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Peter Zijlstra 058ebd0eba 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>		12 years ago
..
Makefile	uprobes: Move to kernel/events/	13 years ago
callchain.c	perf: Add attribute to filter out callchains	13 years ago
core.c	perf: Fix perf_lock_task_context() vs RCU	12 years ago
hw_breakpoint.c	hw_breakpoint: Introduce "struct bp_cpuinfo"	12 years ago
internal.h	perf: Fix mmap() accounting hole	12 years ago
ring_buffer.c	perf: Fix vmalloc ring buffer pages handling	12 years ago
uprobes.c	uretprobes: Remove -ENOSYS as return probes implemented	12 years ago