Re: [PATCH] ref_tracker: add stack_depot_save() failure handling to ref_tracker_alloc()

From: Jakub Kicinski
Date: Mon May 29 2023 - 22:06:12 EST

On Sat, 27 May 2023 20:04:11 +0900 Tetsuo Handa wrote:
> stack_depot_save() cannot accept __GFP_NOFAIL flag because
> __stack_depot_save() drops gfp flags which are not in
> GFP_KERNEL | GFP_ATOMIC | __GFP_NOWARN. Also, changing
> __stack_depot_save() to accept __GFP_NOFAIL is not possible
> because rmqueue() does not want __GFP_NOFAIL flag for
> order == DEPOT_POOL_ORDER allocation request.
> Therefore, assume that stack_depot_save(GFP_KERNEL | __GFP_NOFAIL) from
> ref_tracker_alloc() can silently fail, and emit "unreliable refcount
> tracker." message.

It's probably a good idea to CC netdev@vger. I'm not sure if anyone
will pick this up from LKML.

For the patch itself - I'm not sure it's needed, even if we don't
record the stack we'll have a tracker object and still detect the leak.
So printing the "unreliable refcount" message is not very precise.
At least to me; Eric's opinion matters most.