Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932602AbXBUVu2 (ORCPT ); Wed, 21 Feb 2007 16:50:28 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932622AbXBUVu2 (ORCPT ); Wed, 21 Feb 2007 16:50:28 -0500 Received: from iolanthe.rowland.org ([192.131.102.54]:38683 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S932602AbXBUVu0 (ORCPT ); Wed, 21 Feb 2007 16:50:26 -0500 Date: Wed, 21 Feb 2007 16:50:23 -0500 (EST) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Andrew Morton cc: OGAWA Hirofumi , , Pete Zaitcev , Greg KH , Kumar Gala , Linux Kernel list Subject: Re: [linux-usb-devel] 2.6.20 kernel hang with USB drive and vfat doing ftruncate In-Reply-To: <20070221133112.aec2bdac.akpm@linux-foundation.org> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1888 Lines: 56 On Wed, 21 Feb 2007, Andrew Morton wrote: > On Wed, 21 Feb 2007 16:22:17 -0500 (EST) > Alan Stern wrote: > > > On Wed, 21 Feb 2007, Andrew Morton wrote: > > > > > > > It seems like usb-storage and aio are completely off in the weeds. > > > > > Ideas? > > > > > > > > It seems usb-storage should remove some kmalloc and use mempool() for > > > > urb... Is someone working on this? And idea? > > > > > > I think Pete said that we're supposed to be using GFP_NOIO in there. > > > > We _are_ using it. > > How admirably prompt. Shucks, we've been using it for years... > > > Not that it'll help much: the VM calls throttle_vm_writeout() for GFP_NOIO > > > and GFP_NOFS allocations, which is a bug. Because if the caller holds > > > locks which prevent filesystem or IO progress, we deadlock. > > > > > > I'll fix the VM if someone else fixes USB ;) > > > > What else needs to be fixed? > > Would be nice if someone can confirm that this fixes it: Not having experienced the problem, I can't confirm the fix. However... > + if ((gfp_mask & (__GFP_FS|__GFP_IO)) != (__GFP_FS|__GFP_IO)) { Is that really the correct test? I don't know enough about the memory management subsystem to say one way or the other. What's special about having both flags set? > + /* > + * The caller might hold locks which can prevert IO completion --------------------------------------------------------------^ Typo Although perhaps "prevert" is an acceptable neologism in this context. > + * or progress in the filesystem. So we cannot just sit here > + * waiting for IO to complete. > + */ Alan Stern - 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/