From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 4 Jun 2003 15:37:59 -0700 From: William Lee Irwin III Subject: Re: [PATCH] Remove page_table_lock from vma manipulations Message-ID: <20030604223759.GD15692@holomorphy.com> References: <133290000.1054765825@baldur.austin.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <133290000.1054765825@baldur.austin.ibm.com> Sender: owner-linux-mm@kvack.org Return-Path: To: Dave McCracken Cc: Linux Memory Management , Linux Kernel List-ID: On Wed, Jun 04, 2003 at 05:30:25PM -0500, Dave McCracken wrote: > After more careful consideration, I don't see any reasons why > page_table_lock is necessary for dealing with vmas. I found one spot in > swapoff, but it was easily changed to mmap_sem. I've beat on this code and > mjb has beat on this code with no problems. Here's the patch to remove it. > Feel free to poke holes in it. shrink_list() calls try_to_unmap() under pte_chain_lock(page), and hence try_to_unmap() cannot sleep. Furthermore try_to_unmap() calls find_vma() under the sole protection of spin_trylock(&mm->page_table_lock), which I don't see changed to a read_trylock(&mm->mmap_sem) here. Hence, this is racy. -- wli -- 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/ . Don't email: aart@kvack.org