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authorAnton Vorontsov <anton.vorontsov@linaro.org>2012-02-06 20:29:41 +0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-02-08 16:55:45 -0800
commit294b27119f2e20643e71a0c1a1b511320a11e4c3 (patch)
tree279578d0c662a51f461c087afcc5e6aca8142d6d /drivers/staging/android
parent350a1955957d73352c043d0f948e3f28bb118c57 (diff)
staging: android/lowmemorykiller: Don't grab tasklist_lock
Grabbing tasklist_lock has its disadvantages, i.e. it blocks process creation and destruction. If there are lots of processes, blocking doesn't sound as a great idea. For LMK, it is sufficient to surround tasks list traverse with rcu_read_{,un}lock(). >From now on using force_sig() is not safe, as it can race with an already exiting task, so we use send_sig() now. As a downside, it won't kill PID namespace init processes, but that's not what we want anyway. Suggested-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/staging/android')
-rw-r--r--drivers/staging/android/lowmemorykiller.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/drivers/staging/android/lowmemorykiller.c b/drivers/staging/android/lowmemorykiller.c
index 2d8d2b796101..63da8447218f 100644
--- a/drivers/staging/android/lowmemorykiller.c
+++ b/drivers/staging/android/lowmemorykiller.c
@@ -34,6 +34,7 @@
#include <linux/mm.h>
#include <linux/oom.h>
#include <linux/sched.h>
+#include <linux/rcupdate.h>
#include <linux/profile.h>
#include <linux/notifier.h>
@@ -132,7 +133,7 @@ static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
}
selected_oom_adj = min_adj;
- read_lock(&tasklist_lock);
+ rcu_read_lock();
for_each_process(p) {
struct mm_struct *mm;
struct signal_struct *sig;
@@ -180,12 +181,12 @@ static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)
lowmem_deathpending = selected;
task_handoff_register(&task_nb);
#endif
- force_sig(SIGKILL, selected);
+ send_sig(SIGKILL, selected, 0);
rem -= selected_tasksize;
}
lowmem_print(4, "lowmem_shrink %lu, %x, return %d\n",
sc->nr_to_scan, sc->gfp_mask, rem);
- read_unlock(&tasklist_lock);
+ rcu_read_unlock();
return rem;
}