[PATCH v14 03/11] perf: Use current->flags & PF_KTHREAD|PF_USER_WORKER instead of current->mm == NULL

[Steven Rostedt]

From: Steven Rostedt <rost...@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.ge18...@noisy.programming.kicks-ass.net/
Link: https://lore.kernel.org/all/20250624130744.602c5...@batman.local.home/

Signed-off-by: Steven Rostedt (Google) <rost...@goodmis.org>
---
Changes since v13: https://lore.kernel.org/20250708020050.410920...@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