On Tue, 07 Aug 2018 11:24:13 -0400 Joel Fernandes <joe...@google.com> wrote:
> On August 7, 2018 11:09:06 AM EDT, Steven Rostedt <rost...@goodmis.org> wrote: > >On Tue, 07 Aug 2018 10:48:05 -0400 > >Joel Fernandes <joe...@google.com> wrote: > > > >> >You mean if someone add a tracepoint callback to the irq disable > >> >tracepoint, and did a lockdep assert to make sure interrupts are > >> >disabled? > >> > >> Yes that's what I meant. > > > >That sounds like a "Doctor, it hurts me when I do this" problem ;-) > > Haha, yes true. But just to clarify, I didn't do this to see the problem but > noticed it with turning on existing things. :-) but I see your point... > OK, I hit this bug, but it's not because of the partial revert. This bug seems it needs to be another partial revert. I like you movement of the code, but I'm starting to doubt that we can use a trace event as a hook for critical areas yet. Well, not until we can use srcu in NMI. #define __DO_TRACE(tp, proto, args, cond, rcuidle) \ do { \ struct tracepoint_func *it_func_ptr; \ void *it_func; \ void *__data; \ int __maybe_unused idx = 0; \ \ if (!(cond)) \ return; \ \ /* srcu can't be used from NMI */ \ WARN_ON_ONCE(rcuidle && in_nmi()); <== WARN_ON_ONCE hit! WARNING: CPU: 3 PID: 3727 at /work/build/trace/nobackup/linux-test.git/include/trace/events/preemptirq.h:38 trace_irq_disable_rcuidle+0x2a/0x6c Modules linked in: ip6t_REJECT nf_reject_ipv6 nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables ipv6 crc_ccitt r8169 ppdev parport_pc parport CPU: 3 PID: 3727 Comm: trace-cmd Not tainted 4.18.0-rc6-test+ #14 Hardware name: MSI MS-7823/CSM-H87M-G43 (MS-7823), BIOS V1.6 02/22/2014 EIP: trace_irq_disable_rcuidle+0x2a/0x6c Code: e9 01 00 00 00 c3 64 8b 0d 24 e1 50 c1 0f a3 0d e0 f1 3f c1 73 55 55 89 e5 57 56 53 51 64 8b 0d cc 37 51 c1 0f ba e1 14 73 02 <0f> 0b 89 d7 89 c6 b8 e0 d8 2e c1 e8 8e 5b fa ff 8b 1d 9c 27 3d c1 EAX: c0401509 EBX: efa43680 ECX: 80110000 EDX: c0dc81f3 ESI: ed823d44 EDI: efa43680 EBP: ed823cd0 ESP: ed823cc0 DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 EFLAGS: 00010047 CR0: 80050033 CR2: b7f06000 CR3: 30513b00 CR4: 001406f0 Call Trace: trace_hardirqs_off_caller+0x23/0x2d trace_hardirqs_off_thunk+0xc/0x10 EIP: default_do_nmi+0x1/0x157 -- Steve