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More lockdep gifts, a 5-way lockup race: perf_event_create_kernel_counter() perf_event_alloc() perf_try_init_event() x86_pmu_event_init() __x86_pmu_event_init() x86_reserve_hardware() #0 mutex_lock(&pmc_reserve_mutex); reserve_ds_buffer() #1 get_online_cpus() perf_event_release_kernel() _free_event() hw_perf_event_destroy() x86_release_hardware() #0 mutex_lock(&pmc_reserve_mutex) release_ds_buffer() #1 get_online_cpus() #1 do_cpu_up() perf_event_init_cpu() #2 mutex_lock(&pmus_lock) #3 mutex_lock(&ctx->mutex) sys_perf_event_open() mutex_lock_double() #3 mutex_lock(ctx->mutex) #4 mutex_lock_nested(ctx->mutex, 1); perf_try_init_event() #4 mutex_lock_nested(ctx->mutex, 1) x86_pmu_event_init() intel_pmu_hw_config() x86_add_exclusive() #0 mutex_lock(&pmc_reserve_mutex) Fix it by using ordering constructs instead of locking. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vince Weaver <vincent.weaver@maine.edu> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.