From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 11 Oct 2006 19:21:20 +0200 From: Nick Piggin Subject: Re: SPAM: Re: SPAM: Re: [patch 2/5] mm: fault vs invalidate/truncate race fix Message-ID: <20061011172120.GC5259@wotan.suse.de> References: <20061010121314.19693.75503.sendpatchset@linux.site> <20061010121332.19693.37204.sendpatchset@linux.site> <20061010213843.4478ddfc.akpm@osdl.org> <452C838A.70806@yahoo.com.au> <20061010230042.3d4e4df1.akpm@osdl.org> <20061011165717.GB5259@wotan.suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org Return-Path: To: Linus Torvalds Cc: Andrew Morton , Nick Piggin , Linux Memory Management , Linux Kernel List-ID: On Wed, Oct 11, 2006 at 10:11:43AM -0700, Linus Torvalds wrote: > > > On Wed, 11 Oct 2006, Nick Piggin wrote: > > > > > > The original IO could have been started by a person who didn't have > > > permissions to actually carry it out successfully, so if you enter with > > > the page locked (because somebody else started the IO), and you wait for > > > the page and it's not up-to-date afterwards, you absolutely _have_ to try > > > the IO, and can only return a real IO error after your _own_ IO has > > > failed. > > > > Sure, but we currently try to read _twice_, don't we? > > Well, we have the read-ahead, and then the real read. By the time we do > the real read, we have forgotten about the read-ahead details, so.. I mean filemap_nopage does *two* synchronous reads when finding a !uptodate page. This is despite the comment saying that it retries once on error. -- 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: email@kvack.org