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SubjectRe: Fwd: [REGRESSION 6.0.x / 6.1.x] NULL dereferencing at tracing
Hello everyone,

I have added lot's of debug printk's to see what's happening and I found
that the "cpu" counter, which is used to access the buffer's array
elements (cpu_buffer = buffer->buffers[cpu]) in the ring_buffer_wake_waiters
function, exceeds the maximum number of total of total cores, namely in
my case 24, which means, it should only run from 0..23. However, upon
debugging, it runs up to 31, and thus causing a NULL pointer dereference
(&cpu_buffer->irq_work).

After adding a return statement in case cpu > 24, the bug is no longer
reproducible.

You can find the diff between v6.1-rc2 and the patched version with
added debug log in [1].
The corresponding dmesg output can be found in [2].

I hope this gives you a good hint to find the root cause!

[1] https://paste.opensuse.org/e60601aa
[2] https://paste.opensuse.org/bf1398ce


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