Re: [PATCH v4 04/55] selftests/mm: migration: properly cleanup fork()ed processes

[Luiz Capitulino <luizcap@redhat.com>]

On 2026-05-11 12:27, Mike Rapoport wrote:
> From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
> 
> Several migration test use fork() to create worker processes. These
> processes are later killed, but nothing collects their exit status and they
> remain as zombies in the system.
> 
> Add a helper function that kills the worker processes, waitpid()s for
> them and verifies the exit status.
> 
> Replace the loops that call kill() for each process with a call to that
> helper.
> 
> Reported-by: Luiz Capitulino <luizcap@redhat.com>
> Tested-by: Luiz Capitulino <luizcap@redhat.com>
> Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>

Reviewed-by: Luiz Capitulino <luizcap@redhat.com>

> ---
>   tools/testing/selftests/mm/migration.c | 47 +++++++++++++++++++-------
>   1 file changed, 35 insertions(+), 12 deletions(-)
> 
> diff --git a/tools/testing/selftests/mm/migration.c b/tools/testing/selftests/mm/migration.c
> index 16ffd3c55ee0..e504829df6b6 100644
> --- a/tools/testing/selftests/mm/migration.c
> +++ b/tools/testing/selftests/mm/migration.c
> @@ -67,6 +67,29 @@ FIXTURE_TEARDOWN(migration)
>   	free(self->pids);
>   }
>   
> +static bool kill_children(FIXTURE_DATA(migration) * self)
> +{
> +	bool err = false;
> +	pid_t pid;
> +	int i;
> +
> +	for (i = 0; i < self->nthreads; i++) {
> +		int status = 0;
> +
> +		pid = self->pids[i];
> +		if (pid < 0)
> +			continue;
> +		if (kill(pid, SIGTERM))
> +			err = true;
> +		if (pid != waitpid(pid, &status, 0))
> +			err = true;
> +		if (!WIFSIGNALED(status) || WTERMSIG(status) != SIGTERM)
> +			err = true;
> +	}
> +
> +	return !err;
> +}
> +
>   int migrate(uint64_t *ptr, int n1, int n2)
>   {
>   	int ret, tmp;
> @@ -151,7 +174,7 @@ TEST_F_TIMEOUT(migration, shared_anon, 2*RUNTIME)
>   {
>   	pid_t pid;
>   	uint64_t *ptr;
> -	int i;
> +	int i, err;
>   
>   	ptr = mmap(NULL, TWOMEG, PROT_READ | PROT_WRITE,
>   		MAP_SHARED | MAP_ANONYMOUS, -1, 0);
> @@ -171,9 +194,9 @@ TEST_F_TIMEOUT(migration, shared_anon, 2*RUNTIME)
>   		}
>   	}
>   
> -	ASSERT_EQ(migrate(ptr, self->n1, self->n2), 0);
> -	for (i = 0; i < self->nthreads; i++)
> -		ASSERT_EQ(kill(self->pids[i], SIGTERM), 0);
> +	err = migrate(ptr, self->n1, self->n2);
> +	ASSERT_EQ(kill_children(self), true);
> +	ASSERT_EQ(err, 0);
>   }
>   
>   /*
> @@ -217,7 +240,7 @@ TEST_F_TIMEOUT(migration, shared_anon_thp, 2*RUNTIME)
>   	uint64_t pmdsize;
>   	pid_t pid;
>   	uint64_t *ptr;
> -	int i;
> +	int i, err;
>   
>   	if (!thp_is_enabled())
>   		SKIP(return, "Transparent Hugepages not available");
> @@ -247,9 +270,9 @@ TEST_F_TIMEOUT(migration, shared_anon_thp, 2*RUNTIME)
>   		}
>   	}
>   
> -	ASSERT_EQ(migrate(ptr, self->n1, self->n2), 0);
> -	for (i = 0; i < self->nthreads; i++)
> -		ASSERT_EQ(kill(self->pids[i], SIGTERM), 0);
> +	err = migrate(ptr, self->n1, self->n2);
> +	ASSERT_EQ(kill_children(self), true);
> +	ASSERT_EQ(err, 0);
>   }
>   
>   /*
> @@ -287,7 +310,7 @@ TEST_F_TIMEOUT(migration, shared_anon_htlb, 2*RUNTIME)
>   	unsigned long hugepage_size;
>   	pid_t pid;
>   	uint64_t *ptr;
> -	int i;
> +	int i, err;
>   
>   	hugepage_size = default_huge_page_size();
>   	if (!hugepage_size)
> @@ -311,9 +334,9 @@ TEST_F_TIMEOUT(migration, shared_anon_htlb, 2*RUNTIME)
>   		}
>   	}
>   
> -	ASSERT_EQ(migrate(ptr, self->n1, self->n2), 0);
> -	for (i = 0; i < self->nthreads; i++)
> -		ASSERT_EQ(kill(self->pids[i], SIGTERM), 0);
> +	err = migrate(ptr, self->n1, self->n2);
> +	ASSERT_EQ(kill_children(self), true);
> +	ASSERT_EQ(err, 0);
>   }
>   
>   TEST_HARNESS_MAIN