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Subject[PATCH RT] kmemleak: Change the lock of kmemleak_object to raw_spinlock_t
Date
From: Liu Haitao <haitao.liu@windriver.com>

The following call trace would be triggered as kmemleak is running.

BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:968
in_atomic(): 1, irqs_disabled(): 1, pid: 902, name: kmemleak
4 locks held by kmemleak/902:
#0:
000000001f69be68
(
scan_mutex
){+.+.}
, at: kmemleak_scan_thread+0x7c/0xc3
#1:
00000000a795ae4c
(
mem_hotplug_lock.rw_sem
){++++}
, at: kmemleak_scan+0x1ba/0x7a0
#2:
0000000079c12e8b
(
kmemleak_lock
){....}
, at: scan_block+0x31/0x120
#3:
00000000191afe4b
(
&object->lock
/1
){....}
, at: scan_block+0x8b/0x120
irq event stamp: 16791384
hardirqs last enabled at (16791383): [<ffffffff8326d682>] _raw_spin_unlock_irqrestore+0x82/0x90
hardirqs last disabled at (16791384): [<ffffffff8326d3da>] _raw_spin_lock_irqsave+0x1a/0x80
softirqs last enabled at (0): [<ffffffff824f1f70>] copy_process.part.5+0x760/0x2000
softirqs last disabled at (0): [<0000000000000000>] 0x0
Preemption disabled at:
[<ffffffff82743381>] scan_block+0x31/0x120

CPU: 63 PID: 902 Comm: kmemleak Tainted: G W 5.2.14-rt7-preempt-rt+ #2
Hardware name: Intel Corporation S2600WFS/S2600WFS, BIOS SE5C620.86B.01.00.0694.120620170818 12/06/2017
Call Trace:
dump_stack+0x70/0xa5
___might_sleep+0x140/0x1e0
rt_spin_lock_nested+0x59/0x70
? scan_block+0x8b/0x120
scan_block+0x8b/0x120
kmemleak_scan+0x285/0x7a0
kmemleak_scan_thread+0x81/0xc3
kthread+0x12f/0x150
? kmemleak_write+0x460/0x460
? kthread_park+0xb0/0xb0
ret_from_fork+0x3a/0x50

The commit 3520604cc08dd63c057296c34756da1b6a655f71 changed the kmemleak_lock
to raw spinlock. However the kmemleak_object->lock is held after the
kmemleak_lock is held in scan_block().

scan_block()
|
raw_spin_lock_irqsave(&kmemleak_lock, flags)
|
spin_lock_nested(&object->lock, SINGLE_DEPTH_NESTING);

In this case, the object->lock is implemented by mutex in RT. It could casue a sleeping problem.

Fixes: 3520604cc08d ("kmemleak: Turn kmemleak_lock to raw spinlock on RT")

Signed-off-by: Liu Haitao <haitao.liu@windriver.com>
Signed-off-by: Yongxin Liu <yongxin.liu@windriver.com>
---
mm/kmemleak.c | 72 +++++++++++++++++++++++++++++------------------------------
1 file changed, 36 insertions(+), 36 deletions(-)

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index aaee59c0306a..355dd95d0611 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -135,7 +135,7 @@ struct kmemleak_scan_area {
* (use_count) and freed using the RCU mechanism.
*/
struct kmemleak_object {
- spinlock_t lock;
+ raw_spinlock_t lock;
unsigned int flags; /* object status flags */
struct list_head object_list;
struct list_head gray_list;
@@ -560,7 +560,7 @@ static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
INIT_LIST_HEAD(&object->object_list);
INIT_LIST_HEAD(&object->gray_list);
INIT_HLIST_HEAD(&object->area_list);
- spin_lock_init(&object->lock);
+ raw_spin_lock_init(&object->lock);
atomic_set(&object->use_count, 1);
object->flags = OBJECT_ALLOCATED;
object->pointer = ptr;
@@ -642,9 +642,9 @@ static void __delete_object(struct kmemleak_object *object)
* Locking here also ensures that the corresponding memory block
* cannot be freed when it is being scanned.
*/
- spin_lock_irqsave(&object->lock, flags);
+ raw_spin_lock_irqsave(&object->lock, flags);
object->flags &= ~OBJECT_ALLOCATED;
- spin_unlock_irqrestore(&object->lock, flags);
+ raw_spin_unlock_irqrestore(&object->lock, flags);
put_object(object);
}

@@ -716,9 +716,9 @@ static void paint_it(struct kmemleak_object *object, int color)
{
unsigned long flags;

- spin_lock_irqsave(&object->lock, flags);
+ raw_spin_lock_irqsave(&object->lock, flags);
__paint_it(object, color);
- spin_unlock_irqrestore(&object->lock, flags);
+ raw_spin_unlock_irqrestore(&object->lock, flags);
}

static void paint_ptr(unsigned long ptr, int color)
@@ -778,7 +778,7 @@ static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
goto out;
}

- spin_lock_irqsave(&object->lock, flags);
+ raw_spin_lock_irqsave(&object->lock, flags);
if (size == SIZE_MAX) {
size = object->pointer + object->size - ptr;
} else if (ptr + size > object->pointer + object->size) {
@@ -794,7 +794,7 @@ static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)

hlist_add_head(&area->node, &object->area_list);
out_unlock:
- spin_unlock_irqrestore(&object->lock, flags);
+ raw_spin_unlock_irqrestore(&object->lock, flags);
out:
put_object(object);
}
@@ -817,9 +817,9 @@ static void object_set_excess_ref(unsigned long ptr, unsigned long excess_ref)
return;
}

- spin_lock_irqsave(&object->lock, flags);
+ raw_spin_lock_irqsave(&object->lock, flags);
object->excess_ref = excess_ref;
- spin_unlock_irqrestore(&object->lock, flags);
+ raw_spin_unlock_irqrestore(&object->lock, flags);
put_object(object);
}

@@ -839,9 +839,9 @@ static void object_no_scan(unsigned long ptr)
return;
}

- spin_lock_irqsave(&object->lock, flags);
+ raw_spin_lock_irqsave(&object->lock, flags);
object->flags |= OBJECT_NO_SCAN;
- spin_unlock_irqrestore(&object->lock, flags);
+ raw_spin_unlock_irqrestore(&object->lock, flags);
put_object(object);
}

@@ -902,11 +902,11 @@ static void early_alloc(struct early_log *log)
log->min_count, GFP_ATOMIC);
if (!object)
goto out;
- spin_lock_irqsave(&object->lock, flags);
+ raw_spin_lock_irqsave(&object->lock, flags);
for (i = 0; i < log->trace_len; i++)
object->trace[i] = log->trace[i];
object->trace_len = log->trace_len;
- spin_unlock_irqrestore(&object->lock, flags);
+ raw_spin_unlock_irqrestore(&object->lock, flags);
out:
rcu_read_unlock();
}
@@ -1096,9 +1096,9 @@ void __ref kmemleak_update_trace(const void *ptr)
return;
}

- spin_lock_irqsave(&object->lock, flags);
+ raw_spin_lock_irqsave(&object->lock, flags);
object->trace_len = __save_stack_trace(object->trace);
- spin_unlock_irqrestore(&object->lock, flags);
+ raw_spin_unlock_irqrestore(&object->lock, flags);

put_object(object);
}
@@ -1346,7 +1346,7 @@ static void scan_block(void *_start, void *_end,
* previously acquired in scan_object(). These locks are
* enclosed by scan_mutex.
*/
- spin_lock_nested(&object->lock, SINGLE_DEPTH_NESTING);
+ raw_spin_lock_nested(&object->lock, SINGLE_DEPTH_NESTING);
/* only pass surplus references (object already gray) */
if (color_gray(object)) {
excess_ref = object->excess_ref;
@@ -1355,7 +1355,7 @@ static void scan_block(void *_start, void *_end,
excess_ref = 0;
update_refs(object);
}
- spin_unlock(&object->lock);
+ raw_spin_unlock(&object->lock);

if (excess_ref) {
object = lookup_object(excess_ref, 0);
@@ -1364,9 +1364,9 @@ static void scan_block(void *_start, void *_end,
if (object == scanned)
/* circular reference, ignore */
continue;
- spin_lock_nested(&object->lock, SINGLE_DEPTH_NESTING);
+ raw_spin_lock_nested(&object->lock, SINGLE_DEPTH_NESTING);
update_refs(object);
- spin_unlock(&object->lock);
+ raw_spin_unlock(&object->lock);
}
}
raw_spin_unlock_irqrestore(&kmemleak_lock, flags);
@@ -1402,7 +1402,7 @@ static void scan_object(struct kmemleak_object *object)
* Once the object->lock is acquired, the corresponding memory block
* cannot be freed (the same lock is acquired in delete_object).
*/
- spin_lock_irqsave(&object->lock, flags);
+ raw_spin_lock_irqsave(&object->lock, flags);
if (object->flags & OBJECT_NO_SCAN)
goto out;
if (!(object->flags & OBJECT_ALLOCATED))
@@ -1421,9 +1421,9 @@ static void scan_object(struct kmemleak_object *object)
if (start >= end)
break;

- spin_unlock_irqrestore(&object->lock, flags);
+ raw_spin_unlock_irqrestore(&object->lock, flags);
cond_resched();
- spin_lock_irqsave(&object->lock, flags);
+ raw_spin_lock_irqsave(&object->lock, flags);
} while (object->flags & OBJECT_ALLOCATED);
} else
hlist_for_each_entry(area, &object->area_list, node)
@@ -1431,7 +1431,7 @@ static void scan_object(struct kmemleak_object *object)
(void *)(area->start + area->size),
object);
out:
- spin_unlock_irqrestore(&object->lock, flags);
+ raw_spin_unlock_irqrestore(&object->lock, flags);
}

/*
@@ -1484,7 +1484,7 @@ static void kmemleak_scan(void)
/* prepare the kmemleak_object's */
rcu_read_lock();
list_for_each_entry_rcu(object, &object_list, object_list) {
- spin_lock_irqsave(&object->lock, flags);
+ raw_spin_lock_irqsave(&object->lock, flags);
#ifdef DEBUG
/*
* With a few exceptions there should be a maximum of
@@ -1501,7 +1501,7 @@ static void kmemleak_scan(void)
if (color_gray(object) && get_object(object))
list_add_tail(&object->gray_list, &gray_list);

- spin_unlock_irqrestore(&object->lock, flags);
+ raw_spin_unlock_irqrestore(&object->lock, flags);
}
rcu_read_unlock();

@@ -1569,14 +1569,14 @@ static void kmemleak_scan(void)
*/
rcu_read_lock();
list_for_each_entry_rcu(object, &object_list, object_list) {
- spin_lock_irqsave(&object->lock, flags);
+ raw_spin_lock_irqsave(&object->lock, flags);
if (color_white(object) && (object->flags & OBJECT_ALLOCATED)
&& update_checksum(object) && get_object(object)) {
/* color it gray temporarily */
object->count = object->min_count;
list_add_tail(&object->gray_list, &gray_list);
}
- spin_unlock_irqrestore(&object->lock, flags);
+ raw_spin_unlock_irqrestore(&object->lock, flags);
}
rcu_read_unlock();

@@ -1596,7 +1596,7 @@ static void kmemleak_scan(void)
*/
rcu_read_lock();
list_for_each_entry_rcu(object, &object_list, object_list) {
- spin_lock_irqsave(&object->lock, flags);
+ raw_spin_lock_irqsave(&object->lock, flags);
if (unreferenced_object(object) &&
!(object->flags & OBJECT_REPORTED)) {
object->flags |= OBJECT_REPORTED;
@@ -1606,7 +1606,7 @@ static void kmemleak_scan(void)

new_leaks++;
}
- spin_unlock_irqrestore(&object->lock, flags);
+ raw_spin_unlock_irqrestore(&object->lock, flags);
}
rcu_read_unlock();

@@ -1758,10 +1758,10 @@ static int kmemleak_seq_show(struct seq_file *seq, void *v)
struct kmemleak_object *object = v;
unsigned long flags;

- spin_lock_irqsave(&object->lock, flags);
+ raw_spin_lock_irqsave(&object->lock, flags);
if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object))
print_unreferenced(seq, object);
- spin_unlock_irqrestore(&object->lock, flags);
+ raw_spin_unlock_irqrestore(&object->lock, flags);
return 0;
}

@@ -1791,9 +1791,9 @@ static int dump_str_object_info(const char *str)
return -EINVAL;
}

- spin_lock_irqsave(&object->lock, flags);
+ raw_spin_lock_irqsave(&object->lock, flags);
dump_object_info(object);
- spin_unlock_irqrestore(&object->lock, flags);
+ raw_spin_unlock_irqrestore(&object->lock, flags);

put_object(object);
return 0;
@@ -1812,11 +1812,11 @@ static void kmemleak_clear(void)

rcu_read_lock();
list_for_each_entry_rcu(object, &object_list, object_list) {
- spin_lock_irqsave(&object->lock, flags);
+ raw_spin_lock_irqsave(&object->lock, flags);
if ((object->flags & OBJECT_REPORTED) &&
unreferenced_object(object))
__paint_it(object, KMEMLEAK_GREY);
- spin_unlock_irqrestore(&object->lock, flags);
+ raw_spin_unlock_irqrestore(&object->lock, flags);
}
rcu_read_unlock();

--
2.14.4
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