On Tue, 7 Jul 2015 11:06:27 -0400 Steven Rostedt <[email protected]> wrote:
> On Tue, 30 Jun 2015 22:18:03 +0800 > Fengguang Wu <[email protected]> wrote: > > > Hi Rostedt, > > > > FYI, this merge changes kernel crash to some more obvious kernel BUG > > message. If it's still not helpful, I can try bisect the old crash > > or split up the merge and bisect into them. > > > > git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master > > > > This has been a bug for some time. Does this fix it? > Test this patch instead, this is the one I'm testing and will be pushing to Linus. -- Steve --- kernel/trace/trace.h | 1 + kernel/trace/trace_branch.c | 13 ++++++++----- 2 files changed, 9 insertions(+), 5 deletions(-) Index: linux-trace.git/kernel/trace/trace.h =================================================================== --- linux-trace.git.orig/kernel/trace/trace.h 2015-07-07 14:28:27.391715136 -0400 +++ linux-trace.git/kernel/trace/trace.h 2015-07-07 14:29:08.133213493 -0400 @@ -444,6 +444,7 @@ enum { TRACE_CONTROL_BIT, + TRACE_BRANCH_BIT, /* * Abuse of the trace_recursion. * As we need a way to maintain state if we are tracing the function Index: linux-trace.git/kernel/trace/trace_branch.c =================================================================== --- linux-trace.git.orig/kernel/trace/trace_branch.c 2015-07-07 14:28:27.391715136 -0400 +++ linux-trace.git/kernel/trace/trace_branch.c 2015-07-07 14:56:52.036764240 -0400 @@ -36,9 +36,12 @@ probe_likely_condition(struct ftrace_bra struct trace_branch *entry; struct ring_buffer *buffer; unsigned long flags; - int cpu, pc; + int pc; const char *p; + if (current->trace_recursion & TRACE_BRANCH_BIT) + return; + /* * I would love to save just the ftrace_likely_data pointer, but * this code can also be used by modules. Ugly things can happen @@ -50,9 +53,9 @@ probe_likely_condition(struct ftrace_bra return; local_irq_save(flags); - cpu = raw_smp_processor_id(); - data = per_cpu_ptr(tr->trace_buffer.data, cpu); - if (atomic_inc_return(&data->disabled) != 1) + current->trace_recursion |= TRACE_BRANCH_BIT; + data = this_cpu_ptr(tr->trace_buffer.data); + if (atomic_read(&data->disabled)) goto out; pc = preempt_count(); @@ -81,7 +84,7 @@ probe_likely_condition(struct ftrace_bra __buffer_unlock_commit(buffer, event); out: - atomic_dec(&data->disabled); + current->trace_recursion &= ~TRACE_BRANCH_BIT; local_irq_restore(flags); } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
