On Mon, Jan 23, 2023 at 07:17:25PM +0000, T.J. Mercier wrote: > From: Hridya Valsaraju <hridya@xxxxxxxxxx> > > This patch introduces flag BINDER_FD_FLAG_XFER_CHARGE that a process > sending an individual fd or fd array to another process over binder IPC > can set to relinquish ownership of the fd(s) being sent for memory > accounting purposes. If the flag is found to be set during the fd or fd > array translation and the fd is for a DMA-BUF, the buffer is uncharged > from the sender's cgroup and charged to the receiving process's cgroup > instead. > > It is up to the sending process to ensure that it closes the fds > regardless of whether the transfer failed or succeeded. > > Most graphics shared memory allocations in Android are done by the > graphics allocator HAL process. On requests from clients, the HAL > process allocates memory and sends the fds to the clients over binder > IPC. The graphics allocator HAL will not retain any references to the > buffers. When the HAL sets BINDER_FD_FLAG_XFER_CHARGE, binder will > transfer the charge for the buffer from the allocator process cgroup to > the client process cgroup. > > The pad [1] and pad_flags [2] fields of binder_fd_object and > binder_fda_array_object come from alignment with flat_binder_object and > have never been exposed for use from userspace. This new flags use > follows the pattern set by binder_buffer_object. > > [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/include/uapi/linux/android/binder.h?id=feba3900cabb8e7c87368faa28e7a6936809ba22 > [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/include/uapi/linux/android/binder.h?id=5cdcf4c6a638591ec0e98c57404a19e7f9997567 > > Signed-off-by: Hridya Valsaraju <hridya@xxxxxxxxxx> > Signed-off-by: T.J. Mercier <tjmercier@xxxxxxxxxx> > --- > Documentation/admin-guide/cgroup-v2.rst | 3 ++- > drivers/android/binder.c | 25 +++++++++++++++++++++---- > include/uapi/linux/android/binder.h | 19 +++++++++++++++---- > 3 files changed, 38 insertions(+), 9 deletions(-) > > diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst > index 538ae22bc514..d225295932c0 100644 > --- a/Documentation/admin-guide/cgroup-v2.rst > +++ b/Documentation/admin-guide/cgroup-v2.rst > @@ -1457,7 +1457,8 @@ PAGE_SIZE multiple when read back. > > dmabuf (npn) > Amount of memory used for exported DMA buffers allocated by the cgroup. > - Stays with the allocating cgroup regardless of how the buffer is shared. > + Stays with the allocating cgroup regardless of how the buffer is shared > + unless explicitly transferred. > > workingset_refault_anon > Number of refaults of previously evicted anonymous pages. > diff --git a/drivers/android/binder.c b/drivers/android/binder.c > index 880224ec6abb..5e707974793f 100644 > --- a/drivers/android/binder.c > +++ b/drivers/android/binder.c > @@ -42,6 +42,7 @@ > > #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt > > +#include <linux/dma-buf.h> > #include <linux/fdtable.h> > #include <linux/file.h> > #include <linux/freezer.h> > @@ -2237,7 +2238,7 @@ static int binder_translate_handle(struct flat_binder_object *fp, > return ret; > } > > -static int binder_translate_fd(u32 fd, binder_size_t fd_offset, > +static int binder_translate_fd(u32 fd, binder_size_t fd_offset, __u32 flags, > struct binder_transaction *t, > struct binder_thread *thread, > struct binder_transaction *in_reply_to) > @@ -2275,6 +2276,20 @@ static int binder_translate_fd(u32 fd, binder_size_t fd_offset, > goto err_security; > } > > + if (IS_ENABLED(CONFIG_MEMCG) && (flags & BINDER_FD_FLAG_XFER_CHARGE)) { Do we need to test for MEMCG here? it seems this has been offloaded to dma_buf_transfer_charge()? > + ret = dma_buf_transfer_charge(file, target_proc->tsk); > + if (unlikely(ret == -EBADF)) { > + binder_user_error( > + "%d:%d got transaction with XFER_CHARGE for non-DMA-BUF fd, %d\n", > + proc->pid, thread->pid, fd); > + goto err_dmabuf; > + } else if (ret) { > + pr_warn("%d:%d Unable to transfer DMA-BUF fd charge to %d\n", > + proc->pid, thread->pid, target_proc->pid); > + goto err_xfer; > + } > + } > + > /* > * Add fixup record for this transaction. The allocation > * of the fd in the target needs to be done from a > @@ -2294,6 +2309,8 @@ static int binder_translate_fd(u32 fd, binder_size_t fd_offset, > return ret; > > err_alloc: > +err_xfer: > +err_dmabuf: > err_security: > fput(file); > err_fget: > @@ -2604,7 +2621,7 @@ static int binder_translate_fd_array(struct list_head *pf_head, > > ret = copy_from_user(&fd, sender_ufda_base + sender_uoffset, sizeof(fd)); > if (!ret) > - ret = binder_translate_fd(fd, offset, t, thread, > + ret = binder_translate_fd(fd, offset, fda->flags, t, thread, > in_reply_to); > if (ret) > return ret > 0 ? -EINVAL : ret; > @@ -3383,8 +3400,8 @@ static void binder_transaction(struct binder_proc *proc, > struct binder_fd_object *fp = to_binder_fd_object(hdr); > binder_size_t fd_offset = object_offset + > (uintptr_t)&fp->fd - (uintptr_t)fp; > - int ret = binder_translate_fd(fp->fd, fd_offset, t, > - thread, in_reply_to); > + int ret = binder_translate_fd(fp->fd, fd_offset, fp->flags, > + t, thread, in_reply_to); > > fp->pad_binder = 0; > if (ret < 0 || > diff --git a/include/uapi/linux/android/binder.h b/include/uapi/linux/android/binder.h > index e72e4de8f452..4b20dd1dccb1 100644 > --- a/include/uapi/linux/android/binder.h > +++ b/include/uapi/linux/android/binder.h > @@ -91,14 +91,14 @@ struct flat_binder_object { > /** > * struct binder_fd_object - describes a filedescriptor to be fixed up. > * @hdr: common header structure > - * @pad_flags: padding to remain compatible with old userspace code > + * @flags: One or more BINDER_FD_FLAG_* flags > * @pad_binder: padding to remain compatible with old userspace code > * @fd: file descriptor > * @cookie: opaque data, used by user-space > */ > struct binder_fd_object { > struct binder_object_header hdr; > - __u32 pad_flags; > + __u32 flags; > union { > binder_uintptr_t pad_binder; > __u32 fd; > @@ -107,6 +107,17 @@ struct binder_fd_object { > binder_uintptr_t cookie; > }; > > +enum { > + /** > + * @BINDER_FD_FLAG_XFER_CHARGE > + * > + * When set, the sender of a binder_fd_object wishes to relinquish ownership of the fd for > + * memory accounting purposes. If the fd is for a DMA-BUF, the buffer is uncharged from the > + * sender's cgroup and charged to the receiving process's cgroup instead. > + */ > + BINDER_FD_FLAG_XFER_CHARGE = 0x01, > +}; > + > /* struct binder_buffer_object - object describing a userspace buffer > * @hdr: common header structure > * @flags: one or more BINDER_BUFFER_* flags > @@ -141,7 +152,7 @@ enum { > > /* struct binder_fd_array_object - object describing an array of fds in a buffer > * @hdr: common header structure > - * @pad: padding to ensure correct alignment > + * @flags: One or more BINDER_FD_FLAG_* flags > * @num_fds: number of file descriptors in the buffer > * @parent: index in offset array to buffer holding the fd array > * @parent_offset: start offset of fd array in the buffer > @@ -162,7 +173,7 @@ enum { > */ > struct binder_fd_array_object { > struct binder_object_header hdr; > - __u32 pad; > + __u32 flags; > binder_size_t num_fds; > binder_size_t parent; > binder_size_t parent_offset; > -- > 2.39.0.246.g2a6d74b583-goog > Other than the previous question this looks good to me. Also, the error from the test robot seems to indicate a missing stub for dma_buf_transfer_charg() when !CONFIG_DMA_SHARED_BUFFER. However, this is likely to be fixed outside of this patch. Feel free to add this tag to the following round: Acked-by: Carlos Llamas <cmllamas@xxxxxxxxxx> Thanks,
