Backport request: [PATCH] maple_tree: make maple state reusable after mas_empty_area()

Hi, please backport commit 0257d9908d38c0b1669af4bb1bc4dbca1f273fe6 to 6.1.y onwards. This patch fixes a regression which broke some programs, like GHC (the Haskell compiler). We've been shipping this patch in NixOS unstable for the last couple of weeks, to positive results.

(The patch had "Cc: stable@vger.kernel.org" but from what I can tell has not been selected for backporting. Apologies if I've just missed it.)