From: Steven Rostedt <rostedt@goodmis.org>
Date: Wed, 20 Aug 2025 18:03:41 +0000 (-0400)
Subject: perf: Use current->flags & PF_KTHREAD|PF_USER_WORKER instead of current->mm == NULL
X-Git-Tag: v6.17.7~23
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5050083e1a2f3e5e29cee0205c40e5864b52601d;p=thirdparty%2Fkernel%2Fstable.git

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

[ Upstream commit 90942f9fac05702065ff82ed0bade0d08168d4ea ]

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@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250820180428.592367294@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c
index 6c83ad674d010..decff7266cfbd 100644
--- a/kernel/events/callchain.c
+++ b/kernel/events/callchain.c
@@ -242,10 +242,10 @@ get_perf_callchain(struct pt_regs *regs, u32 init_nr, bool kernel, bool user,
 
 	if (user) {
 		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 6e9427c4aaff7..a3dc79ec6f879 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7440,7 +7440,7 @@ 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;
@@ -8080,7 +8080,7 @@ 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();