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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
