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pm / runtime: introduce pm_runtime_set_memalloc_noio()

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Introduce the flag memalloc_noio in 'struct dev_pm_info' to help PM core
to teach mm not allocating memory with GFP_KERNEL flag for avoiding
probable deadlock.

As explained in the comment, any GFP_KERNEL allocation inside
runtime_resume() or runtime_suspend() on any one of device in the path
from one block or network device to the root device in the device tree
may cause deadlock, the introduced pm_runtime_set_memalloc_noio() sets
or clears the flag on device in the path recursively.

Signed-off-by: Ming Lei <ming.lei@canonical.com>
Cc: 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>
This commit is contained in:
Ming Lei 2013-02-22 16:34:11 -08:00 committed by Linus Torvalds
parent 21caf2fc19
commit e823407f7b
3 changed files with 74 additions and 0 deletions
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70
drivers/base/power/runtime.c
View File

@ -124,6 +124,76 @@ unsigned long pm_runtime_autosuspend_expiration(struct device *dev)
}
EXPORT_SYMBOL_GPL(pm_runtime_autosuspend_expiration);
static int dev_memalloc_noio(struct device *dev, void *data)
{
return dev->power.memalloc_noio;
}
/*
* pm_runtime_set_memalloc_noio - Set a device's memalloc_noio flag.
* @dev: Device to handle.
* @enable: True for setting the flag and False for clearing the flag.
*
* Set the flag for all devices in the path from the device to the
* root device in the device tree if @enable is true, otherwise clear
* the flag for devices in the path whose siblings don't set the flag.
*
* The function should only be called by block device, or network
* device driver for solving the deadlock problem during runtime
* resume/suspend:
*
* If memory allocation with GFP_KERNEL is called inside runtime
* resume/suspend 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. Network device
* are involved in iSCSI kind of situation.
*
* The lock of dev_hotplug_mutex is held in the function for handling
* hotplug race because pm_runtime_set_memalloc_noio() may be called
* in async probe().
*
* The function should be called between device_add() and device_del()
* on the affected device(block/network device).
*/
void pm_runtime_set_memalloc_noio(struct device *dev, bool enable)
{
static DEFINE_MUTEX(dev_hotplug_mutex);
mutex_lock(&dev_hotplug_mutex);
for (;;) {
bool enabled;
/* hold power lock since bitfield is not SMP-safe. */
spin_lock_irq(&dev->power.lock);
enabled = dev->power.memalloc_noio;
dev->power.memalloc_noio = enable;
spin_unlock_irq(&dev->power.lock);
/*
* not need to enable ancestors any more if the device
* has been enabled.
*/
if (enabled && enable)
break;
dev = dev->parent;
/*
* clear flag of the parent device only if all the
* children don't set the flag because ancestor's
* flag was set by any one of the descendants.
*/
if (!dev || (!enable &&
device_for_each_child(dev, NULL,
dev_memalloc_noio)))
break;
}
mutex_unlock(&dev_hotplug_mutex);
}
EXPORT_SYMBOL_GPL(pm_runtime_set_memalloc_noio);
/**
* rpm_check_suspend_allowed - Test whether a device may be suspended.
* @dev: Device to test.

1
include/linux/pm.h
View File

@ -537,6 +537,7 @@ struct dev_pm_info {
unsigned int irq_safe:1;
unsigned int use_autosuspend:1;
unsigned int timer_autosuspends:1;
unsigned int memalloc_noio:1;
enum rpm_request request;
enum rpm_status runtime_status;
int runtime_error;

3
include/linux/pm_runtime.h
View File

@ -47,6 +47,7 @@ extern void pm_runtime_set_autosuspend_delay(struct device *dev, int delay);
extern unsigned long pm_runtime_autosuspend_expiration(struct device *dev);
extern void pm_runtime_update_max_time_suspended(struct device *dev,
s64 delta_ns);
extern void pm_runtime_set_memalloc_noio(struct device *dev, bool enable);
static inline bool pm_children_suspended(struct device *dev)
{
@ -156,6 +157,8 @@ static inline void pm_runtime_set_autosuspend_delay(struct device *dev,
int delay) {}
static inline unsigned long pm_runtime_autosuspend_expiration(
struct device *dev) { return 0; }
static inline void pm_runtime_set_memalloc_noio(struct device *dev,
bool enable){}
#endif /* !CONFIG_PM_RUNTIME */