From: Eric Dumazet <edumazet@google.com>
To: syzkaller <syzkaller@googlegroups.com>,
Eric Dumazet <edumazet@google.com>,
LKML <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
acme@redhat.com, Linus Torvalds <torvalds@linux-foundation.org>,
Alexander Potapenko <glider@google.com>,
Kostya Serebryany <kcc@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
Sasha Levin <sasha.levin@oracle.com>,
"H. Peter Anvin" <hpa@zytor.com>,
jolsa@redhat.com, Ingo Molnar <mingo@kernel.org>,
vincent.weaver@maine.edu, Thomas Gleixner <tglx@linutronix.de>,
acme@kernel.org, Stephane Eranian <eranian@google.com>
Cc: linux-tip-commits@vger.kernel.org
Subject: Re: [tip:perf/core] perf: Fix race in perf_event_exec()
Date: Wed, 6 Jan 2016 13:56:56 -0500 [thread overview]
Message-ID: <CANn89iLzUuR6wM=hOybM25d21PN=Fax5Ms7z2XeArTwAhZ6zqQ@mail.gmail.com> (raw)
In-Reply-To: <tip-c127449944659543e5e2423002f08f0af98dba5c@git.kernel.org>
On Wed, Jan 6, 2016 at 1:46 PM, tip-bot for Peter Zijlstra
<tipbot@zytor.com> wrote:
>
> This is because context switches can swap the task_struct::perf_event_ctxp[]
> pointer around. Therefore you have to either disable preemption when looking
> at current, or hold ctx->lock.
>
>
> void perf_event_exec(void)
> {
> - struct perf_event_context *ctx;
> int ctxn;
>
> rcu_read_lock();
Do we still need this rcu_read_lock(), if perf_event_enable_on_exec()
uses local_irq_save( ?
> - for_each_task_context_nr(ctxn) {
> - ctx = current->perf_event_ctxp[ctxn];
> - if (!ctx)
> - continue;
> -
> - perf_event_enable_on_exec(ctx);
> - }
> + for_each_task_context_nr(ctxn)
> + perf_event_enable_on_exec(ctxn);
> rcu_read_unlock();
> }
>
next prev parent reply other threads:[~2016-01-06 18:57 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-04 20:04 use-after-free in __perf_install_in_context Dmitry Vyukov
2015-12-04 20:32 ` Alexei Starovoitov
2015-12-04 21:00 ` Dmitry Vyukov
2015-12-07 11:04 ` Dmitry Vyukov
2015-12-07 11:06 ` Dmitry Vyukov
2015-12-07 11:24 ` Dmitry Vyukov
2015-12-07 15:36 ` Peter Zijlstra
2015-12-07 16:09 ` Dmitry Vyukov
2015-12-08 3:24 ` Alexei Starovoitov
2015-12-08 16:12 ` Dmitry Vyukov
2015-12-08 17:54 ` Alexei Starovoitov
2015-12-08 17:56 ` Dmitry Vyukov
2015-12-08 18:05 ` Alexei Starovoitov
2015-12-08 18:35 ` Dmitry Vyukov
2015-12-08 19:56 ` Alexei Starovoitov
2015-12-09 9:17 ` Dmitry Vyukov
2015-12-10 3:54 ` Alexei Starovoitov
2015-12-10 9:02 ` Peter Zijlstra
2015-12-10 17:03 ` Alexei Starovoitov
2015-12-11 8:14 ` Ingo Molnar
2015-12-15 13:11 ` Dmitry Vyukov
2015-12-08 16:44 ` Peter Zijlstra
2015-12-08 19:14 ` Dmitry Vyukov
2015-12-10 19:57 ` Peter Zijlstra
2015-12-15 13:09 ` Dmitry Vyukov
2015-12-17 14:06 ` Peter Zijlstra
2015-12-17 14:08 ` Dmitry Vyukov
2015-12-17 14:26 ` Peter Zijlstra
2015-12-17 14:28 ` Peter Zijlstra
2015-12-17 14:35 ` Dmitry Vyukov
2015-12-17 14:43 ` Peter Zijlstra
2015-12-31 17:15 ` Dmitry Vyukov
2016-01-05 12:17 ` Peter Zijlstra
2016-01-08 8:40 ` Dmitry Vyukov
2016-01-08 10:28 ` Dmitry Vyukov
2016-01-06 18:46 ` [tip:perf/core] perf: Fix race in perf_event_exec() tip-bot for Peter Zijlstra
2016-01-06 18:56 ` Eric Dumazet [this message]
2016-01-07 13:40 ` Peter Zijlstra
2016-01-07 16:26 ` Paul E. McKenney
2016-01-07 16:36 ` Eric Dumazet
2016-01-07 16:46 ` Paul E. McKenney
2015-12-08 16:22 ` use-after-free in __perf_install_in_context Peter Zijlstra
2015-12-08 18:57 ` Ingo Molnar
2015-12-09 9:05 ` Peter Zijlstra
2015-12-08 16:27 ` Peter Zijlstra
2015-12-08 16:50 ` Dmitry Vyukov
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