Hi Andi, Thinks for taking the time to review this. On Sun, Apr 26, 2015 at 10:12 PM, Andi Kleen <andi@xxxxxxxxxxxxxx> wrote: > Anisse Astier <anisse@xxxxxxxxx> writes: >> + If unsure, say N. >> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >> index 05fcec9..c71440a 100644 >> --- a/mm/page_alloc.c >> +++ b/mm/page_alloc.c >> @@ -803,6 +803,11 @@ static bool free_pages_prepare(struct page *page, unsigned int order) >> debug_check_no_obj_freed(page_address(page), >> PAGE_SIZE << order); >> } >> + >> +#ifdef CONFIG_SANITIZE_FREED_PAGES >> + zero_pages(page, order); >> +#endif > > And not removing the clear on __GFP_ZERO by remembering that? > > That means all clears would be done twice. > > That patch is far too simple. Clearing is commonly the most > expensive kernel operation. > I thought about this, but if you unconditionally remove the clear on __GFP_ZERO, you wouldn't be guaranteed to have a zeroed page when memory is first used (you would protect the kernel from its own info leaks though); you'd need to clear memory on boot for example. If you try to remember that a page it's cleared, it means using a page flag, which is was previously deemed too precious for this kind of operation. Regarding the expensive operation, I don't think this is an option you'd enable on your systems if you care about performance. Regards, Anisse -- 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>