From patchwork Mon Feb 8 05:37:49 2010 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michael Neuling X-Patchwork-Id: 44757 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from bilbo.ozlabs.org (localhost [127.0.0.1]) by ozlabs.org (Postfix) with ESMTP id BC719B83BC for ; Mon, 8 Feb 2010 16:38:07 +1100 (EST) Received: by ozlabs.org (Postfix) id 7FA19B7D7B; Mon, 8 Feb 2010 16:37:50 +1100 (EST) Delivered-To: linuxppc-dev@ozlabs.org Received: from localhost.localdomain (localhost [127.0.0.1]) by ozlabs.org (Postfix) with ESMTP id D7776B7D18; Mon, 8 Feb 2010 16:37:49 +1100 (EST) Received: by localhost.localdomain (Postfix, from userid 1000) id 2913C12023; Mon, 8 Feb 2010 16:37:49 +1100 (EST) Received: from neuling.org (localhost [127.0.0.1]) by localhost.localdomain (Postfix) with ESMTP id 221D72200D; Mon, 8 Feb 2010 16:37:49 +1100 (EST) From: Michael Neuling To: KOSAKI Motohiro Subject: [PATCH] Restrict stack space reservation to rlimit In-reply-to: <20100208141716.FB55.A69D9226@jp.fujitsu.com> References: <20100208140323.FB52.A69D9226@jp.fujitsu.com> <20100208051104.GL32246@kryten> <20100208141716.FB55.A69D9226@jp.fujitsu.com> Comments: In-reply-to KOSAKI Motohiro message dated "Mon, 08 Feb 2010 14:22:22 +0900." X-Mailer: MH-E 8.2; nmh 1.3; GNU Emacs 23.1.1 Date: Mon, 08 Feb 2010 16:37:49 +1100 Message-ID: <9729.1265607469@neuling.org> Cc: stable@kernel.org, aeb@cwi.nl, James Morris , miltonm@bga.com, Oleg Nesterov , linuxppc-dev@ozlabs.org, Paul Mackerras , Anton Blanchard , WANG Cong , linux-fsdevel@vger.kernel.org, Serge Hallyn , Andrew Morton , Linus Torvalds , Ingo Molnar , linux-kernel@vger.kernel.org, Alexander Viro X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.13 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org > > > > Hi, > > > > > Why do we need page size independent stack size? It seems to have > > > compatibility breaking risk. > > > > I don't think so. The current behaviour is clearly wrong, we dont need a > > 16x larger stack just because you went from a 4kB to a 64kB base page > > size. The user application stack usage is the same in both cases. > > I didn't discuss which behavior is better. Michael said he want to apply > his patch to 2.6.32 & 2.6.33. stable tree never accept the breaking > compatibility patch. > > Your answer doesn't explain why can't we wait it until next merge window. > > btw, personally, I like page size indepent stack size. but I'm not sure > why making stack size independency is related to bug fix. I tend to agree. Below is just the bug fix to limit the reservation size based rlimit. We still reserve different stack sizes based on the page size as before (unless we hit rlimit of course). Mikey Restrict stack space reservation to rlimit When reserving stack space for a new process, make sure we're not attempting to allocate more than rlimit allows. This fixes a bug cause by b6a2fea39318e43fee84fa7b0b90d68bed92d2ba "mm: variable length argument support" and unmasked by fc63cf237078c86214abcb2ee9926d8ad289da9b "exec: setup_arg_pages() fails to return errors". Signed-off-by: Michael Neuling Cc: Anton Blanchard Cc: stable@kernel.org --- fs/exec.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) Index: linux-2.6-ozlabs/fs/exec.c =================================================================== --- linux-2.6-ozlabs.orig/fs/exec.c +++ linux-2.6-ozlabs/fs/exec.c @@ -627,10 +627,13 @@ int setup_arg_pages(struct linux_binprm goto out_unlock; } + stack_base = min(EXTRA_STACK_VM_PAGES * PAGE_SIZE, + current->signal->rlim[RLIMIT_STACK].rlim_cur - + PAGE_SIZE); #ifdef CONFIG_STACK_GROWSUP - stack_base = vma->vm_end + EXTRA_STACK_VM_PAGES * PAGE_SIZE; + stack_base = vma->vm_end + stack_base; #else - stack_base = vma->vm_start - EXTRA_STACK_VM_PAGES * PAGE_SIZE; + stack_base = vma->vm_start - stack_base; #endif ret = expand_stack(vma, stack_base); if (ret)