Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1423142AbXBUVbh (ORCPT ); Wed, 21 Feb 2007 16:31:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1423141AbXBUVbh (ORCPT ); Wed, 21 Feb 2007 16:31:37 -0500 Received: from smtp.osdl.org ([65.172.181.24]:49679 "EHLO smtp.osdl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1423142AbXBUVbg (ORCPT ); Wed, 21 Feb 2007 16:31:36 -0500 Date: Wed, 21 Feb 2007 13:31:12 -0800 From: Andrew Morton To: Alan Stern 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 Message-Id: <20070221133112.aec2bdac.akpm@linux-foundation.org> In-Reply-To: References: <20070221125736.e5ff4206.akpm@linux-foundation.org> X-Mailer: Sylpheed version 2.2.7 (GTK+ 2.8.6; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3901 Lines: 114 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. > > 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: From: Andrew Morton throttle_vm_writeout() is designed to wait for the dirty levels to subside. But if the caller holds IO or FS locks, we might be holding up that writeout. So change it to take a single nap to give other devices a chance to clean some memory, then return. Cc: Nick Piggin Cc: OGAWA Hirofumi Cc: Kumar Gala Cc: Pete Zaitcev Signed-off-by: Andrew Morton --- include/linux/writeback.h | 2 +- mm/page-writeback.c | 13 +++++++++++-- mm/vmscan.c | 2 +- 3 files changed, 13 insertions(+), 4 deletions(-) diff -puN mm/vmscan.c~throttle_vm_writeout-dont-loop-on-gfp_nofs-and-gfp_noio-allocations mm/vmscan.c --- a/mm/vmscan.c~throttle_vm_writeout-dont-loop-on-gfp_nofs-and-gfp_noio-allocations +++ a/mm/vmscan.c @@ -952,7 +952,7 @@ static unsigned long shrink_zone(int pri } } - throttle_vm_writeout(); + throttle_vm_writeout(sc->gfp_mask); atomic_dec(&zone->reclaim_in_progress); return nr_reclaimed; diff -puN mm/page-writeback.c~throttle_vm_writeout-dont-loop-on-gfp_nofs-and-gfp_noio-allocations mm/page-writeback.c --- a/mm/page-writeback.c~throttle_vm_writeout-dont-loop-on-gfp_nofs-and-gfp_noio-allocations +++ a/mm/page-writeback.c @@ -296,11 +296,21 @@ void balance_dirty_pages_ratelimited_nr( } EXPORT_SYMBOL(balance_dirty_pages_ratelimited_nr); -void throttle_vm_writeout(void) +void throttle_vm_writeout(gfp_t gfp_mask) { long background_thresh; long dirty_thresh; + if ((gfp_mask & (__GFP_FS|__GFP_IO)) != (__GFP_FS|__GFP_IO)) { + /* + * The caller might hold locks which can prevert IO completion + * or progress in the filesystem. So we cannot just sit here + * waiting for IO to complete. + */ + congestion_wait(WRITE, HZ/10); + return; + } + for ( ; ; ) { get_dirty_limits(&background_thresh, &dirty_thresh, NULL); @@ -317,7 +327,6 @@ void throttle_vm_writeout(void) } } - /* * writeback at least _min_pages, and keep writing until the amount of dirty * memory is less than the background threshold, or until we're all clean. diff -puN include/linux/writeback.h~throttle_vm_writeout-dont-loop-on-gfp_nofs-and-gfp_noio-allocations include/linux/writeback.h --- a/include/linux/writeback.h~throttle_vm_writeout-dont-loop-on-gfp_nofs-and-gfp_noio-allocations +++ a/include/linux/writeback.h @@ -84,7 +84,7 @@ static inline void wait_on_inode(struct int wakeup_pdflush(long nr_pages); void laptop_io_completion(void); void laptop_sync_completion(void); -void throttle_vm_writeout(void); +void throttle_vm_writeout(gfp_t gfp_mask); /* These are exported to sysctl. */ extern int dirty_background_ratio; _ - 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/