
				goto free_it;

		}



		if (!remove_mapping(mapping, page))

		if (!mapping || !remove_mapping(mapping, page))

			goto keep_locked;



free_it: