Messages in this thread | | | Date | Mon, 16 Jan 2023 22:02:37 -0800 | Subject | Re: WARNING in debug_mutex_unlock | From | Yonghong Song <> |
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On 1/15/23 6:24 PM, Hao Sun wrote: > > >> On 13 Jan 2023, at 2:45 PM, Yonghong Song <yhs@meta.com> wrote: >> >> >> >> On 1/8/23 11:44 PM, Hao Sun wrote: >>> Hi, >>> The following warning can be triggered with the C reproducer in >>> the link. The repro starts 32 threads, each attaches a tracepoint >>> into `ext4_mark_inode_dirty`. The prog loads the following insns >>> that simply sends signal to current proc, and then wait. >>> Seems issues in queued irq_work with `do_bpf_send_signal`, also >>> I'm wondering what if the task in `send_signal_irq_work` exited, >>> at the time the callback invoked. >> >> Somehow, I cannot reproduce the issue in my qemu environment >> with below kernel config and C reproducer. >> >> But could you try the following patch to see whether it >> fixed the issue in your environment? > > Tested the below patch on my local machine, seems fixed the issue. > > Before applying the patch, the reproducer can still trigger the > reported issue on a latest bpf-next build; After applying the > patch, the warning no longer appears. > > The test is conducted on: dfff86f8eb6a (“Merge branch 'samples/bpf: > modernize BPF functionality test programs'")
Thanks for testing. I will submit a patch shortly with your Reported-by and Tested-by.
> > >> >> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c >> index 23ce498bca97..1b26d51caf31 100644 >> --- a/kernel/trace/bpf_trace.c >> +++ b/kernel/trace/bpf_trace.c >> @@ -831,6 +831,7 @@ static void do_bpf_send_signal(struct irq_work *entry) >> >> work = container_of(entry, struct send_signal_irq_work, irq_work); >> group_send_sig_info(work->sig, SEND_SIG_PRIV, work->task, work->type); >> + put_task_struct(work->task); >> } >> >> static int bpf_send_signal_common(u32 sig, enum pid_type type) >> @@ -862,7 +863,7 @@ static int bpf_send_signal_common(u32 sig, enum pid_type type) >> * to the irq_work. The current task may change when queued >> * irq works get executed. >> */ >> - work->task = current; >> + work->task = get_task_struct(current); >> work->sig = sig; >> work->type = type; >> irq_work_queue(&work->irq_work); >> >
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