From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Date: Fri, 29 Apr 2022 22:27:55 +0000 Subject: Re: [PATCH v2 07/12] ptrace: Don't change __state Message-Id: List-Id: References: <87k0b7v9yk.fsf_-_@email.froward.int.ebiederm.org> <20220429214837.386518-7-ebiederm@xmission.com> In-Reply-To: <20220429214837.386518-7-ebiederm@xmission.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: "Eric W. Biederman" Cc: linux-kernel@vger.kernel.org, rjw@rjwysocki.net, Oleg Nesterov , mingo@kernel.org, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, mgorman@suse.de, bigeasy@linutronix.de, Will Deacon , tj@kernel.org, linux-pm@vger.kernel.org, Richard Weinberger , Anton Ivanov , Johannes Berg , linux-um@lists.infradead.org, Chris Zankel , Max Filippov , linux-xtensa@linux-xtensa.org, Kees Cook , Jann Horn , linux-ia64@vger.kernel.org On Fri, Apr 29, 2022 at 04:48:32PM -0500, Eric W. Biederman wrote: > Stop playing with tsk->__state to remove TASK_WAKEKILL while a ptrace > command is executing. > > Instead TASK_WAKEKILL from the definition of TASK_TRACED, and > implemention a new jobctl flag TASK_PTRACE_FROZEN. This new This new > flag is set in jobctl_freeze_task and cleared when ptrace_stop is > awoken or in jobctl_unfreeze_task (when ptrace_stop remains asleep). > > In singal_wake_up add __TASK_TRACED to state along with TASK_WAKEKILL > when it is indicated a fatal signal is pending. Skip adding > __TASK_TRACED when TASK_PTRACE_FROZEN is not set. This has the same > effect as changing TASK_TRACED to __TASK_TRACED as all of the wake_ups > that use TASK_KILLABLE go through signal_wake_up. > > Don't set TASK_TRACED if fatal_signal_pending so that the code > continues not to sleep if there was a pending fatal signal before > ptrace_stop is called. With TASK_WAKEKILL no longer present in > TASK_TRACED signal_pending_state will no longer prevent ptrace_stop > from sleeping if there is a pending fatal signal. > > Previously the __state value of __TASK_TRACED was changed to > TASK_RUNNING when woken up or back to TASK_TRACED when the code was > left in ptrace_stop. Now when woken up ptrace_stop now clears > JOBCTL_PTRACE_FROZEN and when left sleeping ptrace_unfreezed_traced > clears JOBCTL_PTRACE_FROZEN. > > Signed-off-by: "Eric W. Biederman" > --- > include/linux/sched.h | 2 +- > include/linux/sched/jobctl.h | 2 ++ > include/linux/sched/signal.h | 8 +++++++- > kernel/ptrace.c | 21 ++++++++------------- > kernel/signal.c | 9 +++------ > 5 files changed, 21 insertions(+), 21 deletions(-) Please fold this hunk: --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6310,10 +6310,7 @@ static void __sched notrace __schedule(u /* * We must load prev->state once (task_struct::state is volatile), such - * that: - * - * - we form a control dependency vs deactivate_task() below. - * - ptrace_{,un}freeze_traced() can change ->state underneath us. + * that we form a control dependency vs deactivate_task() below. */ prev_state = READ_ONCE(prev->__state); if (!(sched_mode & SM_MASK_PREEMPT) && prev_state) {