Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752828Ab2JOPrc (ORCPT ); Mon, 15 Oct 2012 11:47:32 -0400 Received: from mail-pa0-f46.google.com ([209.85.220.46]:61763 "EHLO mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751292Ab2JOPra (ORCPT ); Mon, 15 Oct 2012 11:47:30 -0400 Date: Tue, 16 Oct 2012 00:47:24 +0900 From: Minchan Kim To: Ming Lei Cc: linux-kernel@vger.kernel.org, Greg Kroah-Hartman , linux-usb@vger.kernel.org, linux-pm@vger.kernel.org, Alan Stern , Oliver Neukum , Jiri Kosina , Andrew Morton , Mel Gorman , KAMEZAWA Hiroyuki , Michal Hocko , Ingo Molnar , Peter Zijlstra , "Rafael J. Wysocki" , linux-mm Subject: Re: [RFC PATCH 1/3] mm: teach mm by current context info to not do I/O during memory allocation Message-ID: <20121015154724.GA2840@barrios> References: <1350278059-14904-1-git-send-email-ming.lei@canonical.com> <1350278059-14904-2-git-send-email-ming.lei@canonical.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1350278059-14904-2-git-send-email-ming.lei@canonical.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4698 Lines: 108 On Mon, Oct 15, 2012 at 01:14:17PM +0800, Ming Lei wrote: > This patch introduces PF_MEMALLOC_NOIO on process flag('flags' field of > 'struct task_struct'), so that the flag can be set by one task > to avoid doing I/O inside memory allocation in the task's context. > > The patch trys to solve one deadlock problem caused by block device, > and the problem can be occured at least in the below situations: > > - during block device runtime resume situation, if memory allocation > with GFP_KERNEL is called inside runtime resume callback of any one > of its ancestors(or the block device itself), the deadlock may be > triggered inside the memory allocation since it might not complete > until the block device becomes active and the involed page I/O finishes. > The situation is pointed out first by Alan Stern. It is not a good > approach to convert all GFP_KERNEL in the path into GFP_NOIO because > several subsystems may be involved(for example, PCI, USB and SCSI may > be involved for usb mass stoarage device) Couldn't we expand pm_restrict_gfp_mask to cover resume path as well as suspend path? > > - during error handling situation of usb mass storage deivce, USB > bus reset will be put on the device, so there shouldn't have any > memory allocation with GFP_KERNEL during USB bus reset, otherwise > the deadlock similar with above may be triggered. Unfortunately, any > usb device may include one mass storage interface in theory, so it > requires all usb interface drivers to handle the situation. In fact, > most usb drivers don't know how to handle bus reset on the device > and don't provide .pre_set() and .post_reset() callback at all, so > USB core has to unbind and bind driver for these devices. So it > is still not practical to resort to GFP_NOIO for solving the problem. I hope this case could be handled by usb core like usb_restrict_gfp_mask rather than adding new branch on fast path. > > Also the introduced solution can be used by block subsystem or block > drivers too, for example, set the PF_MEMALLOC_NOIO flag before doing > actual I/O transfer. > > Cc: Alan Stern > Cc: Oliver Neukum > Cc: Jiri Kosina > Cc: Andrew Morton > Cc: Mel Gorman > Cc: Minchan Kim > Cc: KAMEZAWA Hiroyuki > Cc: Michal Hocko > Cc: Ingo Molnar > Cc: Peter Zijlstra > Cc: "Rafael J. Wysocki" > Cc: linux-mm > > Signed-off-by: Ming Lei > --- > include/linux/sched.h | 5 +++++ > mm/page_alloc.c | 2 ++ > 2 files changed, 7 insertions(+) > > diff --git a/include/linux/sched.h b/include/linux/sched.h > index f6961c9..33be290 100644 > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -1811,6 +1811,7 @@ extern void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t * > #define PF_FROZEN 0x00010000 /* frozen for system suspend */ > #define PF_FSTRANS 0x00020000 /* inside a filesystem transaction */ > #define PF_KSWAPD 0x00040000 /* I am kswapd */ > +#define PF_MEMALLOC_NOIO 0x00080000 /* Allocating memory without IO involved */ > #define PF_LESS_THROTTLE 0x00100000 /* Throttle me less: I clean memory */ > #define PF_KTHREAD 0x00200000 /* I am a kernel thread */ > #define PF_RANDOMIZE 0x00400000 /* randomize virtual address space */ > @@ -1848,6 +1849,10 @@ extern void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t * > #define tsk_used_math(p) ((p)->flags & PF_USED_MATH) > #define used_math() tsk_used_math(current) > > +#define tsk_memalloc_no_io(p) ((p)->flags & PF_MEMALLOC_NOIO) > +#define tsk_memalloc_allow_io(p) do { (p)->flags &= ~PF_MEMALLOC_NOIO; } while (0) > +#define tsk_memalloc_forbid_io(p) do { (p)->flags |= PF_MEMALLOC_NOIO; } while (0) > + > /* > * task->jobctl flags > */ > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 8e1be1c..e15381f 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -2596,6 +2596,8 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, > int alloc_flags = ALLOC_WMARK_LOW|ALLOC_CPUSET; > > gfp_mask &= gfp_allowed_mask; > + if (unlikely(tsk_memalloc_no_io(current))) > + gfp_mask &= ~GFP_IOFS; > > lockdep_trace_alloc(gfp_mask); > > -- > 1.7.9.5 > -- Kind Regards, Minchan Kim -- 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/