Commit c00a8791 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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
parents e53ada65 76ed2760

include/linux/sched.h

+5 −0
Original line number Diff line number Diff line
@@ -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

+1 −1
Original line number Diff line number Diff line
@@ -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

+3 −3
Original line number Diff line number Diff line
@@ -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 &&