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tracing: Disable interrupt or preemption before acquiring arch_spinlo…
…ck_t commit c0a581d upstream. It was found that some tracing functions in kernel/trace/trace.c acquire an arch_spinlock_t with preemption and irqs enabled. An example is the tracing_saved_cmdlines_size_read() function which intermittently causes a "BUG: using smp_processor_id() in preemptible" warning when the LTP read_all_proc test is run. That can be problematic in case preemption happens after acquiring the lock. Add the necessary preemption or interrupt disabling code in the appropriate places before acquiring an arch_spinlock_t. The convention here is to disable preemption for trace_cmdline_lock and interupt for max_lock. Link: https://lkml.kernel.org/r/20220922145622.1744826-1-longman@redhat.com Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Will Deacon <will@kernel.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: stable@vger.kernel.org Fixes: a35873a ("tracing: Add conditional snapshot") Fixes: 939c7a4 ("tracing: Introduce saved_cmdlines_size file") Suggested-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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