From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with ESMTP id 860408D003B for ; Thu, 7 Apr 2011 18:11:39 -0400 (EDT) Received: from kpbe20.cbf.corp.google.com (kpbe20.cbf.corp.google.com [172.25.105.84]) by smtp-out.google.com with ESMTP id p37MBZUR004497 for ; Thu, 7 Apr 2011 15:11:36 -0700 Received: from pzk30 (pzk30.prod.google.com [10.243.19.158]) by kpbe20.cbf.corp.google.com with ESMTP id p37MBXmH005185 (version=TLSv1/SSLv3 cipher=RC4-SHA bits=128 verify=NOT) for ; Thu, 7 Apr 2011 15:11:34 -0700 Received: by pzk30 with SMTP id 30so1676050pzk.17 for ; Thu, 07 Apr 2011 15:11:33 -0700 (PDT) Date: Thu, 7 Apr 2011 15:11:28 -0700 (PDT) From: David Rientjes Subject: Re: [PATCH] print vmalloc() state after allocation failures In-Reply-To: <20110407172302.3B7546DA@kernel> Message-ID: References: <20110407172302.3B7546DA@kernel> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton On Thu, 7 Apr 2011, Dave Hansen wrote: > > 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 will print out messages that look like this: > > [ 30.040774] bash: vmalloc failure allocating after 0 / 73728 bytes > Won't it print "bash: vmalloc: allocation failure, allocated 0 of 73728 bytes" instead? > 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. > > multipathd: page allocation failure. order:0, mode:0xd2 > Call Trace: > [c0000000f34ef570] [c000000000012d84] .show_stack+0x74/0x1c0 (unreliable) > [c0000000f34ef620] [c000000000159ed4] .__alloc_pages_nodemask+0x574/0x830 > [c0000000f34ef7a0] [c00000000019306c] .alloc_pages_current+0x8c/0x110 > [c0000000f34ef840] [c000000000183bdc] .__vmalloc_area_node+0x17c/0x220 > [c0000000f34ef900] [d00000000132bb24] .copy_params+0x74/0xc0 [dm_mod] > [c0000000f34efad0] [d00000000132bcec] .ctl_ioctl+0x17c/0x2c0 [dm_mod] > [c0000000f34efb90] [d00000000132be48] .dm_ctl_ioctl+0x18/0x30 [dm_mod] > [c0000000f34efc00] [c0000000001c4ee4] .vfs_ioctl+0x54/0x140 > [c0000000f34efc90] [c0000000001c5130] .do_vfs_ioctl+0x90/0x7c0 > [c0000000f34efd80] [c0000000001c5914] .SyS_ioctl+0xb4/0xd0 > [c0000000f34efe30] [c00000000000852c] syscall_exit+0x0/0x40 > Mem-Info: > Node 0 DMA per-cpu: > ... > > > Signed-off-by: Dave Hansen > --- > > linux-2.6.git-dave/mm/vmalloc.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff -puN mm/vmalloc.c~vmalloc-warn mm/vmalloc.c > --- linux-2.6.git/mm/vmalloc.c~vmalloc-warn 2011-04-07 10:21:27.792401938 -0700 > +++ linux-2.6.git-dave/mm/vmalloc.c 2011-04-07 10:21:27.800401934 -0700 > @@ -1579,6 +1579,18 @@ static void *__vmalloc_area_node(struct > return area->addr; > > fail: > + if (!(gfp_mask & __GFP_NOWARN) && printk_ratelimit()) { > + /* > + * We probably did a show_mem() and a stack dump above > + * inside of alloc_page*(). This is only so we can > + * tell how big the vmalloc() really was. This will > + * also not be exactly the same as what was passed > + * to vmalloc() due to alignment and the guard page. > + */ > + printk(KERN_WARNING "%s: vmalloc: allocation failure, " > + "allocated %ld of %ld bytes\n", current->comm, > + (area->nr_pages*PAGE_SIZE), area->size); > + } > vfree(area->addr); > return NULL; > } Looks good. Acked-by: David Rientjes __vmalloc_area_node() can also be moved into __vmalloc_node_range() since that's its only caller if you're interested. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org