path: root/mm/page_alloc.c
diff options
authorMing Lei <ming.lei@canonical.com>2013-02-22 16:34:08 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2013-02-23 17:50:16 -0800
commit21caf2fc1931b485483ddd254b634fa8f0099963 (patch)
treee7cbdfe56948775328f7622522620864356d8264 /mm/page_alloc.c
parent258401a60c4df39332f30ef57afbc6dbf29a7e84 (diff)
mm: teach mm by current context info to not do I/O during memory allocation
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. Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: Oliver Neukum <oneukum@suse.de> Cc: Jiri Kosina <jiri.kosina@suse.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Greg KH <greg@kroah.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: "David S. Miller" <davem@davemloft.net> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: David Decotigny <david.decotigny@google.com> Cc: Tom Herbert <therbert@google.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/page_alloc.c')
1 files changed, 8 insertions, 1 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e3fb290194c..3ede25e6686 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2624,10 +2624,17 @@ 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);