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authorSteven Rostedt (VMware) <rostedt@goodmis.org>2018-09-04 23:26:11 +0300
committerSteven Rostedt (VMware) <rostedt@goodmis.org>2018-09-05 18:23:21 +0300
commit865e63b04e9b2a658d7f26bd13a71dcd964a9118 (patch)
treedc10dcc23b3aba7e35595809df1be286e8a8cf1b
parent57361846b52bc686112da6ca5368d11210796804 (diff)
downloadlinux-865e63b04e9b2a658d7f26bd13a71dcd964a9118.tar.xz
tracing: Add back in rcu_irq_enter/exit_irqson() for rcuidle tracepoints
Borislav reported the following splat: ============================= WARNING: suspicious RCU usage 4.19.0-rc1+ #1 Not tainted ----------------------------- ./include/linux/rcupdate.h:631 rcu_read_lock() used illegally while idle! other info that might help us debug this: RCU used illegally from idle CPU! rcu_scheduler_active = 2, debug_locks = 1 RCU used illegally from extended quiescent state! 1 lock held by swapper/0/0: #0: 000000004557ee0e (rcu_read_lock){....}, at: perf_event_output_forward+0x0/0x130 stack backtrace: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.19.0-rc1+ #1 Hardware name: LENOVO 2320CTO/2320CTO, BIOS G2ET86WW (2.06 ) 11/13/2012 Call Trace: dump_stack+0x85/0xcb perf_event_output_forward+0xf6/0x130 __perf_event_overflow+0x52/0xe0 perf_swevent_overflow+0x91/0xb0 perf_tp_event+0x11a/0x350 ? find_held_lock+0x2d/0x90 ? __lock_acquire+0x2ce/0x1350 ? __lock_acquire+0x2ce/0x1350 ? retint_kernel+0x2d/0x2d ? find_held_lock+0x2d/0x90 ? tick_nohz_get_sleep_length+0x83/0xb0 ? perf_trace_cpu+0xbb/0xd0 ? perf_trace_buf_alloc+0x5a/0xa0 perf_trace_cpu+0xbb/0xd0 cpuidle_enter_state+0x185/0x340 do_idle+0x1eb/0x260 cpu_startup_entry+0x5f/0x70 start_kernel+0x49b/0x4a6 secondary_startup_64+0xa4/0xb0 This is due to the tracepoints moving to SRCU usage which does not require RCU to be "watching". But perf uses these tracepoints with RCU and expects it to be. Hence, we still need to add in the rcu_irq_enter/exit_irqson() calls for "rcuidle" tracepoints. This is a temporary fix until we have SRCU working in NMI context, and then perf can be converted to use that instead of normal RCU. Link: http://lkml.kernel.org/r/20180904162611.6a120068@gandalf.local.home Cc: x86-ml <x86@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Reported-by: Borislav Petkov <bp@alien8.de> Tested-by: Borislav Petkov <bp@alien8.de> Reviewed-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Fixes: e6753f23d961d ("tracepoint: Make rcuidle tracepoint callers use SRCU") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
-rw-r--r--include/linux/tracepoint.h8
1 files changed, 6 insertions, 2 deletions
diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 7f2e16e76ac4..041f7e56a289 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -158,8 +158,10 @@ extern void syscall_unregfunc(void);
* For rcuidle callers, use srcu since sched-rcu \
* doesn't work from the idle path. \
*/ \
- if (rcuidle) \
+ if (rcuidle) { \
idx = srcu_read_lock_notrace(&tracepoint_srcu); \
+ rcu_irq_enter_irqson(); \
+ } \
\
it_func_ptr = rcu_dereference_raw((tp)->funcs); \
\
@@ -171,8 +173,10 @@ extern void syscall_unregfunc(void);
} while ((++it_func_ptr)->func); \
} \
\
- if (rcuidle) \
+ if (rcuidle) { \
+ rcu_irq_exit_irqson(); \
srcu_read_unlock_notrace(&tracepoint_srcu, idx);\
+ } \
\
preempt_enable_notrace(); \
} while (0)