Peter Zijlstra 82aad7ff7a perf/hw_breakpoint: Annotate tsk->perf_event_mutex vs ctx->mutex
Perf fuzzer gifted a lockdep splat:

  perf_event_init_context()
    mutex_lock(parent_ctx->mutex);			(B)
    inherit_task_group()
      inherit_group()
        inherit_event()
          perf_event_alloc()
            perf_try_init_event() := hw_breakpoint_event_init()
              register_perf_hw_breakpoint()
                mutex_lock(child->perf_event_mutex);	(A)

Which is against the normal (documented) order. Now, this is a false
positive in that child is not published yet, but also inherited events
never end up on ->perf_event_list.

Annotate this one away.

Fixes: 0912037fec ("perf/hw_breakpoint: Reduce contention with large number of tasks")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2022-10-04 13:32:09 +02:00
2022-09-29 12:20:50 +02:00
2022-09-29 12:20:50 +02:00
2022-09-25 14:01:02 -07:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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