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rcu: Don't use NMIs to dump other CPUs' stacks

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Although NMI-based stack dumps are in principle more accurate, they are
also more likely to trigger deadlocks.  This commit therefore replaces
all uses of trigger_all_cpu_backtrace() with rcu_dump_cpu_stacks(), so
that the CPU detecting an RCU CPU stall does the stack dumping.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
This commit is contained in:
Paul E. McKenney 2014-06-18 09:18:31 -07:00
parent c0f489d2c6
commit bc1dce514e
1 changed files with 3 additions and 7 deletions
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10
kernel/rcu/tree.c
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@ -1013,10 +1013,7 @@ static void record_gp_stall_check_time(struct rcu_state *rsp)
}
/*
* Dump stacks of all tasks running on stalled CPUs. This is a fallback
* for architectures that do not implement trigger_all_cpu_backtrace().
* The NMI-triggered stack traces are more accurate because they are
* printed by the target CPU.
* Dump stacks of all tasks running on stalled CPUs.
*/
static void rcu_dump_cpu_stacks(struct rcu_state *rsp)
{
@ -1094,7 +1091,7 @@ static void print_other_cpu_stall(struct rcu_state *rsp)
(long)rsp->gpnum, (long)rsp->completed, totqlen);
if (ndetected == 0)
pr_err("INFO: Stall ended before state dump start\n");
else if (!trigger_all_cpu_backtrace())
else
rcu_dump_cpu_stacks(rsp);
/* Complain about tasks blocking the grace period. */
@ -1125,8 +1122,7 @@ static void print_cpu_stall(struct rcu_state *rsp)
pr_cont(" (t=%lu jiffies g=%ld c=%ld q=%lu)\n",
jiffies - rsp->gp_start,
(long)rsp->gpnum, (long)rsp->completed, totqlen);
if (!trigger_all_cpu_backtrace())
dump_stack();
rcu_dump_cpu_stacks(rsp);
raw_spin_lock_irqsave(&rnp->lock, flags);
if (ULONG_CMP_GE(jiffies, ACCESS_ONCE(rsp->jiffies_stall)))