Merge tag 'perf-core-2025-05-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull perf events updates from Ingo Molnar:
 "Core & generic-arch updates:

   - Add support for dynamic constraints and propagate it to the Intel
     driver (Kan Liang)

   - Fix & enhance driver-specific throttling support (Kan Liang)

   - Record sample last_period before updating on the x86 and PowerPC
     platforms (Mark Barnett)

   - Make perf_pmu_unregister() usable (Peter Zijlstra)

   - Unify perf_event_free_task() / perf_event_exit_task_context()
     (Peter Zijlstra)

   - Simplify perf_event_release_kernel() and perf_event_free_task()
     (Peter Zijlstra)

   - Allocate non-contiguous AUX pages by default (Yabin Cui)

  Uprobes updates:

   - Add support to emulate NOP instructions (Jiri Olsa)

   - selftests/bpf: Add 5-byte NOP uprobe trigger benchmark (Jiri Olsa)

  x86 Intel PMU enhancements:

   - Support Intel Auto Counter Reload [ACR] (Kan Liang)

   - Add PMU support for Clearwater Forest (Dapeng Mi)

   - Arch-PEBS preparatory changes: (Dapeng Mi)
       - Parse CPUID archPerfmonExt leaves for non-hybrid CPUs
       - Decouple BTS initialization from PEBS initialization
       - Introduce pairs of PEBS static calls

  x86 AMD PMU enhancements:

   - Use hrtimer for handling overflows in the AMD uncore driver
     (Sandipan Das)

   - Prevent UMC counters from saturating (Sandipan Das)

  Fixes and cleanups:

   - Fix put_ctx() ordering (Frederic Weisbecker)

   - Fix irq work dereferencing garbage (Frederic Weisbecker)

   - Misc fixes and cleanups (Changbin Du, Frederic Weisbecker, Ian
     Rogers, Ingo Molnar, Kan Liang, Peter Zijlstra, Qing Wang, Sandipan
     Das, Thorsten Blum)"

* tag 'perf-core-2025-05-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (60 commits)
  perf/headers: Clean up <linux/perf_event.h> a bit
  perf/uapi: Clean up <uapi/linux/perf_event.h> a bit
  perf/uapi: Fix PERF_RECORD_SAMPLE comments in <uapi/linux/perf_event.h>
  mips/perf: Remove driver-specific throttle support
  xtensa/perf: Remove driver-specific throttle support
  sparc/perf: Remove driver-specific throttle support
  loongarch/perf: Remove driver-specific throttle support
  csky/perf: Remove driver-specific throttle support
  arc/perf: Remove driver-specific throttle support
  alpha/perf: Remove driver-specific throttle support
  perf/apple_m1: Remove driver-specific throttle support
  perf/arm: Remove driver-specific throttle support
  s390/perf: Remove driver-specific throttle support
  powerpc/perf: Remove driver-specific throttle support
  perf/x86/zhaoxin: Remove driver-specific throttle support
  perf/x86/amd: Remove driver-specific throttle support
  perf/x86/intel: Remove driver-specific throttle support
  perf: Only dump the throttle log for the leader
  perf: Fix the throttle logic for a group
  perf/core: Add the is_event_in_freq_mode() helper to simplify the code
  ...

1 files changed, 20 insertions, 9 deletions

diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
index 5130b119d0ae..d2aef87c7e9f 100644
--- a/kernel/events/ring_buffer.c
+++ b/kernel/events/ring_buffer.c
@@ -679,7 +679,15 @@ int rb_alloc_aux(struct perf_buffer *rb, struct perf_event *event,
 {
 	bool overwrite = !(flags & RING_BUFFER_WRITABLE);
 	int node = (event->cpu == -1) ? -1 : cpu_to_node(event->cpu);
-	int ret = -ENOMEM, max_order;
+	bool use_contiguous_pages = event->pmu->capabilities & (
+		PERF_PMU_CAP_AUX_NO_SG | PERF_PMU_CAP_AUX_PREFER_LARGE);
+	/*
+	 * Initialize max_order to 0 for page allocation. This allocates single
+	 * pages to minimize memory fragmentation. This is overridden if the
+	 * PMU needs or prefers contiguous pages (use_contiguous_pages = true).
+	 */
+	int max_order = 0;
+	int ret = -ENOMEM;
 
 	if (!has_aux(event))
 		return -EOPNOTSUPP;
@@ -689,8 +697,8 @@ int rb_alloc_aux(struct perf_buffer *rb, struct perf_event *event,
 
 	if (!overwrite) {
 		/*
-		 * Watermark defaults to half the buffer, and so does the
-		 * max_order, to aid PMU drivers in double buffering.
+		 * Watermark defaults to half the buffer, to aid PMU drivers
+		 * in double buffering.
 		 */
 		if (!watermark)
 			watermark = min_t(unsigned long,
@@ -698,16 +706,19 @@ int rb_alloc_aux(struct perf_buffer *rb, struct perf_event *event,
 					  (unsigned long)nr_pages << (PAGE_SHIFT - 1));
 
 		/*
-		 * Use aux_watermark as the basis for chunking to
-		 * help PMU drivers honor the watermark.
+		 * If using contiguous pages, use aux_watermark as the basis
+		 * for chunking to help PMU drivers honor the watermark.
 		 */
-		max_order = get_order(watermark);
+		if (use_contiguous_pages)
+			max_order = get_order(watermark);
 	} else {
 		/*
-		 * We need to start with the max_order that fits in nr_pages,
-		 * not the other way around, hence ilog2() and not get_order.
+		 * If using contiguous pages, we need to start with the
+		 * max_order that fits in nr_pages, not the other way around,
+		 * hence ilog2() and not get_order.
 		 */
-		max_order = ilog2(nr_pages);
+		if (use_contiguous_pages)
+			max_order = ilog2(nr_pages);
 		watermark = 0;
 	}