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Wed, 20 May 2026 20:17:20 -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: Wed, 20 May 2026 23:17:20 -0400 Message-Id: To: "Tejun Heo" , "David Vernet" , "Andrea Righi" , "Changwoo Min" , "Alexei Starovoitov" , "Andrii Nakryiko" , "Daniel Borkmann" , "Martin KaFai Lau" , "Kumar Kartikeya Dwivedi" Cc: "Peter Zijlstra" , "Catalin Marinas" , "Will Deacon" , "Thomas Gleixner" , "Ingo Molnar" , "Borislav Petkov" , "Dave Hansen" , "Andrew Morton" , "David Hildenbrand" , "Mike Rapoport" , "Emil Tsalapatis" , , , , , , Subject: Re: [PATCH 3/8] bpf: Add sleepable variant of bpf_arena_alloc_pages for kernel callers From: "Emil Tsalapatis" X-Mailer: aerc 0.21.0-0-g5549850facc2 References: <20260520235052.4180316-1-tj@kernel.org> <20260520235052.4180316-4-tj@kernel.org> In-Reply-To: <20260520235052.4180316-4-tj@kernel.org> On Wed May 20, 2026 at 7:50 PM EDT, Tejun Heo wrote: > The existing kernel-side export of bpf_arena_alloc_pages is _non_sleepabl= e > only - it's used by the verifier to inline the kfunc when the call site i= s > non-sleepable. There is no sleepable equivalent for kernel callers; the > kfunc bpf_arena_alloc_pages itself is BPF-only. > > sched_ext needs sleepable kernel-side allocs for its arena pool init/grow > paths. Add bpf_arena_alloc_pages_sleepable() mirroring the _non_sleepable > wrapper but passing sleepable=3Dtrue to arena_alloc_pages(). > > Signed-off-by: Tejun Heo Reviewed-by: Emil Tsalapatis > --- > include/linux/bpf.h | 8 ++++++++ > kernel/bpf/arena.c | 13 +++++++++++++ > 2 files changed, 21 insertions(+) > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h > index 831996c411cf..64968ca6db51 100644 > --- a/include/linux/bpf.h > +++ b/include/linux/bpf.h > @@ -679,6 +679,8 @@ int bpf_dynptr_from_file_sleepable(struct file *file,= u32 flags, > void *bpf_arena_alloc_pages_non_sleepable(void *p__map, void *addr__ign,= u32 page_cnt, int node_id, > u64 flags); > void bpf_arena_free_pages_non_sleepable(void *p__map, void *ptr__ign, u3= 2 page_cnt); > +void *bpf_arena_alloc_pages_sleepable(void *p__map, void *addr__ign, u32= page_cnt, int node_id, > + u64 flags); > #else > static inline void *bpf_arena_alloc_pages_non_sleepable(void *p__map, vo= id *addr__ign, u32 page_cnt, > int node_id, u64 flags) > @@ -689,6 +691,12 @@ static inline void *bpf_arena_alloc_pages_non_sleepa= ble(void *p__map, void *addr > static inline void bpf_arena_free_pages_non_sleepable(void *p__map, void= *ptr__ign, u32 page_cnt) > { > } > + > +static inline void *bpf_arena_alloc_pages_sleepable(void *p__map, void *= addr__ign, u32 page_cnt, > + int node_id, u64 flags) > +{ > + return NULL; > +} > #endif > =20 > extern const struct bpf_map_ops bpf_map_offload_ops; > diff --git a/kernel/bpf/arena.c b/kernel/bpf/arena.c > index 1c0b87ecc817..a811cf6170fa 100644 > --- a/kernel/bpf/arena.c > +++ b/kernel/bpf/arena.c > @@ -934,6 +934,19 @@ void *bpf_arena_alloc_pages_non_sleepable(void *p__m= ap, void *addr__ign, u32 pag > =20 > return (void *)arena_alloc_pages(arena, (long)addr__ign, page_cnt, node= _id, false); > } > + > +void *bpf_arena_alloc_pages_sleepable(void *p__map, void *addr__ign, u32= page_cnt, > + int node_id, u64 flags) > +{ > + struct bpf_map *map =3D p__map; > + struct bpf_arena *arena =3D container_of(map, struct bpf_arena, map); > + > + if (map->map_type !=3D BPF_MAP_TYPE_ARENA || flags || !page_cnt) > + return NULL; > + > + return (void *)arena_alloc_pages(arena, (long)addr__ign, page_cnt, node= _id, true); > +} > + > __bpf_kfunc void bpf_arena_free_pages(void *p__map, void *ptr__ign, u32 = page_cnt) > { > struct bpf_map *map =3D p__map;