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From: 王贇 <yun.wang@linux.alibaba.com>
To: Guo Ren <guoren@kernel.org>, Steven Rostedt <rostedt@goodmis.org>,
	Ingo Molnar <mingo@redhat.com>,
	"James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
	Helge Deller <deller@gmx.de>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@alien8.de>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Jiri Kosina <jikos@kernel.org>, Miroslav Benes <mbenes@suse.cz>,
	Petr Mladek <pmladek@suse.com>,
	Joe Lawrence <joe.lawrence@redhat.com>,
	Colin Ian King <colin.king@canonical.com>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>,
	Nicholas Piggin <npiggin@gmail.com>,
	Jisheng Zhang <jszhang@kernel.org>,
	linux-csky@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	linux-riscv@lists.infradead.org, live-patching@vger.kernel.org
Subject: [PATCH v3 2/2] ftrace: do CPU checking after preemption disabled
Date: Wed, 13 Oct 2021 16:52:13 +0800	[thread overview]
Message-ID: <a450a935-17d0-63df-87fd-c27a409ea5de@linux.alibaba.com> (raw)
In-Reply-To: <609b565a-ed6e-a1da-f025-166691b5d994@linux.alibaba.com>

With CONFIG_DEBUG_PREEMPT we observed reports like:

  BUG: using smp_processor_id() in preemptible
  caller is perf_ftrace_function_call+0x6f/0x2e0
  CPU: 1 PID: 680 Comm: a.out Not tainted
  Call Trace:
   <TASK>
   dump_stack_lvl+0x8d/0xcf
   check_preemption_disabled+0x104/0x110
   ? optimize_nops.isra.7+0x230/0x230
   ? text_poke_bp_batch+0x9f/0x310
   perf_ftrace_function_call+0x6f/0x2e0
   ...
   __text_poke+0x5/0x620
   text_poke_bp_batch+0x9f/0x310

This telling us the CPU could be changed after task is preempted, and
the checking on CPU before preemption will be invalid.

Since now ftrace_test_recursion_trylock() will help to disable the
preemption, this patch just do the checking after trylock() to address
the issue.

CC: Steven Rostedt <rostedt@goodmis.org>
Reported-by: Abaci <abaci@linux.alibaba.com>
Signed-off-by: Michael Wang <yun.wang@linux.alibaba.com>
---
 kernel/trace/trace_event_perf.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index 6aed10e..fba8cb7 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -441,13 +441,13 @@ void perf_trace_buf_update(void *record, u16 type)
 	if (!rcu_is_watching())
 		return;

-	if ((unsigned long)ops->private != smp_processor_id())
-		return;
-
 	bit = ftrace_test_recursion_trylock(ip, parent_ip);
 	if (bit < 0)
 		return;

+	if ((unsigned long)ops->private != smp_processor_id())
+		goto out;
+
 	event = container_of(ops, struct perf_event, ftrace_ops);

 	/*
-- 
1.8.3.1


WARNING: multiple messages have this Message-ID (diff)
From: 王贇 <yun.wang@linux.alibaba.com>
To: Guo Ren <guoren@kernel.org>, Steven Rostedt <rostedt@goodmis.org>,
	Ingo Molnar <mingo@redhat.com>,
	"James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
	Helge Deller <deller@gmx.de>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@alien8.de>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Jiri Kosina <jikos@kernel.org>, Miroslav Benes <mbenes@suse.cz>,
	Petr Mladek <pmladek@suse.com>,
	Joe Lawrence <joe.lawrence@redhat.com>,
	Colin Ian King <colin.king@canonical.com>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>,
	Nicholas Piggin <npiggin@gmail.com>,
	Jisheng Zhang <jszhang@kernel.org>,
	linux-csky@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	linux-riscv@lists.infradead.org, live-patching@vger.kernel.org
Subject: [PATCH v3 2/2] ftrace: do CPU checking after preemption disabled
Date: Wed, 13 Oct 2021 16:52:13 +0800	[thread overview]
Message-ID: <a450a935-17d0-63df-87fd-c27a409ea5de@linux.alibaba.com> (raw)
In-Reply-To: <609b565a-ed6e-a1da-f025-166691b5d994@linux.alibaba.com>

With CONFIG_DEBUG_PREEMPT we observed reports like:

  BUG: using smp_processor_id() in preemptible
  caller is perf_ftrace_function_call+0x6f/0x2e0
  CPU: 1 PID: 680 Comm: a.out Not tainted
  Call Trace:
   <TASK>
   dump_stack_lvl+0x8d/0xcf
   check_preemption_disabled+0x104/0x110
   ? optimize_nops.isra.7+0x230/0x230
   ? text_poke_bp_batch+0x9f/0x310
   perf_ftrace_function_call+0x6f/0x2e0
   ...
   __text_poke+0x5/0x620
   text_poke_bp_batch+0x9f/0x310

This telling us the CPU could be changed after task is preempted, and
the checking on CPU before preemption will be invalid.

Since now ftrace_test_recursion_trylock() will help to disable the
preemption, this patch just do the checking after trylock() to address
the issue.

CC: Steven Rostedt <rostedt@goodmis.org>
Reported-by: Abaci <abaci@linux.alibaba.com>
Signed-off-by: Michael Wang <yun.wang@linux.alibaba.com>
---
 kernel/trace/trace_event_perf.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index 6aed10e..fba8cb7 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -441,13 +441,13 @@ void perf_trace_buf_update(void *record, u16 type)
 	if (!rcu_is_watching())
 		return;

-	if ((unsigned long)ops->private != smp_processor_id())
-		return;
-
 	bit = ftrace_test_recursion_trylock(ip, parent_ip);
 	if (bit < 0)
 		return;

+	if ((unsigned long)ops->private != smp_processor_id())
+		goto out;
+
 	event = container_of(ops, struct perf_event, ftrace_ops);

 	/*
-- 
1.8.3.1


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http://lists.infradead.org/mailman/listinfo/linux-riscv

  parent reply	other threads:[~2021-10-13  8:52 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-13  8:51 [PATCH v3 0/2] fix & prevent the missing preemption disabling 王贇
2021-10-13  8:51 ` 王贇
2021-10-13  8:51 ` [PATCH v3 1/2] ftrace: disable preemption between ftrace_test_recursion_trylock/unlock() 王贇
2021-10-13  8:51   ` 王贇
2021-10-14  9:13   ` Miroslav Benes
2021-10-14  9:13     ` Miroslav Benes
2021-10-14  9:13     ` Miroslav Benes
2021-10-14  9:22     ` 王贇
2021-10-14  9:22       ` 王贇
2021-10-14  9:22       ` 王贇
2021-10-14 13:28     ` Steven Rostedt
2021-10-14 13:28       ` Steven Rostedt
2021-10-14 13:28       ` Steven Rostedt
2021-10-14 15:14   ` Petr Mladek
2021-10-14 15:14     ` Petr Mladek
2021-10-14 15:14     ` Petr Mladek
2021-10-15  3:13     ` 王贇
2021-10-15  3:13       ` 王贇
2021-10-15  3:13       ` 王贇
2021-10-15  4:45       ` 王贇
2021-10-15  4:45         ` 王贇
2021-10-15  4:45         ` 王贇
2021-10-15  7:28       ` Petr Mladek
2021-10-15  7:28         ` Petr Mladek
2021-10-15  7:28         ` Petr Mladek
2021-10-15  9:12         ` 王贇
2021-10-15  9:12           ` 王贇
2021-10-15  9:12           ` 王贇
2021-10-15 13:35           ` Steven Rostedt
2021-10-15 13:35             ` Steven Rostedt
2021-10-15 13:35             ` Steven Rostedt
2021-10-15  3:39     ` Steven Rostedt
2021-10-15  3:39       ` Steven Rostedt
2021-10-15  3:39       ` Steven Rostedt
2021-10-13  8:52 ` 王贇 [this message]
2021-10-13  8:52   ` [PATCH v3 2/2] ftrace: do CPU checking after preemption disabled 王贇

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