On 10/9/25 06:49, Alexei Starovoitov wrote: > On Mon, Sep 8, 2025 at 3:42 PM Peilin Ye <yepeilin@xxxxxxxxxx> wrote: >> >> Hi all, >> >>>>> [ 35.955287] BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 >> >> FWIW, I was able to reproduce this pr_err() after enabling >> CONFIG_PREEMPT_RT and CONFIG_DEBUG_ATOMIC_SLEEP. >> >> On Mon, Sep 08, 2025 at 12:29:42PM -0700, Eduard Zingerman wrote: >>> On Mon, 2025-09-08 at 12:20 -0700, Eduard Zingerman wrote: >>>> On Mon, 2025-09-08 at 12:40 +0800, Leon Hwang wrote: >>>>> When enable CONFIG_PREEMPT_RT, the kernel will panic when run timer >>>>> selftests by './test_progs -t timer': >>> >>> Related discussions: >> >> [1] >>> - https://lore.kernel.org/bpf/b634rejnvxqu6knjqlijosxrcnxbbpagt4de4pl6env6dwldz2@hoofqufparh5/T/ >>> - https://lore.kernel.org/bpf/lhmdi6npaxqeuaumjhmq24ckpul7ufopwzxjbsezhepguqkxag@wolz4r2fazu2/T/ >> >> [...] >> >>>> The error is reported because of the kmalloc call in the __bpf_async_init, right? >>>> Instead of disabling timers for PREEMPT_RT, would it be possible to >>>> switch implementation to use kernel/bpf/memalloc.c:bpf_mem_alloc() instead? >> >> Just in case - actually there was a patch that does this: >> >> [2] https://lore.kernel.org/bpf/20250905061919.439648-1-yepeilin@xxxxxxxxxx/ > > Though switch to bpf_mem_alloc() kinda fixes it, > it's too late for this release and it's not a complete fix for RT, > so I think it's better to disable it in the verifier like this patch does. > > Leon, pls respin targeting bpf tree. My original intention for targeting the bpf-next tree was to ensure that the new 'timer_interrupt' selftest is skipped when PREEMPT_RT is enabled. If I respin the patch for the bpf tree, I have to drop the part that skips the timer_interrupt test case. Should I? > Also trim the commit log. It's too verbose and not quite correct. > "kernel will panic" > That's true only if you have panic-on-warn set. > Just say that the kernel will warn. > Sure. I’ll make it more concise and clarify that "the kernel will warn", rather than saying it will always panic. Thanks, Leon
