On Fri, Jun 03, 2011 at 05:45:54PM +0200, Andrea Arcangeli wrote: > On Fri, Jun 03, 2011 at 03:49:41PM +0100, Mel Gorman wrote: > > Right idea of the wrong zone being accounted for but wrong place. I > > think the following patch should fix the problem; > > Looks good thanks. > > I also found this bug during my debugging that made NR_SHMEM underflow. > > === > Subject: migrate: don't account swapcache as shmem > > From: Andrea Arcangeli <[email protected]> > > swapcache will reach the below code path in migrate_page_move_mapping, > and swapcache is accounted as NR_FILE_PAGES but it's not accounted as > NR_SHMEM. > > Signed-off-by: Andrea Arcangeli <[email protected]>
Well spotted. Acked-by: Mel Gorman <[email protected]> Minor nit. swapper_space is rarely referred to outside of the swap code. Might it be more readable to use /* * swapcache is accounted as NR_FILE_PAGES but it is not * accounted as NR_SHMEM * if (PageSwapBacked(page) && !PageSwapCache(page)) ? > --- > > diff --git a/mm/migrate.c b/mm/migrate.c > index e4a5c91..2597a27 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -288,7 +288,7 @@ static int migrate_page_move_mapping(struct address_space > *mapping, > */ > __dec_zone_page_state(page, NR_FILE_PAGES); > __inc_zone_page_state(newpage, NR_FILE_PAGES); > - if (PageSwapBacked(page)) { > + if (mapping != &swapper_space && PageSwapBacked(page)) { > __dec_zone_page_state(page, NR_SHMEM); > __inc_zone_page_state(newpage, NR_SHMEM); > } > > -- Mel Gorman SUSE Labs _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
