From 2a8bc5316adc998951e8f726c31e231a6021eae2 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 8 Mar 2018 16:17:36 +0100 Subject: [PATCH] bpf: add schedule points in percpu arrays management [ upstream commit 32fff239de37ef226d5b66329dd133f64d63b22d ] syszbot managed to trigger RCU detected stalls in bpf_array_free_percpu() It takes time to allocate a huge percpu map, but even more time to free it. Since we run in process context, use cond_resched() to yield cpu if needed. Fixes: a10423b87a7e ("bpf: introduce BPF_MAP_TYPE_PERCPU_ARRAY map") Signed-off-by: Eric Dumazet Reported-by: syzbot Signed-off-by: Daniel Borkmann Signed-off-by: Greg Kroah-Hartman --- kernel/bpf/arraymap.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index 075ddb801422..a38119e4a427 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -20,8 +20,10 @@ static void bpf_array_free_percpu(struct bpf_array *array) { int i; - for (i = 0; i < array->map.max_entries; i++) + for (i = 0; i < array->map.max_entries; i++) { free_percpu(array->pptrs[i]); + cond_resched(); + } } static int bpf_array_alloc_percpu(struct bpf_array *array) @@ -37,6 +39,7 @@ static int bpf_array_alloc_percpu(struct bpf_array *array) return -ENOMEM; } array->pptrs[i] = ptr; + cond_resched(); } return 0; -- 2.17.1