user/sven/linux.git/include/linux/oom.h, branch v3.18.22

OOM, PM: OOM killed task shouldn't escape PM suspend

2014-10-21T21:44:21Z

PM freezer relies on having all tasks frozen by the time devices are getting frozen so that no task will touch them while they are getting frozen. But OOM killer is allowed to kill an already frozen task in order to handle OOM situtation. In order to protect from late wake ups OOM killer is disabled after all tasks are frozen. This, however, still keeps a window open when a killed task didn't manage to die by the time freeze_processes finishes. Reduce the race window by checking all tasks after OOM killer has been disabled. This is still not race free completely unfortunately because oom_killer_disable cannot stop an already ongoing OOM killer so a task might still wake up from the fridge and get killed without freeze_processes noticing. Full synchronization of OOM and freezer is, however, too heavy weight for this highly unlikely case. Introduce and check oom_kills counter which gets incremented early when the allocator enters __alloc_pages_may_oom path and only check all the tasks if the counter changes during the freezing attempt. The counter is updated so early to reduce the race window since allocator checked oom_killer_disabled which is set by PM-freezing code. A false positive will push the PM-freezer into a slow path but that is not a big deal. Changes since v1 - push the re-check loop out of freeze_processes into check_frozen_processes and invert the condition to make the code more readable as per Rafael Fixes: f660daac474c6f (oom: thaw threads if oom killed thread is frozen before deferring) Cc: 3.2+ # 3.2+ Signed-off-by: Michal Hocko Signed-off-by: Rafael J. Wysocki

mm, oom: rename zonelist locking functions

2014-08-07T01:01:21Z

try_set_zonelist_oom() and clear_zonelist_oom() are not named properly to imply that they require locking semantics to avoid out_of_memory() being reordered. zone_scan_lock is required for both functions to ensure that there is proper locking synchronization. Rename try_set_zonelist_oom() to oom_zonelist_trylock() and rename clear_zonelist_oom() to oom_zonelist_unlock() to imply there is proper locking semantics. At the same time, convert oom_zonelist_trylock() to return bool instead of int since only success and failure are tested. Signed-off-by: David Rientjes Cc: "Kirill A. Shutemov" Cc: Johannes Weiner Cc: Rik van Riel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: add a helper function to check may oom condition

2013-11-13T03:09:04Z

Use helper function to check if we need to deal with oom condition. Signed-off-by: Qiang Huang Acked-by: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm, oom: fix race when specifying a thread as the oom origin

2012-12-12T01:22:27Z

test_set_oom_score_adj() and compare_swap_oom_score_adj() are used to specify that current should be killed first if an oom condition occurs in between the two calls. The usage is short oom_score_adj = test_set_oom_score_adj(OOM_SCORE_ADJ_MAX); ... compare_swap_oom_score_adj(OOM_SCORE_ADJ_MAX, oom_score_adj); to store the thread's oom_score_adj, temporarily change it to the maximum score possible, and then restore the old value if it is still the same. This happens to still be racy, however, if the user writes OOM_SCORE_ADJ_MAX to /proc/pid/oom_score_adj in between the two calls. The compare_swap_oom_score_adj() will then incorrectly reset the old value prior to the write of OOM_SCORE_ADJ_MAX. To fix this, introduce a new oom_flags_t member in struct signal_struct that will be used for per-thread oom killer flags. KSM and swapoff can now use a bit in this member to specify that threads should be killed first in oom conditions without playing around with oom_score_adj. This also allows the correct oom_score_adj to always be shown when reading /proc/pid/oom_score. Signed-off-by: David Rientjes Cc: KAMEZAWA Hiroyuki Cc: KOSAKI Motohiro Reviewed-by: Michal Hocko Cc: Anton Vorontsov Cc: Oleg Nesterov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm, oom: change type of oom_score_adj to short

2012-12-12T01:22:27Z

The maximum oom_score_adj is 1000 and the minimum oom_score_adj is -1000, so this range can be represented by the signed short type with no functional change. The extra space this frees up in struct signal_struct will be used for per-thread oom kill flags in the next patch. Signed-off-by: David Rientjes Cc: KAMEZAWA Hiroyuki Cc: KOSAKI Motohiro Reviewed-by: Michal Hocko Cc: Anton Vorontsov Cc: Oleg Nesterov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm, memcg: make mem_cgroup_out_of_memory() static

2012-12-12T01:22:22Z

mem_cgroup_out_of_memory() is only referenced from within file scope, so it can be marked static. Signed-off-by: David Rientjes Acked-by: KAMEZAWA Hiroyuki Acked-by: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

UAPI: (Scripted) Disintegrate include/linux

2012-10-13T09:46:48Z

Signed-off-by: David Howells Acked-by: Arnd Bergmann Acked-by: Thomas Gleixner Acked-by: Michael Kerrisk Acked-by: Paul E. McKenney Acked-by: Dave Jones

oom: remove deprecated oom_adj

2012-10-09T07:22:24Z

The deprecated /proc//oom_adj is scheduled for removal this month. Signed-off-by: Davidlohr Bueso Acked-by: David Rientjes Cc: KOSAKI Motohiro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm, memcg: move all oom handling to memcontrol.c

2012-08-01T01:42:45Z

By globally defining check_panic_on_oom(), the memcg oom handler can be moved entirely to mm/memcontrol.c. This removes the ugly #ifdef in the oom killer and cleans up the code. Signed-off-by: David Rientjes Cc: KAMEZAWA Hiroyuki Acked-by: Michal Hocko Cc: Oleg Nesterov Cc: KOSAKI Motohiro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm, memcg: introduce own oom handler to iterate only over its own threads

2012-08-01T01:42:44Z

The global oom killer is serialized by the per-zonelist try_set_zonelist_oom() which is used in the page allocator. Concurrent oom kills are thus a rare event and only occur in systems using mempolicies and with a large number of nodes. Memory controller oom kills, however, can frequently be concurrent since there is no serialization once the oom killer is called for oom conditions in several different memcgs in parallel. This creates a massive contention on tasklist_lock since the oom killer requires the readside for the tasklist iteration. If several memcgs are calling the oom killer, this lock can be held for a substantial amount of time, especially if threads continue to enter it as other threads are exiting. Since the exit path grabs the writeside of the lock with irqs disabled in a few different places, this can cause a soft lockup on cpus as a result of tasklist_lock starvation. The kernel lacks unfair writelocks, and successful calls to the oom killer usually result in at least one thread entering the exit path, so an alternative solution is needed. This patch introduces a seperate oom handler for memcgs so that they do not require tasklist_lock for as much time. Instead, it iterates only over the threads attached to the oom memcg and grabs a reference to the selected thread before calling oom_kill_process() to ensure it doesn't prematurely exit. This still requires tasklist_lock for the tasklist dump, iterating children of the selected process, and killing all other threads on the system sharing the same memory as the selected victim. So while this isn't a complete solution to tasklist_lock starvation, it significantly reduces the amount of time that it is held. Acked-by: KAMEZAWA Hiroyuki Acked-by: Michal Hocko Signed-off-by: David Rientjes Cc: Oleg Nesterov Cc: KOSAKI Motohiro Reviewed-by: Sha Zhengju Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds