Re: [PATCH] selftests/proc: proc-empty-vm: wait for child's SIGSEGV instead of sleep(1)

[DRIF ABDELMALEK MOHAMED SAID]

Hello Andrew,
Thank you for your reply,

>My review toy claims
>
>: Separately, tools/testing/selftests/ptrace/vmaccess.c has similar
>: sleep-based synchronization. A delayed child can make its attach test
>: fail spuriously, or let its vmaccess test run before the intended
>: blocked-exec state. That deserves a separate fix.

I just checked that file, it tests for a hang/deadlock when a ptrace
attach is run against
a child with one of its threads as a zombie, so they both hold cred_guard_mutex.
This, as far as my understanding and testing locally against upstream,
would cause a hang.

Is this the intended behaviour, and if not, is the problem from kernel
ptrace code or from the test,
please let me know which part of this i should investigate next.
Cordially,