There is absolutely nothing IB specific here. If you want to support
anonymous mmaps to allocate large contiguous pages work with the MM
folks on providing that in a generic fashion.
[full quote alert for reference:]
On Tue, Dec 08, 2015 at 05:15:06PM +0200, Yishai Hadas wrote:
> New structure 'cmem' represents the contiguous allocated memory.
> It supports:
> Allocate, Free, 'Map to virtual address' operations, etc.
>
> Signed-off-by: Yishai Hadas <yishaih@xxxxxxxxxxxx>
> ---
> drivers/infiniband/core/Makefile | 2 +-
> drivers/infiniband/core/cmem.c | 245 +++++++++++++++++++++++++++++++++++++++
> include/rdma/ib_cmem.h | 41 +++++++
> 3 files changed, 287 insertions(+), 1 deletion(-)
> create mode 100644 drivers/infiniband/core/cmem.c
> create mode 100644 include/rdma/ib_cmem.h
>
> diff --git a/drivers/infiniband/core/Makefile b/drivers/infiniband/core/Makefile
> index d43a899..8549ea4 100644
> --- a/drivers/infiniband/core/Makefile
> +++ b/drivers/infiniband/core/Makefile
> @@ -11,7 +11,7 @@ obj-$(CONFIG_INFINIBAND_USER_ACCESS) += ib_uverbs.o ib_ucm.o \
> ib_core-y := packer.o ud_header.o verbs.o sysfs.o \
> device.o fmr_pool.o cache.o netlink.o \
> roce_gid_mgmt.o
> -ib_core-$(CONFIG_INFINIBAND_USER_MEM) += umem.o
> +ib_core-$(CONFIG_INFINIBAND_USER_MEM) += umem.o cmem.o
> ib_core-$(CONFIG_INFINIBAND_ON_DEMAND_PAGING) += umem_odp.o umem_rbtree.o
>
> ib_mad-y := mad.o smi.o agent.o mad_rmpp.o
> diff --git a/drivers/infiniband/core/cmem.c b/drivers/infiniband/core/cmem.c
> new file mode 100644
> index 0000000..21d8573
> --- /dev/null
> +++ b/drivers/infiniband/core/cmem.c
> @@ -0,0 +1,245 @@
> +#include <linux/mm.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/sched.h>
> +#include <linux/export.h>
> +#include <linux/dma-attrs.h>
> +#include <linux/slab.h>
> +#include <rdma/ib_cmem.h>
> +#include "uverbs.h"
> +
> +static void ib_cmem_release(struct kref *ref)
> +{
> + struct ib_cmem *cmem;
> + struct ib_cmem_block *cmem_block, *tmp;
> + unsigned long ntotal_pages;
> +
> + cmem = container_of(ref, struct ib_cmem, refcount);
> +
> + list_for_each_entry_safe(cmem_block, tmp, &cmem->ib_cmem_block, list) {
> + __free_pages(cmem_block->page, cmem->block_order);
> + list_del(&cmem_block->list);
> + kfree(cmem_block);
> + }
> + /* no locking is needed:
> + * ib_cmem_release is called from vm_close which is always called
> + * with mm->mmap_sem held for writing.
> + * The only exception is when the process shutting down but in that case
> + * counter not relevant any more.
> + */
> + if (current->mm) {
> + ntotal_pages = PAGE_ALIGN(cmem->length) >> PAGE_SHIFT;
> + current->mm->pinned_vm -= ntotal_pages;
> + }
> + kfree(cmem);
> +}
> +
> +/**
> + * ib_cmem_release_contiguous_pages - release memory allocated by
> + * ib_cmem_alloc_contiguous_pages.
> + * @cmem: cmem struct to release
> + */
> +void ib_cmem_release_contiguous_pages(struct ib_cmem *cmem)
> +{
> + kref_put(&cmem->refcount, ib_cmem_release);
> +}
> +EXPORT_SYMBOL(ib_cmem_release_contiguous_pages);
> +
> +static void cmem_vma_open(struct vm_area_struct *area)
> +{
> + struct ib_cmem *ib_cmem;
> +
> + ib_cmem = (struct ib_cmem *)(area->vm_private_data);
> +
> + /* vm_open and vm_close are always called with mm->mmap_sem held for
> + * writing. The only exception is when the process is shutting down, at
> + * which point vm_close is called with no locks held, but since it is
> + * after the VMAs have been detached, it is impossible that vm_open will
> + * be called. Therefore, there is no need to synchronize the kref_get and
> + * kref_put calls.
> + */
> + kref_get(&ib_cmem->refcount);
> +}
> +
> +static void cmem_vma_close(struct vm_area_struct *area)
> +{
> + struct ib_cmem *cmem;
> +
> + cmem = (struct ib_cmem *)(area->vm_private_data);
> +
> + ib_cmem_release_contiguous_pages(cmem);
> +}
> +
> +static const struct vm_operations_struct cmem_contig_pages_vm_ops = {
> + .open = cmem_vma_open,
> + .close = cmem_vma_close
> +};
> +
> +/**
> + * ib_cmem_map_contiguous_pages_to_vma - map contiguous pages into VMA
> + * @ib_cmem: cmem structure returned by ib_cmem_alloc_contiguous_pages
> + * @vma: VMA to inject pages into.
> + */
> +int ib_cmem_map_contiguous_pages_to_vma(struct ib_cmem *ib_cmem,
> + struct vm_area_struct *vma)
> +{
> + int ret;
> + unsigned long page_entry;
> + unsigned long ntotal_pages;
> + unsigned long ncontig_pages;
> + unsigned long total_size;
> + struct page *page;
> + unsigned long vma_entry_number = 0;
> + struct ib_cmem_block *ib_cmem_block = NULL;
> +
> + total_size = vma->vm_end - vma->vm_start;
> + if (ib_cmem->length != total_size)
> + return -EINVAL;
> +
> + if (total_size != PAGE_ALIGN(total_size)) {
> + WARN(1,
> + "ib_cmem_map: total size %lu not aligned to page size\n",
> + total_size);
> + return -EINVAL;
> + }
> +
> + ntotal_pages = total_size >> PAGE_SHIFT;
> + ncontig_pages = 1 << ib_cmem->block_order;
> +
> + list_for_each_entry(ib_cmem_block, &ib_cmem->ib_cmem_block, list) {
> + page = ib_cmem_block->page;
> + for (page_entry = 0; page_entry < ncontig_pages; page_entry++) {
> + /* We reached end of vma - going out from both loops */
> + if (vma_entry_number >= ntotal_pages)
> + goto end;
> +
> + ret = vm_insert_page(vma, vma->vm_start +
> + (vma_entry_number << PAGE_SHIFT), page);
> + if (ret < 0)
> + goto err_vm_insert;
> +
> + vma_entry_number++;
> + page++;
> + }
> + }
> +
> +end:
> +
> + /* We expect to have enough pages */
> + if (vma_entry_number >= ntotal_pages) {
> + vma->vm_ops = &cmem_contig_pages_vm_ops;
> + vma->vm_private_data = ib_cmem;
> + return 0;
> + }
> + /* Not expected but if we reached here
> + * not enough contiguous pages were registered
> + */
> + ret = -EINVAL;
> +
> +err_vm_insert:
> +
> + zap_vma_ptes(vma, vma->vm_start, total_size);
> + return ret;
> +}
> +EXPORT_SYMBOL(ib_cmem_map_contiguous_pages_to_vma);
> +
> +/**
> + * ib_cmem_alloc_contiguous_pages - allocate contiguous pages
> + * @context: userspace context to allocate memory for
> + * @total_size: total required size for that allocation.
> + * @page_size_order: order of one contiguous page.
> + * @numa_nude: From which numa node to allocate memory
> + * when numa_nude < 0 use default numa_nude.
> + */
> +struct ib_cmem *ib_cmem_alloc_contiguous_pages(struct ib_ucontext *context,
> + unsigned long total_size,
> + unsigned long page_size_order,
> + int numa_node)
> +{
> + struct ib_cmem *cmem;
> + unsigned long ntotal_pages;
> + unsigned long ncontiguous_pages;
> + unsigned long ncontiguous_groups;
> + struct page *page;
> + int i;
> + int ncontiguous_pages_order;
> + struct ib_cmem_block *ib_cmem_block;
> + unsigned long locked;
> + unsigned long lock_limit;
> +
> + if (page_size_order < PAGE_SHIFT || page_size_order > 31)
> + return ERR_PTR(-EINVAL);
> +
> + cmem = kzalloc(sizeof(*cmem), GFP_KERNEL);
> + if (!cmem)
> + return ERR_PTR(-ENOMEM);
> +
> + kref_init(&cmem->refcount);
> + cmem->context = context;
> + INIT_LIST_HEAD(&cmem->ib_cmem_block);
> +
> + /* Total size is expected to be already page aligned -
> + * verifying anyway.
> + */
> + ntotal_pages = PAGE_ALIGN(total_size) >> PAGE_SHIFT;
> + /* ib_cmem_alloc_contiguous_pages is called as part of mmap
> + * with mm->mmap_sem held for writing.
> + * No need to lock
> + */
> + locked = ntotal_pages + current->mm->pinned_vm;
> + lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
> +
> + if ((locked > lock_limit) && !capable(CAP_IPC_LOCK))
> + goto err_alloc;
> +
> + /* How many contiguous pages do we need in 1 block */
> + ncontiguous_pages = (1 << page_size_order) >> PAGE_SHIFT;
> + ncontiguous_pages_order = ilog2(ncontiguous_pages);
> + ncontiguous_groups = (ntotal_pages >> ncontiguous_pages_order) +
> + (!!(ntotal_pages & (ncontiguous_pages - 1)));
> +
> + /* Checking MAX_ORDER to prevent WARN via calling alloc_pages below */
> + if (ncontiguous_pages_order >= MAX_ORDER)
> + goto err_alloc;
> + /* we set block_order before starting allocation to prevent
> + * a leak in a failure flow in ib_cmem_release.
> + * cmem->length has at that step value 0 from kzalloc as expected
> + */
> + cmem->block_order = ncontiguous_pages_order;
> + for (i = 0; i < ncontiguous_groups; i++) {
> + /* Allocating the managed entry */
> + ib_cmem_block = kmalloc(sizeof(*ib_cmem_block),
> + GFP_KERNEL);
> + if (!ib_cmem_block)
> + goto err_alloc;
> +
> + if (numa_node < 0)
> + page = alloc_pages(GFP_HIGHUSER | __GFP_ZERO |
> + __GFP_COMP | __GFP_NOWARN,
> + ncontiguous_pages_order);
> + else
> + page = alloc_pages_node(numa_node,
> + GFP_HIGHUSER | __GFP_ZERO |
> + __GFP_COMP | __GFP_NOWARN,
> + ncontiguous_pages_order);
> +
> + if (!page) {
> + kfree(ib_cmem_block);
> + /* We should deallocate previous succeeded allocatations
> + * if exists.
> + */
> + goto err_alloc;
> + }
> +
> + ib_cmem_block->page = page;
> + list_add_tail(&ib_cmem_block->list, &cmem->ib_cmem_block);
> + }
> +
> + cmem->length = total_size;
> + current->mm->pinned_vm = locked;
> + return cmem;
> +
> +err_alloc:
> + ib_cmem_release_contiguous_pages(cmem);
> + return ERR_PTR(-ENOMEM);
> +}
> +EXPORT_SYMBOL(ib_cmem_alloc_contiguous_pages);
> diff --git a/include/rdma/ib_cmem.h b/include/rdma/ib_cmem.h
> new file mode 100644
> index 0000000..5f26a49
> --- /dev/null
> +++ b/include/rdma/ib_cmem.h
> @@ -0,0 +1,41 @@
> +#ifndef IB_CMEM_H
> +#define IB_CMEM_H
> +
> +#include <rdma/ib_umem.h>
> +#include <rdma/ib_verbs.h>
> +
> +/* contiguous memory structure */
> +struct ib_cmem {
> + struct ib_ucontext *context;
> + size_t length;
> + /* Link list of contiguous blocks being part of that cmem */
> + struct list_head ib_cmem_block;
> +
> + /* Order of cmem block, 2^ block_order will equal number
> + * of physical pages per block
> + */
> + unsigned long block_order;
> + /* Refernce counter for that memory area
> + * When value became 0 pages will be returned to the kernel.
> + */
> + struct kref refcount;
> +};
> +
> +struct ib_cmem_block {
> + struct list_head list;
> + /* page will point to the page struct of the head page
> + * in the current compound page.
> + * block order is saved once as part of ib_cmem.
> + */
> + struct page *page;
> +};
> +
> +int ib_cmem_map_contiguous_pages_to_vma(struct ib_cmem *ib_cmem,
> + struct vm_area_struct *vma);
> +struct ib_cmem *ib_cmem_alloc_contiguous_pages(struct ib_ucontext *context,
> + unsigned long total_size,
> + unsigned long page_size_order,
> + int numa_node);
> +void ib_cmem_release_contiguous_pages(struct ib_cmem *cmem);
> +
> +#endif
> --
> 1.8.3.1
>
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