Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932432AbVLXMEU (ORCPT ); Sat, 24 Dec 2005 07:04:20 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932517AbVLXMEU (ORCPT ); Sat, 24 Dec 2005 07:04:20 -0500 Received: from 167.imtp.Ilyichevsk.Odessa.UA ([195.66.192.167]:62867 "HELO ilport.com.ua") by vger.kernel.org with SMTP id S932432AbVLXMET (ORCPT ); Sat, 24 Dec 2005 07:04:19 -0500 From: Denis Vlasenko To: "linux-os \(Dick Johnson\)" Subject: Re: 4k stacks Date: Sat, 24 Dec 2005 14:03:38 +0200 User-Agent: KMail/1.8.2 Cc: "Linux kernel" References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="koi8-r" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200512241403.38482.vda@ilport.com.ua> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1903 Lines: 51 On Thursday 22 December 2005 23:53, linux-os (Dick Johnson) wrote: > > Yesterday I sent a patch to add stack-poison so the stack usage > could be observed. > > Today I wrote a small program and tested the stack usage. Both > the program and the patch is attached. The result is: > > Offset : 2ec8f000 Available Stack bytes = 3104 > Offset : 2ecb1000 Available Stack bytes = 3104 > Offset : 2ee5f000 Available Stack bytes = 20 > Offset : 2f36d000 Available Stack bytes = 3104 > Offset : 2fd09000 Available Stack bytes = 3012 > Offset : 2fd0b000 Available Stack bytes = 3312 > Offset : 2fd0f000 Available Stack bytes = 2132 > Offset : 2fd2f000 Available Stack bytes = 2744 > Offset : 2fd57000 Available Stack bytes = 2900 > Offset : 2fdd5000 Available Stack bytes = 1400 > Offset : 2fe35000 Available Stack bytes = 2832 > Offset : 2ff3f000 Available Stack bytes = 776 > Offset : 2ff45000 Available Stack bytes = 3188 > > This, after compiling the kernel. I did not have 4k stacks > enabled for this test so any crashing of the stack beyond > one page will not hurt the system. This was on linux-2.6.13.4. > > Anyway, I tried to enable 4k stacks and the machine would > not boot past trying to install the first module. It just > stopped with the interrupts disabled. So, I am now rebuilding > the kernel back as I write this. That's why I am using 2.6.13 > at the moment. > > Anyway, getting down to 20 bytes of stack-space available > seems to be pretty scary. + movl %esp, %edi + movl %edi, %ecx + andl $~0x1000, %edi + subl %edi, %ecx ecx will be equal to ? + movb $'Q', %al + rep stosb -- vda - 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/