From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757881Ab1DHUW7 (ORCPT ); Fri, 8 Apr 2011 16:22:59 -0400 Received: from e6.ny.us.ibm.com ([32.97.182.146]:48085 "EHLO e6.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757779Ab1DHUW6 (ORCPT ); Fri, 8 Apr 2011 16:22:58 -0400 Subject: [PATCH 2/2] print vmalloc() state after allocation failures To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Johannes Weiner , Dave Hansen From: Dave Hansen Date: Fri, 08 Apr 2011 13:22:55 -0700 References: <20110408202253.6D6D231C@kernel> In-Reply-To: <20110408202253.6D6D231C@kernel> Message-Id: <20110408202255.9EE67DC9@kernel> X-Content-Scanned: Fidelis XPS MAILER Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I was tracking down a page allocation failure that ended up in vmalloc(). Since vmalloc() uses 0-order pages, if somebody asks for an insane amount of memory, we'll still get a warning with "order:0" in it. That's not very useful. During recovery, vmalloc() also nicely frees all of the memory that it got up to the point of the failure. That is wonderful, but it also quickly hides any issues. We have a much different sitation if vmalloc() repeatedly fails 10GB in to: vmalloc(100 * 1<<30); versus repeatedly failing 4096 bytes in to a: vmalloc(8192); This patch will print out messages that look like this: [ 30.040774] bash: vmalloc failure allocating after 0 / 73728 bytes As a side issue, I also noticed that ctl_ioctl() does vmalloc() based solely on an unverified value passed in from userspace. Granted, it's under CAP_SYS_ADMIN, but it still frightens me a bit. Signed-off-by: Dave Hansen --- linux-2.6.git-dave/mm/vmalloc.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff -puN mm/vmalloc.c~vmalloc-warn mm/vmalloc.c --- linux-2.6.git/mm/vmalloc.c~vmalloc-warn 2011-04-08 09:36:05.877020199 -0700 +++ linux-2.6.git-dave/mm/vmalloc.c 2011-04-08 09:38:00.373093593 -0700 @@ -1534,6 +1534,7 @@ static void *__vmalloc_node(unsigned lon static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask, pgprot_t prot, int node, void *caller) { + int order = 0; struct page **pages; unsigned int nr_pages, array_size, i; gfp_t nested_gfp = (gfp_mask & GFP_RECLAIM_MASK) | __GFP_ZERO; @@ -1560,11 +1561,12 @@ static void *__vmalloc_area_node(struct for (i = 0; i < area->nr_pages; i++) { struct page *page; + gfp_t tmp_mask = gfp_mask | __GFP_NOWARN; if (node < 0) - page = alloc_page(gfp_mask); + page = alloc_page(tmp_mask); else - page = alloc_pages_node(node, gfp_mask, 0); + page = alloc_pages_node(node, tmp_mask, order); if (unlikely(!page)) { /* Successfully allocated i pages, free them in __vunmap() */ @@ -1579,6 +1581,9 @@ static void *__vmalloc_area_node(struct return area->addr; fail: + nopage_warning(gfp_mask, order, "vmalloc: allocation failure, " + "allocated %ld of %ld bytes\n", + (area->nr_pages*PAGE_SIZE), area->size); vfree(area->addr); return NULL; } _