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b=YhVvlZImIxqbuB1Yq+sA//Rjnrhz17zbePIJ3Hk12l5kR818rurMHr0iK1fKiEIN4 +3SC+5eCeFgnA5mccvC/WsywRCPcTINbKsGABNrWkQmRL5z816D6nk3pVcta6jXMKD kQqL/rJZ1VIVxJl1oLK+V5U4VJOe1Q5W4ZfPCD/ppDm1g3oYiCeomoXB2l7zGoktNW ATyLovjbAJmTGV4MiVzlVezyw/JrrU1QS2iOvBeque3nEnazbzCiiupN2T8NI3D0TY dpvEcpS/8dYMSr00RAL3b3PfrnQu1MrTRMtgUXjUBfXaOvZfMAAHxuY+/VQgpJS6kX NurVf28Zra+Ag== Date: Fri, 2 Oct 2026 11:09:33 +0100 From: "Lorenzo Stoakes (ARM)" To: "David Hildenbrand (Arm)" Cc: Nguyen Ngoc Thang , akpm@linux-foundation.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, peterx@redhat.com, dave.hansen@linux.intel.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, syzbot+49b1021becba70c1f3f6@syzkaller.appspotmail.com Subject: Re: [PATCH] mm: don't ioremap COWed anon pages in generic_access_phys() Message-ID: References: <699ae98c.050a0220.340abe.0d31.GAE@google.com> <20261001152524.171115-1-ngocthang2710.1999@gmail.com> <32fe40e2-854a-47ec-9d95-93e23f9a7af4@kernel.org> <9d43234f-93cb-4c86-a2a6-a3cdebf48f3b@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9d43234f-93cb-4c86-a2a6-a3cdebf48f3b@kernel.org> X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 96CC6C0005 X-Rspam-User: X-Stat-Signature: tn8zcryo1ah6rgcuqgraxma3rz96bas8 X-HE-Tag: 1790935779-494038 X-HE-Meta: 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 CZmgAmPW 1hvyJ0ISf58WFcbrfLhGyVvzREFyR1DKXjLuuhTpIkxN8wnumuTf5nciMqi1LcqsST+LJ0Z6GwOizpCmEN4G+YCowQwPTrXe2gz3P5uV93bSoedSjzZJKIrd1X67hGZKGXYjQODx6LkTCYe4R11gQMe3cJz7hhFpPjrZ25qlxnUe4sNHm0K4kMB/2alzyqS7AnqJVR/jgu2w8dlNKfgAr7zMLiOJTFEMcmiUINyI9tuLjeRQlKzh/BIxxl+krJ2ZaNKK47QmnNvR/Jbs3hVDWqn2P40nGmbRKzkCsTqpF2YUxIO19Hy55L4nD5e2QZ8gHI2u9c5cCSvHgjLJH1IgbjYLPncqdk29W8Xu9o9FUcg7KEopzG0D5Rbqmf2FYgWljdYiHL+3T7v9nQvHuf79f7YmlyRWqmzhia6Up1wqSks4JULal2KU5TGhmMpYrDMj6A3Wa93Yi6BdRarZ5sXTZj19h8PK+Aa+ppRuz Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Oct 02, 2026 at 12:04:27PM +0200, David Hildenbrand (Arm) wrote: > On 10/2/26 12:02, David Hildenbrand (Arm) wrote: > > On 10/2/26 10:38, Lorenzo Stoakes (ARM) wrote: > >> On Thu, Oct 01, 2026 at 10:22:29PM +0200, David Hildenbrand (Arm) wrote: > >>> > >> > >> Sorry to say this looks schlopped. > >> > >> This guy has sent 10 series across 6 subsystems over ~21 hrs: > >> > >> https://lore.kernel.org/all/?q=f%3Angocthang2710.1999%40gmail.com > >> > >> Nguyen - please do not flood the kernel with patches, and please use the > >> Assisted-by tag for generated content. > >> > >> The original code you submitted is really not great even if the issue may > >> be valid. > >> > >> So I'd say somebody from the core team should take over this if we want to > >> come up with a patch. > > > > Yes, I'll take care of it. > > > > [...] > >>> > >>> Signed-off-by: David Hildenbrand (Arm) > >> > >> This looks reasonable but I hate that we have 'special' CoW overrides like > >> this :) > > > > After sending this yesterday, I concluded that we can do this cleaner: just have > > > > bool normal_page; > > > > (naming suggestions?) > > > > that express that this is something refcounted with a struct page, like > > documented for vm_normal_page(). > > Hmm, have to think about that once more, regarding VM_IO and if there are some > cases that would actually have to work in generic_access_phys(). Well, my series at least makes it easier to reason about VMA_IO_BIT! Though not sure if it really touches PFN map cases specifically. > > -- > Cheers, > > David -- Cheers, Lorenzo