* [for-next][PATCH 1/3] tracing/ring_buffer: Try harder to allocate
2017-07-21 1:24 [for-next][PATCH 0/3] tracing: Updates for 4.13-rc2 Steven Rostedt
@ 2017-07-21 1:24 ` Steven Rostedt
2017-07-21 1:24 ` [for-next][PATCH 2/3] tracing: Fix kmemleak in instance_rmdir Steven Rostedt
2017-07-21 1:24 ` [for-next][PATCH 3/3] trace: fix the errors caused by incompatible type of RCU variables Steven Rostedt
2 siblings, 0 replies; 4+ messages in thread
From: Steven Rostedt @ 2017-07-21 1:24 UTC (permalink / raw)
To: linux-kernel
Cc: Ingo Molnar, Andrew Morton, Tim Murray, Ingo Molnar,
Vlastimil Babka, Johannes Weiner, Michal Hocko, Joel Fernandes
[-- Attachment #1: 0001-tracing-ring_buffer-Try-harder-to-allocate.patch --]
[-- Type: text/plain, Size: 2649 bytes --]
From: Joel Fernandes <joelaf@google.com>
ftrace can fail to allocate per-CPU ring buffer on systems with a large
number of CPUs coupled while large amounts of cache happening in the
page cache. Currently the ring buffer allocation doesn't retry in the VM
implementation even if direct-reclaim made some progress but still
wasn't able to find a free page. On retrying I see that the allocations
almost always succeed. The retry doesn't happen because __GFP_NORETRY is
used in the tracer to prevent the case where we might OOM, however if we
drop __GFP_NORETRY, we risk destabilizing the system if OOM killer is
triggered. To prevent this situation, use the __GFP_RETRY_MAYFAIL flag
introduced recently [1].
Tested the following still succeeds without destabilizing a system with
1GB memory.
echo 300000 > /sys/kernel/debug/tracing/buffer_size_kb
[1] https://marc.info/?l=linux-mm&m=149820805124906&w=2
Link: http://lkml.kernel.org/r/20170713021416.8897-1-joelaf@google.com
Cc: Tim Murray <timmurray@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Joel Fernandes <joelaf@google.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
kernel/trace/ring_buffer.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 4ae268e687fe..529cc50d7243 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1136,12 +1136,12 @@ static int __rb_allocate_pages(long nr_pages, struct list_head *pages, int cpu)
for (i = 0; i < nr_pages; i++) {
struct page *page;
/*
- * __GFP_NORETRY flag makes sure that the allocation fails
- * gracefully without invoking oom-killer and the system is
- * not destabilized.
+ * __GFP_RETRY_MAYFAIL flag makes sure that the allocation fails
+ * gracefully without invoking oom-killer and the system is not
+ * destabilized.
*/
bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()),
- GFP_KERNEL | __GFP_NORETRY,
+ GFP_KERNEL | __GFP_RETRY_MAYFAIL,
cpu_to_node(cpu));
if (!bpage)
goto free_pages;
@@ -1149,7 +1149,7 @@ static int __rb_allocate_pages(long nr_pages, struct list_head *pages, int cpu)
list_add(&bpage->list, pages);
page = alloc_pages_node(cpu_to_node(cpu),
- GFP_KERNEL | __GFP_NORETRY, 0);
+ GFP_KERNEL | __GFP_RETRY_MAYFAIL, 0);
if (!page)
goto free_pages;
bpage->page = page_address(page);
--
2.10.2
^ permalink raw reply related [flat|nested] 4+ messages in thread* [for-next][PATCH 3/3] trace: fix the errors caused by incompatible type of RCU variables
2017-07-21 1:24 [for-next][PATCH 0/3] tracing: Updates for 4.13-rc2 Steven Rostedt
2017-07-21 1:24 ` [for-next][PATCH 1/3] tracing/ring_buffer: Try harder to allocate Steven Rostedt
2017-07-21 1:24 ` [for-next][PATCH 2/3] tracing: Fix kmemleak in instance_rmdir Steven Rostedt
@ 2017-07-21 1:24 ` Steven Rostedt
2 siblings, 0 replies; 4+ messages in thread
From: Steven Rostedt @ 2017-07-21 1:24 UTC (permalink / raw)
To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Chunyan Zhang
[-- Attachment #1: 0003-trace-fix-the-errors-caused-by-incompatible-type-of-.patch --]
[-- Type: text/plain, Size: 6942 bytes --]
From: Chunyan Zhang <zhang.chunyan@linaro.org>
The variables which are processed by RCU functions should be annotated
as RCU, otherwise sparse will report the errors like below:
"error: incompatible types in comparison expression (different
address spaces)"
Link: http://lkml.kernel.org/r/1496823171-7758-1-git-send-email-zhang.chunyan@linaro.org
Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>
[ Updated to not be 100% 80 column strict ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
include/linux/ftrace.h | 6 +++---
include/linux/trace_events.h | 2 +-
kernel/trace/ftrace.c | 41 +++++++++++++++++++++++++++--------------
kernel/trace/trace.h | 6 +++---
4 files changed, 34 insertions(+), 21 deletions(-)
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 5857390ac35a..6383115e9d2c 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -145,8 +145,8 @@ enum {
#ifdef CONFIG_DYNAMIC_FTRACE
/* The hash used to know what functions callbacks trace */
struct ftrace_ops_hash {
- struct ftrace_hash *notrace_hash;
- struct ftrace_hash *filter_hash;
+ struct ftrace_hash __rcu *notrace_hash;
+ struct ftrace_hash __rcu *filter_hash;
struct mutex regex_lock;
};
@@ -168,7 +168,7 @@ static inline void ftrace_free_init_mem(void) { }
*/
struct ftrace_ops {
ftrace_func_t func;
- struct ftrace_ops *next;
+ struct ftrace_ops __rcu *next;
unsigned long flags;
void *private;
ftrace_func_t saved_func;
diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index f73cedfa2e0b..536c80ff7ad9 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -338,7 +338,7 @@ enum {
struct trace_event_file {
struct list_head list;
struct trace_event_call *event_call;
- struct event_filter *filter;
+ struct event_filter __rcu *filter;
struct dentry *dir;
struct trace_array *tr;
struct trace_subsystem_dir *system;
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 53f6b6401cf0..02004ae91860 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -113,7 +113,7 @@ static int ftrace_disabled __read_mostly;
static DEFINE_MUTEX(ftrace_lock);
-static struct ftrace_ops *ftrace_ops_list __read_mostly = &ftrace_list_end;
+static struct ftrace_ops __rcu *ftrace_ops_list __read_mostly = &ftrace_list_end;
ftrace_func_t ftrace_trace_function __read_mostly = ftrace_stub;
static struct ftrace_ops global_ops;
@@ -169,8 +169,11 @@ int ftrace_nr_registered_ops(void)
mutex_lock(&ftrace_lock);
- for (ops = ftrace_ops_list;
- ops != &ftrace_list_end; ops = ops->next)
+ for (ops = rcu_dereference_protected(ftrace_ops_list,
+ lockdep_is_held(&ftrace_lock));
+ ops != &ftrace_list_end;
+ ops = rcu_dereference_protected(ops->next,
+ lockdep_is_held(&ftrace_lock)))
cnt++;
mutex_unlock(&ftrace_lock);
@@ -275,10 +278,11 @@ static void update_ftrace_function(void)
* If there's only one ftrace_ops registered, the ftrace_ops_list
* will point to the ops we want.
*/
- set_function_trace_op = ftrace_ops_list;
+ set_function_trace_op = rcu_dereference_protected(ftrace_ops_list,
+ lockdep_is_held(&ftrace_lock));
/* If there's no ftrace_ops registered, just call the stub function */
- if (ftrace_ops_list == &ftrace_list_end) {
+ if (set_function_trace_op == &ftrace_list_end) {
func = ftrace_stub;
/*
@@ -286,7 +290,8 @@ static void update_ftrace_function(void)
* recursion safe and not dynamic and the arch supports passing ops,
* then have the mcount trampoline call the function directly.
*/
- } else if (ftrace_ops_list->next == &ftrace_list_end) {
+ } else if (rcu_dereference_protected(ftrace_ops_list->next,
+ lockdep_is_held(&ftrace_lock)) == &ftrace_list_end) {
func = ftrace_ops_get_list_func(ftrace_ops_list);
} else {
@@ -348,9 +353,11 @@ int using_ftrace_ops_list_func(void)
return ftrace_trace_function == ftrace_ops_list_func;
}
-static void add_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops)
+static void add_ftrace_ops(struct ftrace_ops __rcu **list,
+ struct ftrace_ops *ops)
{
- ops->next = *list;
+ rcu_assign_pointer(ops->next, *list);
+
/*
* We are entering ops into the list but another
* CPU might be walking that list. We need to make sure
@@ -360,7 +367,8 @@ static void add_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops)
rcu_assign_pointer(*list, ops);
}
-static int remove_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops)
+static int remove_ftrace_ops(struct ftrace_ops __rcu **list,
+ struct ftrace_ops *ops)
{
struct ftrace_ops **p;
@@ -368,7 +376,10 @@ static int remove_ftrace_ops(struct ftrace_ops **list, struct ftrace_ops *ops)
* If we are removing the last function, then simply point
* to the ftrace_stub.
*/
- if (*list == ops && ops->next == &ftrace_list_end) {
+ if (rcu_dereference_protected(*list,
+ lockdep_is_held(&ftrace_lock)) == ops &&
+ rcu_dereference_protected(ops->next,
+ lockdep_is_held(&ftrace_lock)) == &ftrace_list_end) {
*list = &ftrace_list_end;
return 0;
}
@@ -1569,8 +1580,8 @@ ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip, void *regs)
return 0;
#endif
- hash.filter_hash = rcu_dereference_raw_notrace(ops->func_hash->filter_hash);
- hash.notrace_hash = rcu_dereference_raw_notrace(ops->func_hash->notrace_hash);
+ rcu_assign_pointer(hash.filter_hash, ops->func_hash->filter_hash);
+ rcu_assign_pointer(hash.notrace_hash, ops->func_hash->notrace_hash);
if (hash_contains_ip(ip, &hash))
ret = 1;
@@ -2840,7 +2851,8 @@ static int ftrace_shutdown(struct ftrace_ops *ops, int command)
* If there's no more ops registered with ftrace, run a
* sanity check to make sure all rec flags are cleared.
*/
- if (ftrace_ops_list == &ftrace_list_end) {
+ if (rcu_dereference_protected(ftrace_ops_list,
+ lockdep_is_held(&ftrace_lock)) == &ftrace_list_end) {
struct ftrace_page *pg;
struct dyn_ftrace *rec;
@@ -6453,7 +6465,8 @@ ftrace_enable_sysctl(struct ctl_table *table, int write,
if (ftrace_enabled) {
/* we are starting ftrace again */
- if (ftrace_ops_list != &ftrace_list_end)
+ if (rcu_dereference_protected(ftrace_ops_list,
+ lockdep_is_held(&ftrace_lock)) != &ftrace_list_end)
update_ftrace_function();
ftrace_startup_sysctl();
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 6ade1c55cc3a..490ba229931d 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -1210,9 +1210,9 @@ struct ftrace_event_field {
struct event_filter {
int n_preds; /* Number assigned */
int a_preds; /* allocated */
- struct filter_pred *preds;
- struct filter_pred *root;
- char *filter_string;
+ struct filter_pred __rcu *preds;
+ struct filter_pred __rcu *root;
+ char *filter_string;
};
struct event_subsystem {
--
2.10.2
^ permalink raw reply related [flat|nested] 4+ messages in thread