FAILED: patch "[PATCH] bpf: Fix excessive memory allocation in stack_map_alloc()" failed to apply to 5.10-stable tree

The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From b45043192b3e481304062938a6561da2ceea46a6 Mon Sep 17 00:00:00 2001
From: Yuntao Wang <[email protected]>
Date: Thu, 7 Apr 2022 21:04:23 +0800
Subject: [PATCH] bpf: Fix excessive memory allocation in stack_map_alloc()

The 'n_buckets * (value_size + sizeof(struct stack_map_bucket))' part of the allocated memory for 'smap' is never used after the memlock accounting was removed, thus get rid of it.

[ Note, Daniel:

Commit b936ca643ade ("bpf: rework memlock-based memory accounting for maps") moved cost += n_buckets * (value_size + sizeof(struct stack_map_bucket)) up and therefore before the bpf_map_area_alloc() allocation, sigh. In a later step commit c85d69135a91 ("bpf: move memory size checks to bpf_map_charge_init()"), and the overflow checks of cost >= U32_MAX - PAGE_SIZE moved into bpf_map_charge_init(). And then 370868107bf6 ("bpf: Eliminate rlimit-based memory accounting for stackmap maps") finally removed the bpf_map_charge_init(). Anyway, the original code did the allocation same way as /after/ this fix. ]

index 6131b4a19572..1dd5266fbebb 100644
@@ -100,7 +100,6 @@ static struct bpf_map *stack_map_alloc(union bpf_attr *attr)
 		return ERR_PTR(-E2BIG);
 
 	cost = n_buckets * sizeof(struct stack_map_bucket *) + sizeof(*smap);
-	cost += n_buckets * (value_size + sizeof(struct stack_map_bucket));
 	smap = bpf_map_area_alloc(cost, bpf_map_attr_numa_node(attr));
 	if (!smap)
 		return ERR_PTR(-ENOMEM);