From: 王贇 yun.wang@linux.alibaba.com
[ Upstream commit d33cc657372366a8959f099c619a208b4c5dc664 ]
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.
Link: https://lkml.kernel.org/r/54880691-5fe2-33e7-d12f-1fa6136f5183@linux.alibaba...
CC: Steven Rostedt rostedt@goodmis.org Cc: Guo Ren guoren@kernel.org Cc: Ingo Molnar mingo@redhat.com Cc: "James E.J. Bottomley" James.Bottomley@HansenPartnership.com Cc: Helge Deller deller@gmx.de Cc: Michael Ellerman mpe@ellerman.id.au Cc: Benjamin Herrenschmidt benh@kernel.crashing.org Cc: Paul Mackerras paulus@samba.org Cc: Paul Walmsley paul.walmsley@sifive.com Cc: Palmer Dabbelt palmer@dabbelt.com Cc: Albert Ou aou@eecs.berkeley.edu Cc: Thomas Gleixner tglx@linutronix.de Cc: Borislav Petkov bp@alien8.de Cc: "H. Peter Anvin" hpa@zytor.com Cc: Josh Poimboeuf jpoimboe@redhat.com Cc: Jiri Kosina jikos@kernel.org Cc: Miroslav Benes mbenes@suse.cz Cc: Petr Mladek pmladek@suse.com Cc: Joe Lawrence joe.lawrence@redhat.com Cc: Masami Hiramatsu mhiramat@kernel.org Cc: "Peter Zijlstra (Intel)" peterz@infradead.org Cc: Nicholas Piggin npiggin@gmail.com Cc: Jisheng Zhang jszhang@kernel.org Reported-by: Abaci abaci@linux.alibaba.com Signed-off-by: Michael Wang yun.wang@linux.alibaba.com Signed-off-by: Steven Rostedt (VMware) rostedt@goodmis.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 03be4435d103f..50cd5a1a7ab4a 100644 --- a/kernel/trace/trace_event_perf.c +++ b/kernel/trace/trace_event_perf.c @@ -441,13 +441,13 @@ perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip, 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);
/*