Signed-off-by: Jianpeng Ma <[email protected]>
---
mm/kmemleak.c | 8 +-------
1 file changed, 1 insertion(+), 7 deletions(-)
diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index b1525db..f0ece93 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -1225,22 +1225,16 @@ static void scan_gray_list(void)
* from inside the loop. The kmemleak objects cannot be freed from
* outside the loop because their use_count was incremented.
*/
- object = list_entry(gray_list.next, typeof(*object), gray_list);
- while (&object->gray_list != &gray_list) {
+ list_for_each_entry_safe(object, tmp, &gray_list, gray_list) {
cond_resched();
/* may add new objects to the list */
if (!scan_should_stop())
scan_object(object);
- tmp = list_entry(object->gray_list.next, typeof(*object),
- gray_list);
-
/* remove the object from the list and release it */
list_del(&object->gray_list);
put_object(object);
-
- object = tmp;
}
WARN_ON(!list_empty(&gray_list));
}
--
1.8.3.rc1.44.gb387c77
On Tue, May 14, 2013 at 12:49:44PM +0100, majianpeng wrote:
> Signed-off-by: Jianpeng Ma <[email protected]>
> ---
> mm/kmemleak.c | 8 +-------
> 1 file changed, 1 insertion(+), 7 deletions(-)
>
> diff --git a/mm/kmemleak.c b/mm/kmemleak.c
> index b1525db..f0ece93 100644
> --- a/mm/kmemleak.c
> +++ b/mm/kmemleak.c
> @@ -1225,22 +1225,16 @@ static void scan_gray_list(void)
> * from inside the loop. The kmemleak objects cannot be freed from
> * outside the loop because their use_count was incremented.
> */
> - object = list_entry(gray_list.next, typeof(*object), gray_list);
> - while (&object->gray_list != &gray_list) {
> + list_for_each_entry_safe(object, tmp, &gray_list, gray_list) {
> cond_resched();
>
> /* may add new objects to the list */
> if (!scan_should_stop())
> scan_object(object);
>
> - tmp = list_entry(object->gray_list.next, typeof(*object),
> - gray_list);
> -
> /* remove the object from the list and release it */
> list_del(&object->gray_list);
> put_object(object);
> -
> - object = tmp;
> }
> WARN_ON(!list_empty(&gray_list));
I tried this patch for a few days and I hit the WARN_ON after the loop.
During scanning, new entries may be added at the end of the loop but we
need to loop until all the entries have been removed. I probably had a
reason why I had the 'while' loop.
The key difference is that list_for_each_entry_safe() gets the next
entry (n or tmp above) before scan_object() and it may hit the end of
the list. However, scan_object() may do a list_add_tail(&gray_list)
hence we need to get the next entry after this function.
Basically list_for_each_entry_safe() is not safe with tail additions.
I'll revert this patch (hasn't reached mainline anyway).
Thanks.
--
Catalin
>On Tue, May 14, 2013 at 12:49:44PM +0100, majianpeng wrote:
>> Signed-off-by: Jianpeng Ma <[email protected]>
>> ---
>> mm/kmemleak.c | 8 +-------
>> 1 file changed, 1 insertion(+), 7 deletions(-)
>>
>> diff --git a/mm/kmemleak.c b/mm/kmemleak.c
>> index b1525db..f0ece93 100644
>> --- a/mm/kmemleak.c
>> +++ b/mm/kmemleak.c
>> @@ -1225,22 +1225,16 @@ static void scan_gray_list(void)
>> * from inside the loop. The kmemleak objects cannot be freed from
>> * outside the loop because their use_count was incremented.
>> */
>> - object = list_entry(gray_list.next, typeof(*object), gray_list);
>> - while (&object->gray_list != &gray_list) {
>> + list_for_each_entry_safe(object, tmp, &gray_list, gray_list) {
>> cond_resched();
>>
>> /* may add new objects to the list */
>> if (!scan_should_stop())
>> scan_object(object);
>>
>> - tmp = list_entry(object->gray_list.next, typeof(*object),
>> - gray_list);
>> -
>> /* remove the object from the list and release it */
>> list_del(&object->gray_list);
>> put_object(object);
>> -
>> - object = tmp;
>> }
>> WARN_ON(!list_empty(&gray_list));
>
>I tried this patch for a few days and I hit the WARN_ON after the loop.
>During scanning, new entries may be added at the end of the loop but we
>need to loop until all the entries have been removed. I probably had a
>reason why I had the 'while' loop.
>
>The key difference is that list_for_each_entry_safe() gets the next
>entry (n or tmp above) before scan_object() and it may hit the end of
>the list. However, scan_object() may do a list_add_tail(&gray_list)
>hence we need to get the next entry after this function.
>
>Basically list_for_each_entry_safe() is not safe with tail additions.
>I'll revert this patch (hasn't reached mainline anyway).
>
Ok, i see.
Thanks!
>Thanks.
>
>--
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