| Message ID | 20250324171941.GA13114@redhat.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | exit: fix the usage of delay_group_leader->exit_code in do_notify_parent() and pidfs_exit() | expand |
On Mon, 24 Mar 2025 18:19:41 +0100, Oleg Nesterov wrote: > Consider a process with a group leader L and a sub-thread T. > L does sys_exit(1), then T does sys_exit_group(2). > > In this case wait_task_zombie(L) will notice SIGNAL_GROUP_EXIT and use > L->signal->group_exit_code, this is correct. > > But, before that, do_notify_parent(L) called by release_task(T) will use > L->exit_code != L->signal->group_exit_code, and this is not consistent. > We don't really care, I think that nobody relies on the info which comes > with SIGCHLD, if nothing else SIGCHLD < SIGRTMIN can be queued only once. > > [...] Applied to the vfs.fixes branch of the vfs/vfs.git tree. Patches in the vfs.fixes branch should appear in linux-next soon. Please report any outstanding bugs that were missed during review in a new review to the original patch series allowing us to drop it. It's encouraged to provide Acked-bys and Reviewed-bys even though the patch has now been applied. If possible patch trailers will be updated. Note that commit hashes shown below are subject to change due to rebase, trailer updates or similar. If in doubt, please check the listed branch. tree: https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git branch: vfs.fixes [1/1] exit: fix the usage of delay_group_leader->exit_code in do_notify_parent() and pidfs_exit() https://git.kernel.org/vfs/vfs/c/9133607de37a
diff --git a/kernel/exit.c b/kernel/exit.c index d0ebccb9dec0..4a0604f5cedd 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -267,6 +267,9 @@ void release_task(struct task_struct *p) leader = p->group_leader; if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) { + /* for pidfs_exit() and do_notify_parent() */ + if (leader->signal->flags & SIGNAL_GROUP_EXIT) + leader->exit_code = leader->signal->group_exit_code; /* * If we were the last child thread and the leader has * exited already, and the leader's parent ignores SIGCHLD,
Consider a process with a group leader L and a sub-thread T. L does sys_exit(1), then T does sys_exit_group(2). In this case wait_task_zombie(L) will notice SIGNAL_GROUP_EXIT and use L->signal->group_exit_code, this is correct. But, before that, do_notify_parent(L) called by release_task(T) will use L->exit_code != L->signal->group_exit_code, and this is not consistent. We don't really care, I think that nobody relies on the info which comes with SIGCHLD, if nothing else SIGCHLD < SIGRTMIN can be queued only once. But pidfs_exit() is more problematic, I think pidfs_exit_info->exit_code should report ->group_exit_code in this case, just like wait_task_zombie(). TODO: with this change we can hopefully cleanup (or may be even kill) the similar SIGNAL_GROUP_EXIT checks, at least in wait_task_zombie(). Signed-off-by: Oleg Nesterov <oleg@redhat.com> --- kernel/exit.c | 3 +++ 1 file changed, 3 insertions(+)