By default, the timer mode is being initialized to `NO_PREEMPT`. This disables preemption and forces execution in atomic context. This can cause issue with PREEMPT_RT when calling spin_lock_bh() due to sleeping nature of the lock. ... BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 6107, name: syz.0.17 preempt_count: 1, expected: 0 RCU nest depth: 1, expected: 1 Preemption disabled at: [] bpf_test_timer_enter+0xf8/0x140 net/bpf/test_run.c:42 Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 __might_resched+0x44b/0x5d0 kernel/sched/core.c:8957 __rt_spin_lock kernel/locking/spinlock_rt.c:48 [inline] rt_spin_lock+0xc7/0x2c0 kernel/locking/spinlock_rt.c:57 spin_lock_bh include/linux/spinlock_rt.h:88 [inline] __sock_map_delete net/core/sock_map.c:421 [inline] sock_map_delete_elem+0xb7/0x170 net/core/sock_map.c:452 bpf_prog_2c29ac5cdc6b1842+0x43/0x4b bpf_dispatcher_nop_func include/linux/bpf.h:1332 [inline] ... Change initialization to NO_MIGRATE mode to prevent this. Reported-by: syzbot+1f1fbecb9413cdbfbef8@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=1f1fbecb9413cdbfbef8 Tested-by: syzbot+1f1fbecb9413cdbfbef8@syzkaller.appspotmail.com Signed-off-by: Sahil Chandna --- net/bpf/test_run.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c index 4a862d605386..daf966dfed69 100644 --- a/net/bpf/test_run.c +++ b/net/bpf/test_run.c @@ -1368,7 +1368,7 @@ int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog, const union bpf_attr *kattr, union bpf_attr __user *uattr) { - struct bpf_test_timer t = { NO_PREEMPT }; + struct bpf_test_timer t = { NO_MIGRATE }; u32 size = kattr->test.data_size_in; struct bpf_flow_dissector ctx = {}; u32 repeat = kattr->test.repeat; @@ -1436,7 +1436,7 @@ int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog, int bpf_prog_test_run_sk_lookup(struct bpf_prog *prog, const union bpf_attr *kattr, union bpf_attr __user *uattr) { - struct bpf_test_timer t = { NO_PREEMPT }; + struct bpf_test_timer t = { NO_MIGRATE }; struct bpf_prog_array *progs = NULL; struct bpf_sk_lookup_kern ctx = {}; u32 repeat = kattr->test.repeat; -- 2.50.1