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 v4 2/2] ftrace: do CPU checking after preemption disabled
Date: Mon, 18 Oct 2021 11:39:56 +0800 [thread overview]
Message-ID: <bae9073b-6949-d396-69c9-89353c3516ff@linux.alibaba.com> (raw)
In-Reply-To: <32a36348-69ee-6464-390c-3a8d6e9d2b53@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
next prev parent reply other threads:[~2021-10-18 3:40 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-18 3:38 [PATCH v4 0/2] fix & prevent the missing preemption disabling 王贇
2021-10-18 3:39 ` [PATCH v4 1/2] ftrace: disable preemption when recursion locked 王贇
2021-10-18 3:39 ` 王贇 [this message]
2021-10-26 2:09 ` [PATCH v4 0/2] fix & prevent the missing preemption disabling 王贇
2021-10-26 2:42 ` Steven Rostedt
2021-10-26 2:52 ` 王贇
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