Acked-by: Russ Anderson <rja@xxxxxxx> On Thu, Jun 02, 2011 at 11:55:57PM -0300, Rafael Aquini wrote: > When 1GB hugepages are allocated on a system, free(1) reports > less available memory than what really is installed in the box. > Also, if the total size of hugepages allocated on a system is > over half of the total memory size, CommitLimit becomes > a negative number. > > The problem is that gigantic hugepages (order > MAX_ORDER) > can only be allocated at boot with bootmem, thus its frames > are not accounted to 'totalram_pages'. However, they are > accounted to hugetlb_total_pages() > > What happens to turn CommitLimit into a negative number > is this calculation, in fs/proc/meminfo.c: > > allowed = ((totalram_pages - hugetlb_total_pages()) > * sysctl_overcommit_ratio / 100) + total_swap_pages; > > A similar calculation occurs in __vm_enough_memory() in mm/mmap.c. > > Also, every vm statistic which depends on 'totalram_pages' will render > confusing values, as if system were 'missing' some part of its memory. > > Reported-by: Russ Anderson <rja@xxxxxxx> > Signed-off-by: Rafael Aquini <aquini@xxxxxxxxx> > --- > mm/hugetlb.c | 8 ++++++++ > 1 files changed, 8 insertions(+), 0 deletions(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index f33bb31..c67dd0f 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -1111,6 +1111,14 @@ static void __init gather_bootmem_prealloc(void) > WARN_ON(page_count(page) != 1); > prep_compound_huge_page(page, h->order); > prep_new_huge_page(h, page, page_to_nid(page)); > + > + /* if we had gigantic hugepages allocated at boot time, > + * we need to reinstate the 'stolen' pages to totalram_pages, > + * in order to fix confusing memory reports from free(1) > + * and another side-effects, like CommitLimit going negative. > + */ > + if (h->order > (MAX_ORDER - 1)) > + totalram_pages += 1 << h->order; > } > } > > -- > 1.7.4.4 -- Russ Anderson, OS RAS/Partitioning Project Lead SGI - Silicon Graphics Inc rja@xxxxxxx -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx 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>