linux-kernel - [tip: perf/core] perf: Use current->flags & PF_KTHREAD|PF_USER

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Message-ID: <175627712063.1920.17265851610092530439.tip-bot2@tip-bot2>
Date: Wed, 27 Aug 2025 06:45:20 -0000
From: "tip-bot2 for Steven Rostedt" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: "Steven Rostedt (Google)" <rostedt@...dmis.org>,
 "Peter Zijlstra (Intel)" <peterz@...radead.org>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: perf/core] perf: Use current->flags & PF_KTHREAD|PF_USER_WORKER
 instead of current->mm == NULL

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     90942f9fac05702065ff82ed0bade0d08168d4ea
Gitweb:        https://git.kernel.org/tip/90942f9fac05702065ff82ed0bade0d08168d4ea
Author:        Steven Rostedt <rostedt@...dmis.org>
AuthorDate:    Wed, 20 Aug 2025 14:03:41 -04:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Tue, 26 Aug 2025 09:51:13 +02:00

perf: Use current->flags & PF_KTHREAD|PF_USER_WORKER instead of current->mm == NULL

To determine if a task is a kernel thread or not, it is more reliable to
use (current->flags & (PF_KTHREAD|PF_USER_WORKERi)) than to rely on
current->mm being NULL.  That is because some kernel tasks (io_uring
helpers) may have a mm field.

Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lore.kernel.org/r/20250820180428.592367294@kernel.org
---
 kernel/events/callchain.c | 6 +++---
 kernel/events/core.c      | 4 ++--
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c
index cd0e3fc..5982d18 100644
--- a/kernel/events/callchain.c
+++ b/kernel/events/callchain.c
@@ -246,10 +246,10 @@ get_perf_callchain(struct pt_regs *regs, bool kernel, bool user,
 
 	if (user && !crosstask) {
 		if (!user_mode(regs)) {
-			if  (current->mm)
-				regs = task_pt_regs(current);
-			else
+			if (current->flags & (PF_KTHREAD | PF_USER_WORKER))
 				regs = NULL;
+			else
+				regs = task_pt_regs(current);
 		}
 
 		if (regs) {
diff --git a/kernel/events/core.c b/kernel/events/core.c
index bade8e0..f880cec 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7446,7 +7446,7 @@ 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)) {
+	} else if (!(current->flags & (PF_KTHREAD | PF_USER_WORKER))) {
 		perf_get_regs_user(regs_user, regs);
 	} else {
 		regs_user->abi = PERF_SAMPLE_REGS_ABI_NONE;
@@ -8086,7 +8086,7 @@ 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->mm != NULL) {
+		if (!(current->flags & (PF_KTHREAD | PF_USER_WORKER))) {
 			struct page *p;
 
 			pagefault_disable();