[PATCH] timers/itimer: Keep a nonzero value at CPU timer expiry

[PATCH] timers/itimer: Keep a nonzero value at CPU timer expiry

[Hungyu Lin]

get_cpu_itimer() returns a zero remaining time when the sampled CPU time
is exactly equal to the nonzero expiry. This makes an armed ITIMER_VIRTUAL
or ITIMER_PROF timer appear disarmed.

The cputime cleanup replaced cputime_le(), which implements <=, with <.
Restore the inclusive comparison so the equality case returns TICK_NSEC,
like the overdue case and set_process_cpu_timer().

Fixes: 648616343cdb ("[S390] cputime: add sparse checking and cleanup")
Cc: stable@vger.kernel.org
Signed-off-by: Hungyu Lin <dennylin0707@gmail.com>
---
 kernel/time/itimer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/time/itimer.c b/kernel/time/itimer.c
index 03a32dffc56c..f7de39769095 100644
--- a/kernel/time/itimer.c
+++ b/kernel/time/itimer.c
@@ -60,7 +60,7 @@ static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
 		thread_group_sample_cputime(tsk, samples);
 		t = samples[clock_id];
 
-		if (val < t)
+		if (val <= t)
 			/* about to fire */
 			val = TICK_NSEC;
 		else
-- 
2.43.0

[tip: timers/urgent] timers/itimer: Keep a nonzero value at CPU timer expiry

[tip-bot2 for Hungyu Lin]

The following commit has been merged into the timers/urgent branch of tip:

Commit-ID:     ef60f61208a30eb5b941b707debdf04517271b4f
Gitweb:        https://git.kernel.org/tip/ef60f61208a30eb5b941b707debdf04517271b4f
Author:        Hungyu Lin <dennylin0707@gmail.com>
AuthorDate:    Tue, 20 Oct 2026 22:39:57 
Committer:     Thomas Gleixner <tglx@kernel.org>
CommitterDate: Sun, 25 Oct 2026 22:43:19 +01:00

timers/itimer: Keep a nonzero value at CPU timer expiry

get_cpu_itimer() returns a zero remaining time when the sampled CPU time
is exactly equal to the nonzero expiry. This makes an armed ITIMER_VIRTUAL
or ITIMER_PROF timer appear disarmed.

The cputime cleanup replaced cputime_le(), which implements <=, with <.
Restore the inclusive comparison so the equality case returns TICK_NSEC,
like the overdue case and set_process_cpu_timer().

Fixes: 648616343cdb ("[S390] cputime: add sparse checking and cleanup")
Signed-off-by: Hungyu Lin <dennylin0707@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20261020223957.87842-1-dennylin0707@gmail.com
---
 kernel/time/itimer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/time/itimer.c b/kernel/time/itimer.c
index 03a32df..f7de397 100644
--- a/kernel/time/itimer.c
+++ b/kernel/time/itimer.c
@@ -60,7 +60,7 @@ static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
 		thread_group_sample_cputime(tsk, samples);
 		t = samples[clock_id];
 
-		if (val < t)
+		if (val <= t)
 			/* about to fire */
 			val = TICK_NSEC;
 		else