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

[Luiz Capitulino]

On 2026-05-11 12:27, Mike Rapoport wrote:

From: "Mike Rapoport (Microsoft)" <r...@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 <luiz...@redhat.com>
Tested-by: Luiz Capitulino <luiz...@redhat.com>
Signed-off-by: Mike Rapoport (Microsoft) <r...@kernel.org>

Reviewed-by: Luiz Capitulino <luiz...@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