[PATCH 2/2 x86] fix page faults by perf events in nmi if kmemcheck is enabled

Li Zhong
2012-02-20T06:07:55Z

This patch tries to use __get_free_pages for the perf_event and it's
callchain buffers if CONFIG_KMEMCHECK is enabled.

Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
---
kernel/events/callchain.c | 29 +++++++++++++++++++++++++++++
kernel/events/core.c | 13 +++++++++++++
2 files changed, 42 insertions(+), 0 deletions(-)

diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c
index 6581a04..57f5eaa 100644
--- a/kernel/events/callchain.c
+++ b/kernel/events/callchain.c
@@ -38,13 +38,25 @@ static void release_callchain_buffers_rcu(struct
rcu_head *head)
{
struct callchain_cpus_entries *entries;
int cpu;
+#ifdef CONFIG_KMEMCHECK
+ int size;
+
+ size = sizeof(struct perf_callchain_entry) * PERF_NR_CONTEXTS;
+#endif

entries = container_of(head, struct callchain_cpus_entries, rcu_head);

for_each_possible_cpu(cpu)
+#ifdef CONFIG_KMEMCHECK
+ free_pages((unsigned long)entries->cpu_entries[cpu],
+ get_order(size));
+ size = offsetof(struct callchain_cpus_entries,
cpu_entries[nr_cpu_ids]);
+ free_pages((unsigned long)entries, get_order(size));
+#else
kfree(entries->cpu_entries[cpu]);

kfree(entries);
+#endif
}

static void release_callchain_buffers(void)
@@ -69,15 +81,25 @@ static int alloc_callchain_buffers(void)
*/
size = offsetof(struct callchain_cpus_entries,
cpu_entries[nr_cpu_ids]);

+#ifdef CONFIG_KMEMCHECK
+ entries = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
+ get_order(size));
+#else
entries = kzalloc(size, GFP_KERNEL);
+#endif
if (!entries)
return -ENOMEM;

size = sizeof(struct perf_callchain_entry) * PERF_NR_CONTEXTS;

for_each_possible_cpu(cpu) {
+#ifdef CONFIG_KMEMCHECK
+ entries->cpu_entries[cpu] = (void *)__get_free_pages(
+ GFP_KERNEL, get_order(size));
+#else
entries->cpu_entries[cpu] = kmalloc_node(size, GFP_KERNEL,
cpu_to_node(cpu));
+#endif
if (!entries->cpu_entries[cpu])
goto fail;
}
@@ -88,8 +110,15 @@ static int alloc_callchain_buffers(void)

fail:
for_each_possible_cpu(cpu)
+#ifdef CONFIG_KMEMCHECK
+ free_pages((unsigned long)entries->cpu_entries[cpu],
+ get_order(size));
+ size = offsetof(struct callchain_cpus_entries,
cpu_entries[nr_cpu_ids]);
+ free_pages((unsigned long)entries, get_order(size));
+#else
kfree(entries->cpu_entries[cpu]);
kfree(entries);
+#endif

return -ENOMEM;
}
diff --git a/kernel/events/core.c b/kernel/events/core.c
index ba36013..841c2ab 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -2758,7 +2758,11 @@ static void free_event_rcu(struct rcu_head *head)
if (event->ns)
put_pid_ns(event->ns);
perf_event_free_filter(event);
+#ifdef CONFIG_KMEMCHECK
+ free_pages((unsigned long)event, get_order(sizeof(*event)));
+#else
kfree(event);
+#endif
}

static void ring_buffer_put(struct ring_buffer *rb);
@@ -5723,7 +5727,12 @@ perf_event_alloc(struct perf_event_attr *attr,
int cpu,
return ERR_PTR(-EINVAL);
}

+#ifdef CONFIG_KMEMCHECK
+ event = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
+ get_order(sizeof(*event)));
+#else
event = kzalloc(sizeof(*event), GFP_KERNEL);
+#endif
if (!event)
return ERR_PTR(-ENOMEM);

@@ -5810,7 +5819,11 @@ done:
if (err) {
if (event->ns)
put_pid_ns(event->ns);
+#ifdef CONFIG_KMEMCHECK
+ free_pages((unsigned long)event, get_order(sizeof(*event)));
+#else
kfree(event);
+#endif
return ERR_PTR(err);
}

--
1.7.5.4