* [PATCH 16/23] genirq/cpuhotplug: Use RCU to protect access of HK_TYPE_MANAGED_IRQ cpumask
From: Waiman Long @ 2026-04-21 3:03 UTC (permalink / raw)
To: Tejun Heo, Johannes Weiner, Michal Koutný, Jonathan Corbet,
Shuah Khan, Catalin Marinas, Will Deacon, K. Y. Srinivasan,
Haiyang Zhang, Wei Liu, Dexuan Cui, Long Li, Guenter Roeck,
Frederic Weisbecker, Paul E. McKenney, Neeraj Upadhyay,
Joel Fernandes, Josh Triplett, Boqun Feng, Uladzislau Rezki,
Steven Rostedt, Mathieu Desnoyers, Lai Jiangshan, Zqiang,
Anna-Maria Behnsen, Ingo Molnar, Thomas Gleixner, Chen Ridong,
Peter Zijlstra, Juri Lelli, Vincent Guittot, Dietmar Eggemann,
Ben Segall, Mel Gorman, Valentin Schneider, K Prateek Nayak,
David S. Miller, Eric Dumazet, Jakub Kicinski, Paolo Abeni,
Simon Horman
Cc: cgroups, linux-doc, linux-kernel, linux-arm-kernel, linux-hyperv,
linux-hwmon, rcu, netdev, linux-kselftest, Costa Shulyupin,
Qiliang Yuan, Waiman Long
In-Reply-To: <20260421030351.281436-1-longman@redhat.com>
As HK_TYPE_MANAGED_IRQ cpumask is going to be changeable at run time,
use RCU to protect access to the cpumask.
To enable the new HK_TYPE_MANAGED_IRQ cpumask to take effect, the
following steps can be done.
1) Update the HK_TYPE_MANAGED_IRQ cpumask to take out the newly isolated
CPUs and add back the de-isolated CPUs.
2) Tear down the affected CPUs to cause irq_migrate_all_off_this_cpu()
to be called on the affected CPUs to migrate the irqs to other
HK_TYPE_MANAGED_IRQ housekeeping CPUs.
3) Bring up the previously offline CPUs to invoke
irq_affinity_online_cpu() to allow the newly de-isolated CPUs to
be used for managed irqs.
Signed-off-by: Waiman Long <longman@redhat.com>
---
kernel/irq/cpuhotplug.c | 1 +
kernel/irq/manage.c | 1 +
2 files changed, 2 insertions(+)
diff --git a/kernel/irq/cpuhotplug.c b/kernel/irq/cpuhotplug.c
index cd5689e383b0..86437c78f1f2 100644
--- a/kernel/irq/cpuhotplug.c
+++ b/kernel/irq/cpuhotplug.c
@@ -196,6 +196,7 @@ static bool hk_should_isolate(struct irq_data *data, unsigned int cpu)
if (!housekeeping_enabled(HK_TYPE_MANAGED_IRQ))
return false;
+ guard(rcu)();
hk_mask = housekeeping_cpumask(HK_TYPE_MANAGED_IRQ);
if (cpumask_subset(irq_data_get_effective_affinity_mask(data), hk_mask))
return false;
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 2e8072437826..8270c4de260b 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -263,6 +263,7 @@ int irq_do_set_affinity(struct irq_data *data, const struct cpumask *mask, bool
housekeeping_enabled(HK_TYPE_MANAGED_IRQ)) {
const struct cpumask *hk_mask;
+ guard(rcu)();
hk_mask = housekeeping_cpumask(HK_TYPE_MANAGED_IRQ);
cpumask_and(tmp_mask, mask, hk_mask);
--
2.53.0
^ permalink raw reply related
* [PATCH 17/23] sched/isolation: Extend housekeeping_dereference_check() to cover changes in nohz_full or manged_irqs cpumasks
From: Waiman Long @ 2026-04-21 3:03 UTC (permalink / raw)
To: Tejun Heo, Johannes Weiner, Michal Koutný, Jonathan Corbet,
Shuah Khan, Catalin Marinas, Will Deacon, K. Y. Srinivasan,
Haiyang Zhang, Wei Liu, Dexuan Cui, Long Li, Guenter Roeck,
Frederic Weisbecker, Paul E. McKenney, Neeraj Upadhyay,
Joel Fernandes, Josh Triplett, Boqun Feng, Uladzislau Rezki,
Steven Rostedt, Mathieu Desnoyers, Lai Jiangshan, Zqiang,
Anna-Maria Behnsen, Ingo Molnar, Thomas Gleixner, Chen Ridong,
Peter Zijlstra, Juri Lelli, Vincent Guittot, Dietmar Eggemann,
Ben Segall, Mel Gorman, Valentin Schneider, K Prateek Nayak,
David S. Miller, Eric Dumazet, Jakub Kicinski, Paolo Abeni,
Simon Horman
Cc: cgroups, linux-doc, linux-kernel, linux-arm-kernel, linux-hyperv,
linux-hwmon, rcu, netdev, linux-kselftest, Costa Shulyupin,
Qiliang Yuan, Waiman Long
In-Reply-To: <20260421030351.281436-1-longman@redhat.com>
As we are going to make HK_TYPE_KERNEL_NOISE and
HK_TYPE_MANAGED_IRQ housekeeping cpumasks run time changeable, extend
housekeeping_dereference_check() to cover changes to those cpumasks
as well.
Signed-off-by: Waiman Long <longman@redhat.com>
---
kernel/sched/isolation.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index 1f3f1c83dd12..1647e7b08bac 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -38,7 +38,8 @@ EXPORT_SYMBOL_GPL(housekeeping_enabled);
static bool housekeeping_dereference_check(enum hk_type type)
{
- if (IS_ENABLED(CONFIG_LOCKDEP) && type == HK_TYPE_DOMAIN) {
+ if (IS_ENABLED(CONFIG_LOCKDEP) &&
+ (BIT(type) & (HK_FLAG_DOMAIN | HK_FLAG_KERNEL_NOISE | HK_FLAG_MANAGED_IRQ))) {
/* Cpuset isn't even writable yet? */
if (system_state <= SYSTEM_SCHEDULING)
return true;
--
2.53.0
^ permalink raw reply related
* [PATCH 18/23] cpu/hotplug: Add a new cpuhp_offline_cb() API
From: Waiman Long @ 2026-04-21 3:03 UTC (permalink / raw)
To: Tejun Heo, Johannes Weiner, Michal Koutný, Jonathan Corbet,
Shuah Khan, Catalin Marinas, Will Deacon, K. Y. Srinivasan,
Haiyang Zhang, Wei Liu, Dexuan Cui, Long Li, Guenter Roeck,
Frederic Weisbecker, Paul E. McKenney, Neeraj Upadhyay,
Joel Fernandes, Josh Triplett, Boqun Feng, Uladzislau Rezki,
Steven Rostedt, Mathieu Desnoyers, Lai Jiangshan, Zqiang,
Anna-Maria Behnsen, Ingo Molnar, Thomas Gleixner, Chen Ridong,
Peter Zijlstra, Juri Lelli, Vincent Guittot, Dietmar Eggemann,
Ben Segall, Mel Gorman, Valentin Schneider, K Prateek Nayak,
David S. Miller, Eric Dumazet, Jakub Kicinski, Paolo Abeni,
Simon Horman
Cc: cgroups, linux-doc, linux-kernel, linux-arm-kernel, linux-hyperv,
linux-hwmon, rcu, netdev, linux-kselftest, Costa Shulyupin,
Qiliang Yuan, Waiman Long
In-Reply-To: <20260421030351.281436-1-longman@redhat.com>
Add a new cpuhp_offline_cb() API that allows us to offline a set of
CPUs one-by-one, run the given callback function and then bring those
CPUs back online again while inhibiting any concurrent CPU hotplug
operations from happening.
This new API can be used to enable runtime adjustment of nohz_full and
isolcpus boot command line options. A new cpuhp_offline_cb_mode flag
is also added to signal that the system is in this offline callback
transient state so that some hotplug operations can be optimized out
if we choose to.
Signed-off-by: Waiman Long <longman@redhat.com>
---
include/linux/cpuhplock.h | 9 +++++
kernel/cpu.c | 70 +++++++++++++++++++++++++++++++++++++++
2 files changed, 79 insertions(+)
diff --git a/include/linux/cpuhplock.h b/include/linux/cpuhplock.h
index 286b3ab92e15..37637baa32eb 100644
--- a/include/linux/cpuhplock.h
+++ b/include/linux/cpuhplock.h
@@ -9,7 +9,9 @@
#include <linux/cleanup.h>
#include <linux/errno.h>
+#include <linux/cpumask_types.h>
+typedef int (*cpuhp_cb_t)(void *arg);
struct device;
extern int lockdep_is_cpus_held(void);
@@ -29,6 +31,8 @@ void clear_tasks_mm_cpumask(int cpu);
int remove_cpu(unsigned int cpu);
int cpu_device_down(struct device *dev);
void smp_shutdown_nonboot_cpus(unsigned int primary_cpu);
+int cpuhp_offline_cb(struct cpumask *mask, cpuhp_cb_t func, void *arg);
+extern bool cpuhp_offline_cb_mode;
#else /* CONFIG_HOTPLUG_CPU */
@@ -43,6 +47,11 @@ static inline void cpu_hotplug_disable(void) { }
static inline void cpu_hotplug_enable(void) { }
static inline int remove_cpu(unsigned int cpu) { return -EPERM; }
static inline void smp_shutdown_nonboot_cpus(unsigned int primary_cpu) { }
+static inline int cpuhp_offline_cb(struct cpumask *mask, cpuhp_cb_t func, void *arg)
+{
+ return -EPERM;
+}
+#define cpuhp_offline_cb_mode false
#endif /* !CONFIG_HOTPLUG_CPU */
DEFINE_LOCK_GUARD_0(cpus_read_lock, cpus_read_lock(), cpus_read_unlock())
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 0d02b5d7a7ba..9b32f742cd1d 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1520,6 +1520,76 @@ int remove_cpu(unsigned int cpu)
}
EXPORT_SYMBOL_GPL(remove_cpu);
+bool cpuhp_offline_cb_mode;
+
+/**
+ * cpuhp_offline_cb - offline CPUs, invoke callback function & online CPUs afterward
+ * @mask: A mask of CPUs to be taken offline and then online
+ * @func: A callback function to be invoked while the given CPUs are offline
+ * @arg: Argument to be passed back to the callback function
+ *
+ * Return: 0 if successful, an error code otherwise
+ */
+int cpuhp_offline_cb(struct cpumask *mask, cpuhp_cb_t func, void *arg)
+{
+ int off_cpu, on_cpu, ret, ret2 = 0;
+
+ if (WARN_ON_ONCE(cpumask_empty(mask) ||
+ !cpumask_subset(mask, cpu_online_mask)))
+ return -EINVAL;
+
+ pr_debug("%s: begin (CPU list = %*pbl)\n", __func__, cpumask_pr_args(mask));
+ lock_device_hotplug();
+ cpuhp_offline_cb_mode = true;
+ /*
+ * If all offline operations succeed, off_cpu should become nr_cpu_ids.
+ */
+ for_each_cpu(off_cpu, mask) {
+ ret = device_offline(get_cpu_device(off_cpu));
+ if (unlikely(ret))
+ break;
+ }
+ if (!ret)
+ ret = func(arg);
+
+ /* Bring previously offline CPUs back online */
+ for_each_cpu(on_cpu, mask) {
+ int retries = 0;
+
+ if (on_cpu == off_cpu)
+ break;
+
+retry:
+ ret2 = device_online(get_cpu_device(on_cpu));
+
+ /*
+ * With the unlikely event that CPU hotplug is disabled while
+ * this operation is in progress, we will need to wait a bit
+ * for hotplug to hopefully be re-enabled again. If not, print
+ * a warning and return the error.
+ *
+ * cpu_hotplug_disabled is supposed to be accessed while
+ * holding the cpu_add_remove_lock mutex. So we need to
+ * use the data_race() macro to access it here.
+ */
+ while ((ret2 == -EBUSY) && data_race(cpu_hotplug_disabled) &&
+ (++retries <= 5)) {
+ msleep(20);
+ if (!data_race(cpu_hotplug_disabled))
+ goto retry;
+ }
+ if (ret2) {
+ pr_warn("%s: Failed to bring CPU %d back online!\n",
+ __func__, on_cpu);
+ break;
+ }
+ }
+ cpuhp_offline_cb_mode = false;
+ unlock_device_hotplug();
+ pr_debug("%s: end\n", __func__);
+ return ret ? ret : ret2;
+}
+
void smp_shutdown_nonboot_cpus(unsigned int primary_cpu)
{
unsigned int cpu;
--
2.53.0
^ permalink raw reply related
* [PATCH 19/23] cgroup/cpuset: Improve check for calling housekeeping_update()
From: Waiman Long @ 2026-04-21 3:03 UTC (permalink / raw)
To: Tejun Heo, Johannes Weiner, Michal Koutný, Jonathan Corbet,
Shuah Khan, Catalin Marinas, Will Deacon, K. Y. Srinivasan,
Haiyang Zhang, Wei Liu, Dexuan Cui, Long Li, Guenter Roeck,
Frederic Weisbecker, Paul E. McKenney, Neeraj Upadhyay,
Joel Fernandes, Josh Triplett, Boqun Feng, Uladzislau Rezki,
Steven Rostedt, Mathieu Desnoyers, Lai Jiangshan, Zqiang,
Anna-Maria Behnsen, Ingo Molnar, Thomas Gleixner, Chen Ridong,
Peter Zijlstra, Juri Lelli, Vincent Guittot, Dietmar Eggemann,
Ben Segall, Mel Gorman, Valentin Schneider, K Prateek Nayak,
David S. Miller, Eric Dumazet, Jakub Kicinski, Paolo Abeni,
Simon Horman
Cc: cgroups, linux-doc, linux-kernel, linux-arm-kernel, linux-hyperv,
linux-hwmon, rcu, netdev, linux-kselftest, Costa Shulyupin,
Qiliang Yuan, Waiman Long
In-Reply-To: <20260421030351.281436-1-longman@redhat.com>
By making sure that isolated_hk_cpus matches isolated_cpus at boot time,
we can more accurately determine if calling housekeeping_update()
is needed by comparing if the two cpumasks are equal. The
update_housekeeping flag still have a use in cpuset_handle_hotplug()
to determine if a work function should be queued to invoke
cpuset_update_sd_hk_unlock() as it is not supposed to look at
isolated_hk_cpus without holding cpuset_top_mutex.
Signed-off-by: Waiman Long <longman@redhat.com>
---
kernel/cgroup/cpuset.c | 36 ++++++++++++++++++++----------------
1 file changed, 20 insertions(+), 16 deletions(-)
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index a4eccb0ec0d1..1b0c50b46a49 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -1339,26 +1339,29 @@ static void cpuset_update_sd_hk_unlock(void)
__releases(&cpuset_mutex)
__releases(&cpuset_top_mutex)
{
+ update_housekeeping = false;
+
/* force_sd_rebuild will be cleared in rebuild_sched_domains_locked() */
if (force_sd_rebuild)
rebuild_sched_domains_locked();
- if (update_housekeeping) {
- update_housekeeping = false;
- cpumask_copy(isolated_hk_cpus, isolated_cpus);
-
- /*
- * housekeeping_update() is now called without holding
- * cpus_read_lock and cpuset_mutex. Only cpuset_top_mutex
- * is still being held for mutual exclusion.
- */
- mutex_unlock(&cpuset_mutex);
- cpus_read_unlock();
- WARN_ON_ONCE(housekeeping_update(isolated_hk_cpus, BIT(HK_TYPE_DOMAIN)));
- mutex_unlock(&cpuset_top_mutex);
- } else {
+ if (cpumask_equal(isolated_hk_cpus, isolated_cpus)) {
+ /* No housekeeping cpumask update needed */
cpuset_full_unlock();
+ return;
}
+
+ cpumask_copy(isolated_hk_cpus, isolated_cpus);
+
+ /*
+ * housekeeping_update() is now called without holding
+ * cpus_read_lock and cpuset_mutex. Only cpuset_top_mutex
+ * is still being held for mutual exclusion.
+ */
+ mutex_unlock(&cpuset_mutex);
+ cpus_read_unlock();
+ WARN_ON_ONCE(housekeeping_update(isolated_hk_cpus, BIT(HK_TYPE_DOMAIN)));
+ mutex_unlock(&cpuset_top_mutex);
}
/*
@@ -3692,10 +3695,11 @@ int __init cpuset_init(void)
BUG_ON(!alloc_cpumask_var(&cpus_attach, GFP_KERNEL));
- if (housekeeping_enabled(HK_TYPE_DOMAIN_BOOT))
+ if (housekeeping_enabled(HK_TYPE_DOMAIN_BOOT)) {
cpumask_andnot(isolated_cpus, cpu_possible_mask,
housekeeping_cpumask(HK_TYPE_DOMAIN_BOOT));
-
+ cpumask_copy(isolated_hk_cpus, isolated_cpus);
+ }
return 0;
}
--
2.53.0
^ permalink raw reply related
* [PATCH 20/23] cgroup/cpuset: Enable runtime update of HK_TYPE_{KERNEL_NOISE,MANAGED_IRQ} cpumasks
From: Waiman Long @ 2026-04-21 3:03 UTC (permalink / raw)
To: Tejun Heo, Johannes Weiner, Michal Koutný, Jonathan Corbet,
Shuah Khan, Catalin Marinas, Will Deacon, K. Y. Srinivasan,
Haiyang Zhang, Wei Liu, Dexuan Cui, Long Li, Guenter Roeck,
Frederic Weisbecker, Paul E. McKenney, Neeraj Upadhyay,
Joel Fernandes, Josh Triplett, Boqun Feng, Uladzislau Rezki,
Steven Rostedt, Mathieu Desnoyers, Lai Jiangshan, Zqiang,
Anna-Maria Behnsen, Ingo Molnar, Thomas Gleixner, Chen Ridong,
Peter Zijlstra, Juri Lelli, Vincent Guittot, Dietmar Eggemann,
Ben Segall, Mel Gorman, Valentin Schneider, K Prateek Nayak,
David S. Miller, Eric Dumazet, Jakub Kicinski, Paolo Abeni,
Simon Horman
Cc: cgroups, linux-doc, linux-kernel, linux-arm-kernel, linux-hyperv,
linux-hwmon, rcu, netdev, linux-kselftest, Costa Shulyupin,
Qiliang Yuan, Waiman Long
In-Reply-To: <20260421030351.281436-1-longman@redhat.com>
One simple way to enable runtime update of HK_TYPE_KERNEL_NOISE
(nohz_full) and HK_TYPE_MANAGED_IRQ cpumasks is to make use of the CPU
hotplug to facilitate the transition of those CPUs that are changing
states as long as CONFIG_HOTPLUG_CPU is enabled and a nohz_full boot
parameter is provided. Otherwise, only HK_TYPE_DOMAIN cpumask will be
updated at run time.
For changes in HK_TYPE_DOMAIN cpumask, it can be done without using CPU
hotplug. For changes in HK_TYPE_MANAGED_IRQ cpumask, we have to update
the cpumask first and then tear down and bring up the newly isolated
CPUs to migrate the managed irqs in those CPUs to other housekeeping
CPUs.
For changes in HK_TYPE_KERNEL_NOISE, we have to tear down all the newly
isolated and de-isolated CPUs, change the cpumask and then bring all the
offline CPUs back online.
As it is possible that the various boot versions of the housekeeping
cpumasks are different resulting in the use of different set of isolated
cpumasks for calling housekeeping_update(), we may need to pre-allocate
these cpumasks if necessary.
Note that the use of CPU hotplug to facilitate the changing of
HK_TYPE_KERNEL_NOISE and HK_TYPE_MANAGED_IRQ housekeeping cpumasks has
the drawback that during the tear down of a CPU from CPUHP_TEARDOWN_CPU
state to CPUHP_AP_OFFLINE, the stop_machine code will be invoked to stop
all the other CPUs including all the pre-existing isolated CPUs. That
will cause latency spikes on those isolated CPUs. That latency spike
should only happen when the cpuset isolated partition setting is changed
resulting in changes in those housekeeping cpumasks.
One possible workaround that is being used right now is to pre-allocate
a set of nohz_full and managed_irq CPUs at boot time. The semi-isolated
CPUs are then used to create cpuset isolated partitions when needed
to enable full isolation. This will likely continue even if we made
the nohz_full and managed_irq CPUs runtime changeable if they can't
tolerate these latency spikes.
This is a problem we need to address in a future patch series.
Signed-off-by: Waiman Long <longman@redhat.com>
---
kernel/cgroup/cpuset.c | 199 +++++++++++++++++++++++++++++++++++++----
1 file changed, 182 insertions(+), 17 deletions(-)
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 1b0c50b46a49..a927b9cd4f71 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -152,9 +152,17 @@ static cpumask_var_t isolated_cpus; /* CSCB */
static bool update_housekeeping; /* RWCS */
/*
- * Copy of isolated_cpus to be passed to housekeeping_update()
+ * Cpumasks to be passed to housekeeping_update()
+ * isolated_hk_cpus - copy of isolated_cpus for HK_TYPE_DOMAIN
+ * isolated_nohz_cpus - for HK_TYPE_KERNEL_NOISE
+ * isolated_mirq_cpus - for HK_TYPE_MANAGED_IRQ
*/
static cpumask_var_t isolated_hk_cpus; /* T */
+static cpumask_var_t isolated_nohz_cpus; /* T */
+static cpumask_var_t isolated_mirq_cpus; /* T */
+
+static bool boot_nohz_le_domain __ro_after_init;
+static bool boot_mirq_le_domain __ro_after_init;
/*
* A flag to force sched domain rebuild at the end of an operation.
@@ -1328,29 +1336,67 @@ static bool prstate_housekeeping_conflict(int prstate, struct cpumask *new_cpus)
return false;
}
+static int cpuset_nohz_update_cbfunc(void *arg)
+{
+ struct cpumask *isol_cpus = (struct cpumask *)arg;
+
+ if (isol_cpus)
+ housekeeping_update(isol_cpus, BIT(HK_TYPE_KERNEL_NOISE));
+ return 0;
+}
+
/*
- * cpuset_update_sd_hk_unlock - Rebuild sched domains, update HK & unlock
- *
- * Update housekeeping cpumasks and rebuild sched domains if necessary and
- * then do a cpuset_full_unlock().
- * This should be called at the end of cpuset operation.
*/
-static void cpuset_update_sd_hk_unlock(void)
- __releases(&cpuset_mutex)
- __releases(&cpuset_top_mutex)
+static void cpuset_update_housekeeping_unlock(void)
{
- update_housekeeping = false;
+ bool update_nohz, update_mirq;
+ cpumask_var_t cpus;
+ int ret;
- /* force_sd_rebuild will be cleared in rebuild_sched_domains_locked() */
- if (force_sd_rebuild)
- rebuild_sched_domains_locked();
+ if (!tick_nohz_full_enabled())
+ return;
- if (cpumask_equal(isolated_hk_cpus, isolated_cpus)) {
- /* No housekeeping cpumask update needed */
+ update_nohz = boot_nohz_le_domain;
+ update_mirq = boot_mirq_le_domain;
+
+ if (WARN_ON_ONCE(!alloc_cpumask_var(&cpus, GFP_KERNEL))) {
cpuset_full_unlock();
return;
}
+ /*
+ * Update isolated_nohz_cpus/isolated_mirq_cpus if necessary
+ */
+ if (!boot_nohz_le_domain) {
+ cpumask_andnot(cpus, cpu_possible_mask,
+ housekeeping_cpumask(HK_TYPE_KERNEL_NOISE));
+ cpumask_or(cpus, cpus, isolated_cpus);
+ update_nohz = !cpumask_equal(isolated_nohz_cpus, cpus);
+ if (update_nohz)
+ cpumask_copy(isolated_nohz_cpus, cpus);
+ }
+ if (!boot_mirq_le_domain) {
+ cpumask_andnot(cpus, cpu_possible_mask,
+ housekeeping_cpumask(HK_TYPE_MANAGED_IRQ));
+ cpumask_or(cpus, cpus, isolated_cpus);
+ update_mirq = !cpumask_equal(isolated_mirq_cpus, cpus);
+ if (update_mirq)
+ cpumask_copy(isolated_mirq_cpus, cpus);
+ }
+
+ /*
+ * Compute list of CPUs to be brought offline into "cpus"
+ * isolated_hk_cpus - old cpumask
+ * isolated_cpus - new cpumask
+ *
+ * With update_nohz, we need to offline both the newly isolated
+ * and de-isolated CPUs. With only update_mirq, we only need to
+ * offline the new isolated CPUs.
+ */
+ if (update_nohz)
+ cpumask_xor(cpus, isolated_hk_cpus, isolated_cpus);
+ else if (update_mirq)
+ cpumask_andnot(cpus, isolated_cpus, isolated_hk_cpus);
cpumask_copy(isolated_hk_cpus, isolated_cpus);
/*
@@ -1360,10 +1406,103 @@ static void cpuset_update_sd_hk_unlock(void)
*/
mutex_unlock(&cpuset_mutex);
cpus_read_unlock();
- WARN_ON_ONCE(housekeeping_update(isolated_hk_cpus, BIT(HK_TYPE_DOMAIN)));
+
+ if (!update_mirq) {
+ ret = housekeeping_update(isolated_hk_cpus, BIT(HK_TYPE_DOMAIN));
+ } else if (boot_mirq_le_domain) {
+ ret = housekeeping_update(isolated_hk_cpus,
+ BIT(HK_TYPE_DOMAIN)|BIT(HK_TYPE_MANAGED_IRQ));
+ } else {
+ ret = housekeeping_update(isolated_hk_cpus, BIT(HK_TYPE_DOMAIN));
+ if (!ret)
+ ret = housekeeping_update(isolated_mirq_cpus,
+ BIT(HK_TYPE_MANAGED_IRQ));
+ }
+
+ if (WARN_ON_ONCE(ret))
+ goto out_free;
+
+ /*
+ * Calling cpuhp_offline_cb() is only needed if either
+ * HK_TYPE_KERNEL_NOISE and/or HK_TYPE_MANAGED_IRQ cpumasks
+ * needed to be updated.
+ *
+ * TODO: When tearing down a CPU from CPUHP_TEARDOWN_CPU state
+ * downward to CPUHP_AP_OFFLINE, the stop_machine code will be
+ * invoked to stop all the other CPUs in the system. This will
+ * cause latency spikes on existing isolated CPUs. We will need
+ * some new mechanism to enable us to not stop the existing
+ * isolated CPUs whenever possible. A possible workaround is
+ * to pre-allocate a set of nohz_full and manged_irq CPUs at
+ * boot time and use them to create isolated cpuset partitions
+ * so that CPU hotplug won't need to be used.
+ */
+ if (update_mirq || update_nohz) {
+ struct cpumask *nohz_cpus;
+
+ /*
+ * Calling housekeeping_update() is only needed if
+ * update_nohz is set.
+ */
+ nohz_cpus = !update_nohz ? NULL : boot_nohz_le_domain
+ ? isolated_hk_cpus
+ : isolated_nohz_cpus;
+ /*
+ * Mask out offline CPUs in cpus
+ * If there is no online CPUs, we can call
+ * housekeeping_update() directly if needed.
+ */
+ cpumask_and(cpus, cpus, cpu_online_mask);
+ if (!cpumask_empty(cpus))
+ ret = cpuhp_offline_cb(cpus, cpuset_nohz_update_cbfunc,
+ nohz_cpus);
+ else if (nohz_cpus)
+ ret = housekeeping_update(nohz_cpus, BIT(HK_TYPE_KERNEL_NOISE));
+ }
+ WARN_ON_ONCE(ret);
+out_free:
+ free_cpumask_var(cpus);
mutex_unlock(&cpuset_top_mutex);
}
+/*
+ * cpuset_update_sd_hk_unlock - Rebuild sched domains, update HK & unlock
+ *
+ * Update housekeeping cpumasks and rebuild sched domains if necessary and
+ * then do a cpuset_full_unlock().
+ * This should be called at the end of cpuset operation.
+ */
+static void cpuset_update_sd_hk_unlock(void)
+ __releases(&cpuset_mutex)
+ __releases(&cpuset_top_mutex)
+{
+ /* force_sd_rebuild will be cleared in rebuild_sched_domains_locked() */
+ if (force_sd_rebuild)
+ rebuild_sched_domains_locked();
+
+ update_housekeeping = false;
+
+ if (cpumask_equal(isolated_cpus, isolated_hk_cpus)) {
+ cpuset_full_unlock();
+ return;
+ }
+
+ if (!tick_nohz_full_enabled()) {
+ /*
+ * housekeeping_update() is now called without holding
+ * cpus_read_lock and cpuset_mutex. Only cpuset_top_mutex
+ * is still being held for mutual exclusion.
+ */
+ mutex_unlock(&cpuset_mutex);
+ cpus_read_unlock();
+ WARN_ON_ONCE(housekeeping_update(isolated_hk_cpus,
+ BIT(HK_TYPE_DOMAIN)));
+ mutex_unlock(&cpuset_top_mutex);
+ } else {
+ cpuset_update_housekeeping_unlock();
+ }
+}
+
/*
* Work function to invoke cpuset_update_sd_hk_unlock()
*/
@@ -3700,6 +3839,29 @@ int __init cpuset_init(void)
housekeeping_cpumask(HK_TYPE_DOMAIN_BOOT));
cpumask_copy(isolated_hk_cpus, isolated_cpus);
}
+
+ /*
+ * If nohz_full and/or managed_irq cpu list, if present, is a subset
+ * of the domain cpu list, i.e. HK_TYPE_DOMAIN_BOOT cpumask is a subset
+ * of HK_TYPE_KERNEL_NOISE_BOOT/HK_TYPE_MANAGED_IRQ_BOOT cpumask, the
+ * corresponding non-boot housekeeping cpumasks will follow changes
+ * in the HK_TYPE_DOMAIN cpumask. So we don't need to use separate
+ * cpumasks to isolate them.
+ */
+ boot_nohz_le_domain = cpumask_subset(housekeeping_cpumask(HK_TYPE_DOMAIN_BOOT),
+ housekeeping_cpumask(HK_TYPE_KERNEL_NOISE_BOOT));
+ boot_mirq_le_domain = cpumask_subset(housekeeping_cpumask(HK_TYPE_DOMAIN_BOOT),
+ housekeeping_cpumask(HK_TYPE_MANAGED_IRQ_BOOT));
+ if (!boot_nohz_le_domain) {
+ BUG_ON(!alloc_cpumask_var(&isolated_nohz_cpus, GFP_KERNEL));
+ cpumask_andnot(isolated_nohz_cpus, cpu_possible_mask,
+ housekeeping_cpumask(HK_TYPE_KERNEL_NOISE));
+ }
+ if (!boot_mirq_le_domain) {
+ BUG_ON(!alloc_cpumask_var(&isolated_mirq_cpus, GFP_KERNEL));
+ cpumask_andnot(isolated_mirq_cpus, cpu_possible_mask,
+ housekeeping_cpumask(HK_TYPE_MANAGED_IRQ));
+ }
return 0;
}
@@ -3954,7 +4116,10 @@ static void cpuset_handle_hotplug(void)
*/
if (force_sd_rebuild)
rebuild_sched_domains_cpuslocked();
- if (update_housekeeping)
+ /*
+ * Don't need to update housekeeping cpumasks in cpuhp_offline_cb mode.
+ */
+ if (update_housekeeping && !cpuhp_offline_cb_mode)
queue_work(system_dfl_wq, &hk_sd_work);
free_tmpmasks(ptmp);
--
2.53.0
^ permalink raw reply related
* [PATCH 21/23] cgroup/cpuset: Limit the side effect of using CPU hotplug on isolated partition
From: Waiman Long @ 2026-04-21 3:03 UTC (permalink / raw)
To: Tejun Heo, Johannes Weiner, Michal Koutný, Jonathan Corbet,
Shuah Khan, Catalin Marinas, Will Deacon, K. Y. Srinivasan,
Haiyang Zhang, Wei Liu, Dexuan Cui, Long Li, Guenter Roeck,
Frederic Weisbecker, Paul E. McKenney, Neeraj Upadhyay,
Joel Fernandes, Josh Triplett, Boqun Feng, Uladzislau Rezki,
Steven Rostedt, Mathieu Desnoyers, Lai Jiangshan, Zqiang,
Anna-Maria Behnsen, Ingo Molnar, Thomas Gleixner, Chen Ridong,
Peter Zijlstra, Juri Lelli, Vincent Guittot, Dietmar Eggemann,
Ben Segall, Mel Gorman, Valentin Schneider, K Prateek Nayak,
David S. Miller, Eric Dumazet, Jakub Kicinski, Paolo Abeni,
Simon Horman
Cc: cgroups, linux-doc, linux-kernel, linux-arm-kernel, linux-hyperv,
linux-hwmon, rcu, netdev, linux-kselftest, Costa Shulyupin,
Qiliang Yuan, Waiman Long
In-Reply-To: <20260421030351.281436-1-longman@redhat.com>
CPU hotplug is used to facilitate the modification of the
HK_TYPE_KERNEL_NOISE and HK_TYPE_MANAGED_IRQ cpumasks. However, tearing
down and bringing up CPUs can impact the cpuset partition states
as well. For instance, tearing down the last CPU of a partition can
invalidate the partition with active tasks which will not happen if
CPU hotplug isn't used.
A workaround of this issue is disable the invalidation by pretending that
the partition has no task, and making the tasks within the partition
to the effective CPUs of its parent for a short while during the short
transition process where the CPUs will be teared down and the brought
up again.
Signed-off-by: Waiman Long <longman@redhat.com>
---
kernel/cgroup/cpuset.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index a927b9cd4f71..5f6b4e67748f 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -434,6 +434,13 @@ static inline bool partition_is_populated(struct cpuset *cs,
struct cpuset *cp;
struct cgroup_subsys_state *pos_css;
+ /*
+ * Hack: In cpuhp_offline_cb_mode, pretend all partitions are empty
+ * to prevent unnecessary partition invalidation.
+ */
+ if (cpuhp_offline_cb_mode)
+ return false;
+
/*
* We cannot call cs_is_populated(cs) directly, as
* nr_populated_domain_children may include populated
@@ -3881,6 +3888,17 @@ hotplug_update_tasks(struct cpuset *cs,
cs->effective_mems = *new_mems;
spin_unlock_irq(&callback_lock);
+ /*
+ * When cpuhp_offline_cb_mode is active, valid isolated partition
+ * with tasks may have no online CPUs available for a short while.
+ * In that case, we fall back to parent's effective CPUs temporarily
+ * which will be reset back to their rightful value once the affected
+ * CPUs are online again.
+ */
+ if (cpuhp_offline_cb_mode && cpumask_empty(new_cpus) &&
+ (cs->partition_root_state == PRS_ISOLATED))
+ cpumask_copy(new_cpus, parent_cs(cs)->effective_cpus);
+
if (cpus_updated)
cpuset_update_tasks_cpumask(cs, new_cpus);
if (mems_updated)
--
2.53.0
^ permalink raw reply related
* [PATCH 22/23] cgroup/cpuset: Prevent offline_disabled CPUs from being used in isolated partition
From: Waiman Long @ 2026-04-21 3:03 UTC (permalink / raw)
To: Tejun Heo, Johannes Weiner, Michal Koutný, Jonathan Corbet,
Shuah Khan, Catalin Marinas, Will Deacon, K. Y. Srinivasan,
Haiyang Zhang, Wei Liu, Dexuan Cui, Long Li, Guenter Roeck,
Frederic Weisbecker, Paul E. McKenney, Neeraj Upadhyay,
Joel Fernandes, Josh Triplett, Boqun Feng, Uladzislau Rezki,
Steven Rostedt, Mathieu Desnoyers, Lai Jiangshan, Zqiang,
Anna-Maria Behnsen, Ingo Molnar, Thomas Gleixner, Chen Ridong,
Peter Zijlstra, Juri Lelli, Vincent Guittot, Dietmar Eggemann,
Ben Segall, Mel Gorman, Valentin Schneider, K Prateek Nayak,
David S. Miller, Eric Dumazet, Jakub Kicinski, Paolo Abeni,
Simon Horman
Cc: cgroups, linux-doc, linux-kernel, linux-arm-kernel, linux-hyperv,
linux-hwmon, rcu, netdev, linux-kselftest, Costa Shulyupin,
Qiliang Yuan, Waiman Long
In-Reply-To: <20260421030351.281436-1-longman@redhat.com>
If tick_nohz_full_enabled() is true, we are going to use CPU
hotplug to enable runtime changes to the HK_TYPE_KERNEL_NOISE and
HK_TYPE_MANAGED_IRQ cpumasks. However, for some architectures, one
or maybe more CPUs will have the offline_disabled flag set in their
cpu devices. For instance, x64-64 will set this flag for its boot CPU
(typically CPU 0) to disable it from going offline. Those CPUs can't
be used in cpuset isolated partition, or we are going to have problem
in the CPU offline process.
Find out the set of CPUs with offline_disabled set in a
new cpuset_init_late() helper, set the corresponding bits in
offline_disabled_cpus cpumask and check it when isolated partitions are
being created or modified to ensure that we will not use any of those
offline disabled CPUs in an isolated partition.
An error message mentioning those offline disabled CPUs will be
constructed in cpuset_init_late() and shown in "cpuset.cpus.partition"
when isolated creation or modification fails.
Signed-off-by: Waiman Long <longman@redhat.com>
---
kernel/cgroup/cpuset-internal.h | 1 +
kernel/cgroup/cpuset.c | 89 ++++++++++++++++++++++++++++++++-
2 files changed, 88 insertions(+), 2 deletions(-)
diff --git a/kernel/cgroup/cpuset-internal.h b/kernel/cgroup/cpuset-internal.h
index fd7d19842ded..87b7411540ff 100644
--- a/kernel/cgroup/cpuset-internal.h
+++ b/kernel/cgroup/cpuset-internal.h
@@ -35,6 +35,7 @@ enum prs_errcode {
PERR_HKEEPING,
PERR_ACCESS,
PERR_REMOTE,
+ PERR_OL_DISABLED,
};
/* bits in struct cpuset flags field */
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 5f6b4e67748f..f3af8ef6c64e 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -20,6 +20,8 @@
*/
#include "cpuset-internal.h"
+#include <linux/cpu.h>
+#include <linux/device.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
@@ -48,7 +50,7 @@ DEFINE_STATIC_KEY_FALSE(cpusets_enabled_key);
*/
DEFINE_STATIC_KEY_FALSE(cpusets_insane_config_key);
-static const char * const perr_strings[] = {
+static const char *perr_strings[] __ro_after_init = {
[PERR_INVCPUS] = "Invalid cpu list in cpuset.cpus.exclusive",
[PERR_INVPARENT] = "Parent is an invalid partition root",
[PERR_NOTPART] = "Parent is not a partition root",
@@ -59,6 +61,7 @@ static const char * const perr_strings[] = {
[PERR_HKEEPING] = "partition config conflicts with housekeeping setup",
[PERR_ACCESS] = "Enable partition not permitted",
[PERR_REMOTE] = "Have remote partition underneath",
+ [PERR_OL_DISABLED] = "", /* To be set up later */
};
/*
@@ -164,6 +167,12 @@ static cpumask_var_t isolated_mirq_cpus; /* T */
static bool boot_nohz_le_domain __ro_after_init;
static bool boot_mirq_le_domain __ro_after_init;
+/*
+ * Cpumask of CPUs with offline_disabled set
+ * The cpumask is effectively __ro_after_init.
+ */
+static cpumask_var_t offline_disabled_cpus;
+
/*
* A flag to force sched domain rebuild at the end of an operation.
* It can be set in
@@ -1649,6 +1658,8 @@ static int remote_partition_enable(struct cpuset *cs, int new_prs,
* The effective_xcpus mask can contain offline CPUs, but there must
* be at least one or more online CPUs present before it can be enabled.
*
+ * An isolated partition cannot contain CPUs with offline disabled.
+ *
* Note that creating a remote partition with any local partition root
* above it or remote partition root underneath it is not allowed.
*/
@@ -1661,6 +1672,9 @@ static int remote_partition_enable(struct cpuset *cs, int new_prs,
!isolated_cpus_can_update(tmp->new_cpus, NULL)) ||
prstate_housekeeping_conflict(new_prs, tmp->new_cpus))
return PERR_HKEEPING;
+ if (tick_nohz_full_enabled() && (new_prs == PRS_ISOLATED) &&
+ cpumask_intersects(tmp->new_cpus, offline_disabled_cpus))
+ return PERR_OL_DISABLED;
spin_lock_irq(&callback_lock);
partition_xcpus_add(new_prs, NULL, tmp->new_cpus);
@@ -1746,6 +1760,16 @@ static void remote_cpus_update(struct cpuset *cs, struct cpumask *xcpus,
goto invalidate;
}
+ /*
+ * Isolated partition cannot contains CPUs with offline_disabled
+ * bit set.
+ */
+ if (tick_nohz_full_enabled() && (prs == PRS_ISOLATED) &&
+ cpumask_intersects(excpus, offline_disabled_cpus)) {
+ cs->prs_err = PERR_OL_DISABLED;
+ goto invalidate;
+ }
+
adding = cpumask_andnot(tmp->addmask, excpus, cs->effective_xcpus);
deleting = cpumask_andnot(tmp->delmask, cs->effective_xcpus, excpus);
@@ -1913,6 +1937,11 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd,
if (tasks_nocpu_error(parent, cs, xcpus))
return PERR_NOCPUS;
+ if (tick_nohz_full_enabled() &&
+ (new_prs == PRS_ISOLATED) &&
+ cpumask_intersects(xcpus, offline_disabled_cpus))
+ return PERR_OL_DISABLED;
+
/*
* This function will only be called when all the preliminary
* checks have passed. At this point, the following condition
@@ -1979,12 +2008,21 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd,
parent->effective_xcpus);
}
+ /*
+ * Isolated partition cannot contain CPUs with offline_disabled
+ * bit set.
+ */
+ if (tick_nohz_full_enabled() &&
+ ((old_prs == PRS_ISOLATED) ||
+ (old_prs == PRS_INVALID_ISOLATED)) &&
+ cpumask_intersects(newmask, offline_disabled_cpus)) {
+ part_error = PERR_OL_DISABLED;
/*
* TBD: Invalidate a currently valid child root partition may
* still break isolated_cpus_can_update() rule if parent is an
* isolated partition.
*/
- if (is_partition_valid(cs) && (old_prs != parent_prs)) {
+ } else if (is_partition_valid(cs) && (old_prs != parent_prs)) {
if ((parent_prs == PRS_ROOT) &&
/* Adding to parent means removing isolated CPUs */
!isolated_cpus_can_update(tmp->delmask, tmp->addmask))
@@ -1995,6 +2033,19 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd,
part_error = PERR_HKEEPING;
}
+ if (part_error) {
+ deleting = false;
+ /*
+ * For a previously valid partition, we need to move
+ * the exclusive CPUs back to its parent.
+ */
+ if (is_partition_valid(cs) &&
+ !cpumask_empty(cs->effective_xcpus)) {
+ cpumask_copy(tmp->addmask, cs->effective_xcpus);
+ adding = true;
+ }
+ }
+
/*
* The new CPUs to be removed from parent's effective CPUs
* must be present.
@@ -3829,6 +3880,7 @@ int __init cpuset_init(void)
BUG_ON(!zalloc_cpumask_var(&subpartitions_cpus, GFP_KERNEL));
BUG_ON(!zalloc_cpumask_var(&isolated_cpus, GFP_KERNEL));
BUG_ON(!zalloc_cpumask_var(&isolated_hk_cpus, GFP_KERNEL));
+ BUG_ON(!zalloc_cpumask_var(&offline_disabled_cpus, GFP_KERNEL));
cpumask_setall(top_cpuset.cpus_allowed);
nodes_setall(top_cpuset.mems_allowed);
@@ -4188,6 +4240,39 @@ void __init cpuset_init_smp(void)
BUG_ON(!cpuset_migrate_mm_wq);
}
+/**
+ * cpuset_init_late - initialize the list of CPUs with offline_disabled set
+ *
+ * Description: Initialize a cpumask with CPUs that have the offline_disabled
+ * bit set. It is done in a separate initcall as cpuset_init_smp()
+ * is called before driver_init() where the CPU devices will be
+ * set up.
+ */
+static int __init cpuset_init_late(void)
+{
+ int cpu;
+
+ if (!tick_nohz_full_enabled())
+ return 0;
+ /*
+ * Iterate all the possible CPUs to see which one has offline disabled.
+ */
+ for_each_possible_cpu(cpu) {
+ if (get_cpu_device(cpu)->offline_disabled)
+ __cpumask_set_cpu(cpu, offline_disabled_cpus);
+ }
+ if (!cpumask_empty(offline_disabled_cpus)) {
+ char buf[128];
+
+ snprintf(buf, sizeof(buf),
+ "CPU %*pbl with offline disabled not allowed in isolated partition",
+ cpumask_pr_args(offline_disabled_cpus));
+ perr_strings[PERR_OL_DISABLED] = kstrdup(buf, GFP_KERNEL);
+ }
+ return 0;
+}
+pure_initcall(cpuset_init_late);
+
/*
* Return cpus_allowed mask from a task's cpuset.
*/
--
2.53.0
^ permalink raw reply related
* [PATCH 23/23] cgroup/cpuset: Documentation and kselftest updates
From: Waiman Long @ 2026-04-21 3:03 UTC (permalink / raw)
To: Tejun Heo, Johannes Weiner, Michal Koutný, Jonathan Corbet,
Shuah Khan, Catalin Marinas, Will Deacon, K. Y. Srinivasan,
Haiyang Zhang, Wei Liu, Dexuan Cui, Long Li, Guenter Roeck,
Frederic Weisbecker, Paul E. McKenney, Neeraj Upadhyay,
Joel Fernandes, Josh Triplett, Boqun Feng, Uladzislau Rezki,
Steven Rostedt, Mathieu Desnoyers, Lai Jiangshan, Zqiang,
Anna-Maria Behnsen, Ingo Molnar, Thomas Gleixner, Chen Ridong,
Peter Zijlstra, Juri Lelli, Vincent Guittot, Dietmar Eggemann,
Ben Segall, Mel Gorman, Valentin Schneider, K Prateek Nayak,
David S. Miller, Eric Dumazet, Jakub Kicinski, Paolo Abeni,
Simon Horman
Cc: cgroups, linux-doc, linux-kernel, linux-arm-kernel, linux-hyperv,
linux-hwmon, rcu, netdev, linux-kselftest, Costa Shulyupin,
Qiliang Yuan, Waiman Long
In-Reply-To: <20260421030351.281436-1-longman@redhat.com>
As CPU hotplug is now being used to enable runtime update to the list
of nohz_full and managed_irq CPUs, we should avoid using CPU 0 in the
formation of isolated partition as CPU 0 may not be able to be brought
offline like in the case of x86-64 architecture. So a number of the
test cases in test_cpuset_prs.sh will have to be updated accordingly.
A new test will also be run in offline isn't allowed in CPU 0 to verify
that using CPU 0 as part of an isolated partition will fail.
The cgroup-v2.rst is also updated to reflect the new capability of using
CPU hotplug to enable run time change to the nohz_full and managed_irq
CPU lists.
Since there is a slight performance overhead to enable runtime changes
to nohz_full CPU list, users have to explicitly opt in by adding a
"nohz_ful" kernel command line parameter with or without a CPU list.
Signed-off-by: Waiman Long <longman@redhat.com>
---
Documentation/admin-guide/cgroup-v2.rst | 35 +++++++---
.../selftests/cgroup/test_cpuset_prs.sh | 70 +++++++++++++++++--
2 files changed, 92 insertions(+), 13 deletions(-)
diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
index 8ad0b2781317..e97fc031eb86 100644
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -2604,11 +2604,12 @@ Cpuset Interface Files
It accepts only the following input values when written to.
- ========== =====================================
+ ========== ===============================================
"member" Non-root member of a partition
"root" Partition root
- "isolated" Partition root without load balancing
- ========== =====================================
+ "isolated" Partition root without load balancing and other
+ OS noises
+ ========== ===============================================
A cpuset partition is a collection of cpuset-enabled cgroups with
a partition root at the top of the hierarchy and its descendants
@@ -2652,11 +2653,29 @@ Cpuset Interface Files
partition or scheduling domain. The set of exclusive CPUs is
determined by the value of its "cpuset.cpus.exclusive.effective".
- When set to "isolated", the CPUs in that partition will be in
- an isolated state without any load balancing from the scheduler
- and excluded from the unbound workqueues. Tasks placed in such
- a partition with multiple CPUs should be carefully distributed
- and bound to each of the individual CPUs for optimal performance.
+ When set to "isolated", the CPUs in that partition will be in an
+ isolated state without any load balancing from the scheduler and
+ excluded from the unbound workqueues as well as other OS noises.
+ Tasks placed in such a partition with multiple CPUs should be
+ carefully distributed and bound to each of the individual CPUs
+ for optimal performance.
+
+ As CPU hotplug, if supported, is used to improve the degree of
+ CPU isolation close to the "nohz_full" kernel boot parameter.
+ In some architectures, like x86-64, the boot CPU (typically CPU
+ 0) cannot be brought offline, so the boot CPU should not be used
+ for forming isolated partitions. The "nohz_full" kernel boot
+ parameter needs to be present to enable full dynticks support
+ and RCU no-callback CPU mode for CPUs in isolated partitions
+ even if the optional cpu list isn't provided.
+
+ Using CPU hotplug for creating or destroying an isolated
+ partition can cause latency spike in applications running
+ in other isolated partitions. A reserved list of CPUs can
+ optionally be put in the "nohz_full" kernel boot parameter to
+ alleviate this problem. When these reserved CPUs are used for
+ isolated partitions, CPU hotplug won't need to be invoked and
+ so there won't be latency spike in other isolated partitions.
A partition root ("root" or "isolated") can be in one of the
two possible states - valid or invalid. An invalid partition
diff --git a/tools/testing/selftests/cgroup/test_cpuset_prs.sh b/tools/testing/selftests/cgroup/test_cpuset_prs.sh
index a56f4153c64d..eebb4122b581 100755
--- a/tools/testing/selftests/cgroup/test_cpuset_prs.sh
+++ b/tools/testing/selftests/cgroup/test_cpuset_prs.sh
@@ -67,6 +67,12 @@ then
echo Y > /sys/kernel/debug/sched/verbose
fi
+# Enable dynamic debug message if available
+DYN_DEBUG=/proc/dynamic_debug/control
+[[ -f $DYN_DEBUG ]] && {
+ echo "file kernel/cpu.c +p" > $DYN_DEBUG
+}
+
cd $CGROUP2
echo +cpuset > cgroup.subtree_control
@@ -84,6 +90,15 @@ echo member > test/cpuset.cpus.partition
echo "" > test/cpuset.cpus
[[ $RESULT -eq 0 ]] && skip_test "Child cgroups are using cpuset!"
+#
+# If nohz_full parameter is specified and nohz_full file exists, CPU hotplug
+# will be used to modify nohz_full cpumask to include all the isolated CPUs
+# in cpuset isolated partitions.
+#
+NOHZ_FULL=/sys/devices/system/cpu/nohz_full
+BOOT_NOHZ_FULL=$(fmt -1 /proc/cmdline | grep "^nohz_full")
+[[ "$BOOT_NOHZ_FULL" = nohz_full ]] && CHK_NOHZ_FULL=1
+
#
# If isolated CPUs have been reserved at boot time (as shown in
# cpuset.cpus.isolated), these isolated CPUs should be outside of CPUs 0-8
@@ -318,8 +333,8 @@ TEST_MATRIX=(
# Invalid to valid local partition direct transition tests
" C1-3:P2 X4:P2 . . . . . . 0 A1:1-3|XA1:1-3|A2:1-3:XA2: A1:P2|A2:P-2 1-3"
" C1-3:P2 X4:P2 . . . X3:P2 . . 0 A1:1-2|XA1:1-3|A2:3:XA2:3 A1:P2|A2:P2 1-3"
- " C0-3:P2 . . C4-6 C0-4 . . . 0 A1:0-4|B1:5-6 A1:P2|B1:P0"
- " C0-3:P2 . . C4-6 C0-4:C0-3 . . . 0 A1:0-3|B1:4-6 A1:P2|B1:P0 0-3"
+ " C1-3:P2 . . C4-6 C1-4 . . . 0 A1:1-4|B1:5-6 A1:P2|B1:P0"
+ " C1-3:P2 . . C4-6 C1-4:C1-3 . . . 0 A1:1-3|B1:4-6 A1:P2|B1:P0 1-3"
# Local partition invalidation tests
" C0-3:X1-3:P2 C1-3:X2-3:P2 C2-3:X3:P2 \
@@ -329,8 +344,8 @@ TEST_MATRIX=(
" C0-3:X1-3:P2 C1-3:X2-3:P2 C2-3:X3:P2 \
. . C4:X . . 0 A1:1-3|A2:1-3|A3:2-3|XA2:|XA3: A1:P2|A2:P-2|A3:P-2 1-3"
# Local partition CPU change tests
- " C0-5:P2 C4-5:P1 . . . C3-5 . . 0 A1:0-2|A2:3-5 A1:P2|A2:P1 0-2"
- " C0-5:P2 C4-5:P1 . . C1-5 . . . 0 A1:1-3|A2:4-5 A1:P2|A2:P1 1-3"
+ " C1-5:P2 C4-5:P1 . . . C3-5 . . 0 A1:1-2|A2:3-5 A1:P2|A2:P1 1-2"
+ " C1-5:P2 C4-5:P1 . . C2-5 . . . 0 A1:2-3|A2:4-5 A1:P2|A2:P1 2-3"
# cpus_allowed/exclusive_cpus update tests
" C0-3:X2-3 C1-3:X2-3 C2-3:X2-3 \
@@ -442,6 +457,21 @@ TEST_MATRIX=(
" C0-3 . . C4-5 X3-5 . . . 1 A1:0-3|B1:4-5"
)
+#
+# Test matrix to verify that using CPU 0 in isolated (local or remote) partition
+# will fail when offline isn't allowed for CPU 0.
+#
+CPU0_ISOLCPUS_MATRIX=(
+ # old-A1 old-A2 old-A3 old-B1 new-A1 new-A2 new-A3 new-B1 fail ECPUs Pstate ISOLCPUS
+ # ------ ------ ------ ------ ------ ------ ------ ------ ---- ----- ------ --------
+ " C0-3 . . C4-5 P2 . . . 0 A1:0-3|B1:4-5 A1:P-2"
+ " C1-3 . . . P2 . . . 0 A1:1-3 A1:P2"
+ " C1-3 . . . P2:C0-3 . . . 0 A1:0-3 A1:P-2"
+ " CX0-3 C0-3 . . . P2 . . 0 A1:0-3|A2:0-3 A2:P-2"
+ " CX0-3 C0-3:X1-3 . . . P2 . . 0 A1:0|A2:1-3 A2:P2"
+ " CX0-3 C0-3:X1-3 . . . P2:X0-3 . . 0 A1:0-3|A2:0-3 A2:P-2"
+)
+
#
# Cpuset controller remote partition test matrix.
#
@@ -513,7 +543,7 @@ write_cpu_online()
}
fi
echo $VAL > $CPUFILE
- pause 0.05
+ pause 0.10
}
#
@@ -654,6 +684,8 @@ dump_states()
[[ -e $PCPUS ]] && echo "$PCPUS: $(cat $PCPUS)"
[[ -e $ISCPUS ]] && echo "$ISCPUS: $(cat $ISCPUS)"
done
+ # Dump nohz_full
+ [[ -f $NOHZ_FULL ]] && echo "nohz_full: $(cat $NOHZ_FULL)"
}
#
@@ -789,6 +821,18 @@ check_isolcpus()
EXPECTED_SDOMAIN=$EXPECTED_ISOLCPUS
fi
+ #
+ # Check if nohz_full match cpuset.cpus.isolated if nohz_boot parameter
+ # specified with no parameter.
+ #
+ [[ -f $NOHZ_FULL && "$BOOT_NOHZ_FULL" = nohz_full ]] && {
+ NOHZ_FULL_CPUS=$(cat $NOHZ_FULL)
+ [[ "$ISOLCPUS" != "$NOHZ_FULL_CPUS" ]] && {
+ echo "nohz_full ($NOHZ_FULL_CPUS) does not match cpuset.cpus.isolated ($ISOLCPUS)"
+ return 1
+ }
+ }
+
#
# Appending pre-isolated CPUs
# Even though CPU #8 isn't used for testing, it can't be pre-isolated
@@ -1070,6 +1114,21 @@ run_remote_state_test()
echo "All $I tests of $TEST PASSED."
}
+#
+# Testing CPU 0 isolated partition test when offline is disabled
+#
+run_cpu0_isol_test()
+{
+ # Skip the test if CPU0 offline is allowed or if nohz_full kernel
+ # boot parameter is missing.
+ CPU0_ONLINE=/sys/devices/system/cpu/cpu0/online
+ [[ -f $CPU0_ONLINE ]] && return
+ grep -q -w nohz_full /proc/cmdline
+ [[ $? -ne 0 ]] && return
+
+ run_state_test CPU0_ISOLCPUS_MATRIX
+}
+
#
# Testing the new "isolated" partition root type
#
@@ -1207,6 +1266,7 @@ test_inotify()
trap cleanup 0 2 3 6
run_state_test TEST_MATRIX
run_remote_state_test REMOTE_TEST_MATRIX
+run_cpu0_isol_test
test_isolated
test_inotify
echo "All tests PASSED."
--
2.53.0
^ permalink raw reply related
* RE: [EXTERNAL] Re: [PATCH net v2] hv_sock: Report EOF instead of -EIO for FIN
From: Dexuan Cui @ 2026-04-21 3:13 UTC (permalink / raw)
To: patchwork-bot+netdevbpf@kernel.org, kuba@kernel.org,
sgarzare@redhat.com
Cc: KY Srinivasan, Haiyang Zhang, wei.liu@kernel.org, Long Li,
davem@davemloft.net, edumazet@google.com, pabeni@redhat.com,
horms@kernel.org, niuxuewei.nxw@antgroup.com,
linux-hyperv@vger.kernel.org, virtualization@lists.linux.dev,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org, Ben Hillis, levymitchell0@gmail.com
In-Reply-To: <177672238581.1802062.15838493180057695674.git-patchwork-notify@kernel.org>
> From: patchwork-bot+netdevbpf@kernel.org <patchwork-
> bot+netdevbpf@kernel.org>
> Sent: Monday, April 20, 2026 3:00 PM
> > [...]
>
> Here is the summary with links:
> - [net,v2] hv_sock: Report EOF instead of -EIO for FIN
> https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/commit/?id=f63152958994
Hi Jakub, Stefano,
I'm sorry -- I just posted v3
https://lore.kernel.org/linux-hyperv/20260421025950.1099495-1-decui@microsoft.com/T/#u
and then I realized that the v2 had been merged into the main branch :-(
Should I post a new delta patch(with a Fixes tag against the v2) based on the main branch?
Thanks,
Dexuan
^ permalink raw reply
* Re: [net-next v2 3/5] dt-bindings: net: starfive,jh7110-dwmac: Add JHB100 sgmii rx clk
From: Minda Chen @ 2026-04-21 3:07 UTC (permalink / raw)
To: Rob Herring
Cc: Alexandre Torgue, Andrew Lunn, David S . Miller, Eric Dumazet,
Jakub Kicinski, Paolo Abeni, Maxime Coquelin,
Emil Renner Berthing, Krzysztof Kozlowski, Conor Dooley,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-stm32@st-md-mailman.stormreply.com,
devicetree@vger.kernel.org
In-Reply-To: <20260420133930.GA2322456-robh@kernel.org>
>
> On Fri, Apr 17, 2026 at 10:45:21AM +0800, Minda Chen wrote:
> > JHB100 SGMII interface tx/rx mac clock is split and require to set
> > clock rate in 10M/100M/1000M speed. So dts need to add a new rx clock
> > in code, dts and dt binding doc.
> >
> > Signed-off-by: Minda Chen <minda.chen@starfivetech.com>
> > ---
> > .../bindings/net/starfive,jh7110-dwmac.yaml | 42 ++++++++++++++++---
> > 1 file changed, 36 insertions(+), 6 deletions(-)
> >
> > diff --git
> > a/Documentation/devicetree/bindings/net/starfive,jh7110-dwmac.yaml
> > b/Documentation/devicetree/bindings/net/starfive,jh7110-dwmac.yaml
> > index edc246a71ce3..3802cdbf1848 100644
> > --- a/Documentation/devicetree/bindings/net/starfive,jh7110-dwmac.yaml
> > +++ b/Documentation/devicetree/bindings/net/starfive,jh7110-dwmac.yaml
> > @@ -39,20 +39,26 @@ properties:
> > maxItems: 1
> >
> > clocks:
> > + minItems: 5
> > items:
> > - description: GMAC main clock
> > - description: GMAC AHB clock
> > - description: PTP clock
> > - description: TX clock
> > - description: GTX clock
> > + - description: SGMII RX clock
> >
> > clock-names:
> > - items:
> > - - const: stmmaceth
> > - - const: pclk
> > - - const: ptp_ref
> > - - const: tx
> > - - const: gtx
> > + minItems: 5
> > + maxItems: 6
> > + contains:
> > + enum:
> > + - stmmaceth
> > + - pclk
> > + - ptp_ref
> > + - tx
> > + - gtx
> > + - sgmii_rx
>
> No, this allows any of the above strings plus any other random strings.
>
> Rob
Got it. Thanks. In JHB100 I will using "oneOf" 5 clocks or 6 clocks. 7100/7100 are const clock names
^ permalink raw reply
* [PATCH net v2] ipv4: icmp: validate reply type before using icmp_pointers
From: Ren Wei @ 2026-04-21 4:16 UTC (permalink / raw)
To: netdev, edumazet
Cc: davem, dsahern, kuba, pabeni, horms, andreas.a.roeseler,
yuantan098, yifanwucs, tomapufckgml, bird, caoruide123, n05ec
From: Ruide Cao <caoruide123@gmail.com>
Extended echo replies use ICMP_EXT_ECHOREPLY as the outbound reply type.
That value is outside the range covered by icmp_pointers[], which only
describes the traditional ICMP types up to NR_ICMP_TYPES.
Avoid consulting icmp_pointers[] for reply types outside that range, and
use array_index_nospec() for the remaining in-range lookup. Normal ICMP
replies keep their existing behavior unchanged.
Fixes: d329ea5bd884 ("icmp: add response to RFC 8335 PROBE messages")
Cc: stable@kernel.org
Reported-by: Yuan Tan <yuantan098@gmail.com>
Reported-by: Yifan Wu <yifanwucs@gmail.com>
Reported-by: Juefei Pu <tomapufckgml@gmail.com>
Reported-by: Xin Liu <bird@lzu.edu.cn>
Signed-off-by: Ruide Cao <caoruide123@gmail.com>
Signed-off-by: Ren Wei <n05ec@lzu.edu.cn>
---
changes in v2:
use array_index_nospec()
v1 link: https://lore.kernel.org/all/efb2c33f544ece7727704608fc577525b415ae26.1776563662.git.caoruide123@gmail.com/
net/ipv4/icmp.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index 4e2a6c70dcd8..ba4b1eec9ea2 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -64,6 +64,7 @@
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/fcntl.h>
+#include <linux/nospec.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/inet.h>
@@ -373,7 +374,9 @@ static int icmp_glue_bits(void *from, char *to, int offset, int len, int odd,
to, len);
skb->csum = csum_block_add(skb->csum, csum, odd);
- if (icmp_pointers[icmp_param->data.icmph.type].error)
+ if (icmp_param->data.icmph.type <= NR_ICMP_TYPES &&
+ icmp_pointers[array_index_nospec(icmp_param->data.icmph.type,
+ NR_ICMP_TYPES + 1)].error)
nf_ct_attach(skb, icmp_param->skb);
return 0;
}
--
2.34.1
^ permalink raw reply related
* Re: [PATCH net] ipv6: rpl: expand skb head when recompressed SRH grows, not only on last segment
From: Kuniyuki Iwashima @ 2026-04-21 4:52 UTC (permalink / raw)
To: gregkh
Cc: davem, dsahern, edumazet, horms, kuba, linux-kernel, netdev,
pabeni, stable
In-Reply-To: <2026042024-cabbie-gills-9371@gregkh>
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: Mon, 20 Apr 2026 21:32:25 +0200
> ipv6_rpl_srh_rcv() processes a Routing Protocol for LLNs Source Routing
> Header by decompressing it, swapping the next segment address into
> ipv6_hdr->daddr, recompressing, and pushing the new header back. The
> recompressed header can be larger than the original when the
> address-elision opportunities are worse after the swap.
>
> The function pulls (hdr->hdrlen + 1) << 3 bytes (the old header) and
> pushes (chdr->hdrlen + 1) << 3 + sizeof(ipv6hdr) bytes (the new header
> plus the IPv6 header). pskb_expand_head() is called to guarantee
> headroom only when segments_left == 0.
>
> A crafted SRH that loops back to the local host (each segment is a local
> address, so ip6_route_input() delivers it back to ipv6_rpl_srh_rcv())
> with chdr growing on each pass exhausts headroom over several
> iterations.
How could this occur.. ? Did AI generate a repro or just
flagged the possibility ?
ipv6_rpl_sr_hdr.hdrlen >> 3 is the size of addresses in the
header and 1 >> 3 is the size of ipv6_rpl_sr_hdr itself, which
is pulled into skb_headroom in ipv6_rthdr_rcv().
In ipv6_rpl_srh_rcv(), the number of addresses is calculated
based on ipv6_rpl_sr_hdr.hdrlen, and when hdr->segments_left
is not zero in the "if" below, the new header has the exact same
size with the old header, so there should be no overflow.
Also, before the "if", ipv6_rpl_srh_rcv() calls
skb_pull(skb, ((hdr->hdrlen + 1) << 3));
and after that,
skb_push(skb, ((chdr->hdrlen + 1) << 3) + sizeof(struct ipv6hdr));
and if we jump to the looped_back label, it calls
skb_pull(skb, sizeof(struct ipv6hdr));
So, I think the same size are pulled and pushed for each iteration
(except for segments_left == 0 case) even with local addresses.
> When skb_push() lands skb->data exactly at skb->head,
> skb_reset_network_header() stores 0, and skb_mac_header_rebuild()'s
> skb_set_mac_header(skb, -skb->mac_len) computes 0 + (u16)(-14) = 65522.
> The subsequent memmove writes 14 bytes at skb->head + 65522.
>
> Expand the head whenever there is insufficient room for the push, not
> only on the final segment.
>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: David Ahern <dsahern@kernel.org>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Jakub Kicinski <kuba@kernel.org>
> Cc: Paolo Abeni <pabeni@redhat.com>
> Cc: Simon Horman <horms@kernel.org>
> Reported-by: Anthropic
> Cc: stable <stable@kernel.org>
> Assisted-by: gkh_clanker_t1000
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
> net/ipv6/exthdrs.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c
> index 95558fd6f447..d866ab011e0a 100644
> --- a/net/ipv6/exthdrs.c
> +++ b/net/ipv6/exthdrs.c
> @@ -592,7 +592,9 @@ static int ipv6_rpl_srh_rcv(struct sk_buff *skb)
> skb_pull(skb, ((hdr->hdrlen + 1) << 3));
> skb_postpull_rcsum(skb, oldhdr,
> sizeof(struct ipv6hdr) + ((hdr->hdrlen + 1) << 3));
> - if (unlikely(!hdr->segments_left)) {
> + if (unlikely(!hdr->segments_left ||
> + skb_headroom(skb) < sizeof(struct ipv6hdr) +
> + ((chdr->hdrlen + 1) << 3))) {
> if (pskb_expand_head(skb, sizeof(struct ipv6hdr) + ((chdr->hdrlen + 1) << 3), 0,
> GFP_ATOMIC)) {
> __IP6_INC_STATS(net, ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_OUTDISCARDS);
> --
> 2.53.0
>
^ permalink raw reply
* Re: [PATCH net] tcp: make probe0 timer handle expired user timeout
From: Eric Dumazet @ 2026-04-21 4:57 UTC (permalink / raw)
To: Altan Hacigumus
Cc: Neal Cardwell, Kuniyuki Iwashima, David S . Miller, David Ahern,
Jakub Kicinski, Paolo Abeni, Simon Horman, netdev, linux-kernel,
Enke Chen
In-Reply-To: <20260414013634.43997-1-ahacigu.linux@gmail.com>
On Mon, Apr 13, 2026 at 6:36 PM Altan Hacigumus <ahacigu.linux@gmail.com> wrote:
>
> tcp_clamp_probe0_to_user_timeout() computes remaining time in jiffies
> using subtraction with an unsigned lvalue. If elapsed probing time
> already exceeds the configured TCP_USER_TIMEOUT, the subtraction
> underflows and yields a large value.
>
> Handle this expiration case similarly to tcp_clamp_rto_to_user_timeout().
>
> Fixes: 344db93ae3ee ("tcp: make TCP_USER_TIMEOUT accurate for zero window probes")
> Signed-off-by: Altan Hacigumus <ahacigu.linux@gmail.com>
> ---
> net/ipv4/tcp_timer.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
> index 5a14a53a3c9e..4a43356a4e06 100644
> --- a/net/ipv4/tcp_timer.c
> +++ b/net/ipv4/tcp_timer.c
> @@ -50,7 +50,8 @@ static u32 tcp_clamp_rto_to_user_timeout(const struct sock *sk)
> u32 tcp_clamp_probe0_to_user_timeout(const struct sock *sk, u32 when)
> {
> const struct inet_connection_sock *icsk = inet_csk(sk);
> - u32 remaining, user_timeout;
> + u32 user_timeout;
> + s32 remaining;
> s32 elapsed;
>
> user_timeout = READ_ONCE(icsk->icsk_user_timeout);
> @@ -61,6 +62,8 @@ u32 tcp_clamp_probe0_to_user_timeout(const struct sock *sk, u32 when)
> if (unlikely(elapsed < 0))
> elapsed = 0;
> remaining = msecs_to_jiffies(user_timeout) - elapsed;
> + if (remaining <= 0)
> + return 1;
I do not think this chunk is needed ?
If @remaining is signed, then perhaps change the following line to:
remaining = max_t(int, remaining, TCP_TIMEOUT_MIN);
Also, it would be great to have a new packetdrill test.
> remaining = max_t(u32, remaining, TCP_TIMEOUT_MIN);
>
> return min_t(u32, remaining, when);
> --
> 2.43.0
>
^ permalink raw reply
* Re: [net-next v2 2/5] dt-bindings: net: starfive,jh7110-dwmac: Add JHB100 support
From: Minda Chen @ 2026-04-21 3:30 UTC (permalink / raw)
To: Krzysztof Kozlowski
Cc: Alexandre Torgue, Andrew Lunn, David S . Miller, Eric Dumazet,
Jakub Kicinski, Paolo Abeni, Maxime Coquelin,
Emil Renner Berthing, Rob Herring, Krzysztof Kozlowski,
Conor Dooley, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org,
linux-stm32@st-md-mailman.stormreply.com,
devicetree@vger.kernel.org
In-Reply-To: <20260420-messy-elite-panther-a7ffbc@quoll>
>
> On Fri, Apr 17, 2026 at 10:45:20AM +0800, Minda Chen wrote:
> > Add StarFive JHB100 dwmac support and compatible.
> > The JHB100 dwmac shares the same driver code as the JH7110 dwmac,
>
> Please describe the hardware or programming interface, not driver code.
>
> > which contains 2 SGMII interfaces, 1 RGMII/RMII interface and
> > 1 RMII interface.
> > JHB100 dwmac has only one reset signal and one main interrupt line.
>
>
> Drop all below, not relevant.
>
> >
> > Please refer to below:
> >
> > JHB100: reset-names = "stmmaceth";
> >
> > Example usage of JHB100 in the device tree:
> >
> > gmac0: ethernet@11b80000 {
> > compatible = "starfive,jhb100-dwmac",
> > "snps,dwmac-5.20";
> > interrupts = <225>;
> > interrupt-names = "macirq";
> > ...
> > };
> >
> > Signed-off-by: Minda Chen <minda.chen@starfivetech.com>
> > ---
> > .../devicetree/bindings/net/snps,dwmac.yaml | 1 +
> > .../bindings/net/starfive,jh7110-dwmac.yaml | 23 +++++++++++++++++++
> > 2 files changed, 24 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/net/snps,dwmac.yaml
> > b/Documentation/devicetree/bindings/net/snps,dwmac.yaml
> > index 38bc34dc4f09..85cd3252e8b1 100644
> > --- a/Documentation/devicetree/bindings/net/snps,dwmac.yaml
> > +++ b/Documentation/devicetree/bindings/net/snps,dwmac.yaml
> > @@ -115,6 +115,7 @@ properties:
> > - sophgo,sg2044-dwmac
> > - starfive,jh7100-dwmac
> > - starfive,jh7110-dwmac
> > + - starfive,jhb100-dwmac
> > - tesla,fsd-ethqos
> > - thead,th1520-gmac
> >
> > diff --git
> > a/Documentation/devicetree/bindings/net/starfive,jh7110-dwmac.yaml
> > b/Documentation/devicetree/bindings/net/starfive,jh7110-dwmac.yaml
> > index 0d1962980f57..edc246a71ce3 100644
> > --- a/Documentation/devicetree/bindings/net/starfive,jh7110-dwmac.yaml
> > +++ b/Documentation/devicetree/bindings/net/starfive,jh7110-dwmac.yaml
> > @@ -18,6 +18,7 @@ select:
> > enum:
> > - starfive,jh7100-dwmac
> > - starfive,jh7110-dwmac
> > + - starfive,jhb100-dwmac
> > required:
> > - compatible
> >
> > @@ -30,6 +31,9 @@ properties:
> > - items:
> > - const: starfive,jh7110-dwmac
> > - const: snps,dwmac-5.20
> > + - items:
> > + - const: starfive,jhb100-dwmac
>
> So that's an enum in previous "items" list.... but your commit msg said your
> devices are compatible, so confusing.
>
> Best regards,
> Krzysztof
Got it . I will correct the commit messages. Thanks
^ permalink raw reply
* [PATCH iwl-net v2] idpf: do not perform flow ops when netdev is detached
From: Li Li @ 2026-04-21 5:16 UTC (permalink / raw)
To: Tony Nguyen, Przemek Kitszel, David S. Miller, Jakub Kicinski,
Eric Dumazet, intel-wired-lan
Cc: netdev, linux-kernel, David Decotigny, Anjali Singhai,
Sridhar Samudrala, Brian Vazquez, Li Li, emil.s.tantilov, stable
Even though commit 2e281e1155fc ("idpf: detach and close netdevs while
handling a reset") prevents ethtool -N/-n operations to operate on
detached netdevs, we found that out-of-tree workflows like OpenOnload
can bypass ethtool core locks and call idpf_set_rxnfc directly during
an idpf HW reset. When this happens, we could get kernel crashes like
the following:
[ 4045.787439] BUG: kernel NULL pointer dereference, address: 0000000000000070
[ 4045.794420] #PF: supervisor read access in kernel mode
[ 4045.799580] #PF: error_code(0x0000) - not-present page
[ 4045.804739] PGD 0
[ 4045.806772] Oops: Oops: 0000 [#1] SMP NOPTI
...
[ 4045.836425] Workqueue: onload-wqueue oof_do_deferred_work_fn [onload]
[ 4045.842926] RIP: 0010:idpf_del_flow_steer+0x24/0x170 [idpf]
...
[ 4045.946323] Call Trace:
[ 4045.948796] <TASK>
[ 4045.950915] ? show_trace_log_lvl+0x1b0/0x2f0
[ 4045.955293] ? show_trace_log_lvl+0x1b0/0x2f0
[ 4045.959672] ? idpf_set_rxnfc+0x6f/0x80 [idpf]
[ 4046.063613] </TASK>
To prevent this, we need to add checks in idpf_set_rxnfc and
idpf_get_rxnfc to error out if the netdev is already detached.
Tested: synthetically forced idpf into a HW reset by introducing module
parameters to simulate a Tx timeout and force virtual channel
initialization failure. This was done by skipping completion cleaning for
specific queues and returning -EIO during core initialization.
The failure was then triggered by writing 1 to the corresponding sysfs
parameters and calling idpf_get_rxnfc() during the reset process.
Without the patch: encountered NULL pointer and kernel crash.
With the patch: no crashes.
Fixes: 2e281e1155fc ("idpf: detach and close netdevs while handling a reset")
Cc: stable@vger.kernel.org
Signed-off-by: Li Li <boolli@google.com>
---
v2:
- Removed the raw code block from the commit message and replaced it with
a textual description of the test modifications.
drivers/net/ethernet/intel/idpf/idpf_ethtool.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/net/ethernet/intel/idpf/idpf_ethtool.c b/drivers/net/ethernet/intel/idpf/idpf_ethtool.c
index bb99d9e7c65d..8368a7e6a754 100644
--- a/drivers/net/ethernet/intel/idpf/idpf_ethtool.c
+++ b/drivers/net/ethernet/intel/idpf/idpf_ethtool.c
@@ -43,6 +43,9 @@ static int idpf_get_rxnfc(struct net_device *netdev, struct ethtool_rxnfc *cmd,
unsigned int cnt = 0;
int err = 0;
+ if (!netdev || !netif_device_present(netdev))
+ return -ENODEV;
+
idpf_vport_ctrl_lock(netdev);
vport = idpf_netdev_to_vport(netdev);
vport_config = np->adapter->vport_config[np->vport_idx];
@@ -349,6 +352,9 @@ static int idpf_set_rxnfc(struct net_device *netdev, struct ethtool_rxnfc *cmd)
{
int ret = -EOPNOTSUPP;
+ if (!netdev || !netif_device_present(netdev))
+ return -ENODEV;
+
idpf_vport_ctrl_lock(netdev);
switch (cmd->cmd) {
case ETHTOOL_SRXCLSRLINS:
--
2.54.0.rc1.555.g9c883467ad-goog
^ permalink raw reply related
* [PATCH v5 net] ax25: fix OOB read after address header strip in ax25_rcv()
From: Ashutosh Desai @ 2026-04-21 5:46 UTC (permalink / raw)
To: netdev, linux-hams
Cc: jreuter, davem, edumazet, kuba, pabeni, horms, linux-kernel,
stable, Ashutosh Desai
In-Reply-To: <20260417065407.206499-1-ashutoshdesai993@gmail.com>
A crafted AX.25 frame with a valid address header but no control byte
causes skb->len to reach zero after skb_pull() strips the header.
The subsequent reads of skb->data[0] (control) and skb->data[1] (PID)
are then out of bounds.
Linearize the skb after confirming the device is an AX.25 interface.
Guard with skb->len < 1 after the pull - one byte suffices for LAPB
control frames which have no PID byte. Add a separate skb->len < 2
check inside the UI branch before accessing the PID byte.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Ashutosh Desai <ashutoshdesai993@gmail.com>
---
v5:
- Move skb_linearize() to after ax25_dev_ax25dev() check; avoids
unnecessary allocation for frames on non-AX.25 interfaces
- Lower general guard from skb->len < 2 to skb->len < 1; the stricter
limit incorrectly dropped valid 1-byte LAPB control frames (SABM,
DISC, UA, DM, RR) which carry no PID byte
- Add explicit skb->len < 2 check inside UI branch before the PID
byte (skb->data[1]) access
v4:
- Linearize skb at entry to ax25_rcv(); replace pskb_may_pull() with
skb->len < 2 check (per David Laight review)
v3:
- Remove incorrect Suggested-by; add Fixes:, Cc: stable@
v2:
- Replace skb->len check with pskb_may_pull(skb, 2)
Link to v4: https://lore.kernel.org/netdev/20260417065407.206499-1-ashutoshdesai993@gmail.com/
Link to v3: https://lore.kernel.org/netdev/20260415063654.3831353-1-ashutoshdesai993@gmail.com/
Link to v2: https://lore.kernel.org/netdev/20260409152400.2219716-1-ashutoshdesai993@gmail.com/
Link to v1: https://lore.kernel.org/netdev/20260409012235.2049389-1-ashutoshdesai993@gmail.com/
net/ax25/ax25_in.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/net/ax25/ax25_in.c b/net/ax25/ax25_in.c
index d75b3e9ed93d..c81d6830af48 100644
--- a/net/ax25/ax25_in.c
+++ b/net/ax25/ax25_in.c
@@ -199,6 +199,9 @@ static int ax25_rcv(struct sk_buff *skb, struct net_device *dev,
if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
goto free;
+ if (skb_linearize(skb))
+ goto free;
+
/*
* Parse the address header.
*/
@@ -217,6 +220,9 @@ static int ax25_rcv(struct sk_buff *skb, struct net_device *dev,
*/
skb_pull(skb, ax25_addr_size(&dp));
+ if (skb->len < 1)
+ goto free;
+
/* For our port addresses ? */
if (ax25cmp(&dest, dev_addr) == 0 && dp.lastrepeat + 1 == dp.ndigi)
mine = 1;
@@ -227,6 +233,9 @@ static int ax25_rcv(struct sk_buff *skb, struct net_device *dev,
/* UI frame - bypass LAPB processing */
if ((*skb->data & ~0x10) == AX25_UI && dp.lastrepeat + 1 == dp.ndigi) {
+ if (skb->len < 2)
+ goto free;
+
skb_set_transport_header(skb, 2); /* skip control and pid */
ax25_send_to_raw(&dest, skb, skb->data[1]);
--
2.34.1
^ permalink raw reply related
* Re: [PATCH] llc: Return -EINPROGRESS from llc_ui_connect()
From: Ernestas Kulik @ 2026-04-21 5:48 UTC (permalink / raw)
To: Jakub Kicinski; +Cc: netdev, linux-kernel
In-Reply-To: <20260420114138.1aa52551@kernel.org>
On 2026-04-20 21:41, Jakub Kicinski wrote:
> On Wed, 15 Apr 2026 09:34:57 +0300 Ernestas Kulik wrote:
>> Given a zero sk_sndtimeo, llc_ui_connect() skips waiting for state
>> change and returns 0, confusing userspace applications that will assume
>> the socket is connected, making e.g. getpeername() calls error out.
>>
>> Set rc to -EINPROGRESS before considering blocking, akin to AF_INET
>> sockets.
>
> Please add a note on how you discovered this issue.
> Including whether you're actively using this code or just scanning it
> for bugs.
Will do. It was discovered while adding support for AF_LLC sockets in
libcoap, the usual code path for client connections was failing due to
this specific issue, so I figured the behavior should be analogous to
AF_INET.
>> diff --git a/net/llc/af_llc.c b/net/llc/af_llc.c
>> index 59d593bb5d18..9317d092ba84 100644
>> --- a/net/llc/af_llc.c
>> +++ b/net/llc/af_llc.c
>> @@ -515,10 +515,12 @@ static int llc_ui_connect(struct socket *sock, struct sockaddr_unsized *uaddr,
>> sock->state = SS_UNCONNECTED;
>> sk->sk_state = TCP_CLOSE;
>> goto out;
>> }
>>
>> + rc = -EINPROGRESS;
>
> Isn't this a bit of an odd placement? ..
>
>> if (sk->sk_state == TCP_SYN_SENT) {
>> const long timeo = sock_sndtimeo(sk, flags & O_NONBLOCK);
>>
>> if (!timeo || !llc_ui_wait_for_conn(sk, timeo))
>> goto out;
>
> .. I suspect you mean to target this branch, right?
I can’t remember now why I put it there, but you’re right, that would be
the better place.
^ permalink raw reply
* [PATCH v5 net] ax25: fix OOB read after address header strip in ax25_rcv()
From: Ashutosh Desai @ 2026-04-21 5:48 UTC (permalink / raw)
To: netdev, linux-hams
Cc: jreuter, davem, edumazet, kuba, pabeni, horms, linux-kernel,
stable, Ashutosh Desai
A crafted AX.25 frame with a valid address header but no control byte
causes skb->len to reach zero after skb_pull() strips the header.
The subsequent reads of skb->data[0] (control) and skb->data[1] (PID)
are then out of bounds.
Linearize the skb after confirming the device is an AX.25 interface.
Guard with skb->len < 1 after the pull - one byte suffices for LAPB
control frames which have no PID byte. Add a separate skb->len < 2
check inside the UI branch before accessing the PID byte.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Ashutosh Desai <ashutoshdesai993@gmail.com>
---
v5:
- Move skb_linearize() to after ax25_dev_ax25dev() check; avoids
unnecessary allocation for frames on non-AX.25 interfaces
- Lower general guard from skb->len < 2 to skb->len < 1; the stricter
limit incorrectly dropped valid 1-byte LAPB control frames (SABM,
DISC, UA, DM, RR) which carry no PID byte
- Add explicit skb->len < 2 check inside UI branch before the PID
byte (skb->data[1]) access
v4:
- Linearize skb at entry to ax25_rcv(); replace pskb_may_pull() with
skb->len < 2 check (per David Laight review)
v3:
- Remove incorrect Suggested-by; add Fixes:, Cc: stable@
v2:
- Replace skb->len check with pskb_may_pull(skb, 2)
Link to v4: https://lore.kernel.org/netdev/20260417065407.206499-1-ashutoshdesai993@gmail.com/
Link to v3: https://lore.kernel.org/netdev/20260415063654.3831353-1-ashutoshdesai993@gmail.com/
Link to v2: https://lore.kernel.org/netdev/20260409152400.2219716-1-ashutoshdesai993@gmail.com/
Link to v1: https://lore.kernel.org/netdev/20260409012235.2049389-1-ashutoshdesai993@gmail.com/
net/ax25/ax25_in.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/net/ax25/ax25_in.c b/net/ax25/ax25_in.c
index d75b3e9ed93d..c81d6830af48 100644
--- a/net/ax25/ax25_in.c
+++ b/net/ax25/ax25_in.c
@@ -199,6 +199,9 @@ static int ax25_rcv(struct sk_buff *skb, struct net_device *dev,
if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
goto free;
+ if (skb_linearize(skb))
+ goto free;
+
/*
* Parse the address header.
*/
@@ -217,6 +220,9 @@ static int ax25_rcv(struct sk_buff *skb, struct net_device *dev,
*/
skb_pull(skb, ax25_addr_size(&dp));
+ if (skb->len < 1)
+ goto free;
+
/* For our port addresses ? */
if (ax25cmp(&dest, dev_addr) == 0 && dp.lastrepeat + 1 == dp.ndigi)
mine = 1;
@@ -227,6 +233,9 @@ static int ax25_rcv(struct sk_buff *skb, struct net_device *dev,
/* UI frame - bypass LAPB processing */
if ((*skb->data & ~0x10) == AX25_UI && dp.lastrepeat + 1 == dp.ndigi) {
+ if (skb->len < 2)
+ goto free;
+
skb_set_transport_header(skb, 2); /* skip control and pid */
ax25_send_to_raw(&dest, skb, skb->data[1]);
--
2.34.1
^ permalink raw reply related
* Re: [PATCH net] ipv6: rpl: expand skb head when recompressed SRH grows, not only on last segment
From: Greg KH @ 2026-04-21 5:50 UTC (permalink / raw)
To: Kuniyuki Iwashima
Cc: davem, dsahern, edumazet, horms, kuba, linux-kernel, netdev,
pabeni, stable
In-Reply-To: <20260421045510.1546375-1-kuniyu@google.com>
On Tue, Apr 21, 2026 at 04:52:52AM +0000, Kuniyuki Iwashima wrote:
> From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Date: Mon, 20 Apr 2026 21:32:25 +0200
> > ipv6_rpl_srh_rcv() processes a Routing Protocol for LLNs Source Routing
> > Header by decompressing it, swapping the next segment address into
> > ipv6_hdr->daddr, recompressing, and pushing the new header back. The
> > recompressed header can be larger than the original when the
> > address-elision opportunities are worse after the swap.
> >
> > The function pulls (hdr->hdrlen + 1) << 3 bytes (the old header) and
> > pushes (chdr->hdrlen + 1) << 3 + sizeof(ipv6hdr) bytes (the new header
> > plus the IPv6 header). pskb_expand_head() is called to guarantee
> > headroom only when segments_left == 0.
> >
> > A crafted SRH that loops back to the local host (each segment is a local
> > address, so ip6_route_input() delivers it back to ipv6_rpl_srh_rcv())
> > with chdr growing on each pass exhausts headroom over several
> > iterations.
>
> How could this occur.. ? Did AI generate a repro or just
> flagged the possibility ?
It generated a reproducer which caused a crash which made me have to
create this patch. I'll dig it out of the huge pile of mess that was
sent to me and get it into a form that I can reply here to.
thanks,
greg k-h
^ permalink raw reply
* [PATCH v2] llc: Return -EINPROGRESS from llc_ui_connect()
From: Ernestas Kulik @ 2026-04-21 5:54 UTC (permalink / raw)
To: netdev; +Cc: kuba, linux-kernel, Ernestas Kulik
In-Reply-To: <20260415063457.1008868-1-ernestas.k@iconn-networks.com>
Given a zero sk_sndtimeo, llc_ui_connect() skips waiting for state
change and returns 0, confusing userspace applications that will assume
the socket is connected, making e.g. getpeername() calls error out.
More specifically, the issue was discovered in libcoap, where
newly-added AF_LLC socket support was behaving differently from AF_INET
connections due to EINPROGRESS handling being skipped.
Set rc to -EINPROGRESS before considering blocking, akin to AF_INET
sockets.
Signed-off-by: Ernestas Kulik <ernestas.k@iconn-networks.com>
---
net/llc/af_llc.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/net/llc/af_llc.c b/net/llc/af_llc.c
index 59d593bb5d18..1b210db3119e 100644
--- a/net/llc/af_llc.c
+++ b/net/llc/af_llc.c
@@ -518,12 +518,14 @@ static int llc_ui_connect(struct socket *sock, struct sockaddr_unsized *uaddr,
}
if (sk->sk_state == TCP_SYN_SENT) {
const long timeo = sock_sndtimeo(sk, flags & O_NONBLOCK);
- if (!timeo || !llc_ui_wait_for_conn(sk, timeo))
+ if (!timeo || !llc_ui_wait_for_conn(sk, timeo)) {
+ rc = -EINPROGRESS;
goto out;
+ }
rc = sock_intr_errno(timeo);
if (signal_pending(current))
goto out;
}
--
2.53.0
^ permalink raw reply related
* [PATCH v3] llc: Return -EINPROGRESS from llc_ui_connect()
From: Ernestas Kulik @ 2026-04-21 6:02 UTC (permalink / raw)
To: netdev; +Cc: kuba, linux-kernel, Ernestas Kulik
In-Reply-To: <20260415063457.1008868-1-ernestas.k@iconn-networks.com>
Given a zero sk_sndtimeo, llc_ui_connect() skips waiting for state
change and returns 0, confusing userspace applications that will assume
the socket is connected, making e.g. getpeername() calls error out.
More specifically, the issue was discovered in libcoap, where
newly-added AF_LLC socket support was behaving differently from AF_INET
connections due to EINPROGRESS handling being skipped.
Set rc to -EINPROGRESS if connect() would not block, akin to AF_INET
sockets.
Signed-off-by: Ernestas Kulik <ernestas.k@iconn-networks.com>
---
v2:
- Add note about discovering the issue
- Make rc assignment conditional
v3:
- Fix commit message after v2 changes
---
net/llc/af_llc.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/net/llc/af_llc.c b/net/llc/af_llc.c
index 59d593bb5d18..1b210db3119e 100644
--- a/net/llc/af_llc.c
+++ b/net/llc/af_llc.c
@@ -518,12 +518,14 @@ static int llc_ui_connect(struct socket *sock, struct sockaddr_unsized *uaddr,
}
if (sk->sk_state == TCP_SYN_SENT) {
const long timeo = sock_sndtimeo(sk, flags & O_NONBLOCK);
- if (!timeo || !llc_ui_wait_for_conn(sk, timeo))
+ if (!timeo || !llc_ui_wait_for_conn(sk, timeo)) {
+ rc = -EINPROGRESS;
goto out;
+ }
rc = sock_intr_errno(timeo);
if (signal_pending(current))
goto out;
}
--
2.53.0
^ permalink raw reply related
* Re: [PATCH net-deletions] net: remove ISDN subsystem and Bluetooth CMTP
From: Greg KH @ 2026-04-21 6:03 UTC (permalink / raw)
To: Jakub Kicinski
Cc: davem, netdev, edumazet, pabeni, andrew+netdev, horms, corbet,
skhan, marcel, luiz.dentz, mchehab+huawei, jani.nikula, demarchi,
rdunlap, justonli, ivecera, jonathan.cameron, kees,
marco.crivellari, ferr.lambarginio, nihaal, mingo, tglx, linmq006,
linux-doc, linux-bluetooth
In-Reply-To: <20260421022108.1299678-1-kuba@kernel.org>
On Mon, Apr 20, 2026 at 07:21:07PM -0700, Jakub Kicinski wrote:
> Remove the ISDN (mISDN, CAPI) subsystem and Bluetooth CMTP protocol
> from the kernel tree.
>
> ISDN is a pretty old technology and it's unclear whether anyone still
> uses it. I went over the last few years of git history and all the
> commits are either tree-wide conversions or syzbot/static analyzer
> fixes.
>
> When we discussed removal in the past IIRC there were some concerns
> about ISDN still being used in parts of Germany. Unfortunately, the
> code base is quite old, none of the current maintainers are familiar
> with it and AI tools will have a field day finding bugs here.
>
> Delete this code and preserve it in an out-of-tree repository
> for any remaining users:
> https://github.com/linux-netdev/mod-orphan
>
> UAPI constants AF_ISDN/PF_ISDN and the SELinux isdn_socket class
> are preserved for ABI stability, but the rest of uAPI is removed.
>
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
^ permalink raw reply
* Re: [PATCH net-deletions] net: remove ax25 and amateur radio (hamradio) subsystem
From: Greg KH @ 2026-04-21 6:04 UTC (permalink / raw)
To: Jakub Kicinski
Cc: davem, netdev, edumazet, pabeni, andrew+netdev, horms, corbet,
skhan, federico.vaga, carlos.bilbao, avadhut.naik, alexs,
si.yanteng, dzm91, 2023002089, tsbogend, dsahern, jani.nikula,
mchehab+huawei, jirislaby, tytso, herbert, ebiggers,
johannes.berg, geert, pablo, tglx, mashiro.chen, mingo, dqfext,
jreuter, sdf, pkshih, enelsonmoore, mkl, toke, kees, crossd,
jlayton, wangliang74, aha310510, takamitz, kuniyu, linux-doc,
linux-mips
In-Reply-To: <20260421021824.1293976-1-kuba@kernel.org>
On Mon, Apr 20, 2026 at 07:18:23PM -0700, Jakub Kicinski wrote:
> Remove the amateur radio (AX.25, NET/ROM, ROSE) protocol implementation
> and all associated hamradio device drivers from the kernel tree.
> This set of protocols has long been a huge bug/syzbot magnet,
> and since nobody stepped up to help us deal with the influx
> of the AI-generated bug reports we need to move it out of tree
> to protect our sanity.
>
> The code is moved to an out-of-tree repo:
> https://github.com/linux-netdev/mod-orphan
> if it's cleaned up and reworked there we can accept it back.
>
> Minimal stub headers are kept for include/net/ax25.h (AX25_P_IP,
> AX25_ADDR_LEN, ax25_address) and include/net/rose.h (ROSE_ADDR_LEN)
> so that the conditional integration code in arp.c and tun.c continues
> to compile and work when the out-of-tree modules are loaded.
>
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
^ permalink raw reply
* Re: [PATCH v5 net] ax25: fix OOB read after address header strip in ax25_rcv()
From: Ashutosh Desai @ 2026-04-21 6:08 UTC (permalink / raw)
To: netdev
Cc: linux-hams, jreuter, davem, edumazet, kuba, pabeni, horms,
linux-kernel
In-Reply-To: <20260421054858.732939-1-ashutoshdesai993@gmail.com>
[-- Attachment #1: Type: text/plain, Size: 297 bytes --]
On Tue, Apr 21, 2026 at 05:48:58 +0000, Ashutosh Desai wrote:
> [PATCH v5 net] ax25: fix OOB read after address header strip in ax25_rcv()
Please ignore this patch. A net-deletions patch removing the entire ax25
and amateur radio subsystem was posted earlier today. This fix is no
longer needed.
^ permalink raw reply
* Re: Discuss: Future of AX25, NETROM and ROSE in the kernel ?
From: Hugh Blemings @ 2026-04-21 6:28 UTC (permalink / raw)
To: Steve Conklin; +Cc: Stuart Longland VK4MSL, Dan Cross, linux-hams, netdev
In-Reply-To: <CALJxBtX_T8sv11ank-arLfoVqJqXegi3D_ZT9ZFbMHkuf-2RAg@mail.gmail.com>
Hi All,
Just to note in this thread (top posting as it's a bit orthogonal to the
rest of this discussion) that events have preceeded us somewhat here
A patch just recently submitted removes the AX25, NETROM and ROSE code
from the kernel moving it to the mod-orphan sub tree of netdev
https://lore.kernel.org/netdev/20260421021824.1293976-1-kuba@kernel.org/T/#u
A shame but perhaps inevitable - but I think we have a good plan
unfolding to both take care of medium term maintenance of the kernel
code (in tree or out as it may be) as well as a move to userspace in the
longer term.
For the benefit of the netdev readership - we had a thread over in
linux-hams on this but that may not have been visible to folks in
netdev. TL;DR: we think we have a way forward but appreciate this may
not be quick enough to meet the requirements/concerns put forward
If we can delay removal, that'd be grand, but appreciate that moment may
have passed.
Cheers/73
Hugh
VK3YYZ/AD5RV
On 20/4/2026 02:18, Steve Conklin wrote:
> On Sun, Apr 19, 2026 at 4:36 AM Hugh Blemings <hugh@blemings.org> wrote:
>> HI All,
>>
>> On 19/4/2026 14:01, Stuart Longland VK4MSL wrote:
>>> On 19/4/26 05:28, Dan Cross wrote:
>>>> [Top-posting to make meta-commendary]
>>>>
>>>> I wonder if other folks have thoughts, here? It doesn't bode well that
>>>> the discussion hasn't progressed. 🙁
>>> I haven't had a chance to fully review what you've posted… there was a
>>> lot of historical information in there including detail on the
>>> protocols in question. I've earmarked it to go through closely
>>> however. (e.g. I had heard of "ROSE" but never seen a spec for it.)
>>>
>>> My situation was wanting a library that I could use to do AX.25
>>> networking from userspace without having applications having to
>>> elevate to `root` to achieve it. There was also a maintenance
>>> concern. Rather than try and work out the AX.25 kernel stack, I opted
>>> to instead build my own.
>>>
>>> Instructive, but difficult as the documentation is sketchy in places.
>>>
>>> My implementation was written in Python 3.5+ for ease of development.
>>> Probably not the best option, but it got the job done. `aioax25`
>>> allowed me to deliver a project for an emergency comms group and
>>> provides a reasonable foundation for simple tasks. The stack is also
>>> portable to other platforms. (I mostly only care about Linux and
>>> *BSD, but well written software should work elsewhere too. Apparently
>>> it works fine on Apple MacOS X.)
>>>
>>> A userspace AX.25 daemon which implements the stack would seem to be
>>> the best course of action, but the elephant in the room is what the
>>> API would look like.
>>>
>>> The only thing I've seen close to achieving something like that would
>>> be the AGWPE protocol, however the author of that AX.25 stack has
>>> categorically stated that he "owns" that protocol. I don't feel like
>>> going to court to argue copyright of interfaces for the sake of a hobby.
>>>
>>> The AGWPE protocol is also very limiting: a lot of fields in the AX.25
>>> frame are not accessible via this protocol, either for reading or
>>> setting. Want to use the two reserved bits to signal something in a
>>> custom protocol? Too bad.
>>>
>>> I was therefore pondering a "stream"-like protocol using KISS-style
>>> framing (to re-use existing code). The frames would serve as an RPC
>>> mechanism for implementing something like the `libax25` API, exposing
>>> the same functionality and allowing an application to interact with
>>> the AX.25 stack without having to implement the whole protocol (as
>>> they'd have to do with KISS).
>>>
>>> Client applications could connect either via Unix domain sockets or TCP.
>>>
>>> You mention the performance hit of crossing the kernel/user-space
>>> boundary… I think Direwolf experimentally can work as high as
>>> 38400bps. A turn-of-the-century desktop PC was easily able to keep up
>>> with that for PPP links (with `pppd` running in userspace). ARMv7
>>> single board computers made 15 years later can deliver similar
>>> performance. I don't think this will be much of a bottleneck in
>>> practice.
>>>
>>> I think userspace is the right way forward given the niche use case here.
>> Apologies, I kicked off this thread and life intervened a bit and have
>> only now had a chance to get back to read through the excellent
>> discourse since.
>>
>> I did have one off list conversation about this which was similarly
>> leaning towards a well managed/discussed shift to a userspace approach.
>> The individual in question has had quite a lot of both ham radio and
>> FOSS experience - I'll give them a nudge and see if they would be
>> willing to weigh in here too as I think they'd add a lot to the thread.
>>
>> I wonder if anyone on list feels they have the right skills to put
>> together the shim/compatibility library that would be needed to allow
>> the kernel code to be removed? Seems like that might be the next thing
>> to explore ?
>>
>> Hoping things settle down a bit and will be able to contribute more to
>> ongoing discussion
>>
>> vy 73
>> Hugh
>> VK1YYZ/AD5RV
>>
>>
>>
>> --
>> I am slowly moving to hugh@blemings.id.au as my main email address.
>> If you're using hugh@blemings.org please update your address book accordingly.
>> Thank you :)
>>
>>
> Hi all,
>
> I'm another former maintainer who has been less active in the FOSS
> hamm community for a while. Thanks for all the history, and it's been
> great to see familiar names and callsigns again.
> /wave
>
> My personal take is that moving to userspace is the right long-term
> goal. As for deciding the exact form that takes, this thread is a good
> start.
>
> I'd like to make an offer for a long-term home for these components.
>
> I'm a director at ORI (Open Research Institute), and ORI could be a
> home for these. We're a project-based, completely open and volunteer
> nonprofit focused on ham radio and communications. We have volunteers
> with FOSS and ham radio experience, and we're already set up with a
> GitHub org, slack chat, and the infrastructure to manage projects.
>
> https://www.openresearch.institute/
> https://www.openresearch.institute/your-project-is-welcome/
>
> Anyone who currently maintains or has an interest in this is welcome
> to participate there.
> I personally volunteer to help move development infrastructure to ORI,
> if that's the wish of the community.
>
> Steve Conklin AI4QR
>
--
I am slowly moving to hugh@blemings.id.au as my main email address.
If you're using hugh@blemings.org please update your address book accordingly.
Thank you :)
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