The patch titled
Subject: oom: add helpers for setting and clearing TIF_MEMDIE
has been added to the -mm tree. Its filename is
oom-add-helpers-for-setting-and-clearing-tif_memdie.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/oom-add-helpers-for-setting-and-clearing-tif_memdie.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/oom-add-helpers-for-setting-and-clearing-tif_memdie.patch
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From: Michal Hocko <mhocko@xxxxxxx>
Subject: oom: add helpers for setting and clearing TIF_MEMDIE
I have tested the series in KVM with 100M RAM:
- many small tasks (20M anon mmap) which are triggering OOM continually
- s2ram which resumes automatically is triggered in a loop
echo processors > /sys/power/pm_test
while true
do
echo mem > /sys/power/state
sleep 1s
done
- simple module which allocates and frees 20M in 8K chunks. If it sees
freezing(current) then it tries another round of allocation before calling
try_to_freeze
- debugging messages of PM stages and OOM killer enable/disable/fail added
and unmark_oom_victim is delayed by 1s after it clears TIF_MEMDIE and before
it wakes up waiters.
- rebased on top of the current mmotm which means some necessary updates
in mm/oom_kill.c. mark_tsk_oom_victim is now called under task_lock but
I think this should be OK because __thaw_task shouldn't interfere with any
locking down wake_up_process. Oleg?
As expected there are no OOM killed tasks after oom is disabled and
allocations requested by the kernel thread are failing after all the tasks
are frozen and OOM disabled. I wasn't able to catch a race where
oom_killer_disable would really have to wait but I kinda expected the race
is really unlikely.
[ 242.609330] Killed process 2992 (mem_eater) total-vm:24412kB, anon-rss:2164kB, file-rss:4kB
[ 243.628071] Unmarking 2992 OOM victim. oom_victims: 1
[ 243.636072] (elapsed 2.837 seconds) done.
[ 243.641985] Trying to disable OOM killer
[ 243.643032] Waiting for concurent OOM victims
[ 243.644342] OOM killer disabled
[ 243.645447] Freezing remaining freezable tasks ... (elapsed 0.005 seconds) done.
[ 243.652983] Suspending console(s) (use no_console_suspend to debug)
[ 243.903299] kmem_eater: page allocation failure: order:1, mode:0x204010
[...]
[ 243.992600] PM: suspend of devices complete after 336.667 msecs
[ 243.993264] PM: late suspend of devices complete after 0.660 msecs
[ 243.994713] PM: noirq suspend of devices complete after 1.446 msecs
[ 243.994717] ACPI: Preparing to enter system sleep state S3
[ 243.994795] PM: Saving platform NVS memory
[ 243.994796] Disabling non-boot CPUs ...
The first 2 patches are simple cleanups for OOM. They should go in
regardless the rest IMO.
Patches 3 and 4 are trivial printk -> pr_info conversion and they should
go in ditto.
The main patch is the last one and I would appreciate acks from Tejun and
Rafael. I think the OOM part should be OK (except for __thaw_task vs.
task_lock where a look from Oleg would appreciated) but I am not so sure I
haven't screwed anything in the freezer code. I have found several
surprises there.
This patch (of 5):
This patch is just a preparatory and it doesn't introduce any functional
change.
Note:
I am utterly unhappy about lowmemory killer abusing TIF_MEMDIE just to
wait for the oom victim and to prevent from new killing. This is
just a side effect of the flag. The primary meaning is to give the oom
victim access to the memory reserves and that shouldn't be necessary
here.
Signed-off-by: Michal Hocko <mhocko@xxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Cong Wang <xiyou.wangcong@xxxxxxxxx>
Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/staging/android/lowmemorykiller.c | 7 +++++-
include/linux/oom.h | 4 +++
kernel/exit.c | 2 -
mm/memcontrol.c | 2 -
mm/oom_kill.c | 23 +++++++++++++++++---
5 files changed, 32 insertions(+), 6 deletions(-)
diff -puN drivers/staging/android/lowmemorykiller.c~oom-add-helpers-for-setting-and-clearing-tif_memdie drivers/staging/android/lowmemorykiller.c
--- a/drivers/staging/android/lowmemorykiller.c~oom-add-helpers-for-setting-and-clearing-tif_memdie
+++ a/drivers/staging/android/lowmemorykiller.c
@@ -160,7 +160,12 @@ static unsigned long lowmem_scan(struct
selected->pid, selected->comm,
selected_oom_score_adj, selected_tasksize);
lowmem_deathpending_timeout = jiffies + HZ;
- set_tsk_thread_flag(selected, TIF_MEMDIE);
+ /*
+ * FIXME: lowmemorykiller shouldn't abuse global OOM killer
+ * infrastructure. There is no real reason why the selected
+ * task should have access to the memory reserves.
+ */
+ mark_tsk_oom_victim(selected);
send_sig(SIGKILL, selected, 0);
rem += selected_tasksize;
}
diff -puN include/linux/oom.h~oom-add-helpers-for-setting-and-clearing-tif_memdie include/linux/oom.h
--- a/include/linux/oom.h~oom-add-helpers-for-setting-and-clearing-tif_memdie
+++ a/include/linux/oom.h
@@ -47,6 +47,10 @@ static inline bool oom_task_origin(const
return !!(p->signal->oom_flags & OOM_FLAG_ORIGIN);
}
+extern void mark_tsk_oom_victim(struct task_struct *tsk);
+
+extern void unmark_oom_victim(void);
+
extern unsigned long oom_badness(struct task_struct *p,
struct mem_cgroup *memcg, const nodemask_t *nodemask,
unsigned long totalpages);
diff -puN kernel/exit.c~oom-add-helpers-for-setting-and-clearing-tif_memdie kernel/exit.c
--- a/kernel/exit.c~oom-add-helpers-for-setting-and-clearing-tif_memdie
+++ a/kernel/exit.c
@@ -435,7 +435,7 @@ static void exit_mm(struct task_struct *
task_unlock(tsk);
mm_update_next_owner(mm);
mmput(mm);
- clear_thread_flag(TIF_MEMDIE);
+ unmark_oom_victim();
}
static struct task_struct *find_alive_thread(struct task_struct *p)
diff -puN mm/memcontrol.c~oom-add-helpers-for-setting-and-clearing-tif_memdie mm/memcontrol.c
--- a/mm/memcontrol.c~oom-add-helpers-for-setting-and-clearing-tif_memdie
+++ a/mm/memcontrol.c
@@ -1581,7 +1581,7 @@ static void mem_cgroup_out_of_memory(str
* quickly exit and free its memory.
*/
if (fatal_signal_pending(current) || task_will_free_mem(current)) {
- set_thread_flag(TIF_MEMDIE);
+ mark_tsk_oom_victim(current);
return;
}
diff -puN mm/oom_kill.c~oom-add-helpers-for-setting-and-clearing-tif_memdie mm/oom_kill.c
--- a/mm/oom_kill.c~oom-add-helpers-for-setting-and-clearing-tif_memdie
+++ a/mm/oom_kill.c
@@ -416,6 +416,23 @@ void note_oom_kill(void)
atomic_inc(&oom_kills);
}
+/**
+ * mark_tsk_oom_victim - marks the given taks as OOM victim.
+ * @tsk: task to mark
+ */
+void mark_tsk_oom_victim(struct task_struct *tsk)
+{
+ set_tsk_thread_flag(tsk, TIF_MEMDIE);
+}
+
+/**
+ * unmark_oom_victim - unmarks the current task as OOM victim.
+ */
+void unmark_oom_victim(void)
+{
+ clear_thread_flag(TIF_MEMDIE);
+}
+
#define K(x) ((x) << (PAGE_SHIFT-10))
/*
* Must be called while holding a reference to p, which will be released upon
@@ -440,7 +457,7 @@ void oom_kill_process(struct task_struct
*/
task_lock(p);
if (p->mm && task_will_free_mem(p)) {
- set_tsk_thread_flag(p, TIF_MEMDIE);
+ mark_tsk_oom_victim(p);
task_unlock(p);
put_task_struct(p);
return;
@@ -495,7 +512,7 @@ void oom_kill_process(struct task_struct
/* mm cannot safely be dereferenced after task_unlock(victim) */
mm = victim->mm;
- set_tsk_thread_flag(victim, TIF_MEMDIE);
+ mark_tsk_oom_victim(victim);
pr_err("Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB\n",
task_pid_nr(victim), victim->comm, K(victim->mm->total_vm),
K(get_mm_counter(victim->mm, MM_ANONPAGES)),
@@ -652,7 +669,7 @@ void out_of_memory(struct zonelist *zone
*/
if (current->mm &&
(fatal_signal_pending(current) || task_will_free_mem(current))) {
- set_thread_flag(TIF_MEMDIE);
+ mark_tsk_oom_victim(current);
return;
}
_
Patches currently in -mm which might be from mhocko@xxxxxxx are
mm-page_alloc-embed-oom-killing-naturally-into-allocation-slowpath.patch
memcg-zap-__memcg_chargeuncharge_slab.patch
memcg-zap-memcg_name-argument-of-memcg_create_kmem_cache.patch
memcg-zap-memcg_slab_caches-and-memcg_slab_mutex.patch
oom-dont-count-on-mm-less-current-process.patch
oom-make-sure-that-tif_memdie-is-set-under-task_lock.patch
swap-remove-unused-mem_cgroup_uncharge_swapcache-declaration.patch
mm-memcontrol-track-move_lock-state-internally.patch
mm-vmscan-wake-up-all-pfmemalloc-throttled-processes-at-once.patch
mm-hugetlb-reduce-arch-dependent-code-around-follow_huge_.patch
mm-hugetlb-pmd_huge-returns-true-for-non-present-hugepage.patch
mm-hugetlb-take-page-table-lock-in-follow_huge_pmd.patch
mm-hugetlb-fix-getting-refcount-0-page-in-hugetlb_fault.patch
mm-hugetlb-add-migration-hwpoisoned-entry-check-in-hugetlb_change_protection.patch
mm-hugetlb-add-migration-entry-check-in-__unmap_hugepage_range.patch
mm-hugetlb-fix-suboptimal-migration-hwpoisoned-entry-check.patch
mm-hugetlb-cleanup-and-rename-is_hugetlb_entry_migrationhwpoisoned.patch
mm-set-page-pfmemalloc-in-prep_new_page.patch
mm-page_alloc-reduce-number-of-alloc_pages-functions-parameters.patch
mm-reduce-try_to_compact_pages-parameters.patch
mm-microoptimize-zonelist-operations.patch
list_lru-introduce-list_lru_shrink_countwalk.patch
fs-consolidate-nrfree_cached_objects-args-in-shrink_control.patch
vmscan-per-memory-cgroup-slab-shrinkers.patch
vmscan-per-memory-cgroup-slab-shrinkers-fix.patch
memcg-rename-some-cache-id-related-variables.patch
memcg-add-rwsem-to-synchronize-against-memcg_caches-arrays-relocation.patch
list_lru-get-rid-of-active_nodes.patch
list_lru-organize-all-list_lrus-to-list.patch
list_lru-introduce-per-memcg-lists.patch
fs-make-shrinker-memcg-aware.patch
vmscan-force-scan-offline-memory-cgroups.patch
memcg-add-build_bug_on-for-string-tables.patch
mm-page_counter-pull-1-handling-out-of-page_counter_memparse.patch
mm-memcontrol-default-hierarchy-interface-for-memory.patch
oom-add-helpers-for-setting-and-clearing-tif_memdie.patch
oom-thaw-the-oom-victim-if-it-is-frozen.patch
pm-convert-printk-to-pr_-equivalent.patch
sysrq-convert-printk-to-pr_-equivalent.patch
oom-pm-make-oom-detection-in-the-freezer-path-raceless.patch
mm-page_isolation-check-pfn-validity-before-access.patch
mm-support-madvisemadv_free.patch
mm-dont-split-thp-page-when-syscall-is-called.patch
mm-dont-split-thp-page-when-syscall-is-called-fix-2.patch
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