From 8628f489b749a4f9767991631921dbe3fbcdc784 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 17 Feb 2022 10:19:02 -0800 Subject: [PATCH] bpf: Add schedule points in batch ops commit 75134f16e7dd0007aa474b281935c5f42e79f2c8 upstream. syzbot reported various soft lockups caused by bpf batch operations. INFO: task kworker/1:1:27 blocked for more than 140 seconds. INFO: task hung in rcu_barrier Nothing prevents batch ops to process huge amount of data, we need to add schedule points in them. Note that maybe_wait_bpf_programs(map) calls from generic_map_delete_batch() can be factorized by moving the call after the loop. This will be done later in -next tree once we get this fix merged, unless there is strong opinion doing this optimization sooner. Fixes: aa2e93b8e58e ("bpf: Add generic support for update and delete batch ops") Fixes: cb4d03ab499d ("bpf: Add generic support for lookup batch op") Reported-by: syzbot Signed-off-by: Eric Dumazet Signed-off-by: Alexei Starovoitov Reviewed-by: Stanislav Fomichev Acked-by: Brian Vazquez Link: https://lore.kernel.org/bpf/20220217181902.808742-1-eric.dumazet@gmail.com Signed-off-by: Greg Kroah-Hartman --- kernel/bpf/syscall.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index ecd51a8..5338462 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1337,6 +1337,7 @@ int generic_map_delete_batch(struct bpf_map *map, maybe_wait_bpf_programs(map); if (err) break; + cond_resched(); } if (copy_to_user(&uattr->batch.count, &cp, sizeof(cp))) err = -EFAULT; @@ -1394,6 +1395,7 @@ int generic_map_update_batch(struct bpf_map *map, if (err) break; + cond_resched(); } if (copy_to_user(&uattr->batch.count, &cp, sizeof(cp))) @@ -1491,6 +1493,7 @@ int generic_map_lookup_batch(struct bpf_map *map, swap(prev_key, key); retry = MAP_LOOKUP_RETRIES; cp++; + cond_resched(); } if (err == -EFAULT) -- 2.7.4