On 8/20/25 7:02 AM, Catalin Marinas wrote:
On Tue, Aug 19, 2025 at 11:27:23PM -0400, Waiman Long wrote:
On 8/18/25 5:09 AM, Gu Bowen wrote:
@@ -858,8 +870,14 @@ static void delete_object_part(unsigned long ptr, size_t size, object = __find_and_remove_object(ptr, 1, objflags); if (!object) { #ifdef DEBUG
/** Printk deferring due to the kmemleak_lock held.* This is done to avoid deadlock.*/printk_deferred_enter(); kmemleak_warn("Partially freeing unknown object at 0x%08lx (size %zu)\n", ptr, size);printk_deferred_exit();This particular warning message can be moved after unlock by adding a warning flag. Locking is done outside of the other two helper functions above, so it is easier to use printk_deferred_enter/exit() for those.
I thought about this as well but the above is under an #ifdef DEBUG so we end up adding more lines on the unlock path (not sure which one looks better; I'd say the above, marginally).
Another option would be to remove the #ifdef and try to identify the call sites that trigger the warning. Last time I checked (many years ago) they were fairly benign and decided to hide them before an #ifdef.
A bit more code change required the printing is moved.
diff --git a/mm/kmemleak.c b/mm/kmemleak.c index 84265983f239..eb4e0af5edba 100644 --- a/mm/kmemleak.c +++ b/mm/kmemleak.c @@ -856,13 +856,8 @@ static void delete_object_part(unsigned long ptr, size_t size,
raw_spin_lock_irqsave(&kmemleak_lock, flags); object = __find_and_remove_object(ptr, 1, objflags); - if (!object) { -#ifdef DEBUG - kmemleak_warn("Partially freeing unknown object at 0x%08lx (size %zu)\n", - ptr, size); -#endif + if (!object) goto unlock; - }
/* * Create one or two objects that may result from the memory block @@ -882,8 +877,14 @@ static void delete_object_part(unsigned long ptr, size_t size,
unlock: raw_spin_unlock_irqrestore(&kmemleak_lock, flags); - if (object) + if (object) { __delete_object(object); + } else { +#ifdef DEBUG + kmemleak_warn("Partially freeing unknown object at 0x%08lx (size %zu)\n", + ptr, size); +#endif + }
Anyway, I am not against using printk_deferred_enter/exit here. It is just that they should be used as a last resort if there is no easy way to work around it.
Cheers, Longman