From: Mark Rutland <mark.rutland@arm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Arnaldo Carvalho de Melo <acme@redhat.com>,
Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org, jolsa@redhat.com,
dvyukov@google.com, namhyung@kernel.org, xiexiuqi@huawei.com,
syzbot+a24c397a29ad22d86c98@syzkaller.appspotmail.com
Subject: Re: [PATCH] perf: Fix race between close() and fork()
Date: Mon, 1 Jul 2019 10:24:30 +0100 [thread overview]
Message-ID: <20190701092429.GA10975@lakrids.cambridge.arm.com> (raw)
In-Reply-To: <20190628204608.GG3402@hirez.programming.kicks-ass.net>
On Fri, Jun 28, 2019 at 10:46:08PM +0200, Peter Zijlstra wrote:
> On Fri, Jun 28, 2019 at 05:50:03PM +0100, Mark Rutland wrote:
> > > + /*
> > > + * Wake any perf_event_free_task() waiting for this event to be
> > > + * freed.
> > > + */
> > > + smp_mb(); /* pairs with wait_var_event() */
> > > + wake_up_var(var);
> >
> > Huh, so wake_up_var() doesn't imply a RELEASE?
> >
> > As an aside, doesn't that mean all callers of wake_up_var() have to do
> > likewise to ensure it isn't re-ordered with whatever prior stuff they're
> > trying to notify waiters about? Several do an smp_store_release() then a
> > wake_up_var(), but IIUC the wake_up_var() could get pulled before that
> > release...
>
> Yah,...
>
> https://lkml.kernel.org/r/20190624165012.GH3436@hirez.programming.kicks-ass.net
That gets me a 404, so I'll assume that's a speculative store. ;)
> I needs to get back to that.
Ouch; sorry for reminding you of this mess!
Thanks,
Mark.
next prev parent reply other threads:[~2019-07-01 9:24 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-09 5:52 KASAN: use-after-free Write in _free_event syzbot
2018-07-09 10:11 ` Alexander Shishkin
2018-07-09 11:02 ` Dmitry Vyukov
2019-02-16 10:43 ` Xie XiuQi
2019-02-28 14:01 ` [RFC PATCH] perf: Paper over the hw.target problems Alexander Shishkin
[not found] ` <c174549c-d169-7773-2f47-5863ba0b8056@huawei.com>
2019-03-08 12:38 ` Alexander Shishkin
2019-03-11 13:32 ` chengjian (D)
2019-03-08 15:54 ` Mark Rutland
2019-06-24 12:19 ` Peter Zijlstra
2019-06-25 8:49 ` Peter Zijlstra
2019-06-25 10:43 ` [PATCH] perf: Fix race between close() and fork() Peter Zijlstra
2019-06-25 12:20 ` Alexander Shishkin
2019-06-28 16:50 ` Mark Rutland
2019-06-28 20:46 ` Peter Zijlstra
2019-07-01 9:24 ` Mark Rutland [this message]
2018-07-10 2:16 ` KASAN: use-after-free Write in _free_event syzbot
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