On Thu, Aug 22, 2013 at 12:43:08PM -0400, Naoya Horiguchi wrote: > On Thu, Aug 22, 2013 at 05:48:24PM +0800, Wanpeng Li wrote: > > There is a race between hwpoison page and unpoison page, memory_failure > > set the page hwpoison and increase num_poisoned_pages without hold page > > lock, and one page count will be accounted against thp for num_poisoned_pages. > > However, unpoison can occur before memory_failure hold page lock and > > split transparent hugepage, unpoison will decrease num_poisoned_pages > > by 1 << compound_order since memory_failure has not yet split transparent > > hugepage with page lock held. That means we account one page for hwpoison > > and 1 << compound_order for unpoison. This patch fix it by decrease one > > account for num_poisoned_pages against no hugetlbfs pages case. > > > > Signed-off-by: Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx> > > I think that a thp never becomes hwpoisoned without splitting, so "trying > to unpoison thp" never happens (I think that this implicit fact should be > commented somewhere or asserted with VM_BUG_ON().) > And nr_pages in unpoison_memory() can be greater than 1 for hugetlbfs page. > So does this patch break counting when unpoisoning free hugetlbfs pages? Sorry, the latter part of this remark was incorrect. Please ignore it. - Naoya -- 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/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>