From patchwork Sun Nov 11 12:42:33 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ming Lei X-Patchwork-Id: 198258 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 939602C008F for ; Sun, 11 Nov 2012 23:43:10 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752957Ab2KKMmz (ORCPT ); Sun, 11 Nov 2012 07:42:55 -0500 Received: from mail-da0-f46.google.com ([209.85.210.46]:46300 "EHLO mail-da0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752730Ab2KKMmx (ORCPT ); Sun, 11 Nov 2012 07:42:53 -0500 Received: by mail-da0-f46.google.com with SMTP id n41so2340172dak.19 for ; Sun, 11 Nov 2012 04:42:53 -0800 (PST) Received: by 10.66.87.226 with SMTP id bb2mr46865739pab.57.1352637773314; Sun, 11 Nov 2012 04:42:53 -0800 (PST) Received: from localhost ([183.37.194.51]) by mx.google.com with ESMTPS id ku7sm2485226pbc.0.2012.11.11.04.42.43 (version=TLSv1/SSLv3 cipher=OTHER); Sun, 11 Nov 2012 04:42:52 -0800 (PST) From: Ming Lei To: linux-kernel@vger.kernel.org Cc: Alan Stern , Oliver Neukum , Minchan Kim , Greg Kroah-Hartman , "Rafael J. Wysocki" , Jens Axboe , "David S. Miller" , Andrew Morton , netdev@vger.kernel.org, linux-usb@vger.kernel.org, linux-pm@vger.kernel.org, linux-mm@kvack.org, Ming Lei , Jiri Kosina , Mel Gorman , KAMEZAWA Hiroyuki , Michal Hocko , Ingo Molnar , Peter Zijlstra Subject: [PATCH v5 1/6] mm: teach mm by current context info to not do I/O during memory allocation Date: Sun, 11 Nov 2012 20:42:33 +0800 Message-Id: <1352637753-20243-1-git-send-email-ming.lei@canonical.com> X-Mailer: git-send-email 1.7.9.5 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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 may happen at least in the below situations: - during block device runtime resume, 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[1] 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, network devices involved too in the iSCSI case) - during block device runtime suspend, because runtime resume need to wait for completion of concurrent runtime suspend. - during error handling 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. 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. It is not a good idea to convert all these GFP_KERNEL in the affected path into GFP_NOIO because these functions doing that may be implemented as library and will be called in many other contexts. In fact, memalloc_noio_flags() can convert some of current static GFP_NOIO allocation into GFP_KERNEL back in other non-affected contexts, at least almost all GFP_NOIO in USB subsystem can be converted into GFP_KERNEL after applying the approach and make allocation with GFP_NOIO only happen in runtime resume/bus reset/block I/O transfer contexts generally. [1], several GFP_KERNEL allocation examples in runtime resume path - pci subsystem acpi_os_allocate <-acpi_ut_allocate <-ACPI_ALLOCATE_ZEROED <-acpi_evaluate_object <-__acpi_bus_set_power <-acpi_bus_set_power <-acpi_pci_set_power_state <-platform_pci_set_power_state <-pci_platform_power_transition <-__pci_complete_power_transition <-pci_set_power_state <-pci_restore_standard_config <-pci_pm_runtime_resume - usb subsystem usb_get_status <-finish_port_resume <-usb_port_resume <-generic_resume <-usb_resume_device <-usb_resume_both <-usb_runtime_resume - some individual usb drivers usblp, uvc, gspca, most of dvb-usb-v2 media drivers, cpia2, az6007, .... That is just what I have found. Unfortunately, this allocation can only be found by human being now, and there should be many not found since any function in the resume path(call tree) may allocate memory with GFP_KERNEL. Cc: Alan Stern Cc: Oliver Neukum Cc: Jiri Kosina Cc: Andrew Morton Cc: Mel Gorman Cc: KAMEZAWA Hiroyuki Cc: Michal Hocko Cc: Ingo Molnar Cc: Peter Zijlstra Cc: "Rafael J. Wysocki" Signed-off-by: Minchan Kim Signed-off-by: Ming Lei --- v5: - use inline instead of macro to define memalloc_noio_* - replace memalloc_noio() with memalloc_noio_flags() to make code neater - don't clear GFP_FS because no GFP_IO means that allocation won't enter device driver as pointed by Andrew Morton v4: - fix comment v3: - no change v2: - remove changes on 'may_writepage' and 'may_swap' because that isn't related with the patchset, and can't introduce I/O in allocation path if GFP_IOFS is unset, so handing 'may_swap' and may_writepage on GFP_NOIO or GFP_NOFS should be a mm internal thing, and let mm guys deal with that, :-). Looks clearing the two may_XXX flag only excludes dirty pages and anon pages for relaiming, and the behaviour should be decided by GFP FLAG, IMO. - unset GFP_IOFS in try_to_free_pages() path since alloc_page_buffers() and dma_alloc_from_contiguous may drop into the path, as pointed by KAMEZAWA Hiroyuki v1: - take Minchan's change to avoid the check in alloc_page hot path - change the helpers' style into save/restore as suggested by Alan Stern --- include/linux/sched.h | 22 ++++++++++++++++++++++ mm/page_alloc.c | 9 ++++++++- mm/vmscan.c | 4 ++-- 3 files changed, 32 insertions(+), 3 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index f2ece18..527f2a4 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -51,6 +51,7 @@ struct sched_param { #include #include #include +#include #include @@ -1807,6 +1808,7 @@ 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 */ @@ -1844,6 +1846,26 @@ 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) +/* GFP_IO isn't allowed if PF_MEMALLOC_NOIO is set in current->flags */ +static inline gfp_t memalloc_noio_flags(gfp_t flags) +{ + if (unlikely(current->flags & PF_MEMALLOC_NOIO)) + flags &= ~GFP_IO; + return flags; +} + +static inline gfp_t memalloc_noio_save(void) +{ + gfp_t flags = current->flags & PF_MEMALLOC_NOIO; + current->flags |= PF_MEMALLOC_NOIO; + return flags; +} + +static inline void memalloc_noio_restore(gfp_t flags) +{ + current->flags = (current->flags & ~PF_MEMALLOC_NOIO) | flags; +} + /* * task->jobctl flags */ diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 6b990cb..b56f763 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2644,10 +2644,17 @@ retry_cpuset: page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, nodemask, order, zonelist, high_zoneidx, alloc_flags, preferred_zone, migratetype); - if (unlikely(!page)) + if (unlikely(!page)) { + /* + * Runtime PM, block IO and its error handling path + * can deadlock because I/O on the device might not + * complete. + */ + gfp_mask = memalloc_noio_flags(gfp_mask); page = __alloc_pages_slowpath(gfp_mask, order, zonelist, high_zoneidx, nodemask, preferred_zone, migratetype); + } trace_mm_page_alloc(page, order, gfp_mask, migratetype); diff --git a/mm/vmscan.c b/mm/vmscan.c index 370244c..f28919a 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2301,7 +2301,7 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order, { unsigned long nr_reclaimed; struct scan_control sc = { - .gfp_mask = gfp_mask, + .gfp_mask = (gfp_mask = memalloc_noio_flags(gfp_mask)), .may_writepage = !laptop_mode, .nr_to_reclaim = SWAP_CLUSTER_MAX, .may_unmap = 1, @@ -3308,7 +3308,7 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order) .may_swap = 1, .nr_to_reclaim = max_t(unsigned long, nr_pages, SWAP_CLUSTER_MAX), - .gfp_mask = gfp_mask, + .gfp_mask = (gfp_mask = memalloc_noio_flags(gfp_mask)), .order = order, .priority = ZONE_RECLAIM_PRIORITY, };