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Revert "oom_kill.c: futex: delay the OOM reaper to allow time for proper futex cleanup"

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This reverts commit ed5d4efb4d which is
commit e4a38402c36e42df28eb1a5394be87e6571fb48a upstream.

It breaks the kernel ABI and should not be an issue for Android at this
point in time.  If it is, it can come back in a different, abi-stable
form.

Bug: 161946584
Fixes: ed5d4efb4d ("oom_kill.c: futex: delay the OOM reaper to allow time for proper futex cleanup")
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I729614c373a7b28546376913e719bbaf6dd306a9
This commit is contained in:
Greg Kroah-Hartman
2022-05-12 12:02:54 +02:00
parent ca9b002a16
commit 141fbd343b
2 changed files with 15 additions and 42 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/sched.h
View File

@@ -1346,7 +1346,6 @@ struct task_struct {
int pagefault_disabled;
#ifdef CONFIG_MMU
struct task_struct *oom_reaper_list;
struct timer_list oom_reaper_timer;
#endif
#ifdef CONFIG_VMAP_STACK
struct vm_struct *stack_vm_area;

56
mm/oom_kill.c
View File

@@ -673,7 +673,7 @@ done:
*/
set_bit(MMF_OOM_SKIP, &mm->flags);
/* Drop a reference taken by queue_oom_reaper */
/* Drop a reference taken by wake_oom_reaper */
put_task_struct(tsk);
}
@@ -683,12 +683,12 @@ static int oom_reaper(void *unused)
struct task_struct *tsk = NULL;
wait_event_freezable(oom_reaper_wait, oom_reaper_list != NULL);
spin_lock_irq(&oom_reaper_lock);
spin_lock(&oom_reaper_lock);
if (oom_reaper_list != NULL) {
tsk = oom_reaper_list;
oom_reaper_list = tsk->oom_reaper_list;
}
spin_unlock_irq(&oom_reaper_lock);
spin_unlock(&oom_reaper_lock);
if (tsk)
oom_reap_task(tsk);
@@ -697,46 +697,20 @@ static int oom_reaper(void *unused)
return 0;
}
static void wake_oom_reaper(struct timer_list *timer)
{
struct task_struct *tsk = container_of(timer, struct task_struct,
oom_reaper_timer);
struct mm_struct *mm = tsk->signal->oom_mm;
unsigned long flags;
/* The victim managed to terminate on its own - see exit_mmap */
if (test_bit(MMF_OOM_SKIP, &mm->flags)) {
put_task_struct(tsk);
return;
}
spin_lock_irqsave(&oom_reaper_lock, flags);
tsk->oom_reaper_list = oom_reaper_list;
oom_reaper_list = tsk;
spin_unlock_irqrestore(&oom_reaper_lock, flags);
trace_wake_reaper(tsk->pid);
wake_up(&oom_reaper_wait);
}
/*
* Give the OOM victim time to exit naturally before invoking the oom_reaping.
* The timers timeout is arbitrary... the longer it is, the longer the worst
* case scenario for the OOM can take. If it is too small, the oom_reaper can
* get in the way and release resources needed by the process exit path.
* e.g. The futex robust list can sit in Anon|Private memory that gets reaped
* before the exit path is able to wake the futex waiters.
*/
#define OOM_REAPER_DELAY (2*HZ)
static void queue_oom_reaper(struct task_struct *tsk)
static void wake_oom_reaper(struct task_struct *tsk)
{
/* mm is already queued? */
if (test_and_set_bit(MMF_OOM_REAP_QUEUED, &tsk->signal->oom_mm->flags))
return;
get_task_struct(tsk);
timer_setup(&tsk->oom_reaper_timer, wake_oom_reaper, 0);
tsk->oom_reaper_timer.expires = jiffies + OOM_REAPER_DELAY;
add_timer(&tsk->oom_reaper_timer);
spin_lock(&oom_reaper_lock);
tsk->oom_reaper_list = oom_reaper_list;
oom_reaper_list = tsk;
spin_unlock(&oom_reaper_lock);
trace_wake_reaper(tsk->pid);
wake_up(&oom_reaper_wait);
}
static int __init oom_init(void)
@@ -746,7 +720,7 @@ static int __init oom_init(void)
}
subsys_initcall(oom_init)
#else
static inline void queue_oom_reaper(struct task_struct *tsk)
static inline void wake_oom_reaper(struct task_struct *tsk)
{
}
#endif /* CONFIG_MMU */
@@ -1006,7 +980,7 @@ static void __oom_kill_process(struct task_struct *victim, const char *message)
rcu_read_unlock();
if (can_oom_reap)
queue_oom_reaper(victim);
wake_oom_reaper(victim);
mmdrop(mm);
put_task_struct(victim);
@@ -1042,7 +1016,7 @@ static void oom_kill_process(struct oom_control *oc, const char *message)
task_lock(victim);
if (task_will_free_mem(victim)) {
mark_oom_victim(victim);
queue_oom_reaper(victim);
wake_oom_reaper(victim);
task_unlock(victim);
put_task_struct(victim);
return;
@@ -1140,7 +1114,7 @@ bool out_of_memory(struct oom_control *oc)
*/
if (task_will_free_mem(current)) {
mark_oom_victim(current);
queue_oom_reaper(current);
wake_oom_reaper(current);
return true;
}