On Tue, Jul 21, 2026 at 10:02:51AM +0300, Adrian Hunter wrote:
> Hi
> 
> Here is a fix for Intel PT.
> 
> There are 2 preparatory patches with no functional change intended.
> 
> The fix is to prevent nesting of perf_aux_output_begin() which
> triggers the WARNING in perf_aux_output_begin():
> 
> 	nest = READ_ONCE(rb->aux_nest);
> 	/*
> 	 * Nesting is not supported for AUX area, make sure nested
> 	 * writers are caught early
> 	 */
> 	if (WARN_ON_ONCE(nest))
> 		goto err_put;
> 
> The nesting happens when Intel PT gets throttled.  See the patch for more
> details.
> 
> 
> Adrian Hunter (3):
>       perf/x86/intel/pt: Factor out pt_config_enable()
>       perf/x86/intel/pt: Use bitwise access for PERF_HES_STOPPED
>       perf/x86/intel/pt: Fix stop/start with no update
> 
>  arch/x86/events/intel/pt.c | 96 +++++++++++++++++++++++++++++++---------------
>  1 file changed, 65 insertions(+), 31 deletions(-)
> 
>

Applied this series on top of v7.2-rc5. After forcing perf throttling,
the WARNING in perf_aux_output_begin no longer appears.

Tested-by: Yi Lai <yi1.lai@intel.com>


> Regards
> Adrian