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Commit 752f5aec authored by Laura Abbott's avatar Laura Abbott Committed by Matt Wagantall
Browse files

mm: Mark free pages as read only 



Drivers have a tendency to scribble on everything, including free
pages. Make life easier by marking free pages as read only when
on the buddy list and re-marking as read/write when allocating.

Change-Id: I978ed2921394919917307b9c99217fdc22f82c59
Signed-off-by: default avatarLaura Abbott <lauraa@codeaurora.org>
parent 193121a0

mm/debug-pagealloc.c

+10 −0
Original line number Diff line number Diff line
@@ -6,6 +6,14 @@ 
#include <linux/poison.h>

#include <linux/ratelimit.h>



#ifndef mark_addr_rdonly

#define mark_addr_rdonly(a)

#endif



#ifndef mark_addr_rdwrite

#define mark_addr_rdwrite(a)

#endif



static inline void set_page_poison(struct page *page)

{

	__set_bit(PAGE_DEBUG_FLAG_POISON, &page->debug_flags);
@@ -27,6 +35,7 @@ static void poison_page(struct page *page) 


	set_page_poison(page);

	memset(addr, PAGE_POISON, PAGE_SIZE);

	mark_addr_rdonly(addr);

	kunmap_atomic(addr);

}
@@ -81,6 +90,7 @@ static void unpoison_page(struct page *page) 


	addr = kmap_atomic(page);

	check_poison_mem(addr, PAGE_SIZE);

	mark_addr_rdwrite(addr);

	clear_page_poison(page);

	kunmap_atomic(addr);

}