From: Muhammad Usama Anjum <usama.anjum@arm.com>
To: Arnd Bergmann <arnd@arndb.de>, Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
Valentin Schneider <vschneid@redhat.com>,
Kees Cook <kees@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
David Hildenbrand <david@kernel.org>,
Lorenzo Stoakes <ljs@kernel.org>,
"Liam R. Howlett" <Liam.Howlett@oracle.com>,
Vlastimil Babka <vbabka@kernel.org>,
Mike Rapoport <rppt@kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Michal Hocko <mhocko@suse.com>,
Uladzislau Rezki <urezki@gmail.com>,
linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, Andrey Konovalov <andreyknvl@gmail.com>,
Marco Elver <elver@google.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Peter Collingbourne <pcc@google.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Ryan.Roberts@arm.com, david.hildenbrand@arm.com
Cc: Muhammad Usama Anjum <usama.anjum@arm.com>,
Ryan Roberts <ryan.roberts@arm.com>
Subject: [PATCH v2 3/3] mm: skip KASAN tagging for page-allocated page tables
Date: Tue, 24 Mar 2026 13:26:29 +0000 [thread overview]
Message-ID: <20260324132631.482520-4-usama.anjum@arm.com> (raw)
In-Reply-To: <20260324132631.482520-1-usama.anjum@arm.com>
Page tables are always accessed via the linear mapping with a match-all
tag, so HW-tag KASAN never checks them. For page-allocated tables (PTEs
and PGDs etc), avoid the tag setup and poisoning overhead by using
__GFP_SKIP_KASAN. SLUB-backed page tables are unchanged for now. (They
aren't widely used and require more SLUB related skip logic. Leave it
later.)
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Muhammad Usama Anjum <usama.anjum@arm.com>
---
Changes since v1:
- Update description to mention SLUB-backed page tables are unchanged
---
include/asm-generic/pgalloc.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/asm-generic/pgalloc.h b/include/asm-generic/pgalloc.h
index 57137d3ac1592..051aa1331051c 100644
--- a/include/asm-generic/pgalloc.h
+++ b/include/asm-generic/pgalloc.h
@@ -4,7 +4,7 @@
#ifdef CONFIG_MMU
-#define GFP_PGTABLE_KERNEL (GFP_KERNEL | __GFP_ZERO)
+#define GFP_PGTABLE_KERNEL (GFP_KERNEL | __GFP_ZERO | __GFP_SKIP_KASAN)
#define GFP_PGTABLE_USER (GFP_PGTABLE_KERNEL | __GFP_ACCOUNT)
/**
--
2.47.3
prev parent reply other threads:[~2026-03-24 13:27 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-24 13:26 [PATCH v2 0/3] KASAN: HW_TAGS: Disable tagging for stack and page-tables Muhammad Usama Anjum
2026-03-24 13:26 ` [PATCH v2 1/3] vmalloc: add __GFP_SKIP_KASAN support Muhammad Usama Anjum
2026-03-24 13:26 ` [PATCH v2 2/3] kasan: skip HW tagging for all kernel thread stacks Muhammad Usama Anjum
2026-03-24 13:26 ` Muhammad Usama Anjum [this message]
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