linux-kernel - Re: [PATCH 3/5] mm: export zap_page_range_single and list_lru

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Message-ID: <e7247f3e-8a88-4b46-91ba-cb73cce1346a@lucifer.local>
Date: Thu, 5 Feb 2026 12:10:38 +0000
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: Alice Ryhl <aliceryhl@...gle.com>
Cc: "David Hildenbrand (arm)" <david@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Carlos Llamas <cmllamas@...gle.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>,
        Paul Moore <paul@...l-moore.com>, James Morris <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Dave Chinner <david@...morbit.com>,
        Qi Zheng <zhengqi.arch@...edance.com>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Muchun Song <muchun.song@...ux.dev>,
        "Liam R. Howlett" <Liam.Howlett@...cle.com>,
        Vlastimil Babka <vbabka@...e.cz>, Mike Rapoport <rppt@...nel.org>,
        Suren Baghdasaryan <surenb@...gle.com>, Michal Hocko <mhocko@...e.com>,
        Miguel Ojeda <ojeda@...nel.org>, Boqun Feng <boqun.feng@...il.com>,
        Gary Guo <gary@...yguo.net>,
        Björn Roy Baron <bjorn3_gh@...tonmail.com>,
        Benno Lossin <lossin@...nel.org>,
        Andreas Hindborg <a.hindborg@...nel.org>,
        Trevor Gross <tmgross@...ch.edu>, Danilo Krummrich <dakr@...nel.org>,
        kernel-team@...roid.com, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-security-module@...r.kernel.org,
        linux-mm@...ck.org, rust-for-linux@...r.kernel.org
Subject: Re: [PATCH 3/5] mm: export zap_page_range_single and list_lru_add/del

On Thu, Feb 05, 2026 at 11:58:00AM +0000, Alice Ryhl wrote:
> On Thu, Feb 05, 2026 at 12:43:03PM +0100, David Hildenbrand (arm) wrote:
> > On 2/5/26 12:29, Lorenzo Stoakes wrote:
> > > On Thu, Feb 05, 2026 at 10:51:28AM +0000, Alice Ryhl wrote:
> > > >   bool list_lru_del_obj(struct list_lru *lru, struct list_head *item)
> > > >   {
> > > > diff --git a/mm/memory.c b/mm/memory.c
> > > > index da360a6eb8a48e29293430d0c577fb4b6ec58099..64083ace239a2caf58e1645dd5d91a41d61492c4 100644
> > > > --- a/mm/memory.c
> > > > +++ b/mm/memory.c
> > > > @@ -2168,6 +2168,7 @@ void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
> > > >   	zap_page_range_single_batched(&tlb, vma, address, size, details);
> > > >   	tlb_finish_mmu(&tlb);
> > > >   }
> > > > +EXPORT_SYMBOL(zap_page_range_single);
> > >
> > > Sorry but I don't want this exported at all.
> > >
> > > This is an internal implementation detail which allows fine-grained control of
> > > behaviour via struct zap_details (which binder doesn't use, of course :)
> >
> > I don't expect anybody to set zap_details, but yeah, it could be abused.
> > It could be abused right now from anywhere else in the kernel
> > where we don't build as a module :)
> >
> > Apparently we export a similar function in rust where we just removed the last parameter.
>
> To clarify, said Rust function gets inlined into Rust Binder, so Rust
> Binder calls the zap_page_range_single() symbol directly.

Presumably only for things compiled into the kernel right?