From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 23 Mar 2001 17:23:29 -0500 (EST) From: Alexander Viro Subject: Re: [PATCH] Fix races in 2.4.2-ac22 SysV shared memory In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Alan Cox Cc: Linus Torvalds , "Stephen C. Tweedie" , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Ben LaHaise , Christoph Rohland List-ID: On Fri, 23 Mar 2001, Alan Cox wrote: > > On Fri, 23 Mar 2001, Stephen C. Tweedie wrote: > > > > > > The patch below is for two races in sysV shared memory. > > > > + spin_lock (&info->lock); > > + > > + /* The shmem_swp_entry() call may have blocked, and > > + * shmem_writepage may have been moving a page between the page > > + * cache and swap cache. We need to recheck the page cache > > + * under the protection of the info->lock spinlock. */ > > + > > + page = find_lock_page(mapping, idx); > > > > Ehh.. Sleeping with the spin-lock held? Sounds like a truly bad idea. > > Umm find_lock_page doesnt sleep does it ? It certainly does. find_lock_page() -> __find_lock_page() -> lock_page() -> -> __lock_page() -> schedule(). -- 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.eu.org/Linux-MM/