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Message-Id: <20250505231817.2697367-11-sashal@kernel.org>
Date: Mon, 5 May 2025 19:16:34 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
stable@...r.kernel.org
Cc: Oleg Nesterov <oleg@...hat.com>,
Christian Brauner <brauner@...nel.org>,
Sasha Levin <sashal@...nel.org>,
akpm@...ux-foundation.org,
mhocko@...e.com,
Liam.Howlett@...cle.com,
mjguzik@...il.com,
alexjlzheng@...cent.com,
pasha.tatashin@...een.com
Subject: [PATCH AUTOSEL 5.10 011/114] exit: fix the usage of delay_group_leader->exit_code in do_notify_parent() and pidfs_exit()
From: Oleg Nesterov <oleg@...hat.com>
[ Upstream commit 9133607de37a4887c6f89ed937176a0a0c1ebb17 ]
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@...hat.com>
Link: https://lore.kernel.org/r/20250324171941.GA13114@redhat.com
Signed-off-by: Christian Brauner <brauner@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
kernel/exit.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/kernel/exit.c b/kernel/exit.c
index af9c8e794e4d7..05f682cfdd6a7 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -254,6 +254,9 @@ 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,
--
2.39.5
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