From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sat, 30 Jun 2001 13:47:55 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sat, 30 Jun 2001 13:47:45 -0400 Received: from [192.48.153.1] ([192.48.153.1]:41262 "EHLO sgi.com") by vger.kernel.org with ESMTP id ; Sat, 30 Jun 2001 13:47:25 -0400 Message-Id: <200106301748.f5UHmLs03109@jen.americas.sgi.com> X-Mailer: exmh version 2.2 06/23/2000 with nmh-1.0.4 To: Linus Torvalds cc: Steve Lord , Marcelo Tosatti , lkml Subject: Re: Bounce buffer deadlock In-Reply-To: Message from Linus Torvalds of "Sat, 30 Jun 2001 10:39:59 PDT." Date: Sat, 30 Jun 2001 12:48:21 -0500 From: Steve Lord Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > > On Sat, 30 Jun 2001, Steve Lord wrote: > > > > It looks to me as if all memory allocations of type GFP_BUFFER which happen > > in generic_make_request downwards can hit the same type of deadlock, so > > bounce buffers, the request functions of the raid and lvm paths can all > > end up in try_to_free_buffers on a buffer they themselves hold the lock on. > > .. which is why GFP_BUFFER doesn't exist any more in the most recent > pre-kernels (oops, this is pre8 only, not pre7 like I said in the previous > email) > > The problem is that GFP_BUFFER used to mean two things: "don't call > low-level filesystem" and "don't do IO". Some of the pre-kernels starting > to make it mean "don't call low-level FS" only. The later ones split up > the semantics, so that the cases which care about FS deadlocks use > "GFP_NOFS", and the cases that care about IO recursion use "GFP_NOIO", so > that we don't overload the meaning of GFP_BUFFER. > > That allows us to do the best we can - still flushing out dirty buffers > when that's ok (like when a filesystem wants more memory), and giving the > allocator better control over exactly _what_ he objects to. > > Linus OK, sounds reasonable, time to go download and merge again I guess! Steve