diff options
| author | Mel Gorman | 2012-01-10 15:07:15 -0800 |
|---|---|---|
| committer | Linus Torvalds | 2012-01-10 16:30:42 -0800 |
| commit | f90ac3982a78d36f894824636beeef13361d7c59 (patch) | |
| tree | 64bbe3b415bdfc151dc44f6b4c216c65351eb53c /include/linux | |
| parent | 938929f14cb595f43cd1a4e63e22d36cab1e4a1f (diff) | |
mm: avoid livelock on !__GFP_FS allocations
Colin Cross reported;
Under the following conditions, __alloc_pages_slowpath can loop forever:
gfp_mask & __GFP_WAIT is true
gfp_mask & __GFP_FS is false
reclaim and compaction make no progress
order <= PAGE_ALLOC_COSTLY_ORDER
These conditions happen very often during suspend and resume,
when pm_restrict_gfp_mask() effectively converts all GFP_KERNEL
allocations into __GFP_WAIT.
The oom killer is not run because gfp_mask & __GFP_FS is false,
but should_alloc_retry will always return true when order is less
than PAGE_ALLOC_COSTLY_ORDER.
In his fix, he avoided retrying the allocation if reclaim made no progress
and __GFP_FS was not set. The problem is that this would result in
GFP_NOIO allocations failing that previously succeeded which would be very
unfortunate.
The big difference between GFP_NOIO and suspend converting GFP_KERNEL to
behave like GFP_NOIO is that normally flushers will be cleaning pages and
kswapd reclaims pages allowing GFP_NOIO to succeed after a short delay.
The same does not necessarily apply during suspend as the storage device
may be suspended.
This patch special cases the suspend case to fail the page allocation if
reclaim cannot make progress and adds some documentation on how
gfp_allowed_mask is currently used. Failing allocations like this may
cause suspend to abort but that is better than a livelock.
[mgorman@suse.de: Rework fix to be suspend specific]
[rientjes@google.com: Move suspended device check to should_alloc_retry]
Reported-by: Colin Cross <ccross@android.com>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/gfp.h | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/include/linux/gfp.h b/include/linux/gfp.h index 656295865d58..91812df1351a 100644 --- a/include/linux/gfp.h +++ b/include/linux/gfp.h @@ -368,9 +368,25 @@ void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp); void drain_all_pages(void); void drain_local_pages(void *dummy); +/* + * gfp_allowed_mask is set to GFP_BOOT_MASK during early boot to restrict what + * GFP flags are used before interrupts are enabled. Once interrupts are + * enabled, it is set to __GFP_BITS_MASK while the system is running. During + * hibernation, it is used by PM to avoid I/O during memory allocation while + * devices are suspended. + */ extern gfp_t gfp_allowed_mask; extern void pm_restrict_gfp_mask(void); extern void pm_restore_gfp_mask(void); +#ifdef CONFIG_PM_SLEEP +extern bool pm_suspended_storage(void); +#else +static inline bool pm_suspended_storage(void) +{ + return false; +} +#endif /* CONFIG_PM_SLEEP */ + #endif /* __LINUX_GFP_H */ |