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Thu, 19 Oct 2023 19:18:52 -0700 (PDT) MIME-Version: 1.0 References: <20231018113343.2446300-1-houtao@huaweicloud.com> <20231018113343.2446300-3-houtao@huaweicloud.com> In-Reply-To: <20231018113343.2446300-3-houtao@huaweicloud.com> From: Alexei Starovoitov Date: Thu, 19 Oct 2023 19:18:41 -0700 Message-ID: Subject: Re: [PATCH bpf-next v2 2/7] mm/percpu.c: introduce pcpu_alloc_size() To: Hou Tao Cc: bpf , linux-mm , Martin KaFai Lau , Andrii Nakryiko , Song Liu , Hao Luo , Yonghong Song , Daniel Borkmann , KP Singh , Stanislav Fomichev , Jiri Olsa , John Fastabend , Hou Tao , Dennis Zhou , Tejun Heo , Christoph Lameter , Andrew Morton Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 8C5AE1C000A X-Stat-Signature: to7sq5burjm56ixr6y9xg7z4nbsn651o X-Rspam-User: X-HE-Tag: 1697768334-844560 X-HE-Meta: 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 /94XJvNF 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Oct 18, 2023 at 4:32=E2=80=AFAM Hou Tao wr= ote: > > From: Hou Tao > > Introduce pcpu_alloc_size() to get the size of the dynamic per-cpu > area. It will be used by bpf memory allocator in the following patches. > BPF memory allocator maintains per-cpu area caches for multiple area > sizes and its free API only has the to-be-freed per-cpu pointer, so it > needs the size of dynamic per-cpu area to select the corresponding cache > when bpf program frees the dynamic per-cpu pointer. > > Signed-off-by: Hou Tao > --- > include/linux/percpu.h | 1 + > mm/percpu.c | 30 ++++++++++++++++++++++++++++++ > 2 files changed, 31 insertions(+) > > diff --git a/include/linux/percpu.h b/include/linux/percpu.h > index 68fac2e7cbe6..8c677f185901 100644 > --- a/include/linux/percpu.h > +++ b/include/linux/percpu.h > @@ -132,6 +132,7 @@ extern void __init setup_per_cpu_areas(void); > extern void __percpu *__alloc_percpu_gfp(size_t size, size_t align, gfp_= t gfp) __alloc_size(1); > extern void __percpu *__alloc_percpu(size_t size, size_t align) __alloc_= size(1); > extern void free_percpu(void __percpu *__pdata); > +extern size_t pcpu_alloc_size(void __percpu *__pdata); > > DEFINE_FREE(free_percpu, void __percpu *, free_percpu(_T)) > > diff --git a/mm/percpu.c b/mm/percpu.c > index 76b9c5e63c56..b0cea2dc16a9 100644 > --- a/mm/percpu.c > +++ b/mm/percpu.c > @@ -2244,6 +2244,36 @@ static void pcpu_balance_workfn(struct work_struct= *work) > mutex_unlock(&pcpu_alloc_mutex); > } > > +/** > + * pcpu_alloc_size - the size of the dynamic percpu area > + * @ptr: pointer to the dynamic percpu area > + * > + * Return the size of the dynamic percpu area @ptr. > + * > + * RETURNS: > + * The size of the dynamic percpu area. > + * > + * CONTEXT: > + * Can be called from atomic context. > + */ > +size_t pcpu_alloc_size(void __percpu *ptr) > +{ > + struct pcpu_chunk *chunk; > + unsigned long bit_off, end; > + void *addr; > + > + if (!ptr) > + return 0; > + > + addr =3D __pcpu_ptr_to_addr(ptr); > + /* No pcpu_lock here: ptr has not been freed, so chunk is still a= live */ > + chunk =3D pcpu_chunk_addr_search(addr); > + bit_off =3D (addr - chunk->base_addr) / PCPU_MIN_ALLOC_SIZE; > + end =3D find_next_bit(chunk->bound_map, pcpu_chunk_map_bits(chunk= ), > + bit_off + 1); > + return (end - bit_off) * PCPU_MIN_ALLOC_SIZE; > +} Dennis, Tejun, or Christoph, Could you please Ack patch 1 and 2, so we can apply this fix to bpf tree before the merge window. The series fixes a serious bug.