This issue is related to task iterators over vma. A system crash can occur when a task iterator travels through vma of tasks as the death of a task will clear the pointer to its mm, even though the task_struct is still held. As a result, an unexpected crash happens due to a null pointer. To address this problem, a reference to mm is kept on the iterator to make sure that the pointer is always valid. This patch set provides a solution for this crash by properly referencing mm on task iterators over vma. The major changes from v1 are: - Fix commit logs of the test case. - Use reverse Christmas tree coding style. - Remove unnecessary error handling for time(). v1: https://lore.kernel.org/bpf/20221216015912.991616-1-kuifeng@xxxxxxxx/ Kui-Feng Lee (2): bpf: keep a reference to the mm, in case the task is dead. selftests/bpf: add a test for iter/task_vma for short-lived processes kernel/bpf/task_iter.c | 39 +++++++--- .../selftests/bpf/prog_tests/bpf_iter.c | 73 +++++++++++++++++++ 2 files changed, 100 insertions(+), 12 deletions(-) -- 2.30.2
