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| author | Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> | 2016-03-08 11:01:32 (GMT) |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-04-04 19:41:24 (GMT) |
| commit | 77ed2c5745d93416992857d124f35834b62b3e70 (patch) | |
| tree | 205e9362221f554bd9da0f83418481236ecc3ed3 | |
| parent | eb7bfed901b9fea6e48bec10009dc8c8641e36e7 (diff) | |
| download | linux-77ed2c5745d93416992857d124f35834b62b3e70.tar.xz | |
android,lowmemorykiller: Don't abuse TIF_MEMDIE.
Currently, lowmemorykiller (LMK) is using TIF_MEMDIE for two purposes.
One is to remember processes killed by LMK, and the other is to
accelerate termination of processes killed by LMK.
But since LMK is invoked as a memory shrinker function, there still
should be some memory available. It is very likely that memory
allocations by processes killed by LMK will succeed without using
ALLOC_NO_WATERMARKS via TIF_MEMDIE. Even if their allocations cannot
escape from memory allocation loop unless they use ALLOC_NO_WATERMARKS,
lowmem_deathpending_timeout can guarantee forward progress by choosing
next victim process.
On the other hand, mark_oom_victim() assumes that it must be called with
oom_lock held and it must not be called after oom_killer_disable() was
called. But LMK is calling it without holding oom_lock and checking
oom_killer_disabled. It is possible that LMK calls mark_oom_victim()
due to allocation requests by kernel threads after current thread
returned from oom_killer_disabled(). This will break synchronization
for PM/suspend.
This patch introduces per a task_struct flag for remembering processes
killed by LMK, and replaces TIF_MEMDIE with that flag. By applying this
patch, assumption by mark_oom_victim() becomes true.
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Arve Hjonnevag <arve@android.com>
Cc: Riley Andrews <riandrews@android.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/staging/android/lowmemorykiller.c | 9 | ||||
| -rw-r--r-- | include/linux/sched.h | 4 |
2 files changed, 6 insertions, 7 deletions
diff --git a/drivers/staging/android/lowmemorykiller.c b/drivers/staging/android/lowmemorykiller.c index 2509e5d..c79f224 100644 --- a/drivers/staging/android/lowmemorykiller.c +++ b/drivers/staging/android/lowmemorykiller.c @@ -131,7 +131,7 @@ static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control *sc) if (!p) continue; - if (test_tsk_thread_flag(p, TIF_MEMDIE) && + if (task_lmk_waiting(p) && p->mm && time_before_eq(jiffies, lowmem_deathpending_timeout)) { task_unlock(p); rcu_read_unlock(); @@ -162,13 +162,8 @@ static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control *sc) if (selected) { task_lock(selected); send_sig(SIGKILL, selected, 0); - /* - * 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. - */ if (selected->mm) - mark_oom_victim(selected); + task_set_lmk_waiting(selected); task_unlock(selected); lowmem_print(1, "Killing '%s' (%d), adj %hd,\n" " to free %ldkB on behalf of '%s' (%d) because\n" diff --git a/include/linux/sched.h b/include/linux/sched.h index 60bba7e..9dff190 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2184,6 +2184,7 @@ static inline void memalloc_noio_restore(unsigned int flags) #define PFA_NO_NEW_PRIVS 0 /* May not gain new privileges. */ #define PFA_SPREAD_PAGE 1 /* Spread page cache over cpuset */ #define PFA_SPREAD_SLAB 2 /* Spread some slab caches over cpuset */ +#define PFA_LMK_WAITING 3 /* Lowmemorykiller is waiting */ #define TASK_PFA_TEST(name, func) \ @@ -2207,6 +2208,9 @@ TASK_PFA_TEST(SPREAD_SLAB, spread_slab) TASK_PFA_SET(SPREAD_SLAB, spread_slab) TASK_PFA_CLEAR(SPREAD_SLAB, spread_slab) +TASK_PFA_TEST(LMK_WAITING, lmk_waiting) +TASK_PFA_SET(LMK_WAITING, lmk_waiting) + /* * task->jobctl flags */ |