| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.15 054/139] bpf: Add schedule points in batch ops | Date | Mon, 28 Feb 2022 18:23:48 +0100 |
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From: Eric Dumazet <edumazet@google.com>
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 <syzkaller@googlegroups.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Reviewed-by: Stanislav Fomichev <sdf@google.com> Acked-by: Brian Vazquez <brianvv@google.com> Link: https://lore.kernel.org/bpf/20220217181902.808742-1-eric.dumazet@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- kernel/bpf/syscall.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1337,6 +1337,7 @@ int generic_map_delete_batch(struct bpf_ 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_ 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_ swap(prev_key, key); retry = MAP_LOOKUP_RETRIES; cp++; + cond_resched(); } if (err == -EFAULT)
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