linux-kernel - [PATCH v1 09/11] x86/mm/pat: remove MEMTYPE_*

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Message-ID: <20250425081715.1341199-10-david@redhat.com>
Date: Fri, 25 Apr 2025 10:17:13 +0200
From: David Hildenbrand <david@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: linux-mm@...ck.org,
	x86@...nel.org,
	intel-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org,
	linux-trace-kernel@...r.kernel.org,
	David Hildenbrand <david@...hat.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Andy Lutomirski <luto@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Jani Nikula <jani.nikula@...ux.intel.com>,
	Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
	Rodrigo Vivi <rodrigo.vivi@...el.com>,
	Tvrtko Ursulin <tursulin@...ulin.net>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	"Liam R. Howlett" <Liam.Howlett@...cle.com>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	Vlastimil Babka <vbabka@...e.cz>,
	Jann Horn <jannh@...gle.com>,
	Pedro Falcato <pfalcato@...e.de>,
	Peter Xu <peterx@...hat.com>
Subject: [PATCH v1 09/11] x86/mm/pat: remove MEMTYPE_*_MATCH

The "memramp() shrinking" scenario no longer applies, so let's remove
that now-unnecessary handling.

Signed-off-by: David Hildenbrand <david@...hat.com>
---
 arch/x86/mm/pat/memtype_interval.c | 44 ++++--------------------------
 1 file changed, 6 insertions(+), 38 deletions(-)

diff --git a/arch/x86/mm/pat/memtype_interval.c b/arch/x86/mm/pat/memtype_interval.c
index 645613d59942a..9d03f0dbc4715 100644
--- a/arch/x86/mm/pat/memtype_interval.c
+++ b/arch/x86/mm/pat/memtype_interval.c
@@ -49,26 +49,15 @@ INTERVAL_TREE_DEFINE(struct memtype, rb, u64, subtree_max_end,
 
 static struct rb_root_cached memtype_rbroot = RB_ROOT_CACHED;
 
-enum {
-	MEMTYPE_EXACT_MATCH	= 0,
-	MEMTYPE_END_MATCH	= 1
-};
-
-static struct memtype *memtype_match(u64 start, u64 end, int match_type)
+static struct memtype *memtype_match(u64 start, u64 end)
 {
 	struct memtype *entry_match;
 
 	entry_match = interval_iter_first(&memtype_rbroot, start, end-1);
 
 	while (entry_match != NULL && entry_match->start < end) {
-		if ((match_type == MEMTYPE_EXACT_MATCH) &&
-		    (entry_match->start == start) && (entry_match->end == end))
-			return entry_match;
-
-		if ((match_type == MEMTYPE_END_MATCH) &&
-		    (entry_match->start < start) && (entry_match->end == end))
+		if (entry_match->start == start && entry_match->end == end)
 			return entry_match;
-
 		entry_match = interval_iter_next(entry_match, start, end-1);
 	}
 
@@ -132,32 +121,11 @@ struct memtype *memtype_erase(u64 start, u64 end)
 {
 	struct memtype *entry_old;
 
-	/*
-	 * Since the memtype_rbroot tree allows overlapping ranges,
-	 * memtype_erase() checks with EXACT_MATCH first, i.e. free
-	 * a whole node for the munmap case.  If no such entry is found,
-	 * it then checks with END_MATCH, i.e. shrink the size of a node
-	 * from the end for the mremap case.
-	 */
-	entry_old = memtype_match(start, end, MEMTYPE_EXACT_MATCH);
-	if (!entry_old) {
-		entry_old = memtype_match(start, end, MEMTYPE_END_MATCH);
-		if (!entry_old)
-			return ERR_PTR(-EINVAL);
-	}
-
-	if (entry_old->start == start) {
-		/* munmap: erase this node */
-		interval_remove(entry_old, &memtype_rbroot);
-	} else {
-		/* mremap: update the end value of this node */
-		interval_remove(entry_old, &memtype_rbroot);
-		entry_old->end = start;
-		interval_insert(entry_old, &memtype_rbroot);
-
-		return NULL;
-	}
+	entry_old = memtype_match(start, end);
+	if (!entry_old)
+		return ERR_PTR(-EINVAL);
 
+	interval_remove(entry_old, &memtype_rbroot);
 	return entry_old;
 }
 
-- 
2.49.0