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charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, Dec 22, 2025 at 4:36=E2=80=AFPM Joanne Koong wrote: > > Allow kernel-managed buffers to be selected. This requires modifying the > io_br_sel struct to separate the fields for address and val, since a > kernel address cannot be distinguished from a negative val when error > checking. > > Auto-commit any selected kernel-managed buffer. > > Signed-off-by: Joanne Koong > --- > include/linux/io_uring_types.h | 8 ++++---- > io_uring/kbuf.c | 15 ++++++++++++--- > 2 files changed, 16 insertions(+), 7 deletions(-) > > diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_type= s.h > index e1adb0d20a0a..36fac08db636 100644 > --- a/include/linux/io_uring_types.h > +++ b/include/linux/io_uring_types.h > @@ -93,13 +93,13 @@ struct io_mapped_region { > */ > struct io_br_sel { > struct io_buffer_list *buf_list; > - /* > - * Some selection parts return the user address, others return an= error. > - */ > union { > + /* for classic/ring provided buffers */ > void __user *addr; > - ssize_t val; > + /* for kernel-managed buffers */ > + void *kaddr; > }; > + ssize_t val; > }; > > > diff --git a/io_uring/kbuf.c b/io_uring/kbuf.c > index 68469efe5552..8f63924bc9f7 100644 > --- a/io_uring/kbuf.c > +++ b/io_uring/kbuf.c > @@ -155,7 +155,8 @@ static int io_provided_buffers_select(struct io_kiocb= *req, size_t *len, > return 1; > } > > -static bool io_should_commit(struct io_kiocb *req, unsigned int issue_fl= ags) > +static bool io_should_commit(struct io_kiocb *req, struct io_buffer_list= *bl, > + unsigned int issue_flags) > { > /* > * If we came in unlocked, we have no choice but to consume the > @@ -170,7 +171,11 @@ static bool io_should_commit(struct io_kiocb *req, u= nsigned int issue_flags) > if (issue_flags & IO_URING_F_UNLOCKED) > return true; > > - /* uring_cmd commits kbuf upfront, no need to auto-commit */ > + /* kernel-managed buffers are auto-committed */ > + if (bl->flags & IOBL_KERNEL_MANAGED) > + return true; > + > + /* multishot uring_cmd commits kbuf upfront, no need to auto-comm= it */ > if (!io_file_can_poll(req) && req->opcode !=3D IORING_OP_URING_CM= D) > return true; > return false; > @@ -201,8 +206,12 @@ static struct io_br_sel io_ring_buffer_select(struct= io_kiocb *req, size_t *len, > req->buf_index =3D READ_ONCE(buf->bid); > sel.buf_list =3D bl; > sel.addr =3D u64_to_user_ptr(READ_ONCE(buf->addr)); Drop this assignment as it's overwritten by the assignments below? Best, Caleb > + if (bl->flags & IOBL_KERNEL_MANAGED) > + sel.kaddr =3D (void *)(uintptr_t)buf->addr; > + else > + sel.addr =3D u64_to_user_ptr(READ_ONCE(buf->addr)); > > - if (io_should_commit(req, issue_flags)) { > + if (io_should_commit(req, bl, issue_flags)) { > io_kbuf_commit(req, sel.buf_list, *len, 1); > sel.buf_list =3D NULL; > } > -- > 2.47.3 >