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

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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
This commit is contained in:
Steven Rostedt
2025-08-20 14:03:41 -04:00
committed by Peter Zijlstra
parent 153f9e74de
commit 90942f9fac
2 changed files with 5 additions and 5 deletions
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6
kernel/events/callchain.c
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@@ -246,10 +246,10 @@ get_perf_callchain(struct pt_regs *regs, bool kernel, bool user,
if (user && !crosstask) { if (user && !crosstask) {
if (!user_mode(regs)) { if (!user_mode(regs)) {
if (current->mm) if (current->flags & (PF_KTHREAD | PF_USER_WORKER))
regs = task_pt_regs(current);
else
regs = NULL; regs = NULL;
else
regs = task_pt_regs(current);
} }
if (regs) { if (regs) {

4
kernel/events/core.c
View File

@@ -7446,7 +7446,7 @@ static void perf_sample_regs_user(struct perf_regs *regs_user,
if (user_mode(regs)) { if (user_mode(regs)) {
regs_user->abi = perf_reg_abi(current); regs_user->abi = perf_reg_abi(current);
regs_user->regs = regs; 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); perf_get_regs_user(regs_user, regs);
} else { } else {
regs_user->abi = PERF_SAMPLE_REGS_ABI_NONE; 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. * Try IRQ-safe get_user_page_fast_only first.
* If failed, leave phys_addr as 0. * If failed, leave phys_addr as 0.
*/ */
if (current->mm != NULL) { if (!(current->flags & (PF_KTHREAD | PF_USER_WORKER))) {
struct page *p; struct page *p;
pagefault_disable(); pagefault_disable();