All DMA heaps now register a new GPU cgroup bucket upon creation, and the system_heap now exports buffers associated with its GPU cgroup bucket for tracking purposes.

In order to support GPU cgroup charge transfer on a dma-buf, the current GPU cgroup information must be stored inside the dma-buf struct. For tracked buffers, exporters include the struct gpucg and struct gpucg_bucket pointers in the export info which can later be modified if the charge is migrated to another cgroup.

Signed-off-by: Hridya Valsaraju hridya@google.com Signed-off-by: T.J. Mercier tjmercier@google.com --- v7 changes Adapt to new gpucg_register_bucket API.

v5 changes Merge dmabuf: Use the GPU cgroup charge/uncharge APIs into this patch.

Remove all GPU cgroup code from dma-buf except what's necessary to support charge transfer. Previously charging was done in export, but for non-Android graphics use-cases this is not ideal since there may be a dealy between allocation and export, during which time there is no accounting.

Append "-heap" to gpucg_bucket names.

Charge on allocation instead of export. This should more closely mirror non-Android use-cases where there is potentially a delay between allocation and export.

Put the charge and uncharge code in the same file (system_heap_allocate, system_heap_dma_buf_release) instead of splitting them between the heap and the dma_buf_release.

Move no-op code to header file to match other files in the series.

v3 changes Use more common dual author commit message format per John Stultz.

v2 changes Move dma-buf cgroup charge transfer from a dma_buf_op defined by every heap to a single dma-buf function for all heaps per Daniel Vetter and Christian König. --- drivers/dma-buf/dma-buf.c | 19 +++++++++++++ drivers/dma-buf/dma-heap.c | 38 ++++++++++++++++++++++++++ drivers/dma-buf/heaps/system_heap.c | 28 +++++++++++++++++--- include/linux/dma-buf.h | 41 +++++++++++++++++++++++------ include/linux/dma-heap.h | 15 +++++++++++ 5 files changed, 129 insertions(+), 12 deletions(-)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index df23239b04fc..bc89c44bd9b9 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -462,6 +462,24 @@ static struct file *dma_buf_getfile(struct dma_buf *dmabuf, int flags) * &dma_buf_ops. */

+#ifdef CONFIG_CGROUP_GPU +static void dma_buf_set_gpucg(struct dma_buf *dmabuf, const struct dma_buf_export_info *exp) +{ + dmabuf->gpucg = exp->gpucg; + dmabuf->gpucg_bucket = exp->gpucg_bucket; +} + +void dma_buf_exp_info_set_gpucg(struct dma_buf_export_info *exp_info, + struct gpucg *gpucg, + struct gpucg_bucket *gpucg_bucket) +{ + exp_info->gpucg = gpucg; + exp_info->gpucg_bucket = gpucg_bucket; +} +#else +static void dma_buf_set_gpucg(struct dma_buf *dmabuf, struct dma_buf_export_info *exp) {} +#endif + /** * dma_buf_export - Creates a new dma_buf, and associates an anon file * with this buffer, so it can be exported. @@ -527,6 +545,7 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info) init_waitqueue_head(&dmabuf->poll); dmabuf->cb_in.poll = dmabuf->cb_out.poll = &dmabuf->poll; dmabuf->cb_in.active = dmabuf->cb_out.active = 0; + dma_buf_set_gpucg(dmabuf, exp_info);

if (!resv) { resv = (struct dma_resv *)&dmabuf[1]; diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c index 8f5848aa144f..48173a66d70d 100644 --- a/drivers/dma-buf/dma-heap.c +++ b/drivers/dma-buf/dma-heap.c @@ -7,10 +7,12 @@ */

#include <linux/cdev.h> +#include <linux/cgroup_gpu.h> #include <linux/debugfs.h> #include <linux/device.h> #include <linux/dma-buf.h> #include <linux/err.h> +#include <linux/kconfig.h> #include <linux/xarray.h> #include <linux/list.h> #include <linux/slab.h> @@ -21,6 +23,7 @@ #include <uapi/linux/dma-heap.h>

#define DEVNAME "dma_heap" +#define HEAP_NAME_SUFFIX "-heap"

#define NUM_HEAP_MINORS 128

@@ -31,6 +34,7 @@ * @heap_devt heap device node * @list list head connecting to list of heaps * @heap_cdev heap char device + * @gpucg_bucket gpu cgroup bucket for memory accounting * * Represents a heap of memory from which buffers can be made. */ @@ -41,6 +45,9 @@ struct dma_heap { dev_t heap_devt; struct list_head list; struct cdev heap_cdev; +#ifdef CONFIG_CGROUP_GPU + struct gpucg_bucket *gpucg_bucket; +#endif };

static LIST_HEAD(heap_list); @@ -216,6 +223,18 @@ const char *dma_heap_get_name(struct dma_heap *heap) return heap->name; }

+/** + * dma_heap_get_gpucg_bucket() - get struct gpucg_bucket pointer for the heap. + * @heap: DMA-Heap to get the gpucg_bucket struct for. + * + * Returns: + * The gpucg_bucket struct pointer for the heap. NULL if the GPU cgroup controller is not enabled. + */ +struct gpucg_bucket *dma_heap_get_gpucg_bucket(struct dma_heap *heap) +{ + return heap->gpucg_bucket; +} + struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info) { struct dma_heap *heap, *h, *err_ret; @@ -228,6 +247,12 @@ struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info) return ERR_PTR(-EINVAL); }

+ if (IS_ENABLED(CONFIG_CGROUP_GPU) && strlen(exp_info->name) + strlen(HEAP_NAME_SUFFIX) >= + GPUCG_BUCKET_NAME_MAX_LEN) { + pr_err("dma_heap: Name is too long for GPU cgroup\n"); + return ERR_PTR(-ENAMETOOLONG); + } + if (!exp_info->ops || !exp_info->ops->allocate) { pr_err("dma_heap: Cannot add heap with invalid ops struct\n"); return ERR_PTR(-EINVAL); @@ -253,6 +278,19 @@ struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info) heap->ops = exp_info->ops; heap->priv = exp_info->priv;

+ if (IS_ENABLED(CONFIG_CGROUP_GPU)) { + char gpucg_bucket_name[GPUCG_BUCKET_NAME_MAX_LEN]; + + snprintf(gpucg_bucket_name, sizeof(gpucg_bucket_name), "%s%s", + exp_info->name, HEAP_NAME_SUFFIX); + + heap->gpucg_bucket = gpucg_register_bucket(gpucg_bucket_name); + if (IS_ERR(heap->gpucg_bucket)) { + err_ret = ERR_CAST(heap->gpucg_bucket); + goto err0; + } + } + /* Find unused minor number */ ret = xa_alloc(&dma_heap_minors, &minor, heap, XA_LIMIT(0, NUM_HEAP_MINORS - 1), GFP_KERNEL); diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c index fcf836ba9c1f..27f686faef00 100644 --- a/drivers/dma-buf/heaps/system_heap.c +++ b/drivers/dma-buf/heaps/system_heap.c @@ -297,6 +297,11 @@ static void system_heap_dma_buf_release(struct dma_buf *dmabuf) } sg_free_table(table); kfree(buffer); + + if (dmabuf->gpucg && dmabuf->gpucg_bucket) { + gpucg_uncharge(dmabuf->gpucg, dmabuf->gpucg_bucket, dmabuf->size); + gpucg_put(dmabuf->gpucg); + } }

static const struct dma_buf_ops system_heap_buf_ops = { @@ -346,11 +351,21 @@ static struct dma_buf *system_heap_allocate(struct dma_heap *heap, struct scatterlist *sg; struct list_head pages; struct page *page, *tmp_page; - int i, ret = -ENOMEM; + struct gpucg *gpucg; + struct gpucg_bucket *gpucg_bucket; + int i, ret; + + gpucg = gpucg_get(current); + gpucg_bucket = dma_heap_get_gpucg_bucket(heap); + ret = gpucg_charge(gpucg, gpucg_bucket, len); + if (ret) + goto put_gpucg;

buffer = kzalloc(sizeof(*buffer), GFP_KERNEL); - if (!buffer) - return ERR_PTR(-ENOMEM); + if (!buffer) { + ret = -ENOMEM; + goto uncharge_gpucg; + }

INIT_LIST_HEAD(&buffer->attachments); mutex_init(&buffer->lock); @@ -396,6 +411,8 @@ static struct dma_buf *system_heap_allocate(struct dma_heap *heap, exp_info.size = buffer->len; exp_info.flags = fd_flags; exp_info.priv = buffer; + dma_buf_exp_info_set_gpucg(&exp_info, gpucg, gpucg_bucket); + dmabuf = dma_buf_export(&exp_info); if (IS_ERR(dmabuf)) { ret = PTR_ERR(dmabuf); @@ -414,7 +431,10 @@ static struct dma_buf *system_heap_allocate(struct dma_heap *heap, list_for_each_entry_safe(page, tmp_page, &pages, lru) __free_pages(page, compound_order(page)); kfree(buffer); - +uncharge_gpucg: + gpucg_uncharge(gpucg, gpucg_bucket, len); +put_gpucg: + gpucg_put(gpucg); return ERR_PTR(ret); }

diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h index 2097760e8e95..8e7c55c830b3 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -13,6 +13,7 @@ #ifndef __DMA_BUF_H__ #define __DMA_BUF_H__

+#include <linux/cgroup_gpu.h> #include <linux/iosys-map.h> #include <linux/file.h> #include <linux/err.h> @@ -303,7 +304,7 @@ struct dma_buf { /** * @size: * - * Size of the buffer; invariant over the lifetime of the buffer. + * Size of the buffer in bytes; invariant over the lifetime of the buffer. */ size_t size;

@@ -453,6 +454,14 @@ struct dma_buf { struct dma_buf *dmabuf; } *sysfs_entry; #endif + +#ifdef CONFIG_CGROUP_GPU + /** @gpucg: Pointer to the GPU cgroup this buffer currently belongs to. */ + struct gpucg *gpucg; + + /* @gpucg_bucket: Pointer to the GPU cgroup bucket whence this buffer originates. */ + struct gpucg_bucket *gpucg_bucket; +#endif };

/** @@ -526,13 +535,15 @@ struct dma_buf_attachment {

/** * struct dma_buf_export_info - holds information needed to export a dma_buf - * @exp_name: name of the exporter - useful for debugging. - * @owner: pointer to exporter module - used for refcounting kernel module - * @ops: Attach allocator-defined dma buf ops to the new buffer - * @size: Size of the buffer - invariant over the lifetime of the buffer - * @flags: mode flags for the file - * @resv: reservation-object, NULL to allocate default one - * @priv: Attach private data of allocator to this buffer + * @exp_name: name of the exporter - useful for debugging. + * @owner: pointer to exporter module - used for refcounting kernel module + * @ops: Attach allocator-defined dma buf ops to the new buffer + * @size: Size of the buffer in bytes - invariant over the lifetime of the buffer + * @flags: mode flags for the file + * @resv: reservation-object, NULL to allocate default one + * @priv: Attach private data of allocator to this buffer + * @gpucg: Pointer to GPU cgroup this buffer is charged to, or NULL if not charged + * @gpucg_bucket: Pointer to GPU cgroup bucket this buffer comes from, or NULL if not charged * * This structure holds the information required to export the buffer. Used * with dma_buf_export() only. @@ -545,6 +556,10 @@ struct dma_buf_export_info { int flags; struct dma_resv *resv; void *priv; +#ifdef CONFIG_CGROUP_GPU + struct gpucg *gpucg; + struct gpucg_bucket *gpucg_bucket; +#endif };

/** @@ -630,4 +645,14 @@ int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *, unsigned long); int dma_buf_vmap(struct dma_buf *dmabuf, struct iosys_map *map); void dma_buf_vunmap(struct dma_buf *dmabuf, struct iosys_map *map); + +#ifdef CONFIG_CGROUP_GPU +void dma_buf_exp_info_set_gpucg(struct dma_buf_export_info *exp_info, + struct gpucg *gpucg, + struct gpucg_bucket *gpucg_bucket); +#else/* CONFIG_CGROUP_GPU */ +static inline void dma_buf_exp_info_set_gpucg(struct dma_buf_export_info *exp_info, + struct gpucg *gpucg, + struct gpucg_bucket *gpucg_bucket) {} +#endif /* CONFIG_CGROUP_GPU */ #endif /* __DMA_BUF_H__ */ diff --git a/include/linux/dma-heap.h b/include/linux/dma-heap.h index 0c05561cad6e..6321e7636538 100644 --- a/include/linux/dma-heap.h +++ b/include/linux/dma-heap.h @@ -10,6 +10,7 @@ #define _DMA_HEAPS_H

#include <linux/cdev.h> +#include <linux/cgroup_gpu.h> #include <linux/types.h>

struct dma_heap; @@ -59,6 +60,20 @@ void *dma_heap_get_drvdata(struct dma_heap *heap); */ const char *dma_heap_get_name(struct dma_heap *heap);

+#ifdef CONFIG_CGROUP_GPU +/** + * dma_heap_get_gpucg_bucket() - get a pointer to the struct gpucg_bucket for the heap. + * @heap: DMA-Heap to retrieve gpucg_bucket for + * + * Returns: + * The gpucg_bucket struct for the heap. + */ +struct gpucg_bucket *dma_heap_get_gpucg_bucket(struct dma_heap *heap); +#else /* CONFIG_CGROUP_GPU */ +static inline struct gpucg_bucket *dma_heap_get_gpucg_bucket(struct dma_heap *heap) +{ return NULL; } +#endif /* CONFIG_CGROUP_GPU */ + /** * dma_heap_add - adds a heap to dmabuf heaps * @exp_info: information needed to register this heap

From: Hridya Valsaraju hridya@google.com

This patch introduces flags BINDER_FD_FLAG_XFER_CHARGE, and 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 fds 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 *_FLAG_XFER_CHARGE for fd arrays holding DMA-BUF fds, or individual fd objects, the gpu cgroup controller will be able to correctly charge the buffers to the client processes instead of the graphics allocator HAL.

Since this is a new feature exposed to userspace, the kernel and userspace must be compatible for the accounting to work for transfers. In all cases the allocation and transport of DMA buffers via binder will succeed, but only when both the kernel supports, and userspace depends on this feature will the transfer accounting work. The possible scenarios are detailed below:

1. new kernel + old userspace The kernel supports the feature but userspace does not use it. The old userspace won't mount the new cgroup controller, accounting is not performed, charge is not transferred.

2. old kernel + new userspace The new cgroup controller is not supported by the kernel, accounting is not performed, charge is not transferred.

3. old kernel + old userspace Same as #2

4. new kernel + new userspace Cgroup is mounted, feature is supported and used.

Signed-off-by: Hridya Valsaraju hridya@google.com Signed-off-by: T.J. Mercier tjmercier@google.com

--- v6 changes Rename BINDER_FD{A}_FLAG_SENDER_NO_NEED -> BINDER_FD{A}_FLAG_XFER_CHARGE per Carlos Llamas.

Return error on transfer failure per Carlos Llamas.

v5 changes Support both binder_fd_array_object and binder_fd_object. This is necessary because new versions of Android will use binder_fd_object instead of binder_fd_array_object, and we need to support both.

Use the new, simpler dma_buf_transfer_charge API.

v3 changes Remove android from title per Todd Kjos.

Use more common dual author commit message format per John Stultz.

Include details on behavior for all combinations of kernel/userspace versions in changelog (thanks Suren Baghdasaryan) per Greg Kroah-Hartman.

v2 changes Move dma-buf cgroup charge transfer from a dma_buf_op defined by every heap to a single dma-buf function for all heaps per Daniel Vetter and Christian König. --- drivers/android/binder.c | 31 +++++++++++++++++++++++++---- drivers/dma-buf/dma-buf.c | 4 ++-- include/linux/dma-buf.h | 2 +- include/uapi/linux/android/binder.h | 23 +++++++++++++++++---- 4 files changed, 49 insertions(+), 11 deletions(-)

diff --git a/drivers/android/binder.c b/drivers/android/binder.c index 8351c5638880..1f39b24498f1 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> @@ -2170,7 +2171,7 @@ 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) @@ -2208,6 +2209,26 @@ static int binder_translate_fd(u32 fd, binder_size_t fd_offset, goto err_security; }

+ if (IS_ENABLED(CONFIG_CGROUP_GPU) && (flags & BINDER_FD_FLAG_XFER_CHARGE)) { + struct dma_buf *dmabuf; + + if (!is_dma_buf_file(file)) { + binder_user_error( + "%d:%d got transaction with XFER_CHARGE for non-dmabuf fd, %d\n", + proc->pid, thread->pid, fd); + ret = -EINVAL; + goto err_dmabuf; + } + + dmabuf = file->private_data; + ret = dma_buf_transfer_charge(dmabuf, target_proc->tsk); + 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 @@ -2226,6 +2247,8 @@ 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: @@ -2528,7 +2551,7 @@ 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; @@ -3179,8 +3202,8 @@ 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/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index f3fb844925e2..36ed6cd4ddcc 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -31,7 +31,6 @@

#include "dma-buf-sysfs-stats.h"

-static inline int is_dma_buf_file(struct file *);

struct dma_buf_list { struct list_head head; @@ -400,10 +399,11 @@ static const struct file_operations dma_buf_fops = { /* * is_dma_buf_file - Check if struct file* is associated with dma_buf */ -static inline int is_dma_buf_file(struct file *file) +int is_dma_buf_file(struct file *file) { return file->f_op == &dma_buf_fops; } +EXPORT_SYMBOL_NS_GPL(is_dma_buf_file, DMA_BUF);

static struct file *dma_buf_getfile(struct dma_buf *dmabuf, int flags) { diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h index 438ad8577b76..2b9812758fee 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -614,7 +614,7 @@ dma_buf_attachment_is_dynamic(struct dma_buf_attachment *attach) { return !!attach->importer_ops; } - +int is_dma_buf_file(struct file *file); struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf, struct device *dev); struct dma_buf_attachment * diff --git a/include/uapi/linux/android/binder.h b/include/uapi/linux/android/binder.h index 11157fae8a8e..d17e791b38ab 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 = 0x2000, +}; + /* 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_FDA_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 @@ -162,12 +173,16 @@ 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; };

+enum { + BINDER_FDA_FLAG_XFER_CHARGE = BINDER_FD_FLAG_XFER_CHARGE, +}; + /* * On 64-bit platforms where user code may run in 32-bits the driver must * translate the buffer (and local binder) addresses appropriately.

From: Enric Balletbo i Serra eballetbo@kernel.org

On Tue, 10 May 2022 23:56:45 +0000, T.J. Mercier wrote:

From: Hridya Valsaraju hridya@google.com

Hi T.J. Mercier,

Many thanks for this effort. It caught my attention because we might have a use case where this feature can be useful for us. Hence I'd like to jump and be part of the discussion, I'd really appreciate if you can cc'me for next versions.

While reading the full patchset I was a bit confused about the status of this proposal. In fact, the rfc in the subject combined with the number of iterations (already seven) confused me. So I'm wondering if this is a RFC or a 'real' proposal already that you want to land.

If this is still a RFC I'd remove the 'rfc: Proposal' and use the more canonical way that is put RFC in the []. I.e [PATCH RFC v7] cgroup: Add a GPU cgroup controller.

If it is not, I'd just remove the RFC and make the subject in the cgroup subsystem instead of the gpu. I.E [PATCH v7] cgroup: Add a GPU cgroup

I don't want to nitpick but IMO that helps new people to join to the history of the patchset.

This patch adds a proposal for a new GPU cgroup controller for accounting/limiting GPU and GPU-related memory allocations.

As far as I can see the only thing that is adding here is the accounting, so I'd remove any reference to limiting and just explain what the patch really introduces, not the future, otherwise is confusing an you expect more than the patch really does.

It is important maintain the commit message sync with what the patch really does.

The proposed controller is based on the DRM cgroup controller[1] and follows the design of the RDMA cgroup controller.

The new cgroup controller would:

• Allow setting per-device limits on the total size of buffers allocated by device within a cgroup.
• Expose a per-device/allocator breakdown of the buffers charged to a cgroup.

The prototype in the following patches is only for memory accounting using the GPU cgroup controller and does not implement limit setting.

I think this is material for the cover more than the commit message. When I read this I was expecting all this in this patch.

Signed-off-by: Hridya Valsaraju hridya@google.com Signed-off-by: T.J. Mercier tjmercier@google.com

---

v7 changes Remove comment about duplicate name rejection which is not relevant to cgroups users per Michal Koutný.

v6 changes Move documentation into cgroup-v2.rst per Tejun Heo.

v5 changes Drop the global GPU cgroup "total" (sum of all device totals) portion of the design since there is no currently known use for this per Tejun Heo.

Update for renamed functions/variables.

v3 changes Remove Upstreaming Plan from gpu-cgroup.rst per John Stultz.

Use more common dual author commit message format per John Stultz.

Documentation/admin-guide/cgroup-v2.rst | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+)

diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst index 69d7a6983f78..2e1d26e327c7 100644 --- a/Documentation/admin-guide/cgroup-v2.rst +++ b/Documentation/admin-guide/cgroup-v2.rst @@ -2352,6 +2352,29 @@ first, and stays charged to that cgroup until that resource is freed. Migrating a process to a different cgroup does not move the charge to the destination cgroup where the process has moved.

+GPU +---

+The GPU controller accounts for device and system memory allocated by the GPU +and related subsystems for graphics use. Resource limits are not currently +supported.

+GPU Interface Files +~~~~~~~~~~~~~~~~~~~~

• gpu.memory.current
• A read-only file containing memory allocations in flat-keyed format. The key
• is a string representing the device name. The value is the size of the memory
• charged to the device in bytes. The device names are globally unique.::

•  $ cat /sys/kernel/fs/cgroup1/gpu.memory.current
  

I think this is outdated, you are using cgroup v2, right?

•  dev1 4194304
  

•  dev2 104857600
  

When I applied the full series I was expecting see the memory allocated by the gpu devices or users of the gpu in this file but, after some experiments, what I saw is the memory allocated via any process that uses the dma-buf heap API (not necessary gpu users). For example, if you create a small program that allocates some memory via the dma-buf heap API and then you cat the gpu.memory.current file, you see that the memory accounted is not related to the gpu.

This is really confusing, looks to me that the patches evolved to account memory that is not really related to the GPU but allocated vi the dma-buf heap API. IMO the name of the file should be according to what really does to avoid confusions.

So, is this patchset meant to be GPU specific? If the answer is yes that's good but that's not what I experienced. I'm missing something?

If the answer is that evolved to track dma-buf heap allocations I think all the patches need some rework to adapt the wording as right now, the gpu wording seems confusing to me.

• The device name string is set by a device driver when it registers with the
• GPU cgroup controller to participate in resource accounting.

Others

Thanks, Enric

From: Enric Balletbo i Serra eballetbo@kernel.org

On Tue, 10 May 2022 23:56:46 +0000, T.J. Mercier wrote

From: Hridya Valsaraju hridya@google.com

The cgroup controller provides accounting for GPU and GPU-related memory allocations. The memory being accounted can be device memory or memory allocated from pools dedicated to serve GPU-related tasks.

This patch adds APIs to: -allow a device to register for memory accounting using the GPU cgroup controller. -charge and uncharge allocated memory to a cgroup.

When the cgroup controller is enabled, it would expose information about the memory allocated by each device(registered for GPU cgroup memory accounting) for each cgroup.

The API/UAPI can be extended to set per-device/total allocation limits in the future.

The cgroup controller has been named following the discussion in [1].

Signed-off-by: Hridya Valsaraju hridya@google.com Signed-off-by: T.J. Mercier tjmercier@google.com

---

v7 changes Hide gpucg and gpucg_bucket struct definitions per Michal Koutný. This means gpucg_register_bucket now returns an internally allocated struct gpucg_bucket.

Move all public function documentation to the cgroup_gpu.h header.

v5 changes Support all strings for gpucg_register_device instead of just string literals.

Enforce globally unique gpucg_bucket names.

Constrain gpucg_bucket name lengths to 64 bytes.

Obtain just a single css refcount instead of nr_pages for each charge.

Rename: gpucg_try_charge -> gpucg_charge find_cg_rpool_locked -> cg_rpool_find_locked init_cg_rpool -> cg_rpool_init get_cg_rpool_locked -> cg_rpool_get_locked "gpu cgroup controller" -> "GPU controller" gpucg_device -> gpucg_bucket usage -> size

v4 changes Adjust gpucg_try_charge critical section for future charge transfer functionality.

v3 changes Use more common dual author commit message format per John Stultz.

v2 changes Fix incorrect Kconfig help section indentation per Randy Dunlap.

---

include/linux/cgroup_gpu.h | 122 ++++++++++++ include/linux/cgroup_subsys.h | 4 + init/Kconfig | 7 + kernel/cgroup/Makefile | 1 + kernel/cgroup/gpu.c | 339 ++++++++++++++++++++++++++++++++++ 5 files changed, 473 insertions(+) create mode 100644 include/linux/cgroup_gpu.h create mode 100644 kernel/cgroup/gpu.c

diff --git a/include/linux/cgroup_gpu.h b/include/linux/cgroup_gpu.h new file mode 100644 index 000000000000..cb228a16aa1f --- /dev/null +++ b/include/linux/cgroup_gpu.h @@ -0,0 +1,122 @@ +/* SPDX-License-Identifier: MIT

• • Copyright 2019 Advanced Micro Devices, Inc.
• • Copyright (C) 2022 Google LLC.
• */

+#ifndef _CGROUP_GPU_H +#define _CGROUP_GPU_H

+#include <linux/cgroup.h>

+#define GPUCG_BUCKET_NAME_MAX_LEN 64

+struct gpucg; +struct gpucg_bucket;

+#ifdef CONFIG_CGROUP_GPU

+/**

• • css_to_gpucg - get the corresponding gpucg ref from a cgroup_subsys_state
• • @css: the target cgroup_subsys_state
• • Returns: gpu cgroup that contains the @css
• */

+struct gpucg *css_to_gpucg(struct cgroup_subsys_state *css);

+/**

• • gpucg_get - get the gpucg reference that a task belongs to
• • @task: the target task
• • This increases the reference count of the css that the @task belongs to.
• • Returns: reference to the gpu cgroup the task belongs to.
• */

+struct gpucg *gpucg_get(struct task_struct *task);

+/**

• • gpucg_put - put a gpucg reference
• • @gpucg: the target gpucg
• • Put a reference obtained via gpucg_get
• */

+void gpucg_put(struct gpucg *gpucg);

+/**

• • gpucg_parent - find the parent of a gpu cgroup
• • @cg: the target gpucg
• • This does not increase the reference count of the parent cgroup
• • Returns: parent gpu cgroup of @cg
• */

+struct gpucg *gpucg_parent(struct gpucg *cg);

+/**

• • gpucg_charge - charge memory to the specified gpucg and gpucg_bucket.
• • Caller must hold a reference to @gpucg obtained through gpucg_get(). The size of the memory is
• • rounded up to be a multiple of the page size.
• • @gpucg: The gpu cgroup to charge the memory to.
• • @bucket: The bucket to charge the memory to.
• • @size: The size of memory to charge in bytes.

• •    This size will be rounded up to the nearest page size.
    

• • Return: returns 0 if the charging is successful and otherwise returns an error code.
• */

+int gpucg_charge(struct gpucg *gpucg, struct gpucg_bucket *bucket, u64 size);

+/**

• • gpucg_uncharge - uncharge memory from the specified gpucg and gpucg_bucket.
• • The caller must hold a reference to @gpucg obtained through gpucg_get().
• • @gpucg: The gpu cgroup to uncharge the memory from.
• • @bucket: The bucket to uncharge the memory from.
• • @size: The size of memory to uncharge in bytes.

• •    This size will be rounded up to the nearest page size.
    

• */

+void gpucg_uncharge(struct gpucg *gpucg, struct gpucg_bucket *bucket, u64 size);

+/**

• • gpucg_register_bucket - Registers a bucket for memory accounting using the GPU cgroup controller.
• • @name: Pointer to a null-terminated string to denote the name of the bucket. This name should be

• •    globally unique, and should not exceed @GPUCG_BUCKET_NAME_MAX_LEN bytes.
    

• • @bucket must remain valid. @name will be copied.
• • Returns a pointer to a newly allocated bucket on success, or an errno code otherwise. As buckets
• • cannot be unregistered, this can never be freed.
• */

+struct gpucg_bucket *gpucg_register_bucket(const char *name); +#else /* CONFIG_CGROUP_GPU */

+static inline struct gpucg *css_to_gpucg(struct cgroup_subsys_state *css) +{

• return NULL;

+}

+static inline struct gpucg *gpucg_get(struct task_struct *task) +{

• return NULL;

+}

+static inline void gpucg_put(struct gpucg *gpucg) {}

+static inline struct gpucg *gpucg_parent(struct gpucg *cg) +{

• return NULL;

+}

+static inline int gpucg_charge(struct gpucg *gpucg,

• 	       struct gpucg_bucket *bucket,
  

• 	       u64 size)
  

+{

• return 0;

+}

+static inline void gpucg_uncharge(struct gpucg *gpucg,

• 		  struct gpucg_bucket *bucket,
  

• 		  u64 size) {}
  

+static inline struct gpucg_bucket *gpucg_register_bucket(const char *name) {}

I think this needs to return NULL, otherwise you'll get a compiler error when CONFIG_CGROUP_GPU is not set.

I found other build errors when CONFIG_CGROUP_GPU is not set, please fix them in the next versioon.

Thanks, Enric

+#endif /* CONFIG_CGROUP_GPU */ +#endif /* _CGROUP_GPU_H */ diff --git a/include/linux/cgroup_subsys.h b/include/linux/cgroup_subsys.h index 445235487230..46a2a7b93c41 100644 --- a/include/linux/cgroup_subsys.h +++ b/include/linux/cgroup_subsys.h @@ -65,6 +65,10 @@ SUBSYS(rdma) SUBSYS(misc) #endif

+#if IS_ENABLED(CONFIG_CGROUP_GPU) +SUBSYS(gpu) +#endif

/*

• The following subsystems are not supported on the default hierarchy.

*/ diff --git a/init/Kconfig b/init/Kconfig index ddcbefe535e9..2e00a190e170 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -984,6 +984,13 @@ config BLK_CGROUP

See Documentation/admin-guide/cgroup-v1/blkio-controller.rst for more information.

+config CGROUP_GPU

• bool "GPU controller (EXPERIMENTAL)"
• select PAGE_COUNTER
• help

•  Provides accounting and limit setting for memory allocations by the GPU and
  

•  GPU-related subsystems.
  

config CGROUP_WRITEBACK bool depends on MEMCG && BLK_CGROUP diff --git a/kernel/cgroup/Makefile b/kernel/cgroup/Makefile index 12f8457ad1f9..be95a5a532fc 100644 --- a/kernel/cgroup/Makefile +++ b/kernel/cgroup/Makefile @@ -7,3 +7,4 @@ obj-$(CONFIG_CGROUP_RDMA) += rdma.o obj-$(CONFIG_CPUSETS) += cpuset.o obj-$(CONFIG_CGROUP_MISC) += misc.o obj-$(CONFIG_CGROUP_DEBUG) += debug.o +obj-$(CONFIG_CGROUP_GPU) += gpu.o diff --git a/kernel/cgroup/gpu.c b/kernel/cgroup/gpu.c new file mode 100644 index 000000000000..ad16ea15d427 --- /dev/null +++ b/kernel/cgroup/gpu.c @@ -0,0 +1,339 @@ +// SPDX-License-Identifier: MIT +// Copyright 2019 Advanced Micro Devices, Inc. +// Copyright (C) 2022 Google LLC.

+#include <linux/cgroup.h> +#include <linux/cgroup_gpu.h> +#include <linux/err.h> +#include <linux/gfp.h> +#include <linux/list.h> +#include <linux/mm.h> +#include <linux/page_counter.h> +#include <linux/seq_file.h> +#include <linux/slab.h> +#include <linux/string.h>

+static struct gpucg *root_gpucg __read_mostly;

+/*

• • Protects list of resource pools maintained on per cgroup basis and list
• • of buckets registered for memory accounting using the GPU cgroup controller.
• */

+static DEFINE_MUTEX(gpucg_mutex); +static LIST_HEAD(gpucg_buckets);

+/* The GPU cgroup controller data structure */ +struct gpucg {

• struct cgroup_subsys_state css;
• /* list of all resource pools that belong to this cgroup */
• struct list_head rpools;

+};

+/* A named entity representing bucket of tracked memory. */ +struct gpucg_bucket {

• /* list of various resource pools in various cgroups that the bucket is part of */
• struct list_head rpools;
• /* list of all buckets registered for GPU cgroup accounting */
• struct list_head bucket_node;
• /* string to be used as identifier for accounting and limit setting */
• const char *name;

+};

+struct gpucg_resource_pool {

• /* The bucket whose resource usage is tracked by this resource pool */
• struct gpucg_bucket *bucket;
• /* list of all resource pools for the cgroup */
• struct list_head cg_node;
• /* list maintained by the gpucg_bucket to keep track of its resource pools */
• struct list_head bucket_node;
• /* tracks memory usage of the resource pool */
• struct page_counter total;

+};

+static void free_cg_rpool_locked(struct gpucg_resource_pool *rpool) +{

• lockdep_assert_held(&gpucg_mutex);
• list_del(&rpool->cg_node);
• list_del(&rpool->bucket_node);
• kfree(rpool);

+}

+static void gpucg_css_free(struct cgroup_subsys_state *css) +{

• struct gpucg_resource_pool *rpool, *tmp;
• struct gpucg *gpucg = css_to_gpucg(css);
• // delete all resource pools
• mutex_lock(&gpucg_mutex);
• list_for_each_entry_safe(rpool, tmp, &gpucg->rpools, cg_node)

• free_cg_rpool_locked(rpool);
  

• mutex_unlock(&gpucg_mutex);
• kfree(gpucg);

+}

+static struct cgroup_subsys_state * +gpucg_css_alloc(struct cgroup_subsys_state *parent_css) +{

• struct gpucg *gpucg, *parent;
• gpucg = kzalloc(sizeof(struct gpucg), GFP_KERNEL);
• if (!gpucg)

• return ERR_PTR(-ENOMEM);
  

• parent = css_to_gpucg(parent_css);
• if (!parent)

• root_gpucg = gpucg;
  

• INIT_LIST_HEAD(&gpucg->rpools);
• return &gpucg->css;

+}

+static struct gpucg_resource_pool *cg_rpool_find_locked(

• struct gpucg *cg,
• struct gpucg_bucket *bucket)

+{

• struct gpucg_resource_pool *rpool;
• lockdep_assert_held(&gpucg_mutex);
• list_for_each_entry(rpool, &cg->rpools, cg_node)

• if (rpool->bucket == bucket)
  

• 	return rpool;
  

• return NULL;

+}

+static struct gpucg_resource_pool *cg_rpool_init(struct gpucg *cg,

• 				 struct gpucg_bucket *bucket)
  

+{

• struct gpucg_resource_pool *rpool = kzalloc(sizeof(*rpool),

• 					GFP_KERNEL);
  

• if (!rpool)

• return ERR_PTR(-ENOMEM);
  

• rpool->bucket = bucket;
• page_counter_init(&rpool->total, NULL);
• INIT_LIST_HEAD(&rpool->cg_node);
• INIT_LIST_HEAD(&rpool->bucket_node);
• list_add_tail(&rpool->cg_node, &cg->rpools);
• list_add_tail(&rpool->bucket_node, &bucket->rpools);
• return rpool;

+}

+/**

• • get_cg_rpool_locked - find the resource pool for the specified bucket and
• • specified cgroup. If the resource pool does not exist for the cg, it is
• • created in a hierarchical manner in the cgroup and its ancestor cgroups who
• • do not already have a resource pool entry for the bucket.
• • @cg: The cgroup to find the resource pool for.
• • @bucket: The bucket associated with the returned resource pool.
• • Return: return resource pool entry corresponding to the specified bucket in
• • the specified cgroup (hierarchically creating them if not existing already).
• */

+static struct gpucg_resource_pool * +cg_rpool_get_locked(struct gpucg *cg, struct gpucg_bucket *bucket) +{

• struct gpucg *parent_cg, *p, *stop_cg;
• struct gpucg_resource_pool *rpool, *tmp_rpool;
• struct gpucg_resource_pool *parent_rpool = NULL, *leaf_rpool = NULL;
• rpool = cg_rpool_find_locked(cg, bucket);
• if (rpool)

• return rpool;
  

• stop_cg = cg;
• do {

• rpool = cg_rpool_init(stop_cg, bucket);
  

• if (IS_ERR(rpool))
  

• 	goto err;
  

• if (!leaf_rpool)
  

• 	leaf_rpool = rpool;
  

• stop_cg = gpucg_parent(stop_cg);
  

• if (!stop_cg)
  

• 	break;
  

• rpool = cg_rpool_find_locked(stop_cg, bucket);
  

• } while (!rpool);
• /*

• * Re-initialize page counters of all rpools created in this invocation
  

• * to enable hierarchical charging.
  

• * stop_cg is the first ancestor cg who already had a resource pool for
  

• * the bucket. It can also be NULL if no ancestors had a pre-existing
  

• * resource pool for the bucket before this invocation.
  

• */
  

• rpool = leaf_rpool;
• for (p = cg; p != stop_cg; p = parent_cg) {

• parent_cg = gpucg_parent(p);
  

• if (!parent_cg)
  

• 	break;
  

• parent_rpool = cg_rpool_find_locked(parent_cg, bucket);
  

• page_counter_init(&rpool->total, &parent_rpool->total);
  

• rpool = parent_rpool;
  

• }
• return leaf_rpool;

+err:

• for (p = cg; p != stop_cg; p = gpucg_parent(p)) {

• tmp_rpool = cg_rpool_find_locked(p, bucket);
  

• free_cg_rpool_locked(tmp_rpool);
  

• }
• return rpool;

+}

+struct gpucg *css_to_gpucg(struct cgroup_subsys_state *css) +{

• return css ? container_of(css, struct gpucg, css) : NULL;

+}

+struct gpucg *gpucg_get(struct task_struct *task) +{

• if (!cgroup_subsys_enabled(gpu_cgrp_subsys))

• return NULL;
  

• return css_to_gpucg(task_get_css(task, gpu_cgrp_id));

+}

+void gpucg_put(struct gpucg *gpucg) +{

• if (gpucg)

• css_put(&gpucg->css);
  

+}

+struct gpucg *gpucg_parent(struct gpucg *cg) +{

• return css_to_gpucg(cg->css.parent);

+}

+int gpucg_charge(struct gpucg *gpucg, struct gpucg_bucket *bucket, u64 size) +{

• struct page_counter *counter;
• u64 nr_pages;
• struct gpucg_resource_pool *rp;
• int ret = 0;
• nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
• mutex_lock(&gpucg_mutex);
• rp = cg_rpool_get_locked(gpucg, bucket);
• /*

• * Continue to hold gpucg_mutex because we use it to block charges while transfers are in
  

• * progress to avoid potentially exceeding a limit.
  

• */
  

• if (IS_ERR(rp)) {

• mutex_unlock(&gpucg_mutex);
  

• return PTR_ERR(rp);
  

• }
• if (page_counter_try_charge(&rp->total, nr_pages, &counter))

• css_get(&gpucg->css);
  

• else

• ret = -ENOMEM;
  

• mutex_unlock(&gpucg_mutex);
• return ret;

+}

+void gpucg_uncharge(struct gpucg *gpucg, struct gpucg_bucket *bucket, u64 size) +{

• u64 nr_pages;
• struct gpucg_resource_pool *rp;
• mutex_lock(&gpucg_mutex);
• rp = cg_rpool_find_locked(gpucg, bucket);
• /*

• * gpucg_mutex can be unlocked here, rp will stay valid until gpucg is freed and there are
  

• * active refs on gpucg. Uncharges are fine while transfers are in progress since there is
  

• * no potential to exceed a limit while uncharging and transferring.
  

• */
  

• mutex_unlock(&gpucg_mutex);
• if (unlikely(!rp)) {

• pr_err("Resource pool not found, incorrect charge/uncharge ordering?\n");
  

• return;
  

• }
• nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
• page_counter_uncharge(&rp->total, nr_pages);
• css_put(&gpucg->css);

+}

+struct gpucg_bucket *gpucg_register_bucket(const char *name) +{

• struct gpucg_bucket *bucket, *b;
• if (!name)

• return ERR_PTR(-EINVAL);
  

• if (strlen(name) >= GPUCG_BUCKET_NAME_MAX_LEN)

• return ERR_PTR(-ENAMETOOLONG);
  

• bucket = kzalloc(sizeof(struct gpucg_bucket), GFP_KERNEL);
• if (!bucket)

• return ERR_PTR(-ENOMEM);
  

• INIT_LIST_HEAD(&bucket->bucket_node);
• INIT_LIST_HEAD(&bucket->rpools);
• bucket->name = kstrdup_const(name, GFP_KERNEL);
• mutex_lock(&gpucg_mutex);
• list_for_each_entry(b, &gpucg_buckets, bucket_node) {

• if (strncmp(b->name, bucket->name, GPUCG_BUCKET_NAME_MAX_LEN) == 0) {
  

• 	mutex_unlock(&gpucg_mutex);
  

• 	kfree_const(bucket->name);
  

• 	kfree(bucket);
  

• 	return ERR_PTR(-EEXIST);
  

• }
  

• }
• list_add_tail(&bucket->bucket_node, &gpucg_buckets);
• mutex_unlock(&gpucg_mutex);
• return bucket;

+}

+static int gpucg_resource_show(struct seq_file *sf, void *v) +{

• struct gpucg_resource_pool *rpool;
• struct gpucg *cg = css_to_gpucg(seq_css(sf));
• mutex_lock(&gpucg_mutex);
• list_for_each_entry(rpool, &cg->rpools, cg_node) {

• seq_printf(sf, "%s %lu\n", rpool->bucket->name,
  

• 	   page_counter_read(&rpool->total) * PAGE_SIZE);
  

• }
• mutex_unlock(&gpucg_mutex);
• return 0;

+}

+struct cftype files[] = {

• {

• .name = "memory.current",
  

• .seq_show = gpucg_resource_show,
  

• },
• { } /* terminate */

+};

+struct cgroup_subsys gpu_cgrp_subsys = {

• .css_alloc = gpucg_css_alloc,
• .css_free = gpucg_css_free,
• .early_init = false,
• .legacy_cftypes = files,
• .dfl_cftypes = files,

+};

-- 2.36.0.512.ge40c2bad7a-goog