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 14:55:57 +0200 [thread overview]
Message-ID: <20190529125557.GU2623@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20190529102022.GC4485@fuggles.cambridge.arm.com>
On Wed, May 29, 2019 at 11:20:22AM +0100, Will Deacon wrote:
> Anyway, you can add my ack to your patch, but I bet we can remove that mm
> check :D
I've ended up with the below. Ravi, can you test if that does indeed
obsolete your PPC patch?
---
Subject: perf: Fix perf_sample_regs_user()
From: Peter Zijlstra <peterz@infradead.org>
Date: Wed May 29 14:37:24 CEST 2019
perf_sample_regs_user() uses 'current->mm' to test for the presence of
userspace, but this is insufficient, consider use_mm().
A better test is: '!(current->flags & PF_KTHREAD)', exec() clears
PF_KTHREAD after it sets the new ->mm but before it drops to userspace
for the first time.
Possibly obsoletes: bf05fc25f268 ("powerpc/perf: Fix oops when kthread execs user process")
Reported-by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Reported-by: Young Xiao <92siuyang@gmail.com>
Cc: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Fixes: 4018994f3d87 ("perf: Add ability to attach user level registers dump to sample")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
kernel/events/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -5923,7 +5923,7 @@ static void perf_sample_regs_user(struct
if (user_mode(regs)) {
regs_user->abi = perf_reg_abi(current);
regs_user->regs = regs;
- } else if (current->mm) {
+ } else if (!(current->flags & PF_KTHREAD)) {
perf_get_regs_user(regs_user, regs, regs_user_copy);
} else {
regs_user->abi = PERF_SAMPLE_REGS_ABI_NONE;
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-05-29 12:56 UTC|newest]
Thread overview: 30+ 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 12:41 ` Russell King - ARM Linux admin
2019-05-28 14:01 ` Peter Zijlstra
2019-05-28 15:32 ` Will Deacon
2019-05-28 16:12 ` Mark Rutland
2019-05-28 17:32 ` Peter Zijlstra
2019-05-29 9:17 ` Will Deacon
2019-05-29 10:10 ` Peter Zijlstra
2019-05-29 10:20 ` Will Deacon
2019-05-29 12:55 ` Peter Zijlstra [this message]
2019-05-29 13:05 ` Will Deacon
2019-05-29 13:25 ` Peter Zijlstra
2019-05-29 14:35 ` Will Deacon
2019-05-29 16:19 ` Peter Zijlstra
2019-05-29 16:24 ` Mark Rutland
2019-05-29 16:38 ` Mark Rutland
2019-05-29 17:03 ` Peter Zijlstra
2019-05-30 10:35 ` Mark Rutland
2019-05-29 16:25 ` Will Deacon
2019-05-29 16:44 ` Peter Zijlstra
2019-05-30 7:28 ` Will Deacon
2019-05-30 8:38 ` Ravi Bangoria
2019-05-30 10:27 ` Ravi Bangoria
2019-05-31 15:37 ` Will Deacon
2019-06-03 11:23 ` Will Deacon
2019-06-03 11:48 ` Peter Zijlstra
2019-06-03 13:30 ` Michael Ellerman
2019-05-29 10:11 ` Mark Rutland
2019-05-29 4:21 ` Michael Ellerman
2019-05-29 1:44 ` Michael Ellerman
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190529125557.GU2623@hirez.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=92siuyang@gmail.com \
--cc=acme@redhat.com \
--cc=bp@alien8.de \
--cc=eranian@google.com \
--cc=fweisbec@gmail.com \
--cc=hpa@zytor.com \
--cc=jolsa@redhat.com \
--cc=kan.liang@linux.intel.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux@armlinux.org.uk \
--cc=mark.rutland@arm.com \
--cc=mingo@redhat.com \
--cc=mpe@ellerman.id.au \
--cc=ravi.bangoria@linux.vnet.ibm.com \
--cc=will.deacon@arm.com \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).