From patchwork Thu Oct 2 13:05:16 2008 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [12/32] mm: system wide ALLOC_NO_WATERMARK Date: Thu, 02 Oct 2008 03:05:16 -0000 From: Peter Zijlstra X-Patchwork-Id: 2387 Message-Id: <20081002131608.372668704@chello.nl> To: Linus Torvalds , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, trond.myklebust@fys.uio.no, Daniel Lezcano , Pekka Enberg , Peter Zijlstra , Neil Brown , David Miller The reserve is proportionally distributed over all (!highmem) zones in the system. So we need to allow an emergency allocation access to all zones. In order to do that we need to break out of any mempolicy boundaries we might have. In my opinion that does not break mempolicies as those are user oriented and not system oriented. That is, system allocations are not guaranteed to be within mempolicy boundaries. For instance IRQs don't even have a mempolicy. So breaking out of mempolicy boundaries for 'rare' emergency allocations, which are always system allocations (as opposed to user) is ok. Signed-off-by: Peter Zijlstra --- mm/page_alloc.c | 5 +++++ 1 file changed, 5 insertions(+) Index: linux-2.6/mm/page_alloc.c =================================================================== --- linux-2.6.orig/mm/page_alloc.c +++ linux-2.6/mm/page_alloc.c @@ -1533,6 +1533,11 @@ restart: rebalance: if (alloc_flags & ALLOC_NO_WATERMARKS) { nofail_alloc: + /* + * break out of mempolicy boundaries + */ + zonelist = node_zonelist(numa_node_id(), gfp_mask); + /* go through the zonelist yet again, ignoring mins */ page = get_page_from_freelist(gfp_mask, nodemask, order, zonelist, high_zoneidx, ALLOC_NO_WATERMARKS);