When a task iterator traverses vma(s), it is possible task->mm might become invalid in the middle of traversal and this may cause kernel misbehave (e.g., crash) This test case creates iterators repeatedly and forks short-lived processes in the background to detect this bug. The test will last for 3 seconds to get the chance to trigger the issue. Signed-off-by: Kui-Feng Lee <kuifeng@meta.com> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/r/20221216221855.4122288-3-kuifeng@meta.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>