On Tue 15-11-11 16:06:16, Wang Sheng-Hui wrote: > Per the void prep_compound_page(struct page *page, unsigned long order) code, > compound pages use PG_head/PG_tail, This is true only for CONFIG_PAGEFLAGS_EXTENDED otherwise we trick it by PG_compound & ~PG_reclaim = head page PG_compound & PG_reclaim = tail page Have a look at PG_head_tail_mask > and only tail pages point at head page using their ->first_page field. This part is correct. > > Signed-off-by: Wang Sheng-Hui <shhuiw@xxxxxxxxx> > --- > mm/page_alloc.c | 4 ++-- > 1 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 6e8ecb6..f645ce8 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -332,8 +332,8 @@ out: > * > * The remaining PAGE_SIZE pages are called "tail pages". > * > - * All pages have PG_compound set. All pages have their ->private pointing at > - * the head page (even the head page has this). > + * Head page has PG_head set, and all tail pages have PG_tail set. All tail > + * pages have their ->first_page pointing at the head page. > * > * The first tail page's ->lru.next holds the address of the compound page's > * put_page() function. Its ->lru.prev holds the order of allocation. > -- > 1.7.1 > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@xxxxxxxxx. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ > Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a> -- Michal Hocko SUSE Labs SUSE LINUX s.r.o. Lihovarska 1060/12 190 00 Praha 9 Czech Republic -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>