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Subject[ANNOUNCE] v5.16.1-rt17
Dear RT folks!

I'm pleased to announce the v5.16.1-rt17 patch set.

Changes since v5.16.1-rt16:

- Make sure that the local_lock_*() are completely optimized away on
!RT without debug.

- Updates to memcg: Disable the threshold handler on RT which is a
cgroup v1 feature (deprecated).

- i2c:
- Host notify on smbus seems not working on RT. Reported by Michael
Below, waiting for feedback.

- The rcar host driver must not disable force threading.

Known issues
- netconsole triggers WARN.

- Valentin Schneider reported a few splats on ARM64, see
https://lkml.kernel.org/r/20210810134127.1394269-1-valentin.schneider@arm.com

The delta patch against v5.16.1-rt16 is appended below and can be found here:

https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.16/incr/patch-5.16.1-rt16-rt17.patch.xz

You can get this release via the git tree at:

git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git v5.16.1-rt17

The RT patch against v5.16.1 can be found here:

https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.16/older/patch-5.16.1-rt17.patch.xz

The split quilt queue is available at:

https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.16/older/patches-5.16.1-rt17.tar.xz

Sebastian

diff --git a/Documentation/admin-guide/cgroup-v1/memory.rst b/Documentation/admin-guide/cgroup-v1/memory.rst
index faac50149a222..2cc502a75ef64 100644
--- a/Documentation/admin-guide/cgroup-v1/memory.rst
+++ b/Documentation/admin-guide/cgroup-v1/memory.rst
@@ -64,6 +64,7 @@ Brief summary of control files.
threads
cgroup.procs show list of processes
cgroup.event_control an interface for event_fd()
+ This knob is not available on CONFIG_PREEMPT_RT systems.
memory.usage_in_bytes show current usage for memory
(See 5.5 for details)
memory.memsw.usage_in_bytes show current usage for memory+Swap
@@ -75,6 +76,7 @@ Brief summary of control files.
memory.max_usage_in_bytes show max memory usage recorded
memory.memsw.max_usage_in_bytes show max memory+Swap usage recorded
memory.soft_limit_in_bytes set/show soft limit of memory usage
+ This knob is not available on CONFIG_PREEMPT_RT systems.
memory.stat show various statistics
memory.use_hierarchy set/show hierarchical account enabled
This knob is deprecated and shouldn't be
diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
index fc13511f4562c..37e7bf4c14cea 100644
--- a/drivers/i2c/busses/i2c-rcar.c
+++ b/drivers/i2c/busses/i2c-rcar.c
@@ -1025,7 +1025,6 @@ static int rcar_i2c_probe(struct platform_device *pdev)
struct rcar_i2c_priv *priv;
struct i2c_adapter *adap;
struct device *dev = &pdev->dev;
- unsigned long irqflags = 0;
irqreturn_t (*irqhandler)(int irq, void *ptr) = rcar_i2c_gen3_irq;
int ret;

@@ -1076,7 +1075,6 @@ static int rcar_i2c_probe(struct platform_device *pdev)
rcar_i2c_write(priv, ICSAR, 0); /* Gen2: must be 0 if not using slave */

if (priv->devtype < I2C_RCAR_GEN3) {
- irqflags |= IRQF_NO_THREAD;
irqhandler = rcar_i2c_gen2_irq;
}

@@ -1102,7 +1100,7 @@ static int rcar_i2c_probe(struct platform_device *pdev)
if (ret < 0)
goto out_pm_disable;
priv->irq = ret;
- ret = devm_request_irq(dev, priv->irq, irqhandler, irqflags, dev_name(dev), priv);
+ ret = devm_request_irq(dev, priv->irq, irqhandler, 0, dev_name(dev), priv);
if (ret < 0) {
dev_err(dev, "cannot get irq %d\n", priv->irq);
goto out_pm_disable;
diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 73253e667de1d..30e93651d5b6b 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -1423,7 +1423,10 @@ int i2c_handle_smbus_host_notify(struct i2c_adapter *adap, unsigned short addr)
if (irq <= 0)
return -ENXIO;

- generic_handle_irq(irq);
+ if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+ generic_handle_irq(irq);
+ else
+ handle_nested_irq(irq);

return 0;
}
diff --git a/include/linux/local_lock_internal.h b/include/linux/local_lock_internal.h
index 975e33b793a77..6d635e8306d64 100644
--- a/include/linux/local_lock_internal.h
+++ b/include/linux/local_lock_internal.h
@@ -44,9 +44,9 @@ static inline void local_lock_debug_init(local_lock_t *l)
}
#else /* CONFIG_DEBUG_LOCK_ALLOC */
# define LOCAL_LOCK_DEBUG_INIT(lockname)
-static inline void local_lock_acquire(local_lock_t *l) { }
-static inline void local_lock_release(local_lock_t *l) { }
-static inline void local_lock_debug_init(local_lock_t *l) { }
+# define local_lock_acquire(__ll) do { typecheck(local_lock_t *, __ll); } while (0)
+# define local_lock_release(__ll) do { typecheck(local_lock_t *, __ll); } while (0)
+# define local_lock_debug_init(__ll) do { typecheck(local_lock_t *, __ll); } while (0)
#endif /* !CONFIG_DEBUG_LOCK_ALLOC */

#define INIT_LOCAL_LOCK(lockname) { LOCAL_LOCK_DEBUG_INIT(lockname) }
diff --git a/localversion-rt b/localversion-rt
index 1199ebade17b4..1e584b47c987e 100644
--- a/localversion-rt
+++ b/localversion-rt
@@ -1 +1 @@
--rt16
+-rt17
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index bfb99225527fe..eb6873f43ef56 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -169,7 +169,6 @@ struct mem_cgroup_event {
struct work_struct remove;
};

-static void mem_cgroup_threshold(struct mem_cgroup *memcg);
static void mem_cgroup_oom_notify(struct mem_cgroup *memcg);

/* Stuffs for move charges at task migration. */
@@ -523,43 +522,6 @@ static unsigned long soft_limit_excess(struct mem_cgroup *memcg)
return excess;
}

-static void mem_cgroup_update_tree(struct mem_cgroup *memcg, int nid)
-{
- unsigned long excess;
- struct mem_cgroup_per_node *mz;
- struct mem_cgroup_tree_per_node *mctz;
-
- mctz = soft_limit_tree.rb_tree_per_node[nid];
- if (!mctz)
- return;
- /*
- * Necessary to update all ancestors when hierarchy is used.
- * because their event counter is not touched.
- */
- for (; memcg; memcg = parent_mem_cgroup(memcg)) {
- mz = memcg->nodeinfo[nid];
- excess = soft_limit_excess(memcg);
- /*
- * We have to update the tree if mz is on RB-tree or
- * mem is over its softlimit.
- */
- if (excess || mz->on_tree) {
- unsigned long flags;
-
- spin_lock_irqsave(&mctz->lock, flags);
- /* if on-tree, remove it */
- if (mz->on_tree)
- __mem_cgroup_remove_exceeded(mz, mctz);
- /*
- * Insert again. mz->usage_in_excess will be updated.
- * If excess is 0, no tree ops.
- */
- __mem_cgroup_insert_exceeded(mz, mctz, excess);
- spin_unlock_irqrestore(&mctz->lock, flags);
- }
- }
-}
-
static void mem_cgroup_remove_from_trees(struct mem_cgroup *memcg)
{
struct mem_cgroup_tree_per_node *mctz;
@@ -673,14 +635,8 @@ void __mod_memcg_state(struct mem_cgroup *memcg, int idx, int val)
if (mem_cgroup_disabled())
return;

- if (IS_ENABLED(CONFIG_PREEMPT_RT))
- preempt_disable();
-
__this_cpu_add(memcg->vmstats_percpu->state[idx], val);
memcg_rstat_updated(memcg);
-
- if (IS_ENABLED(CONFIG_PREEMPT_RT))
- preempt_enable();
}

/* idx can be of type enum memcg_stat_item or node_stat_item. */
@@ -709,7 +665,6 @@ void __mod_memcg_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx,

if (IS_ENABLED(CONFIG_PREEMPT_RT))
preempt_disable();
-
/* Update memcg */
__this_cpu_add(memcg->vmstats_percpu->state[idx], val);

@@ -717,7 +672,6 @@ void __mod_memcg_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx,
__this_cpu_add(pn->lruvec_stats_percpu->state[idx], val);

memcg_rstat_updated(memcg);
-
if (IS_ENABLED(CONFIG_PREEMPT_RT))
preempt_enable();
}
@@ -804,7 +758,6 @@ void __count_memcg_events(struct mem_cgroup *memcg, enum vm_event_item idx,

if (IS_ENABLED(PREEMPT_RT))
preempt_disable();
-
__this_cpu_add(memcg->vmstats_percpu->events[idx], count);
memcg_rstat_updated(memcg);
if (IS_ENABLED(PREEMPT_RT))
@@ -829,9 +782,6 @@ static unsigned long memcg_events_local(struct mem_cgroup *memcg, int event)
static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg,
int nr_pages)
{
- if (IS_ENABLED(CONFIG_PREEMPT_RT))
- preempt_disable();
-
/* pagein of a big page is an event. So, ignore page size */
if (nr_pages > 0)
__count_memcg_events(memcg, PGPGIN, 1);
@@ -841,59 +791,6 @@ static void mem_cgroup_charge_statistics(struct mem_cgroup *memcg,
}

__this_cpu_add(memcg->vmstats_percpu->nr_page_events, nr_pages);
-
- if (IS_ENABLED(CONFIG_PREEMPT_RT))
- preempt_enable();
-}
-
-static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg,
- enum mem_cgroup_events_target target)
-{
- unsigned long val, next;
- bool ret = false;
-
- if (IS_ENABLED(CONFIG_PREEMPT_RT))
- preempt_disable();
-
- val = __this_cpu_read(memcg->vmstats_percpu->nr_page_events);
- next = __this_cpu_read(memcg->vmstats_percpu->targets[target]);
- /* from time_after() in jiffies.h */
- if ((long)(next - val) < 0) {
- switch (target) {
- case MEM_CGROUP_TARGET_THRESH:
- next = val + THRESHOLDS_EVENTS_TARGET;
- break;
- case MEM_CGROUP_TARGET_SOFTLIMIT:
- next = val + SOFTLIMIT_EVENTS_TARGET;
- break;
- default:
- break;
- }
- __this_cpu_write(memcg->vmstats_percpu->targets[target], next);
- ret = true;
- }
- if (IS_ENABLED(CONFIG_PREEMPT_RT))
- preempt_enable();
- return ret;
-}
-
-/*
- * Check events in order.
- *
- */
-static void memcg_check_events(struct mem_cgroup *memcg, int nid)
-{
- /* threshold event is triggered in finer grain than soft limit */
- if (unlikely(mem_cgroup_event_ratelimit(memcg,
- MEM_CGROUP_TARGET_THRESH))) {
- bool do_softlimit;
-
- do_softlimit = mem_cgroup_event_ratelimit(memcg,
- MEM_CGROUP_TARGET_SOFTLIMIT);
- mem_cgroup_threshold(memcg);
- if (unlikely(do_softlimit))
- mem_cgroup_update_tree(memcg, nid);
- }
}

struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
@@ -3834,8 +3731,12 @@ static ssize_t mem_cgroup_write(struct kernfs_open_file *of,
}
break;
case RES_SOFT_LIMIT:
+#ifndef CONFIG_PREEMPT_RT
memcg->soft_limit = nr_pages;
ret = 0;
+#else
+ ret = -EOPNOTSUPP;
+#endif
break;
}
return ret ?: nbytes;
@@ -4140,82 +4041,6 @@ static int mem_cgroup_swappiness_write(struct cgroup_subsys_state *css,
return 0;
}

-static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
-{
- struct mem_cgroup_threshold_ary *t;
- unsigned long usage;
- int i;
-
- rcu_read_lock();
- if (!swap)
- t = rcu_dereference(memcg->thresholds.primary);
- else
- t = rcu_dereference(memcg->memsw_thresholds.primary);
-
- if (!t)
- goto unlock;
-
- usage = mem_cgroup_usage(memcg, swap);
-
- /*
- * current_threshold points to threshold just below or equal to usage.
- * If it's not true, a threshold was crossed after last
- * call of __mem_cgroup_threshold().
- */
- i = t->current_threshold;
-
- /*
- * Iterate backward over array of thresholds starting from
- * current_threshold and check if a threshold is crossed.
- * If none of thresholds below usage is crossed, we read
- * only one element of the array here.
- */
- for (; i >= 0 && unlikely(t->entries[i].threshold > usage); i--)
- eventfd_signal(t->entries[i].eventfd, 1);
-
- /* i = current_threshold + 1 */
- i++;
-
- /*
- * Iterate forward over array of thresholds starting from
- * current_threshold+1 and check if a threshold is crossed.
- * If none of thresholds above usage is crossed, we read
- * only one element of the array here.
- */
- for (; i < t->size && unlikely(t->entries[i].threshold <= usage); i++)
- eventfd_signal(t->entries[i].eventfd, 1);
-
- /* Update current_threshold */
- t->current_threshold = i - 1;
-unlock:
- rcu_read_unlock();
-}
-
-static void mem_cgroup_threshold(struct mem_cgroup *memcg)
-{
- while (memcg) {
- __mem_cgroup_threshold(memcg, false);
- if (do_memsw_account())
- __mem_cgroup_threshold(memcg, true);
-
- memcg = parent_mem_cgroup(memcg);
- }
-}
-
-static int compare_thresholds(const void *a, const void *b)
-{
- const struct mem_cgroup_threshold *_a = a;
- const struct mem_cgroup_threshold *_b = b;
-
- if (_a->threshold > _b->threshold)
- return 1;
-
- if (_a->threshold < _b->threshold)
- return -1;
-
- return 0;
-}
-
static int mem_cgroup_oom_notify_cb(struct mem_cgroup *memcg)
{
struct mem_cgroup_eventfd_list *ev;
@@ -4237,234 +4062,6 @@ static void mem_cgroup_oom_notify(struct mem_cgroup *memcg)
mem_cgroup_oom_notify_cb(iter);
}

-static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
- struct eventfd_ctx *eventfd, const char *args, enum res_type type)
-{
- struct mem_cgroup_thresholds *thresholds;
- struct mem_cgroup_threshold_ary *new;
- unsigned long threshold;
- unsigned long usage;
- int i, size, ret;
-
- ret = page_counter_memparse(args, "-1", &threshold);
- if (ret)
- return ret;
-
- mutex_lock(&memcg->thresholds_lock);
-
- if (type == _MEM) {
- thresholds = &memcg->thresholds;
- usage = mem_cgroup_usage(memcg, false);
- } else if (type == _MEMSWAP) {
- thresholds = &memcg->memsw_thresholds;
- usage = mem_cgroup_usage(memcg, true);
- } else
- BUG();
-
- /* Check if a threshold crossed before adding a new one */
- if (thresholds->primary)
- __mem_cgroup_threshold(memcg, type == _MEMSWAP);
-
- size = thresholds->primary ? thresholds->primary->size + 1 : 1;
-
- /* Allocate memory for new array of thresholds */
- new = kmalloc(struct_size(new, entries, size), GFP_KERNEL);
- if (!new) {
- ret = -ENOMEM;
- goto unlock;
- }
- new->size = size;
-
- /* Copy thresholds (if any) to new array */
- if (thresholds->primary)
- memcpy(new->entries, thresholds->primary->entries,
- flex_array_size(new, entries, size - 1));
-
- /* Add new threshold */
- new->entries[size - 1].eventfd = eventfd;
- new->entries[size - 1].threshold = threshold;
-
- /* Sort thresholds. Registering of new threshold isn't time-critical */
- sort(new->entries, size, sizeof(*new->entries),
- compare_thresholds, NULL);
-
- /* Find current threshold */
- new->current_threshold = -1;
- for (i = 0; i < size; i++) {
- if (new->entries[i].threshold <= usage) {
- /*
- * new->current_threshold will not be used until
- * rcu_assign_pointer(), so it's safe to increment
- * it here.
- */
- ++new->current_threshold;
- } else
- break;
- }
-
- /* Free old spare buffer and save old primary buffer as spare */
- kfree(thresholds->spare);
- thresholds->spare = thresholds->primary;
-
- rcu_assign_pointer(thresholds->primary, new);
-
- /* To be sure that nobody uses thresholds */
- synchronize_rcu();
-
-unlock:
- mutex_unlock(&memcg->thresholds_lock);
-
- return ret;
-}
-
-static int mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
- struct eventfd_ctx *eventfd, const char *args)
-{
- return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEM);
-}
-
-static int memsw_cgroup_usage_register_event(struct mem_cgroup *memcg,
- struct eventfd_ctx *eventfd, const char *args)
-{
- return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEMSWAP);
-}
-
-static void __mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
- struct eventfd_ctx *eventfd, enum res_type type)
-{
- struct mem_cgroup_thresholds *thresholds;
- struct mem_cgroup_threshold_ary *new;
- unsigned long usage;
- int i, j, size, entries;
-
- mutex_lock(&memcg->thresholds_lock);
-
- if (type == _MEM) {
- thresholds = &memcg->thresholds;
- usage = mem_cgroup_usage(memcg, false);
- } else if (type == _MEMSWAP) {
- thresholds = &memcg->memsw_thresholds;
- usage = mem_cgroup_usage(memcg, true);
- } else
- BUG();
-
- if (!thresholds->primary)
- goto unlock;
-
- /* Check if a threshold crossed before removing */
- __mem_cgroup_threshold(memcg, type == _MEMSWAP);
-
- /* Calculate new number of threshold */
- size = entries = 0;
- for (i = 0; i < thresholds->primary->size; i++) {
- if (thresholds->primary->entries[i].eventfd != eventfd)
- size++;
- else
- entries++;
- }
-
- new = thresholds->spare;
-
- /* If no items related to eventfd have been cleared, nothing to do */
- if (!entries)
- goto unlock;
-
- /* Set thresholds array to NULL if we don't have thresholds */
- if (!size) {
- kfree(new);
- new = NULL;
- goto swap_buffers;
- }
-
- new->size = size;
-
- /* Copy thresholds and find current threshold */
- new->current_threshold = -1;
- for (i = 0, j = 0; i < thresholds->primary->size; i++) {
- if (thresholds->primary->entries[i].eventfd == eventfd)
- continue;
-
- new->entries[j] = thresholds->primary->entries[i];
- if (new->entries[j].threshold <= usage) {
- /*
- * new->current_threshold will not be used
- * until rcu_assign_pointer(), so it's safe to increment
- * it here.
- */
- ++new->current_threshold;
- }
- j++;
- }
-
-swap_buffers:
- /* Swap primary and spare array */
- thresholds->spare = thresholds->primary;
-
- rcu_assign_pointer(thresholds->primary, new);
-
- /* To be sure that nobody uses thresholds */
- synchronize_rcu();
-
- /* If all events are unregistered, free the spare array */
- if (!new) {
- kfree(thresholds->spare);
- thresholds->spare = NULL;
- }
-unlock:
- mutex_unlock(&memcg->thresholds_lock);
-}
-
-static void mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
- struct eventfd_ctx *eventfd)
-{
- return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEM);
-}
-
-static void memsw_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
- struct eventfd_ctx *eventfd)
-{
- return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEMSWAP);
-}
-
-static int mem_cgroup_oom_register_event(struct mem_cgroup *memcg,
- struct eventfd_ctx *eventfd, const char *args)
-{
- struct mem_cgroup_eventfd_list *event;
-
- event = kmalloc(sizeof(*event), GFP_KERNEL);
- if (!event)
- return -ENOMEM;
-
- spin_lock(&memcg_oom_lock);
-
- event->eventfd = eventfd;
- list_add(&event->list, &memcg->oom_notify);
-
- /* already in OOM ? */
- if (memcg->under_oom)
- eventfd_signal(eventfd, 1);
- spin_unlock(&memcg_oom_lock);
-
- return 0;
-}
-
-static void mem_cgroup_oom_unregister_event(struct mem_cgroup *memcg,
- struct eventfd_ctx *eventfd)
-{
- struct mem_cgroup_eventfd_list *ev, *tmp;
-
- spin_lock(&memcg_oom_lock);
-
- list_for_each_entry_safe(ev, tmp, &memcg->oom_notify, list) {
- if (ev->eventfd == eventfd) {
- list_del(&ev->list);
- kfree(ev);
- }
- }
-
- spin_unlock(&memcg_oom_lock);
-}
-
static int mem_cgroup_oom_control_read(struct seq_file *sf, void *v)
{
struct mem_cgroup *memcg = mem_cgroup_from_seq(sf);
@@ -4705,6 +4302,7 @@ static void memcg_wb_domain_size_changed(struct mem_cgroup *memcg)

#endif /* CONFIG_CGROUP_WRITEBACK */

+#ifndef CONFIG_PREEMPT_RT
/*
* DO NOT USE IN NEW FILES.
*
@@ -4718,6 +4316,391 @@ static void memcg_wb_domain_size_changed(struct mem_cgroup *memcg)
* possible.
*/

+static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg,
+ enum mem_cgroup_events_target target)
+{
+ unsigned long val, next;
+
+ val = __this_cpu_read(memcg->vmstats_percpu->nr_page_events);
+ next = __this_cpu_read(memcg->vmstats_percpu->targets[target]);
+ /* from time_after() in jiffies.h */
+ if ((long)(next - val) < 0) {
+ switch (target) {
+ case MEM_CGROUP_TARGET_THRESH:
+ next = val + THRESHOLDS_EVENTS_TARGET;
+ break;
+ case MEM_CGROUP_TARGET_SOFTLIMIT:
+ next = val + SOFTLIMIT_EVENTS_TARGET;
+ break;
+ default:
+ break;
+ }
+ __this_cpu_write(memcg->vmstats_percpu->targets[target], next);
+ return true;
+ }
+ return false;
+}
+
+static void mem_cgroup_update_tree(struct mem_cgroup *memcg, int nid)
+{
+ unsigned long excess;
+ struct mem_cgroup_per_node *mz;
+ struct mem_cgroup_tree_per_node *mctz;
+
+ mctz = soft_limit_tree.rb_tree_per_node[nid];
+ if (!mctz)
+ return;
+ /*
+ * Necessary to update all ancestors when hierarchy is used.
+ * because their event counter is not touched.
+ */
+ for (; memcg; memcg = parent_mem_cgroup(memcg)) {
+ mz = memcg->nodeinfo[nid];
+ excess = soft_limit_excess(memcg);
+ /*
+ * We have to update the tree if mz is on RB-tree or
+ * mem is over its softlimit.
+ */
+ if (excess || mz->on_tree) {
+ unsigned long flags;
+
+ spin_lock_irqsave(&mctz->lock, flags);
+ /* if on-tree, remove it */
+ if (mz->on_tree)
+ __mem_cgroup_remove_exceeded(mz, mctz);
+ /*
+ * Insert again. mz->usage_in_excess will be updated.
+ * If excess is 0, no tree ops.
+ */
+ __mem_cgroup_insert_exceeded(mz, mctz, excess);
+ spin_unlock_irqrestore(&mctz->lock, flags);
+ }
+ }
+}
+
+static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
+{
+ struct mem_cgroup_threshold_ary *t;
+ unsigned long usage;
+ int i;
+
+ rcu_read_lock();
+ if (!swap)
+ t = rcu_dereference(memcg->thresholds.primary);
+ else
+ t = rcu_dereference(memcg->memsw_thresholds.primary);
+
+ if (!t)
+ goto unlock;
+
+ usage = mem_cgroup_usage(memcg, swap);
+
+ /*
+ * current_threshold points to threshold just below or equal to usage.
+ * If it's not true, a threshold was crossed after last
+ * call of __mem_cgroup_threshold().
+ */
+ i = t->current_threshold;
+
+ /*
+ * Iterate backward over array of thresholds starting from
+ * current_threshold and check if a threshold is crossed.
+ * If none of thresholds below usage is crossed, we read
+ * only one element of the array here.
+ */
+ for (; i >= 0 && unlikely(t->entries[i].threshold > usage); i--)
+ eventfd_signal(t->entries[i].eventfd, 1);
+
+ /* i = current_threshold + 1 */
+ i++;
+
+ /*
+ * Iterate forward over array of thresholds starting from
+ * current_threshold+1 and check if a threshold is crossed.
+ * If none of thresholds above usage is crossed, we read
+ * only one element of the array here.
+ */
+ for (; i < t->size && unlikely(t->entries[i].threshold <= usage); i++)
+ eventfd_signal(t->entries[i].eventfd, 1);
+
+ /* Update current_threshold */
+ t->current_threshold = i - 1;
+unlock:
+ rcu_read_unlock();
+}
+
+static void mem_cgroup_threshold(struct mem_cgroup *memcg)
+{
+ while (memcg) {
+ __mem_cgroup_threshold(memcg, false);
+ if (do_memsw_account())
+ __mem_cgroup_threshold(memcg, true);
+
+ memcg = parent_mem_cgroup(memcg);
+ }
+}
+
+/*
+ * Check events in order.
+ *
+ */
+static void memcg_check_events(struct mem_cgroup *memcg, int nid)
+{
+ /* threshold event is triggered in finer grain than soft limit */
+ if (unlikely(mem_cgroup_event_ratelimit(memcg,
+ MEM_CGROUP_TARGET_THRESH))) {
+ bool do_softlimit;
+
+ do_softlimit = mem_cgroup_event_ratelimit(memcg,
+ MEM_CGROUP_TARGET_SOFTLIMIT);
+ mem_cgroup_threshold(memcg);
+ if (unlikely(do_softlimit))
+ mem_cgroup_update_tree(memcg, nid);
+ }
+}
+
+static int compare_thresholds(const void *a, const void *b)
+{
+ const struct mem_cgroup_threshold *_a = a;
+ const struct mem_cgroup_threshold *_b = b;
+
+ if (_a->threshold > _b->threshold)
+ return 1;
+
+ if (_a->threshold < _b->threshold)
+ return -1;
+
+ return 0;
+}
+
+static int __mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
+ struct eventfd_ctx *eventfd, const char *args, enum res_type type)
+{
+ struct mem_cgroup_thresholds *thresholds;
+ struct mem_cgroup_threshold_ary *new;
+ unsigned long threshold;
+ unsigned long usage;
+ int i, size, ret;
+
+ ret = page_counter_memparse(args, "-1", &threshold);
+ if (ret)
+ return ret;
+
+ mutex_lock(&memcg->thresholds_lock);
+
+ if (type == _MEM) {
+ thresholds = &memcg->thresholds;
+ usage = mem_cgroup_usage(memcg, false);
+ } else if (type == _MEMSWAP) {
+ thresholds = &memcg->memsw_thresholds;
+ usage = mem_cgroup_usage(memcg, true);
+ } else
+ BUG();
+
+ /* Check if a threshold crossed before adding a new one */
+ if (thresholds->primary)
+ __mem_cgroup_threshold(memcg, type == _MEMSWAP);
+
+ size = thresholds->primary ? thresholds->primary->size + 1 : 1;
+
+ /* Allocate memory for new array of thresholds */
+ new = kmalloc(struct_size(new, entries, size), GFP_KERNEL);
+ if (!new) {
+ ret = -ENOMEM;
+ goto unlock;
+ }
+ new->size = size;
+
+ /* Copy thresholds (if any) to new array */
+ if (thresholds->primary)
+ memcpy(new->entries, thresholds->primary->entries,
+ flex_array_size(new, entries, size - 1));
+
+ /* Add new threshold */
+ new->entries[size - 1].eventfd = eventfd;
+ new->entries[size - 1].threshold = threshold;
+
+ /* Sort thresholds. Registering of new threshold isn't time-critical */
+ sort(new->entries, size, sizeof(*new->entries),
+ compare_thresholds, NULL);
+
+ /* Find current threshold */
+ new->current_threshold = -1;
+ for (i = 0; i < size; i++) {
+ if (new->entries[i].threshold <= usage) {
+ /*
+ * new->current_threshold will not be used until
+ * rcu_assign_pointer(), so it's safe to increment
+ * it here.
+ */
+ ++new->current_threshold;
+ } else
+ break;
+ }
+
+ /* Free old spare buffer and save old primary buffer as spare */
+ kfree(thresholds->spare);
+ thresholds->spare = thresholds->primary;
+
+ rcu_assign_pointer(thresholds->primary, new);
+
+ /* To be sure that nobody uses thresholds */
+ synchronize_rcu();
+
+unlock:
+ mutex_unlock(&memcg->thresholds_lock);
+
+ return ret;
+}
+
+static int mem_cgroup_usage_register_event(struct mem_cgroup *memcg,
+ struct eventfd_ctx *eventfd, const char *args)
+{
+ return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEM);
+}
+
+static int memsw_cgroup_usage_register_event(struct mem_cgroup *memcg,
+ struct eventfd_ctx *eventfd, const char *args)
+{
+ return __mem_cgroup_usage_register_event(memcg, eventfd, args, _MEMSWAP);
+}
+
+static void __mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
+ struct eventfd_ctx *eventfd, enum res_type type)
+{
+ struct mem_cgroup_thresholds *thresholds;
+ struct mem_cgroup_threshold_ary *new;
+ unsigned long usage;
+ int i, j, size, entries;
+
+ mutex_lock(&memcg->thresholds_lock);
+
+ if (type == _MEM) {
+ thresholds = &memcg->thresholds;
+ usage = mem_cgroup_usage(memcg, false);
+ } else if (type == _MEMSWAP) {
+ thresholds = &memcg->memsw_thresholds;
+ usage = mem_cgroup_usage(memcg, true);
+ } else
+ BUG();
+
+ if (!thresholds->primary)
+ goto unlock;
+
+ /* Check if a threshold crossed before removing */
+ __mem_cgroup_threshold(memcg, type == _MEMSWAP);
+
+ /* Calculate new number of threshold */
+ size = entries = 0;
+ for (i = 0; i < thresholds->primary->size; i++) {
+ if (thresholds->primary->entries[i].eventfd != eventfd)
+ size++;
+ else
+ entries++;
+ }
+
+ new = thresholds->spare;
+
+ /* If no items related to eventfd have been cleared, nothing to do */
+ if (!entries)
+ goto unlock;
+
+ /* Set thresholds array to NULL if we don't have thresholds */
+ if (!size) {
+ kfree(new);
+ new = NULL;
+ goto swap_buffers;
+ }
+
+ new->size = size;
+
+ /* Copy thresholds and find current threshold */
+ new->current_threshold = -1;
+ for (i = 0, j = 0; i < thresholds->primary->size; i++) {
+ if (thresholds->primary->entries[i].eventfd == eventfd)
+ continue;
+
+ new->entries[j] = thresholds->primary->entries[i];
+ if (new->entries[j].threshold <= usage) {
+ /*
+ * new->current_threshold will not be used
+ * until rcu_assign_pointer(), so it's safe to increment
+ * it here.
+ */
+ ++new->current_threshold;
+ }
+ j++;
+ }
+
+swap_buffers:
+ /* Swap primary and spare array */
+ thresholds->spare = thresholds->primary;
+
+ rcu_assign_pointer(thresholds->primary, new);
+
+ /* To be sure that nobody uses thresholds */
+ synchronize_rcu();
+
+ /* If all events are unregistered, free the spare array */
+ if (!new) {
+ kfree(thresholds->spare);
+ thresholds->spare = NULL;
+ }
+unlock:
+ mutex_unlock(&memcg->thresholds_lock);
+}
+
+static void mem_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
+ struct eventfd_ctx *eventfd)
+{
+ return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEM);
+}
+
+static void memsw_cgroup_usage_unregister_event(struct mem_cgroup *memcg,
+ struct eventfd_ctx *eventfd)
+{
+ return __mem_cgroup_usage_unregister_event(memcg, eventfd, _MEMSWAP);
+}
+
+static int mem_cgroup_oom_register_event(struct mem_cgroup *memcg,
+ struct eventfd_ctx *eventfd, const char *args)
+{
+ struct mem_cgroup_eventfd_list *event;
+
+ event = kmalloc(sizeof(*event), GFP_KERNEL);
+ if (!event)
+ return -ENOMEM;
+
+ spin_lock(&memcg_oom_lock);
+
+ event->eventfd = eventfd;
+ list_add(&event->list, &memcg->oom_notify);
+
+ /* already in OOM ? */
+ if (memcg->under_oom)
+ eventfd_signal(eventfd, 1);
+ spin_unlock(&memcg_oom_lock);
+
+ return 0;
+}
+
+static void mem_cgroup_oom_unregister_event(struct mem_cgroup *memcg,
+ struct eventfd_ctx *eventfd)
+{
+ struct mem_cgroup_eventfd_list *ev, *tmp;
+
+ spin_lock(&memcg_oom_lock);
+
+ list_for_each_entry_safe(ev, tmp, &memcg->oom_notify, list) {
+ if (ev->eventfd == eventfd) {
+ list_del(&ev->list);
+ kfree(ev);
+ }
+ }
+
+ spin_unlock(&memcg_oom_lock);
+}
+
/*
* Unregister event and free resources.
*
@@ -4928,6 +4911,18 @@ static ssize_t memcg_write_event_control(struct kernfs_open_file *of,
return ret;
}

+#else
+
+static ssize_t memcg_write_event_control(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ return -EOPNOTSUPP;
+}
+
+static void memcg_check_events(struct mem_cgroup *memcg, int nid) { }
+
+#endif
+
static struct cftype mem_cgroup_legacy_files[] = {
{
.name = "usage_in_bytes",
@@ -5728,14 +5723,12 @@ static int mem_cgroup_move_account(struct page *page,
ret = 0;
nid = folio_nid(folio);

- if (!IS_ENABLED(CONFIG_PREEMPT_RT))
- local_irq_disable();
+ local_irq_disable();
mem_cgroup_charge_statistics(to, nr_pages);
memcg_check_events(to, nid);
mem_cgroup_charge_statistics(from, -nr_pages);
memcg_check_events(from, nid);
- if (!IS_ENABLED(CONFIG_PREEMPT_RT))
- local_irq_enable();
+ local_irq_enable();
out_unlock:
folio_unlock(folio);
out:
@@ -6755,12 +6748,10 @@ static int charge_memcg(struct folio *folio, struct mem_cgroup *memcg,
css_get(&memcg->css);
commit_charge(folio, memcg);

- if (!IS_ENABLED(CONFIG_PREEMPT_RT))
- local_irq_disable();
+ local_irq_disable();
mem_cgroup_charge_statistics(memcg, nr_pages);
memcg_check_events(memcg, folio_nid(folio));
- if (!IS_ENABLED(CONFIG_PREEMPT_RT))
- local_irq_enable();
+ local_irq_enable();
out:
return ret;
}
@@ -6872,20 +6863,11 @@ static void uncharge_batch(const struct uncharge_gather *ug)
memcg_oom_recover(ug->memcg);
}

- if (!IS_ENABLED(CONFIG_PREEMPT_RT)) {
- local_irq_save(flags);
- __count_memcg_events(ug->memcg, PGPGOUT, ug->pgpgout);
- __this_cpu_add(ug->memcg->vmstats_percpu->nr_page_events, ug->nr_memory);
- memcg_check_events(ug->memcg, ug->nid);
- local_irq_restore(flags);
- } else {
- preempt_disable();
- __count_memcg_events(ug->memcg, PGPGOUT, ug->pgpgout);
- __this_cpu_add(ug->memcg->vmstats_percpu->nr_page_events, ug->nr_memory);
- preempt_enable();
-
- memcg_check_events(ug->memcg, ug->nid);
- }
+ local_irq_save(flags);
+ __count_memcg_events(ug->memcg, PGPGOUT, ug->pgpgout);
+ __this_cpu_add(ug->memcg->vmstats_percpu->nr_page_events, ug->nr_memory);
+ memcg_check_events(ug->memcg, ug->nid);
+ local_irq_restore(flags);

/* drop reference from uncharge_folio */
css_put(&ug->memcg->css);
@@ -7026,12 +7008,10 @@ void mem_cgroup_migrate(struct folio *old, struct folio *new)
css_get(&memcg->css);
commit_charge(new, memcg);

- if (!IS_ENABLED(CONFIG_PREEMPT_RT))
- local_irq_save(flags);
+ local_irq_save(flags);
mem_cgroup_charge_statistics(memcg, nr_pages);
memcg_check_events(memcg, folio_nid(new));
- if (!IS_ENABLED(CONFIG_PREEMPT_RT))
- local_irq_restore(flags);
+ local_irq_restore(flags);
}

DEFINE_STATIC_KEY_FALSE(memcg_sockets_enabled_key);
@@ -7258,8 +7238,15 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
* On PREEMPT_RT interrupts are never disabled and the updates to per-CPU
* variables are synchronised by keeping preemption disabled.
*/
- VM_BUG_ON(!IS_ENABLED(CONFIG_PREEMPT_RT) && !irqs_disabled());
- mem_cgroup_charge_statistics(memcg, -nr_entries);
+ if (!IS_ENABLED(CONFIG_PREEMPT_RT)) {
+ VM_BUG_ON(!irqs_disabled());
+ mem_cgroup_charge_statistics(memcg, -nr_entries);
+ } else {
+ preempt_disable();
+ mem_cgroup_charge_statistics(memcg, -nr_entries);
+ preempt_enable();
+ }
+
memcg_check_events(memcg, page_to_nid(page));

css_put(&memcg->css);
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