From 294b27119f2e20643e71a0c1a1b511320a11e4c3 Mon Sep 17 00:00:00 2001 From: Anton Vorontsov Date: Mon, 6 Feb 2012 20:29:41 +0400 Subject: [PATCH] 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 Signed-off-by: Anton Vorontsov Reviewed-by: Oleg Nesterov Signed-off-by: Greg Kroah-Hartman --- drivers/staging/android/lowmemorykiller.c | 7 ++++--- 1 file 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 #include #include +#include #include #include @@ -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; } -- 2.30.2