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Fri, 17 Jul 2026 16:32:33 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Fri, 17 Jul 2026 19:32:30 -0400 Message-Id: Subject: Re: [PATCH bpf-next v2 1/4] bpf: Pass arena instead of scratch_page to the pte callbacks From: "Emil Tsalapatis" To: "Jiayuan Chen" , Cc: "Alexei Starovoitov" , "Daniel Borkmann" , "Andrii Nakryiko" , "Eduard Zingerman" , "Kumar Kartikeya Dwivedi" , "Martin KaFai Lau" , "Song Liu" , "Yonghong Song" , "Jiri Olsa" , "Emil Tsalapatis" , "Shuah Khan" , "Woojin Ji" , "Puranjay Mohan" , "Saket Kumar Bhaskar" , "Ihor Solodrai" , , X-Mailer: aerc 0.21.0-0-g5549850facc2 References: <20260717114117.350851-1-jiayuan.chen@linux.dev> <20260717114117.350851-2-jiayuan.chen@linux.dev> In-Reply-To: <20260717114117.350851-2-jiayuan.chen@linux.dev> On Fri Jul 17, 2026 at 7:37 AM EDT, Jiayuan Chen wrote: > Replace the scratch_page field in the pte-callback data with the arena > pointer; later patches use other arena fields from these callbacks. No > functional change. > > Signed-off-by: Jiayuan Chen Reviewed-by: Emil Tsalapatis > --- > kernel/bpf/arena.c | 17 ++++++++--------- > 1 file changed, 8 insertions(+), 9 deletions(-) > > diff --git a/kernel/bpf/arena.c b/kernel/bpf/arena.c > index 80b7b8a69446..8dbc24460890 100644 > --- a/kernel/bpf/arena.c > +++ b/kernel/bpf/arena.c > @@ -143,14 +143,14 @@ static long compute_pgoff(struct bpf_arena *arena, = long uaddr) > } > =20 > struct apply_range_data { > + struct bpf_arena *arena; > struct page **pages; > - struct page *scratch_page; > int i; > }; > =20 > struct clear_range_data { > + struct bpf_arena *arena; > struct llist_head *free_pages; > - struct page *scratch_page; > }; > =20 > static int apply_range_set_cb(pte_t *pte, unsigned long addr, void *data= ) > @@ -180,7 +180,7 @@ static int apply_range_set_cb(pte_t *pte, unsigned lo= ng addr, void *data) > =20 > if (pte_none(old)) > continue; > - if (WARN_ON_ONCE(pte_page(old) !=3D d->scratch_page)) > + if (WARN_ON_ONCE(pte_page(old) !=3D d->arena->scratch_page)) > return -EBUSY; > ptep_get_and_clear(&init_mm, addr, pte); > flush_tlb_before_set(addr); > @@ -227,7 +227,7 @@ static int apply_range_clear_cb(pte_t *pte, unsigned = long addr, void *data) > * scratches its PTE. A later bpf_arena_free_pages() over that range wa= lks > * here. Without the skip, scratch_page would be freed. > */ > - if (page =3D=3D d->scratch_page) > + if (page =3D=3D d->arena->scratch_page) > return 0; > =20 > __llist_add(&page->pcp_llist, d->free_pages); > @@ -506,8 +506,7 @@ static vm_fault_t arena_vm_fault(struct vm_fault *vmf= ) > if (ret) > goto out_sigsegv_memcg; > =20 > - struct apply_range_data data =3D { .pages =3D &page, .i =3D 0, > - .scratch_page =3D arena->scratch_page }; > + struct apply_range_data data =3D { .arena =3D arena, .pages =3D &page, = .i =3D 0 }; > /* Account into memcg of the process that created bpf_arena */ > ret =3D bpf_map_alloc_pages(map, NUMA_NO_NODE, 1, &page); > if (ret) { > @@ -696,8 +695,8 @@ static long arena_alloc_pages(struct bpf_arena *arena= , long uaddr, long page_cnt > bpf_map_memcg_exit(old_memcg, new_memcg); > return 0; > } > + data.arena =3D arena; > data.pages =3D pages; > - data.scratch_page =3D arena->scratch_page; > =20 > if (raw_res_spin_lock_irqsave(&arena->spinlock, flags)) > goto out_free_pages; > @@ -873,8 +872,8 @@ static void arena_free_pages(struct bpf_arena *arena,= long uaddr, long page_cnt, > range_tree_set(&arena->rt, pgoff, page_cnt); > =20 > init_llist_head(&free_pages); > + cdata.arena =3D arena; > cdata.free_pages =3D &free_pages; > - cdata.scratch_page =3D arena->scratch_page; > /* clear ptes and collect struct pages */ > apply_to_existing_page_range(&init_mm, kaddr, page_cnt << PAGE_SHIFT, > apply_range_clear_cb, &cdata); > @@ -981,8 +980,8 @@ static void arena_free_worker(struct work_struct *wor= k) > bpf_map_memcg_enter(&arena->map, &old_memcg, &new_memcg); > =20 > init_llist_head(&free_pages); > + cdata.arena =3D arena; > cdata.free_pages =3D &free_pages; > - cdata.scratch_page =3D arena->scratch_page; > arena_vm_start =3D bpf_arena_get_kern_vm_start(arena); > user_vm_start =3D bpf_arena_get_user_vm_start(arena); > =20