From: Peter Zijlstra <peterz@infradead.org>
To: Will Deacon <will.deacon@arm.com>
Cc: Young Xiao <92siuyang@gmail.com>,
linux@armlinux.org.uk, mark.rutland@arm.com, mingo@redhat.com,
bp@alien8.de, hpa@zytor.com, x86@kernel.org,
kan.liang@linux.intel.com, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, ravi.bangoria@linux.vnet.ibm.com,
mpe@ellerman.id.au, acme@redhat.com, eranian@google.com,
fweisbec@gmail.com, jolsa@redhat.com
Subject: Re: [PATCH] perf: Fix oops when kthread execs user process
Date: Wed, 29 May 2019 15:25:15 +0200 [thread overview]
Message-ID: <20190529132515.GW2623@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20190529130521.GA11023@fuggles.cambridge.arm.com>
On Wed, May 29, 2019 at 02:05:21PM +0100, Will Deacon wrote:
> On Wed, May 29, 2019 at 02:55:57PM +0200, Peter Zijlstra wrote:
> > if (user_mode(regs)) {
>
> Hmm, so it just occurred to me that Mark's observation is that the regs
> can be junk in some cases. In which case, should we be checking for
> kthreads first?
task_pt_regs() can return garbage, but @regs is the exception (or
perf_arch_fetch_caller_regs()) regs, and for those user_mode() had
better be correct.
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Will Deacon <will.deacon@arm.com>
Cc: mark.rutland@arm.com, Young Xiao <92siuyang@gmail.com>,
mpe@ellerman.id.au, jolsa@redhat.com, x86@kernel.org,
linux@armlinux.org.uk, eranian@google.com,
linux-kernel@vger.kernel.org, acme@redhat.com, mingo@redhat.com,
bp@alien8.de, hpa@zytor.com, ravi.bangoria@linux.vnet.ibm.com,
fweisbec@gmail.com, linux-arm-kernel@lists.infradead.org,
kan.liang@linux.intel.com
Subject: Re: [PATCH] perf: Fix oops when kthread execs user process
Date: Wed, 29 May 2019 15:25:15 +0200 [thread overview]
Message-ID: <20190529132515.GW2623@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20190529130521.GA11023@fuggles.cambridge.arm.com>
On Wed, May 29, 2019 at 02:05:21PM +0100, Will Deacon wrote:
> On Wed, May 29, 2019 at 02:55:57PM +0200, Peter Zijlstra wrote:
> > if (user_mode(regs)) {
>
> Hmm, so it just occurred to me that Mark's observation is that the regs
> can be junk in some cases. In which case, should we be checking for
> kthreads first?
task_pt_regs() can return garbage, but @regs is the exception (or
perf_arch_fetch_caller_regs()) regs, and for those user_mode() had
better be correct.
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next prev parent reply other threads:[~2019-05-29 13:25 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-28 12:31 [PATCH] perf: Fix oops when kthread execs user process Young Xiao
2019-05-28 12:31 ` Young Xiao
2019-05-28 12:41 ` Russell King - ARM Linux admin
2019-05-28 12:41 ` Russell King - ARM Linux admin
2019-05-28 14:01 ` Peter Zijlstra
2019-05-28 14:01 ` Peter Zijlstra
2019-05-28 15:32 ` Will Deacon
2019-05-28 15:32 ` Will Deacon
2019-05-28 16:12 ` Mark Rutland
2019-05-28 16:12 ` Mark Rutland
2019-05-28 17:32 ` Peter Zijlstra
2019-05-28 17:32 ` Peter Zijlstra
2019-05-29 9:17 ` Will Deacon
2019-05-29 9:17 ` Will Deacon
2019-05-29 10:10 ` Peter Zijlstra
2019-05-29 10:10 ` Peter Zijlstra
2019-05-29 10:20 ` Will Deacon
2019-05-29 10:20 ` Will Deacon
2019-05-29 12:55 ` Peter Zijlstra
2019-05-29 12:55 ` Peter Zijlstra
2019-05-29 13:05 ` Will Deacon
2019-05-29 13:05 ` Will Deacon
2019-05-29 13:25 ` Peter Zijlstra [this message]
2019-05-29 13:25 ` Peter Zijlstra
2019-05-29 14:35 ` Will Deacon
2019-05-29 14:35 ` Will Deacon
2019-05-29 16:19 ` Peter Zijlstra
2019-05-29 16:19 ` Peter Zijlstra
2019-05-29 16:24 ` Mark Rutland
2019-05-29 16:24 ` Mark Rutland
2019-05-29 16:38 ` Mark Rutland
2019-05-29 16:38 ` Mark Rutland
2019-05-29 17:03 ` Peter Zijlstra
2019-05-29 17:03 ` Peter Zijlstra
2019-05-30 10:35 ` Mark Rutland
2019-05-30 10:35 ` Mark Rutland
2019-05-29 16:25 ` Will Deacon
2019-05-29 16:25 ` Will Deacon
2019-05-29 16:44 ` Peter Zijlstra
2019-05-29 16:44 ` Peter Zijlstra
2019-05-30 7:28 ` Will Deacon
2019-05-30 7:28 ` Will Deacon
2019-05-30 8:38 ` Ravi Bangoria
2019-05-30 8:38 ` Ravi Bangoria
2019-05-30 10:27 ` Ravi Bangoria
2019-05-30 10:27 ` Ravi Bangoria
2019-05-31 15:37 ` Will Deacon
2019-05-31 15:37 ` Will Deacon
2019-06-03 11:23 ` Will Deacon
2019-06-03 11:23 ` Will Deacon
2019-06-03 11:48 ` Peter Zijlstra
2019-06-03 11:48 ` Peter Zijlstra
2019-06-03 13:30 ` Michael Ellerman
2019-06-03 13:30 ` Michael Ellerman
2019-05-29 10:11 ` Mark Rutland
2019-05-29 10:11 ` Mark Rutland
2019-05-29 4:21 ` Michael Ellerman
2019-05-29 4:21 ` Michael Ellerman
2019-05-29 1:44 ` Michael Ellerman
2019-05-29 1:44 ` Michael Ellerman
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