mm: add comment on storage key dirty bit semantics

Add comments that dirty bit in storage key gets set whenever page content
is changed.  Hopefully if someone will use this function, he'll have a
look at one of the two places where we comment on this.

Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jan Kara
2012-12-11 16:01:09 -08:00
committed by Linus Torvalds
parent 712cd386fd
commit e749eb9553
2 changed files with 8 additions and 3 deletions

View File

@@ -158,6 +158,9 @@ static inline int page_reset_referenced(unsigned long addr)
* race against modification of the referenced bit. This function
* should therefore only be called if it is not mapped in any
* address space.
*
* Note that the bit gets set whenever page content is changed. That means
* also when the page is modified by DMA or from inside the kernel.
*/
#define __HAVE_ARCH_PAGE_TEST_AND_CLEAR_DIRTY
static inline int page_test_and_clear_dirty(unsigned long pfn, int mapped)