From: Peter Zijlstra <peterz@infradead.org>
To: Kees Cook <keescook@chromium.org>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
juri.lelli@redhat.com, vincent.guittot@linaro.org,
dietmar.eggemann@arm.com, rostedt@goodmis.org,
bsegall@google.com, mgorman@suse.de, bristot@redhat.com,
akpm@linux-foundation.org, mark.rutland@arm.com,
zhengqi.arch@bytedance.com, linux@armlinux.org.uk,
catalin.marinas@arm.com, will@kernel.org, mpe@ellerman.id.au,
paul.walmsley@sifive.com, palmer@dabbelt.com, hca@linux.ibm.com,
gor@linux.ibm.com, borntraeger@de.ibm.com,
linux-arch@vger.kernel.org, ardb@kernel.org
Subject: Re: [PATCH 2/7] stacktrace,sched: Make stack_trace_save_tsk() more robust
Date: Fri, 22 Oct 2021 18:45:14 +0200 [thread overview]
Message-ID: <20211022164514.GE174703@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <202110220919.46F58199D@keescook>
On Fri, Oct 22, 2021 at 09:25:02AM -0700, Kees Cook wrote:
> On Fri, Oct 22, 2021 at 05:09:35PM +0200, Peter Zijlstra wrote:
> > /**
> > * stack_trace_save_tsk - Save a task stack trace into a storage array
> > * @task: The task to examine
> > @@ -135,7 +142,6 @@ EXPORT_SYMBOL_GPL(stack_trace_save);
> > unsigned int stack_trace_save_tsk(struct task_struct *tsk, unsigned long *store,
> > unsigned int size, unsigned int skipnr)
> > {
> > - stack_trace_consume_fn consume_entry = stack_trace_consume_entry_nosched;
> > struct stacktrace_cookie c = {
> > .store = store,
> > .size = size,
> > @@ -143,11 +149,8 @@ unsigned int stack_trace_save_tsk(struct
> > .skip = skipnr + (current == tsk),
> > };
> >
> > - if (!try_get_task_stack(tsk))
> > - return 0;
> > + task_try_func(tsk, try_arch_stack_walk_tsk, &c);
>
> Pardon my thin understanding of the scheduler, but I assume this change
> doesn't mean stack_trace_save_tsk() stops working for "current", right?
> In trying to answer this for myself, I couldn't convince myself what value
> current->__state have here. Is it one of TASK_(UN)INTERRUPTIBLE ?
current really shouldn't be using stack_trace_save_tsk(), and no you're
quite right, it will not work for current, irrespective of ->__state,
current will always be ->on_rq.
I started auditing stack_trace_save_tsk() users a few days ago, but
didn't look for this particular issue. I suppose I'll have to start over
with that.
next prev parent reply other threads:[~2021-10-22 16:49 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-22 15:09 [PATCH 0/7] arch: More wchan fixes Peter Zijlstra
2021-10-22 15:09 ` [PATCH 1/7] x86: Fix __get_wchan() for !STACKTRACE Peter Zijlstra
2021-10-22 16:25 ` Kees Cook
2021-10-26 19:16 ` [tip: sched/core] " tip-bot2 for Peter Zijlstra
2021-10-22 15:09 ` [PATCH 2/7] stacktrace,sched: Make stack_trace_save_tsk() more robust Peter Zijlstra
2021-10-22 16:25 ` Kees Cook
2021-10-22 16:45 ` Peter Zijlstra [this message]
2021-10-22 16:57 ` Mark Rutland
2021-10-22 16:54 ` Mark Rutland
2021-10-22 17:01 ` Peter Zijlstra
2021-10-25 20:38 ` Peter Zijlstra
2021-10-25 20:52 ` Kees Cook
2021-10-26 9:33 ` Mark Rutland
2021-10-25 16:27 ` Peter Zijlstra
2021-10-22 15:09 ` [PATCH 3/7] ARM: implement ARCH_STACKWALK Peter Zijlstra
2021-10-22 16:18 ` Kees Cook
2021-10-22 15:09 ` [PATCH 4/7] arch: Make ARCH_STACKWALK independent of STACKTRACE Peter Zijlstra
2021-10-22 16:18 ` Kees Cook
2021-10-22 16:36 ` Peter Zijlstra
2021-10-22 17:06 ` Mark Rutland
2021-10-22 15:09 ` [PATCH 5/7] powerpc, arm64: Mark __switch_to() as __sched Peter Zijlstra
2021-10-22 16:15 ` Kees Cook
2021-10-22 17:40 ` Mark Rutland
2021-10-22 15:09 ` [PATCH 6/7] arch: __get_wchan() || ARCH_STACKWALK Peter Zijlstra
2021-10-22 16:13 ` Kees Cook
2021-10-22 17:52 ` Mark Rutland
2021-10-22 15:09 ` [PATCH 7/7] selftests: proc: Make sure wchan works when it exists Peter Zijlstra
2021-10-22 15:27 ` [PATCH 0/7] arch: More wchan fixes Peter Zijlstra
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