diff options
author | David Rientjes <rientjes@google.com> | 2012-04-09 23:56:18 (GMT) |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-04-10 03:48:44 (GMT) |
commit | 83dbbdbb38666e20a75fad2294cf1df77c52f121 (patch) | |
tree | cfed4ddb4468615cec47e086955672b306f8b993 /drivers/staging/android/lowmemorykiller.c | |
parent | 0034102808e0dbbf3a2394b82b1bb40b5778de9e (diff) | |
download | linux-83dbbdbb38666e20a75fad2294cf1df77c52f121.tar.xz |
android, lowmemorykiller: remove task handoff notifier
The task handoff notifier leaks task_struct since it never gets freed
after the callback returns NOTIFY_OK, which means it is responsible for
doing so.
It turns out the lowmemorykiller actually doesn't need this notifier at
all. It's used to prevent unnecessary killing by waiting for a thread
to exit as a result of lowmem_shrink(), however, it's possible to do
this in the same way the kernel oom killer works by setting TIF_MEMDIE
and avoid killing if we're still waiting for it to exit.
The kernel oom killer will already automatically set TIF_MEMDIE for
threads that are attempting to allocate memory that have a fatal signal.
The thread selected by lowmem_shrink() will have such a signal after the
lowmemorykiller sends it a SIGKILL, so this won't result in an
unnecessary use of memory reserves for the thread to exit.
This has the added benefit that we don't have to rely on
CONFIG_PROFILING to prevent needlessly killing tasks.
Reported-by: Werner Landgraf <w.landgraf@ru.ru>
Cc: stable@vger.kernel.org
Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Colin Cross <ccross@android.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/staging/android/lowmemorykiller.c')
-rw-r--r-- | drivers/staging/android/lowmemorykiller.c | 48 |
1 files changed, 7 insertions, 41 deletions
diff --git a/drivers/staging/android/lowmemorykiller.c b/drivers/staging/android/lowmemorykiller.c index 052b43e..b91e4bc 100644 --- a/drivers/staging/android/lowmemorykiller.c +++ b/drivers/staging/android/lowmemorykiller.c @@ -55,7 +55,6 @@ static int lowmem_minfree[6] = { }; static int lowmem_minfree_size = 4; -static struct task_struct *lowmem_deathpending; static unsigned long lowmem_deathpending_timeout; #define lowmem_print(level, x...) \ @@ -64,24 +63,6 @@ static unsigned long lowmem_deathpending_timeout; printk(x); \ } while (0) -static int -task_notify_func(struct notifier_block *self, unsigned long val, void *data); - -static struct notifier_block task_nb = { - .notifier_call = task_notify_func, -}; - -static int -task_notify_func(struct notifier_block *self, unsigned long val, void *data) -{ - struct task_struct *task = data; - - if (task == lowmem_deathpending) - lowmem_deathpending = NULL; - - return NOTIFY_OK; -} - static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc) { struct task_struct *tsk; @@ -97,19 +78,6 @@ static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc) int other_file = global_page_state(NR_FILE_PAGES) - global_page_state(NR_SHMEM); - /* - * If we already have a death outstanding, then - * bail out right away; indicating to vmscan - * that we have nothing further to offer on - * this pass. - * - * Note: Currently you need CONFIG_PROFILING - * for this to work correctly. - */ - if (lowmem_deathpending && - time_before_eq(jiffies, lowmem_deathpending_timeout)) - return 0; - if (lowmem_adj_size < array_size) array_size = lowmem_adj_size; if (lowmem_minfree_size < array_size) @@ -148,6 +116,12 @@ static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc) if (!p) continue; + if (test_tsk_thread_flag(p, TIF_MEMDIE) && + time_before_eq(jiffies, lowmem_deathpending_timeout)) { + task_unlock(p); + rcu_read_unlock(); + return 0; + } oom_score_adj = p->signal->oom_score_adj; if (oom_score_adj < min_score_adj) { task_unlock(p); @@ -174,15 +148,9 @@ static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc) lowmem_print(1, "send sigkill to %d (%s), adj %d, size %d\n", selected->pid, selected->comm, selected_oom_score_adj, selected_tasksize); - /* - * If CONFIG_PROFILING is off, then we don't want to stall - * the killer by setting lowmem_deathpending. - */ -#ifdef CONFIG_PROFILING - lowmem_deathpending = selected; lowmem_deathpending_timeout = jiffies + HZ; -#endif send_sig(SIGKILL, selected, 0); + set_tsk_thread_flag(selected, TIF_MEMDIE); rem -= selected_tasksize; } lowmem_print(4, "lowmem_shrink %lu, %x, return %d\n", @@ -198,7 +166,6 @@ static struct shrinker lowmem_shrinker = { static int __init lowmem_init(void) { - task_handoff_register(&task_nb); register_shrinker(&lowmem_shrinker); return 0; } @@ -206,7 +173,6 @@ static int __init lowmem_init(void) static void __exit lowmem_exit(void) { unregister_shrinker(&lowmem_shrinker); - task_handoff_unregister(&task_nb); } module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO | S_IWUSR); |