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io_uring: get rid of remap_pfn_range() for mapping rings/sqes
Rather than use remap_pfn_range() for this and manually free later, switch to using vm_insert_pages() and have it Just Work. If possible, allocate a single compound page that covers the range that is needed. If that works, then we can just use page_address() on that page. If we fail to get a compound page, allocate single pages and use vmap() to map them into the kernel virtual address space. This just covers the rings/sqes, the other remaining user of the mmap remap_pfn_range() user will be converted separately. Once that is done, we can kill the old alloc/free code. Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe
parent
62346c6cb2
commit
3ab1db3c60
@ -2599,6 +2599,36 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
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return READ_ONCE(rings->cq.head) == READ_ONCE(rings->cq.tail) ? ret : 0;
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}
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static void io_pages_unmap(void *ptr, struct page ***pages,
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unsigned short *npages)
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{
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bool do_vunmap = false;
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if (!ptr)
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return;
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if (*npages) {
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struct page **to_free = *pages;
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int i;
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/*
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* Only did vmap for the non-compound multiple page case.
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* For the compound page, we just need to put the head.
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*/
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if (PageCompound(to_free[0]))
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*npages = 1;
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else if (*npages > 1)
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do_vunmap = true;
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for (i = 0; i < *npages; i++)
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put_page(to_free[i]);
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}
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if (do_vunmap)
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vunmap(ptr);
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kvfree(*pages);
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*pages = NULL;
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*npages = 0;
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}
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void io_mem_free(void *ptr)
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{
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if (!ptr)
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@ -2699,8 +2729,8 @@ static void *io_sqes_map(struct io_ring_ctx *ctx, unsigned long uaddr,
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static void io_rings_free(struct io_ring_ctx *ctx)
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{
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if (!(ctx->flags & IORING_SETUP_NO_MMAP)) {
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io_mem_free(ctx->rings);
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io_mem_free(ctx->sq_sqes);
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io_pages_unmap(ctx->rings, &ctx->ring_pages, &ctx->n_ring_pages);
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io_pages_unmap(ctx->sq_sqes, &ctx->sqe_pages, &ctx->n_sqe_pages);
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} else {
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io_pages_free(&ctx->ring_pages, ctx->n_ring_pages);
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ctx->n_ring_pages = 0;
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@ -2712,6 +2742,80 @@ static void io_rings_free(struct io_ring_ctx *ctx)
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ctx->sq_sqes = NULL;
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}
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static void *io_mem_alloc_compound(struct page **pages, int nr_pages,
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size_t size, gfp_t gfp)
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{
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struct page *page;
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int i, order;
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order = get_order(size);
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if (order > MAX_PAGE_ORDER)
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return ERR_PTR(-ENOMEM);
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else if (order)
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gfp |= __GFP_COMP;
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page = alloc_pages(gfp, order);
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if (!page)
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return ERR_PTR(-ENOMEM);
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for (i = 0; i < nr_pages; i++)
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pages[i] = page + i;
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return page_address(page);
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}
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static void *io_mem_alloc_single(struct page **pages, int nr_pages, size_t size,
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gfp_t gfp)
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{
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void *ret;
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int i;
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for (i = 0; i < nr_pages; i++) {
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pages[i] = alloc_page(gfp);
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if (!pages[i])
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goto err;
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}
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ret = vmap(pages, nr_pages, VM_MAP, PAGE_KERNEL);
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if (ret)
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return ret;
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err:
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while (i--)
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put_page(pages[i]);
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return ERR_PTR(-ENOMEM);
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}
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static void *io_pages_map(struct page ***out_pages, unsigned short *npages,
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size_t size)
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{
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gfp_t gfp = GFP_KERNEL_ACCOUNT | __GFP_ZERO | __GFP_NOWARN;
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struct page **pages;
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int nr_pages;
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void *ret;
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nr_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
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pages = kvmalloc_array(nr_pages, sizeof(struct page *), gfp);
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if (!pages)
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return ERR_PTR(-ENOMEM);
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ret = io_mem_alloc_compound(pages, nr_pages, size, gfp);
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if (!IS_ERR(ret))
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goto done;
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ret = io_mem_alloc_single(pages, nr_pages, size, gfp);
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if (!IS_ERR(ret)) {
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done:
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*out_pages = pages;
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*npages = nr_pages;
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return ret;
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}
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kvfree(pages);
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*out_pages = NULL;
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*npages = 0;
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return ret;
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}
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void *io_mem_alloc(size_t size)
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{
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gfp_t gfp = GFP_KERNEL_ACCOUNT | __GFP_ZERO | __GFP_NOWARN | __GFP_COMP;
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@ -3298,14 +3402,12 @@ static void *io_uring_validate_mmap_request(struct file *file,
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/* Don't allow mmap if the ring was setup without it */
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if (ctx->flags & IORING_SETUP_NO_MMAP)
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return ERR_PTR(-EINVAL);
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ptr = ctx->rings;
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break;
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return ctx->rings;
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case IORING_OFF_SQES:
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/* Don't allow mmap if the ring was setup without it */
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if (ctx->flags & IORING_SETUP_NO_MMAP)
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return ERR_PTR(-EINVAL);
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ptr = ctx->sq_sqes;
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break;
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return ctx->sq_sqes;
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case IORING_OFF_PBUF_RING: {
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struct io_buffer_list *bl;
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unsigned int bgid;
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@ -3329,11 +3431,22 @@ static void *io_uring_validate_mmap_request(struct file *file,
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return ptr;
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}
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int io_uring_mmap_pages(struct io_ring_ctx *ctx, struct vm_area_struct *vma,
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struct page **pages, int npages)
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{
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unsigned long nr_pages = npages;
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vm_flags_set(vma, VM_DONTEXPAND);
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return vm_insert_pages(vma, vma->vm_start, pages, &nr_pages);
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}
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#ifdef CONFIG_MMU
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static __cold int io_uring_mmap(struct file *file, struct vm_area_struct *vma)
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{
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struct io_ring_ctx *ctx = file->private_data;
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size_t sz = vma->vm_end - vma->vm_start;
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long offset = vma->vm_pgoff << PAGE_SHIFT;
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unsigned long pfn;
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void *ptr;
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@ -3341,6 +3454,16 @@ static __cold int io_uring_mmap(struct file *file, struct vm_area_struct *vma)
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if (IS_ERR(ptr))
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return PTR_ERR(ptr);
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switch (offset & IORING_OFF_MMAP_MASK) {
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case IORING_OFF_SQ_RING:
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case IORING_OFF_CQ_RING:
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return io_uring_mmap_pages(ctx, vma, ctx->ring_pages,
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ctx->n_ring_pages);
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case IORING_OFF_SQES:
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return io_uring_mmap_pages(ctx, vma, ctx->sqe_pages,
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ctx->n_sqe_pages);
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}
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pfn = virt_to_phys(ptr) >> PAGE_SHIFT;
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return remap_pfn_range(vma, vma->vm_start, pfn, sz, vma->vm_page_prot);
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}
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@ -3630,7 +3753,7 @@ static __cold int io_allocate_scq_urings(struct io_ring_ctx *ctx,
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return -EOVERFLOW;
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if (!(ctx->flags & IORING_SETUP_NO_MMAP))
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rings = io_mem_alloc(size);
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rings = io_pages_map(&ctx->ring_pages, &ctx->n_ring_pages, size);
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else
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rings = io_rings_map(ctx, p->cq_off.user_addr, size);
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@ -3655,7 +3778,7 @@ static __cold int io_allocate_scq_urings(struct io_ring_ctx *ctx,
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}
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if (!(ctx->flags & IORING_SETUP_NO_MMAP))
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ptr = io_mem_alloc(size);
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ptr = io_pages_map(&ctx->sqe_pages, &ctx->n_sqe_pages, size);
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else
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ptr = io_sqes_map(ctx, p->sq_off.user_addr, size);
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@ -70,6 +70,8 @@ bool io_req_post_cqe(struct io_kiocb *req, s32 res, u32 cflags);
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void __io_commit_cqring_flush(struct io_ring_ctx *ctx);
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struct page **io_pin_pages(unsigned long ubuf, unsigned long len, int *npages);
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int io_uring_mmap_pages(struct io_ring_ctx *ctx, struct vm_area_struct *vma,
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struct page **pages, int npages);
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struct file *io_file_get_normal(struct io_kiocb *req, int fd);
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struct file *io_file_get_fixed(struct io_kiocb *req, int fd,
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