The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 1b5a42d9c85f0e731f01c8d1129001fd8531a8a0 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" ebiederm@xmission.com Date: Mon, 3 Jan 2022 11:32:36 -0600 Subject: [PATCH] taskstats: Cleanup the use of task->exit_code
In the function bacct_add_task the code reading task->exit_code was introduced in commit f3cef7a99469 ("[PATCH] csa: basic accounting over taskstats"), and it is not entirely clear what the taskstats interface is trying to return as only returning the exit_code of the first task in a process doesn't make a lot of sense.
As best as I can figure the intent is to return task->exit_code after a task exits. The field is returned with per task fields, so the exit_code of the entire process is not wanted. Only the value of the first task is returned so this is not a useful way to get the per task ptrace stop code. The ordinary case of returning this value is returning after a task exits, which also precludes use for getting a ptrace value.
It is common to for the first task of a process to also be the last task of a process so this field may have done something reasonable by accident in testing.
Make ac_exitcode a reliable per task value by always returning it for every exited task.
Setting ac_exitcode in a sensible mannter makes it possible to continue to provide this value going forward.
Cc: Balbir Singh bsingharora@gmail.com Fixes: f3cef7a99469 ("[PATCH] csa: basic accounting over taskstats") Link: https://lkml.kernel.org/r/20220103213312.9144-5-ebiederm@xmission.com Signed-off-by: "Eric W. Biederman" ebiederm@xmission.com
diff --git a/kernel/tsacct.c b/kernel/tsacct.c index f00de83d0246..1d261fbe367b 100644 --- a/kernel/tsacct.c +++ b/kernel/tsacct.c @@ -38,11 +38,10 @@ void bacct_add_tsk(struct user_namespace *user_ns, stats->ac_btime = clamp_t(time64_t, btime, 0, U32_MAX); stats->ac_btime64 = btime;
- if (thread_group_leader(tsk)) { + if (tsk->flags & PF_EXITING) stats->ac_exitcode = tsk->exit_code; - if (tsk->flags & PF_FORKNOEXEC) - stats->ac_flag |= AFORK; - } + if (thread_group_leader(tsk) && (tsk->flags & PF_FORKNOEXEC)) + stats->ac_flag |= AFORK; if (tsk->flags & PF_SUPERPRIV) stats->ac_flag |= ASU; if (tsk->flags & PF_DUMPCORE)