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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2014-10-23 23:02:45 +0200
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2014-10-23 23:02:45 +0200
commit96ed753235c674a8cb261dac1a258cf6e50c6cd4 (patch)
treef9210625db82644ebcf88d1879288b2fc389d211
parent37c72cac0e2ef9cd3c53dc9369a35dad6ef23f00 (diff)
parent71be2114a5474a76edad95343d89b8731457fccd (diff)
Merge branch 'freezer'
* freezer: PM / freezer: Clean up code after recent fixes PM: convert do_each_thread to for_each_process_thread OOM, PM: OOM killed task shouldn't escape PM suspend freezer: remove obsolete comments in __thaw_task() freezer: Do not freeze tasks killed by OOM killer
-rw-r--r--include/linux/oom.h3
-rw-r--r--kernel/freezer.c9
-rw-r--r--kernel/power/process.c57
-rw-r--r--mm/oom_kill.c17
-rw-r--r--mm/page_alloc.c8
5 files changed, 79 insertions, 15 deletions
diff --git a/include/linux/oom.h b/include/linux/oom.h
index 647395a1a550..e8d6e1058723 100644
--- a/include/linux/oom.h
+++ b/include/linux/oom.h
@@ -50,6 +50,9 @@ static inline bool oom_task_origin(const struct task_struct *p)
extern unsigned long oom_badness(struct task_struct *p,
struct mem_cgroup *memcg, const nodemask_t *nodemask,
unsigned long totalpages);
+
+extern int oom_kills_count(void);
+extern void note_oom_kill(void);
extern void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
unsigned int points, unsigned long totalpages,
struct mem_cgroup *memcg, nodemask_t *nodemask,
diff --git a/kernel/freezer.c b/kernel/freezer.c
index aa6a8aadb911..a8900a3bc27a 100644
--- a/kernel/freezer.c
+++ b/kernel/freezer.c
@@ -42,6 +42,9 @@ bool freezing_slow_path(struct task_struct *p)
if (p->flags & (PF_NOFREEZE | PF_SUSPEND_TASK))
return false;
+ if (test_thread_flag(TIF_MEMDIE))
+ return false;
+
if (pm_nosig_freezing || cgroup_freezing(p))
return true;
@@ -147,12 +150,6 @@ void __thaw_task(struct task_struct *p)
{
unsigned long flags;
- /*
- * Clear freezing and kick @p if FROZEN. Clearing is guaranteed to
- * be visible to @p as waking up implies wmb. Waking up inside
- * freezer_lock also prevents wakeups from leaking outside
- * refrigerator.
- */
spin_lock_irqsave(&freezer_lock, flags);
if (frozen(p))
wake_up_process(p);
diff --git a/kernel/power/process.c b/kernel/power/process.c
index 7b323221b9ee..5a6ec8678b9a 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -46,13 +46,13 @@ static int try_to_freeze_tasks(bool user_only)
while (true) {
todo = 0;
read_lock(&tasklist_lock);
- do_each_thread(g, p) {
+ for_each_process_thread(g, p) {
if (p == current || !freeze_task(p))
continue;
if (!freezer_should_skip(p))
todo++;
- } while_each_thread(g, p);
+ }
read_unlock(&tasklist_lock);
if (!user_only) {
@@ -93,11 +93,11 @@ static int try_to_freeze_tasks(bool user_only)
if (!wakeup) {
read_lock(&tasklist_lock);
- do_each_thread(g, p) {
+ for_each_process_thread(g, p) {
if (p != current && !freezer_should_skip(p)
&& freezing(p) && !frozen(p))
sched_show_task(p);
- } while_each_thread(g, p);
+ }
read_unlock(&tasklist_lock);
}
} else {
@@ -108,6 +108,30 @@ static int try_to_freeze_tasks(bool user_only)
return todo ? -EBUSY : 0;
}
+static bool __check_frozen_processes(void)
+{
+ struct task_struct *g, *p;
+
+ for_each_process_thread(g, p)
+ if (p != current && !freezer_should_skip(p) && !frozen(p))
+ return false;
+
+ return true;
+}
+
+/*
+ * Returns true if all freezable tasks (except for current) are frozen already
+ */
+static bool check_frozen_processes(void)
+{
+ bool ret;
+
+ read_lock(&tasklist_lock);
+ ret = __check_frozen_processes();
+ read_unlock(&tasklist_lock);
+ return ret;
+}
+
/**
* freeze_processes - Signal user space processes to enter the refrigerator.
* The current thread will not be frozen. The same process that calls
@@ -118,6 +142,7 @@ static int try_to_freeze_tasks(bool user_only)
int freeze_processes(void)
{
int error;
+ int oom_kills_saved;
error = __usermodehelper_disable(UMH_FREEZING);
if (error)
@@ -132,11 +157,25 @@ int freeze_processes(void)
pm_wakeup_clear();
printk("Freezing user space processes ... ");
pm_freezing = true;
+ oom_kills_saved = oom_kills_count();
error = try_to_freeze_tasks(true);
if (!error) {
- printk("done.");
__usermodehelper_set_disable_depth(UMH_DISABLED);
oom_killer_disable();
+
+ /*
+ * There might have been an OOM kill while we were
+ * freezing tasks and the killed task might be still
+ * on the way out so we have to double check for race.
+ */
+ if (oom_kills_count() != oom_kills_saved &&
+ !check_frozen_processes()) {
+ __usermodehelper_set_disable_depth(UMH_ENABLED);
+ printk("OOM in progress.");
+ error = -EBUSY;
+ } else {
+ printk("done.");
+ }
}
printk("\n");
BUG_ON(in_atomic());
@@ -191,11 +230,11 @@ void thaw_processes(void)
thaw_workqueues();
read_lock(&tasklist_lock);
- do_each_thread(g, p) {
+ for_each_process_thread(g, p) {
/* No other threads should have PF_SUSPEND_TASK set */
WARN_ON((p != curr) && (p->flags & PF_SUSPEND_TASK));
__thaw_task(p);
- } while_each_thread(g, p);
+ }
read_unlock(&tasklist_lock);
WARN_ON(!(curr->flags & PF_SUSPEND_TASK));
@@ -218,10 +257,10 @@ void thaw_kernel_threads(void)
thaw_workqueues();
read_lock(&tasklist_lock);
- do_each_thread(g, p) {
+ for_each_process_thread(g, p) {
if (p->flags & (PF_KTHREAD | PF_WQ_WORKER))
__thaw_task(p);
- } while_each_thread(g, p);
+ }
read_unlock(&tasklist_lock);
schedule();
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index bbf405a3a18f..5340f6b91312 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -404,6 +404,23 @@ static void dump_header(struct task_struct *p, gfp_t gfp_mask, int order,
dump_tasks(memcg, nodemask);
}
+/*
+ * Number of OOM killer invocations (including memcg OOM killer).
+ * Primarily used by PM freezer to check for potential races with
+ * OOM killed frozen task.
+ */
+static atomic_t oom_kills = ATOMIC_INIT(0);
+
+int oom_kills_count(void)
+{
+ return atomic_read(&oom_kills);
+}
+
+void note_oom_kill(void)
+{
+ atomic_inc(&oom_kills);
+}
+
#define K(x) ((x) << (PAGE_SHIFT-10))
/*
* Must be called while holding a reference to p, which will be released upon
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 736d8e1b6381..9cd36b822444 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2252,6 +2252,14 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
}
/*
+ * PM-freezer should be notified that there might be an OOM killer on
+ * its way to kill and wake somebody up. This is too early and we might
+ * end up not killing anything but false positives are acceptable.
+ * See freeze_processes.
+ */
+ note_oom_kill();
+
+ /*
* Go through the zonelist yet one more time, keep very high watermark
* here, this is only to catch a parallel oom killing, we must fail if
* we're still under heavy pressure.