Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758233Ab2HIQdK (ORCPT ); Thu, 9 Aug 2012 12:33:10 -0400 Received: from mail-bk0-f74.google.com ([209.85.214.74]:47445 "EHLO mail-bk0-f74.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756080Ab2HIQdH (ORCPT ); Thu, 9 Aug 2012 12:33:07 -0400 From: Greg Thelen To: Glauber Costa Cc: , , , , Michal Hocko , Johannes Weiner , Andrew Morton , , Christoph Lameter , David Rientjes , Pekka Enberg , Pekka Enberg , Suleiman Souhlal Subject: Re: [PATCH v2 07/11] mm: Allocate kernel pages to the right memcg References: <1344517279-30646-1-git-send-email-glommer@parallels.com> <1344517279-30646-8-git-send-email-glommer@parallels.com> Date: Thu, 09 Aug 2012 09:33:03 -0700 In-Reply-To: <1344517279-30646-8-git-send-email-glommer@parallels.com> (Glauber Costa's message of "Thu, 9 Aug 2012 17:01:15 +0400") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3425 Lines: 85 On Thu, Aug 09 2012, Glauber Costa wrote: > When a process tries to allocate a page with the __GFP_KMEMCG flag, the > page allocator will call the corresponding memcg functions to validate > the allocation. Tasks in the root memcg can always proceed. > > To avoid adding markers to the page - and a kmem flag that would > necessarily follow, as much as doing page_cgroup lookups for no reason, > whoever is marking its allocations with __GFP_KMEMCG flag is responsible > for telling the page allocator that this is such an allocation at > free_pages() time. This is done by the invocation of > __free_accounted_pages() and free_accounted_pages(). > > Signed-off-by: Glauber Costa > CC: Christoph Lameter > CC: Pekka Enberg > CC: Michal Hocko > CC: Kamezawa Hiroyuki > CC: Johannes Weiner > CC: Suleiman Souhlal > --- > include/linux/gfp.h | 3 +++ > mm/page_alloc.c | 38 ++++++++++++++++++++++++++++++++++++++ > 2 files changed, 41 insertions(+) > > diff --git a/include/linux/gfp.h b/include/linux/gfp.h > index d8eae4d..029570f 100644 > --- a/include/linux/gfp.h > +++ b/include/linux/gfp.h > @@ -370,6 +370,9 @@ extern void free_pages(unsigned long addr, unsigned int order); > extern void free_hot_cold_page(struct page *page, int cold); > extern void free_hot_cold_page_list(struct list_head *list, int cold); > > +extern void __free_accounted_pages(struct page *page, unsigned int order); > +extern void free_accounted_pages(unsigned long addr, unsigned int order); > + > #define __free_page(page) __free_pages((page), 0) > #define free_page(addr) free_pages((addr), 0) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index b956cec..da341dc 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -2532,6 +2532,7 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, > struct page *page = NULL; > int migratetype = allocflags_to_migratetype(gfp_mask); > unsigned int cpuset_mems_cookie; > + void *handle = NULL; > > gfp_mask &= gfp_allowed_mask; > > @@ -2543,6 +2544,13 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, > return NULL; > > /* > + * Will only have any effect when __GFP_KMEMCG is set. > + * This is verified in the (always inline) callee > + */ > + if (!memcg_kmem_new_page(gfp_mask, &handle, order)) > + return NULL; > + > + /* > * Check the zones suitable for the gfp_mask contain at least one > * valid zone. It's possible to have an empty zonelist as a result > * of GFP_THISNODE and a memoryless node If memcg_kmem_new_page() succeeds then it may have obtained a memcg reference with mem_cgroup_get(). I think this reference is leaked when returning below: /* * Check the zones suitable for the gfp_mask contain at least one * valid zone. It's possible to have an empty zonelist as a result * of GFP_THISNODE and a memoryless node */ if (unlikely(!zonelist->_zonerefs->zone)) return NULL; I suspect the easiest fix is to swap the call to memcg_kmem_new_page() and the (!zonelist->_zonerefs->zone) check. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/