From: Matthew Wilcox <willy@infradead.org>
To: David Carlier <devnexen@gmail.com>
Cc: akpm@linux-foundation.org,
syzbot+fd95a72470f5a44e464c@syzkaller.appspotmail.com,
David Hildenbrand <david@kernel.org>,
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>, Kevin Tian <kevin.tian@intel.com>,
Jason Gunthorpe <jgg@ziepe.ca>,
Dave Hansen <dave.hansen@linux.intel.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] mm: pgtable: protect lockless kernel page table walks with RCU
Date: Fri, 12 Jun 2026 18:39:56 +0100 [thread overview]
Message-ID: <aixEbMI0kK9in7AF@casper.infradead.org> (raw)
In-Reply-To: <20260612172356.356894-1-devnexen@gmail.com>
On Fri, Jun 12, 2026 at 06:23:55PM +0100, David Carlier wrote:
> ptdump walks the kernel page tables locklessly through
> walk_kernel_page_table_range_lockless(). It only holds the init_mm
> mmap lock and the memory hotplug lock, and neither excludes
> vmalloc/ioremap teardown from freeing kernel PTE pages via
> pmd_free_pte_page() -> pagetable_free_kernel(). syzbot hit a
> use-after-free in ptdump_pte_entry() reading a PTE page that was freed
> underneath the walk.
Does it make sense to walk the iomap / vmap ranges in ptdump? I can't
really tell if this is something that's useful, or something that nobody
thought to exclude.
next prev parent reply other threads:[~2026-06-12 17:40 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-12 4:38 [PATCH] mm: pgtable: protect lockless kernel page table walks with RCU David Carlier
2026-06-12 4:52 ` Matthew Wilcox
2026-06-12 4:59 ` David CARLIER
2026-06-12 5:05 ` [PATCH v2] " David Carlier
2026-06-12 16:12 ` Andrew Morton
2026-06-12 17:21 ` David CARLIER
2026-06-12 17:23 ` [PATCH v3] " David Carlier
2026-06-12 17:39 ` Matthew Wilcox [this message]
2026-06-12 18:10 ` David CARLIER
2026-06-12 18:29 ` Lorenzo Stoakes
2026-06-12 18:48 ` David CARLIER
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