From: Steven Rostedt <rostedt@kernel.org>
To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
linux-perf-users@vger.kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Josh Poimboeuf <jpoimboe@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>,
Namhyung Kim <namhyung@kernel.org>,
Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Jens Axboe <axboe@kernel.dk>,
Masami Hiramatsu <mhiramat@kernel.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: [PATCH 3/5] perf: Use current->flags & PF_KTHREAD|PF_USER_WORKER instead of current->mm == NULL
Date: Thu, 17 Jul 2025 13:31:28 -0400 [thread overview]
Message-ID: <20250717173333.468514575@kernel.org> (raw)
In-Reply-To: 20250717173125.434618999@kernel.org
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>
---
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
next prev parent reply other threads:[~2025-07-17 17:33 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-17 17:31 [PATCH 0/5] perf: Clean ups and simplifications Steven Rostedt
2025-07-17 17:31 ` [PATCH 1/5] perf: Remove get_perf_callchain() init_nr argument Steven Rostedt
2025-07-17 17:31 ` [PATCH 2/5] perf: Have get_perf_callchain() return NULL if crosstask and user are set Steven Rostedt
2025-07-17 17:31 ` Steven Rostedt [this message]
2025-07-17 17:31 ` [PATCH 4/5] perf: Simplify get_perf_callchain() user logic Steven Rostedt
2025-07-17 17:31 ` [PATCH 5/5] perf: Skip user unwind if the task is a kernel thread Steven Rostedt
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