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Date: Mon, 25 Mar 2024 13:04:26 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Edward Liaw <edliaw@google.com>
Cc: linux-kernel@vger.kernel.org, Alexei Starovoitov <ast@kernel.org>,
 Daniel Borkmann <daniel@iogearbox.net>, John Fastabend
 <john.fastabend@gmail.com>, Andrii Nakryiko <andrii@kernel.org>, Martin
 KaFai Lau <martin.lau@linux.dev>, Eduard Zingerman <eddyz87@gmail.com>,
 Song Liu <song@kernel.org>, Yonghong Song <yonghong.song@linux.dev>, KP
 Singh <kpsingh@kernel.org>, Stanislav Fomichev <sdf@google.com>, Hao Luo
 <haoluo@google.com>, Jiri Olsa <jolsa@kernel.org>, "David S. Miller"
 <davem@davemloft.net>, Eric Dumazet <edumazet@google.com>, Jakub Kicinski
 <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>, Shuah Khan
 <shuah@kernel.org>, Nathan Chancellor <nathan@kernel.org>, Nick Desaulniers
 <ndesaulniers@google.com>, Bill Wendling <morbo@google.com>, Justin Stitt
 <justinstitt@google.com>, Jann Horn <jannh@google.com>,
 linux-kselftest@vger.kernel.org, kernel-team@android.com, Lokesh Gidra
 <lokeshgidra@google.com>, bpf@vger.kernel.org, netdev@vger.kernel.org,
 linux-mm@kvack.org, llvm@lists.linux.dev, Peter Xu <peterx@redhat.com>
Subject: Re: [PATCH v3] selftests/mm: Fix ARM related issue with fork after
 pthread_create
Message-Id: <20240325130426.fba5287fcc437475123e76cc@linux-foundation.org>
In-Reply-To: <20240325194100.775052-1-edliaw@google.com>
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On Mon, 25 Mar 2024 19:40:52 +0000 Edward Liaw <edliaw@google.com> wrote:

> Following issue was observed while running the uffd-unit-tests selftest
> on ARM devices. On x86_64 no issues were detected:
> 
> pthread_create followed by fork caused deadlock in certain cases
> wherein fork required some work to be completed by the created thread.
> Used synchronization to ensure that created thread's start function has
> started before invoking fork.

hm, you cc'ed the whole world apart from peterx.  Fixed.

> Signed-off-by: Lokesh Gidra <lokeshgidra@google.com>
> [edliaw: Refactored to use atomic_bool]
> Signed-off-by: Edward Liaw <edliaw@google.com>

I'll add cc:stable.  For which a Fixes: is desirable.  I used
760aee0b71e3 ("selftests/mm: add tests for RO pinning vs fork()"),
please check that.