From 848618857d2535176037bdc085f8d012d907071f Mon Sep 17 00:00:00 2001
From: Joel Fernandes <joelaf@google.com>
Date: Wed, 12 Jul 2017 19:14:16 -0700
Subject: [PATCH 1/3] tracing/ring_buffer: Try harder to allocate
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);
From db9108e054700c96322b0f0028546aa4e643cf0b Mon Sep 17 00:00:00 2001
From: Chunyu Hu <chuhu@redhat.com>
Date: Thu, 20 Jul 2017 18:36:09 +0800
Subject: [PATCH 2/3] tracing: Fix kmemleak in instance_rmdir
Hit the kmemleak when executing instance_rmdir, it forgot releasing
mem of tracing_cpumask. With this fix, the warn does not appear any
more.
unreferenced object 0xffff93a8dfaa7c18 (size 8):
comm "mkdir", pid 1436, jiffies 4294763622 (age 9134.308s)
hex dump (first 8 bytes):
ff ff ff ff ff ff ff ff ........
backtrace:
[<ffffffff88b6567a>] kmemleak_alloc+0x4a/0xa0
[<ffffffff8861ea41>] __kmalloc_node+0xf1/0x280
[<ffffffff88b505d3>] alloc_cpumask_var_node+0x23/0x30
[<ffffffff88b5060e>] alloc_cpumask_var+0xe/0x10
[<ffffffff88571ab0>] instance_mkdir+0x90/0x240
[<ffffffff886e5100>] tracefs_syscall_mkdir+0x40/0x70
[<ffffffff886565c9>] vfs_mkdir+0x109/0x1b0
[<ffffffff8865b1d0>] SyS_mkdir+0xd0/0x100
[<ffffffff88403857>] do_syscall_64+0x67/0x150
[<ffffffff88b710e7>] return_from_SYSCALL_64+0x0/0x6a
[<ffffffffffffffff>] 0xffffffffffffffff
Link: http://lkml.kernel.org/r/1500546969-12594-1-git-send-email-chuhu@redhat.com
Cc: stable@vger.kernel.org
Fixes: ccfe9e42e451 ("tracing: Make tracing_cpumask available for all instances")
Signed-off-by: Chunyu Hu <chuhu@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
kernel/trace/trace.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 2d0ffcc49dba..42b9355033d4 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -7774,6 +7774,7 @@ static int instance_rmdir(const char *name)
}
kfree(tr->topts);
+ free_cpumask_var(tr->tracing_cpumask);
kfree(tr->name);
kfree(tr);
From f86f418059b94aa01f9342611a272ca60c583e89 Mon Sep 17 00:00:00 2001
From: Chunyan Zhang <zhang.chunyan@linaro.org>
Date: Wed, 7 Jun 2017 16:12:51 +0800
Subject: [PATCH 3/3] trace: fix the errors caused by incompatible type of RCU
variables
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 {