6.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Leon Hwang leon.hwang@linux.dev
[ Upstream commit e25ddfb388c8b7e5f20e3bf38d627fb485003781 ]
When enable CONFIG_PREEMPT_RT, the kernel will warn when run timer selftests by './test_progs -t timer':
BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48
In order to avoid such warning, reject bpf_timer in verifier when PREEMPT_RT is enabled.
Signed-off-by: Leon Hwang leon.hwang@linux.dev Link: https://lore.kernel.org/r/20250910125740.52172-2-leon.hwang@linux.dev Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/bpf/verifier.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index ead1811534a0d..276a0de9a1bb2 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -5733,6 +5733,10 @@ static int process_timer_func(struct bpf_verifier_env *env, int regno, verbose(env, "verifier bug. Two map pointers in a timer helper\n"); return -EFAULT; } + if (IS_ENABLED(CONFIG_PREEMPT_RT)) { + verbose(env, "bpf_timer cannot be used for PREEMPT_RT.\n"); + return -EOPNOTSUPP; + } meta->map_uid = reg->map_uid; meta->map_ptr = map; return 0;