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authorDavid Rientjes <rientjes@google.com>2012-04-09 16:56:18 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-04-09 20:48:44 -0700
commit83dbbdbb38666e20a75fad2294cf1df77c52f121 (patch)
treecfed4ddb4468615cec47e086955672b306f8b993 /drivers/staging
parent0034102808e0dbbf3a2394b82b1bb40b5778de9e (diff)
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')
-rw-r--r--drivers/staging/android/lowmemorykiller.c48
1 files changed, 7 insertions, 41 deletions
diff --git a/drivers/staging/android/lowmemorykiller.c b/drivers/staging/android/lowmemorykiller.c
index 052b43e4e50..b91e4bc332a 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);