From: Steven Rostedt <rostedt@goodmis.org>
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.
Link: https://lore.kernel.org/linux-trace-kernel/20250424163607.GE18306@noisy.programming.kicks-ass.net/
Link: https://lore.kernel.org/all/20250624130744.602c5b5f@batman.local.home/
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
Changes since v13: https://lore.kernel.org/20250708020050.410920799@kernel.org
- Missed one location that still only checked PF_KTHREAD
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 cd0e3fc7ed05..5982d18f169b 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 b2a53cabcb17..1fa554e2666d 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7414,7 +7414,7 @@ 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;
@@ -8054,7 +8054,7 @@ 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();
--
2.47.2