From e6edd4723129b31402ad2da3d579abfaf5286f4d Mon Sep 17 00:00:00 2001 From: Anton Vorontsov Date: Mon, 6 Feb 2012 20:29:41 +0400 Subject: 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 Conflicts: drivers/staging/android/lowmemorykiller.c --- 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 fa3f521..d091c80 100644 --- a/drivers/staging/android/lowmemorykiller.c +++ b/drivers/staging/android/lowmemorykiller.c @@ -34,6 +34,7 @@ #include #include #include +#include #include #define ENHANCED_LMK_ROUTINE @@ -178,7 +179,7 @@ static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc) selected_oom_adj = min_adj; #endif - read_lock(&tasklist_lock); + rcu_read_lock(); for_each_process(p) { struct mm_struct *mm; struct signal_struct *sig; @@ -273,13 +274,13 @@ static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc) selected_oom_adj, selected_tasksize); lowmem_deathpending = selected; lowmem_deathpending_timeout = jiffies + HZ; - force_sig(SIGKILL, selected); + send_sig(SIGKILL, selected, 0); rem -= selected_tasksize; } #endif 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; } -- cgit v1.1