From: "David Hildenbrand (Arm)" <david@kernel.org>
To: vrilutza@gmail.com, Dave Hansen <dave.hansen@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@kernel.org>, Ingo Molnar <mingo@redhat.com>,
Borislav Petkov <bp@alien8.de>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Alexander Potapenko <glider@google.com>,
Marco Elver <elver@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Kairui Song <kasong@tencent.com>, Qi Zheng <qi.zheng@linux.dev>,
Shakeel Butt <shakeel.butt@linux.dev>,
Barry Song <baohua@kernel.org>,
Axel Rasmussen <axelrasmussen@google.com>,
Yuanchu Xie <yuanchu@google.com>, Wei Xu <weixugc@google.com>,
Baoquan He <baoquan.he@linux.dev>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
Lorenzo Stoakes <ljs@kernel.org>,
"Liam R. Howlett" <liam@infradead.org>,
Vlastimil Babka <vbabka@kernel.org>,
Mike Rapoport <rppt@kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Michal Hocko <mhocko@suse.com>, Kees Cook <kees@kernel.org>
Cc: Borislav Petkov <bp@suse.de>,
linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com,
linux-mm@kvack.org, Ilya Leoshkevich <iii@linux.ibm.com>
Subject: Re: [PATCH v2 3/4] mm: Factor __pfn_valid() out of pfn_valid()
Date: Sun, 1 Nov 2026 19:03:01 +0100 [thread overview]
Message-ID: <e1e54f29-6c06-4e81-b310-d6a10114720f@kernel.org> (raw)
In-Reply-To: <20261101-kmsan-serie-v2-3-f97f66dc57ef@gmail.com>
On 11/1/26 18:04, Viorel Cernateanu via B4 Relay wrote:
> From: Viorel Cernateanu <vrilutza@gmail.com>
>
> KMSAN needs to validate a PFN during metadata lookup without entering
> instrumented code. Calling pfn_valid() also calls
> rcu_read_lock_sched(), which can enter instrumented code and recurse
> into the metadata lookup.
>
> Extract the PFN checks into __pfn_valid(), whose caller must already
> be in an RCU-sched read-side critical section. Keep pfn_valid() as
> the wrapper that acquires and releases that protection.
>
> This lets KMSAN reuse the existing PFN validation while providing
> the required protection without instrumented helpers.
>
> The wrapper now also holds the RCU-sched read lock during the
> initial range checks, which previously ran before acquiring it.
>
> Suggested-by: Alexander Potapenko <glider@google.com>
> Signed-off-by: Viorel Cernateanu <vrilutza@gmail.com>
> ---
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
--
Cheers,
David
next prev parent reply other threads:[~2026-11-01 18:03 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-01 17:04 [PATCH v2 0/4] x86/kmsan: Fix two bugs in the metadata lookup Viorel Cernateanu via B4 Relay
2026-11-01 17:04 ` [PATCH v2 1/4] x86/mm: Don't randomize the CPU entry area with KMSAN Viorel Cernateanu via B4 Relay
2026-11-01 17:04 ` [PATCH v2 2/4] x86/kmsan: Use the per-CPU area base for metadata lookup Viorel Cernateanu via B4 Relay
2026-11-01 17:04 ` [PATCH v2 3/4] mm: Factor __pfn_valid() out of pfn_valid() Viorel Cernateanu via B4 Relay
2026-11-01 18:03 ` David Hildenbrand (Arm) [this message]
2026-11-01 20:02 ` Mike Rapoport
2026-11-01 17:04 ` [PATCH v2 4/4] x86/kmsan: Don't call instrumented code from kmsan_virt_addr_valid() Viorel Cernateanu via B4 Relay
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