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>
Subject: [PATCH 3/3] mm: SKIP KASAN for page table allocations
Date: Thu, 19 Mar 2026 11:49:46 +0000 [thread overview]
Message-ID: <20260319114952.3241359-4-usama.anjum@arm.com> (raw)
In-Reply-To: <20260319114952.3241359-1-usama.anjum@arm.com>
Page tables are always accessed via __va(phys) / phys_to_virt(phys).
With a match-all tag in the pointer, MTE never checks memory tags on
access. Therefore: KASAN HW tags are set during page table allocation
but never checked during use. KASAN poisoning on free provides no
value for these pages as well. Its pure overhead - both at allocation
time and free time. Hence, skip the tag setting for all page tables.
Signed-off-by: Muhammad Usama Anjum <usama.anjum@arm.com>
---
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
next prev parent reply other threads:[~2026-03-19 11:50 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-19 11:49 [PATCH 0/3] KASAN: HW_TAGS: Disable tagging for stack and page-tables Muhammad Usama Anjum
2026-03-19 11:49 ` [PATCH 1/3] vmalloc: add __GFP_SKIP_KASAN support Muhammad Usama Anjum
2026-03-19 12:22 ` Ryan Roberts
2026-03-19 12:57 ` Muhammad Usama Anjum
2026-03-19 11:49 ` [PATCH 2/3] fork: skip MTE tagging for kernel stacks Muhammad Usama Anjum
2026-03-19 12:09 ` Ryan Roberts
2026-03-19 12:29 ` Muhammad Usama Anjum
2026-03-19 11:49 ` Muhammad Usama Anjum [this message]
2026-03-19 12:09 ` [PATCH 3/3] mm: SKIP KASAN for page table allocations Ryan Roberts
2026-03-20 3:10 ` [PATCH 0/3] KASAN: HW_TAGS: Disable tagging for stack and page-tables Andrew Morton
2026-03-23 14:53 ` Muhammad Usama Anjum
2026-03-20 8:53 ` David Hildenbrand (Arm)
2026-03-23 15:06 ` Muhammad Usama Anjum
2026-03-26 13:40 ` David Hildenbrand (Arm)
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20260319114952.3241359-4-usama.anjum@arm.com \
--to=usama.anjum@arm.com \
--cc=Liam.Howlett@oracle.com \
--cc=Ryan.Roberts@arm.com \
--cc=akpm@linux-foundation.org \
--cc=andreyknvl@gmail.com \
--cc=arnd@arndb.de \
--cc=bsegall@google.com \
--cc=catalin.marinas@arm.com \
--cc=david.hildenbrand@arm.com \
--cc=david@kernel.org \
--cc=dietmar.eggemann@arm.com \
--cc=elver@google.com \
--cc=juri.lelli@redhat.com \
--cc=kees@kernel.org \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=ljs@kernel.org \
--cc=mgorman@suse.de \
--cc=mhocko@suse.com \
--cc=mingo@redhat.com \
--cc=pcc@google.com \
--cc=peterz@infradead.org \
--cc=rostedt@goodmis.org \
--cc=rppt@kernel.org \
--cc=surenb@google.com \
--cc=urezki@gmail.com \
--cc=vbabka@kernel.org \
--cc=vincent.guittot@linaro.org \
--cc=vincenzo.frascino@arm.com \
--cc=vschneid@redhat.com \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox