Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754914Ab1DORFj (ORCPT ); Fri, 15 Apr 2011 13:05:39 -0400 Received: from e1.ny.us.ibm.com ([32.97.182.141]:49439 "EHLO e1.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751692Ab1DORFh (ORCPT ); Fri, 15 Apr 2011 13:05:37 -0400 Subject: [PATCH 2/2] print vmalloc() state after allocation failures To: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Johannes Weiner , David Rientjes , Michal Nazarewicz , akpm@osdl.org, Dave Hansen From: Dave Hansen Date: Fri, 15 Apr 2011 10:04:38 -0700 References: <20110415170437.17E1AF36@kernel> In-Reply-To: <20110415170437.17E1AF36@kernel> Message-Id: <20110415170438.D5C317D5@kernel> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3316 Lines: 87 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: [ 68.123503] vmalloc: allocation failure, allocated 6680576 of 13426688 bytes [ 68.124218] bash: page allocation failure: order:0, mode:0xd2 [ 68.124811] Pid: 3770, comm: bash Not tainted 2.6.39-rc3-00082-g85f2e68-dirty #333 [ 68.125579] Call Trace: [ 68.125853] [] warn_alloc_failed+0x146/0x170 [ 68.126464] [] ? printk+0x6c/0x70 [ 68.126791] [] ? alloc_pages_current+0x94/0xe0 [ 68.127661] [] __vmalloc_node_range+0x237/0x290 ... The 'order' variable is added for clarity when calling warn_alloc_failed() to avoid having an unexplained '0' as an argument. The 'tmp_mask' is there to keep the alloc_pages_node() looking sane. Adding __GFP_NOWARN is done because we now have our own, full error message in vmalloc code. 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 2011-04-15 08:49:06.823306620 -0700 +++ linux-2.6.git-dave/mm/vmalloc.c 2011-04-15 09:20:17.926460283 -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: + warn_alloc_failed(gfp_mask, order, "vmalloc: allocation failure, " + "allocated %ld of %ld bytes\n", + (area->nr_pages*PAGE_SIZE), area->size); vfree(area->addr); return NULL; } _ -- 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/