On Thu, May 07, 2020 at 01:29:04PM -0400, Qian Cai wrote: > On May 7, 2020, at 1:16 PM, Catalin Marinas <catalin.marinas@xxxxxxx> wrote: > > I don't mind adding additional tracking info if it helps with debugging. > > But if it's for improving false positives, I'd prefer to look deeper > > into figure out why the pointer reference graph tracking failed. > > No, the task struct leaks are real leaks. It is just painful to figure > out the missing or misplaced put_task_struct() from the kmemleak > reports at the moment. We could log the callers to get_task_struct() and put_task_struct(), something like __builtin_return_address(0) (how does this work if the function is inlined?). If it's not the full backtrace, it shouldn't slow down kmemleak considerably. I don't think it's worth logging only the first/last calls to get/put. You'd hope that put is called in reverse order to get. I think it may be better if this is added as a new allocation pointed to from kmemleak_object rather than increasing this structure since it will be added on a case by case basis. When dumping the leak information, it would also dump the get/put calls, in the order they were called. We could add some simple refcount tracking (++ for get, -- for put) to easily notice any imbalance. I'm pretty busy next week but happy to review if you have a patch ;). -- Catalin
