Messages in this thread | | | Subject | Re: Linux-next POWER9 NULL pointer NIP since 1st Apr. | From | Qian Cai <> | Date | Fri, 10 Apr 2020 15:20:49 -0400 |
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> On Apr 9, 2020, at 10:14 AM, Steven Rostedt <rostedt@goodmis.org> wrote: > > On Thu, 9 Apr 2020 06:06:35 -0400 > Qian Cai <cai@lca.pw> wrote: > >>>> I’ll go to bisect some more but it is going to take a while. >>>> >>>> $ git log --oneline 4c205c84e249..8e99cf91b99b >>>> 8e99cf91b99b tracing: Do not allocate buffer in trace_find_next_entry() in atomic >>>> 2ab2a0924b99 tracing: Add documentation on set_ftrace_notrace_pid and set_event_notrace_pid >>>> ebed9628f5c2 selftests/ftrace: Add test to test new set_event_notrace_pid file >>>> ed8839e072b8 selftests/ftrace: Add test to test new set_ftrace_notrace_pid file >>>> 276836260301 tracing: Create set_event_notrace_pid to not trace tasks >>> >>>> b3b1e6ededa4 ftrace: Create set_ftrace_notrace_pid to not trace tasks >>>> 717e3f5ebc82 ftrace: Make function trace pid filtering a bit more exact >>> >>> If it is affecting function tracing, it is probably one of the above two >>> commits. >> >> OK, it was narrowed down to one of those messed with mcount here, > > Thing is, nothing here touches mcount.
Yes, you are right. I went back to test the commit just before the 5.7-trace merge request, I did reproduce there. The thing is that this bastard could take more 6-hour to happen, so my previous attempt did not wait long enough. Back to the square one...
> >> >> 8e99cf91b99b tracing: Do not allocate buffer in trace_find_next_entry() in atomic > > Touches reading the trace buffer. > >> 2ab2a0924b99 tracing: Add documentation on set_ftrace_notrace_pid and set_event_notrace_pid > > Documentation. > >> 6a13a0d7b4d1 ftrace/kprobe: Show the maxactive number on kprobe_events > > kprobe output. > >> c9b7a4a72ff6 ring-buffer/tracing: Have iterator acknowledge dropped events > > Reading the buffer. > >> 06e0a548bad0 tracing: Do not disable tracing when reading the trace file > > Reading the buffer. > >> 1039221cc278 ring-buffer: Do not disable recording when there is an iterator > > Reading the buffer. > >> 07b8b10ec94f ring-buffer: Make resize disable per cpu buffer instead of total buffer > > Resizing the buffer. > >> 153368ce1bd0 ring-buffer: Optimize rb_iter_head_event() > > Reading the buffer. > >> ff84c50cfb4b ring-buffer: Do not die if rb_iter_peek() fails more than thrice > > Reading the buffer. > >> 785888c544e0 ring-buffer: Have rb_iter_head_event() handle concurrent writer > > Reading the buffer. > >> 28e3fc56a471 ring-buffer: Add page_stamp to iterator for synchronization > > Reading the buffer. > >> bc1a72afdc4a ring-buffer: Rename ring_buffer_read() to read_buffer_iter_advance() > > Reading the buffer. > >> ead6ecfddea5 ring-buffer: Have ring_buffer_empty() not depend on tracing stopped > > Reading the buffer. > >> ff895103a84a tracing: Save off entry when peeking at next entry > > Reading the buffer. > >> bf2cbe044da2 tracing: Use address-of operator on section symbols > > Affects trace_printk() > >> bbd9d05618a6 gpu/trace: add a gpu total memory usage tracepoint > > New tracepoint infrastructure (just new trace events for gpu) > >> 89b74cac7834 tools/bootconfig: Show line and column in parse error > > Extended command line boot config. > >> 306b69dce926 bootconfig: Support O=<builddir> option > > Extended command line boot config > >> 5412e0b763e0 tracing: Remove unused TRACE_BUFFER bits > > Removed unused enums. > >> b396bfdebffc tracing: Have hwlat ts be first instance and record count of instances > > Affects only the hard ware latency detector (most likely not even > configured in the kernel). > > So I don't understand how any of the above commits can cause a problem. > > -- Steve
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