Merge tag 'perf-urgent-2026-02-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull perf events fix from Ingo Molnar:
 "Fix a race in the user-callchains code"

* tag 'perf-urgent-2026-02-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf: sched: Fix perf crash with new is_user_task() helper

Author: torvalds

include/linux/sched.h

@@ -1776,6 +1776,11 @@ static __always_inline bool is_percpu_thread(void)
 		(current->nr_cpus_allowed  == 1);
 }
 
+static __always_inline bool is_user_task(struct task_struct *task)
+{
+	return task->mm && !(task->flags & (PF_KTHREAD | PF_USER_WORKER));
+}
+
 /* Per-process atomic flags. */
 #define PFA_NO_NEW_PRIVS		0	/* May not gain new privileges. */
 #define PFA_SPREAD_PAGE			1	/* Spread page cache over cpuset */

kernel/events/callchain.c

@@ -246,7 +246,7 @@ get_perf_callchain(struct pt_regs *regs, bool kernel, bool user,
 
 	if (user && !crosstask) {
 		if (!user_mode(regs)) {
-			if (current->flags & (PF_KTHREAD | PF_USER_WORKER))
+			if (!is_user_task(current))
 				goto exit_put;
 			regs = task_pt_regs(current);
 		}

kernel/events/core.c

@@ -7460,7 +7460,7 @@ static void perf_sample_regs_user(struct perf_regs *regs_user,
 	if (user_mode(regs)) {
 		regs_user->abi = perf_reg_abi(current);
 		regs_user->regs = regs;
-	} else if (!(current->flags & (PF_KTHREAD | PF_USER_WORKER))) {
+	} else if (is_user_task(current)) {
 		perf_get_regs_user(regs_user, regs);
 	} else {
 		regs_user->abi = PERF_SAMPLE_REGS_ABI_NONE;
@@ -8100,7 +8100,7 @@ static u64 perf_virt_to_phys(u64 virt)
 		 * Try IRQ-safe get_user_page_fast_only first.
 		 * If failed, leave phys_addr as 0.
 		 */
-		if (!(current->flags & (PF_KTHREAD | PF_USER_WORKER))) {
+		if (is_user_task(current)) {
 			struct page *p;
 
 			pagefault_disable();
@@ -8215,7 +8215,7 @@ perf_callchain(struct perf_event *event, struct pt_regs *regs)
 {
 	bool kernel = !event->attr.exclude_callchain_kernel;
 	bool user   = !event->attr.exclude_callchain_user &&
-		!(current->flags & (PF_KTHREAD | PF_USER_WORKER));
+		is_user_task(current);
 	/* Disallow cross-task user callchains. */
 	bool crosstask = event->ctx->task && event->ctx->task != current;
 	bool defer_user = IS_ENABLED(CONFIG_UNWIND_USER) && user &&