On Mon, Jan 25, 2021 at 11:38:17PM +0200, Mike Rapoport wrote:
I cannot use __GFP_ACCOUNT because cma_alloc() does not use gfp. Besides, kmem accounting with __GFP_ACCOUNT does not seem to update stats and there was an explicit request for statistics: https://lore.kernel.org/lkml/CALo0P13aq3GsONnZrksZNU9RtfhMsZXGWhK1n=xYJWQizC...
As for (ab)using NR_SLAB_UNRECLAIMABLE_B, as it was already discussed here:
https://lore.kernel.org/lkml/20201129172625.GD557259@kernel.org/
I think that a dedicated stats counter would be too much at the moment and NR_SLAB_UNRECLAIMABLE_B is the only explicit stat for unreclaimable memory.
That's not true -- Mlocked is also unreclaimable. And doesn't this feel more like mlocked memory than unreclaimable slab? It's also Unevictable, so could be counted there instead.