linux-kernel - Re: [PATCH 15/22] selftests/coredump: fix userspace coredump client detection

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Message-ID: <CAJqdLrqc54CU+pvt9BMGv6ZmwK-=CjYAV8qGmtVpLEAjS8dcYA@mail.gmail.com>
Date: Tue, 4 Nov 2025 10:12:48 +0100
From: Alexander Mikhalitsyn <alexander@...alicyn.com>
To: Christian Brauner <brauner@...nel.org>
Cc: linux-fsdevel@...r.kernel.org, Oleg Nesterov <oleg@...hat.com>, 
	Amir Goldstein <amir73il@...il.com>, Aleksa Sarai <cyphar@...har.com>, 
	Yu Watanabe <watanabe.yu+github@...il.com>, Josef Bacik <josef@...icpanda.com>, 
	Jeff Layton <jlayton@...nel.org>, Jann Horn <jannh@...gle.com>, 
	Luca Boccassi <luca.boccassi@...il.com>, linux-kernel@...r.kernel.org, 
	Alexander Viro <viro@...iv.linux.org.uk>, Jan Kara <jack@...e.cz>, 
	Lennart Poettering <lennart@...ttering.net>, Mike Yuan <me@...dnzj.com>, 
	Zbigniew Jędrzejewski-Szmek <zbyszek@...waw.pl>
Subject: Re: [PATCH 15/22] selftests/coredump: fix userspace coredump client detection

Am Di., 28. Okt. 2025 um 09:47 Uhr schrieb Christian Brauner
<brauner@...nel.org>:
>
> PIDFD_INFO_COREDUMP is only retrievable until the task has exited. After
> it has exited task->mm is NULL. So if the task didn't actually coredump
> we can't retrieve it's dumpability settings anymore. Only if the task
> did coredump will we have stashed the coredump information in the
> respective struct pid.
>
> Signed-off-by: Christian Brauner <brauner@...nel.org>

Reviewed-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@...onical.com>

> ---
>  tools/testing/selftests/coredump/coredump_socket_test.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/tools/testing/selftests/coredump/coredump_socket_test.c b/tools/testing/selftests/coredump/coredump_socket_test.c
> index 658f3966064f..5103d9f13003 100644
> --- a/tools/testing/selftests/coredump/coredump_socket_test.c
> +++ b/tools/testing/selftests/coredump/coredump_socket_test.c
> @@ -271,22 +271,26 @@ TEST_F(coredump, socket_detect_userspace_client)
>                         _exit(EXIT_FAILURE);
>
>                 close(fd_socket);
> +               pause();
>                 _exit(EXIT_SUCCESS);
>         }
>
>         pidfd = sys_pidfd_open(pid, 0);
>         ASSERT_GE(pidfd, 0);
>
> -       waitpid(pid, &status, 0);
> -       ASSERT_TRUE(WIFEXITED(status));
> -       ASSERT_EQ(WEXITSTATUS(status), 0);
> -
>         ASSERT_TRUE(get_pidfd_info(pidfd, &info));
>         ASSERT_GT((info.mask & PIDFD_INFO_COREDUMP), 0);
>         ASSERT_EQ((info.coredump_mask & PIDFD_COREDUMPED), 0);
>
>         wait_and_check_coredump_server(pid_coredump_server, _metadata, self);
>
> +       ASSERT_EQ(sys_pidfd_send_signal(pidfd, SIGKILL, NULL, 0), 0);
> +       ASSERT_EQ(close(pidfd), 0);
> +
> +       waitpid(pid, &status, 0);
> +       ASSERT_TRUE(WIFSIGNALED(status));
> +       ASSERT_EQ(WTERMSIG(status), SIGKILL);
> +
>         ASSERT_NE(stat("/tmp/coredump.file", &st), 0);
>         ASSERT_EQ(errno, ENOENT);
>  }
>
> --
> 2.47.3
>