diff options
author | Peter Zijlstra <peterz@infradead.org> | 2013-07-12 11:08:33 +0200 |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2013-07-12 11:11:09 +0200 |
commit | 058ebd0eba3aff16b144eabf4510ed9510e1416e (patch) | |
tree | 1e35463a05e5b6109baf409a947d661a638d140b /COPYING | |
parent | 06f417968beac6e6b614e17b37d347aa6a6b1d30 (diff) |
perf: Fix perf_lock_task_context() vs RCU
Jiri managed to trigger this warning:
[] ======================================================
[] [ INFO: possible circular locking dependency detected ]
[] 3.10.0+ #228 Tainted: G W
[] -------------------------------------------------------
[] p/6613 is trying to acquire lock:
[] (rcu_node_0){..-...}, at: [<ffffffff810ca797>] rcu_read_unlock_special+0xa7/0x250
[]
[] but task is already holding lock:
[] (&ctx->lock){-.-...}, at: [<ffffffff810f2879>] perf_lock_task_context+0xd9/0x2c0
[]
[] which lock already depends on the new lock.
[]
[] the existing dependency chain (in reverse order) is:
[]
[] -> #4 (&ctx->lock){-.-...}:
[] -> #3 (&rq->lock){-.-.-.}:
[] -> #2 (&p->pi_lock){-.-.-.}:
[] -> #1 (&rnp->nocb_gp_wq[1]){......}:
[] -> #0 (rcu_node_0){..-...}:
Paul was quick to explain that due to preemptible RCU we cannot call
rcu_read_unlock() while holding scheduler (or nested) locks when part
of the read side critical section was preemptible.
Therefore solve it by making the entire RCU read side non-preemptible.
Also pull out the retry from under the non-preempt to play nice with RT.
Reported-by: Jiri Olsa <jolsa@redhat.com>
Helped-out-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: <stable@kernel.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'COPYING')
0 files changed, 0 insertions, 0 deletions