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SubjectRe: [PATCH 1/3] x86,mm/pat: Use generic interval trees
On Tue, Aug 13, 2019 at 03:46:18PM -0700, Davidlohr Bueso wrote:

> diff --git a/arch/x86/mm/pat_rbtree.c b/arch/x86/mm/pat_rbtree.c
> index fa16036fa592..1be4d1856a9b 100644
> --- a/arch/x86/mm/pat_rbtree.c
> +++ b/arch/x86/mm/pat_rbtree.c

> @@ -34,68 +34,41 @@
> * memtype_lock protects the rbtree.
> */
>
> +static struct rb_root_cached memtype_rbroot = RB_ROOT_CACHED;
> +
> +#define START(node) ((node)->start)
> +#define END(node) ((node)->end)

Afaict these could actually be inlines, but I see other interval tree
users also use macros for them, albeit with END called LAST.

> +INTERVAL_TREE_DEFINE(struct memtype, rb, u64, subtree_max_end,
> + START, END, static, memtype_interval)
>
> static int is_node_overlap(struct memtype *node, u64 start, u64 end)
> {
> + /*
> + * Unlike generic interval trees, the memtype nodes are ]a, b[
> + * therefore we need to adjust the ranges accordingly. Missing
> + * an overlap can lead to incorrectly detecting conflicts,
> + * for example.
> + */
> + if (node->start + 1 >= end || node->end - 1 <= start)
> return 0;
>
> return 1;
> }

I've not looked yet; but how horrible would it be to change that
weirdness?

> @@ -149,10 +116,8 @@ static int memtype_rb_check_conflict(struct rb_root *root,
> dprintk("Overlap at 0x%Lx-0x%Lx\n", match->start, match->end);
> found_type = match->type;
>
> + match = memtype_interval_iter_next(match, start, end);
> + while (match) {

whilespace fail

> if (match->start >= end) /* Checked all possible matches */
> goto success;
>

> @@ -176,43 +141,21 @@ static int memtype_rb_check_conflict(struct rb_root *root,
> return -EBUSY;
> }
>
> int rbt_memtype_check_insert(struct memtype *new,
> enum page_cache_mode *ret_type)
> {
> + int err;
>
> + err = memtype_rb_check_conflict(&memtype_rbroot,
> + new->start, new->end,
> + new->type, ret_type);

whitespace fail

> + if (err)
> + return err;
>
> + if (ret_type)
> + new->type = *ret_type;
>
> + memtype_interval_insert(new, &memtype_rbroot);
> return err;
> }
>

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