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@xxxxxxxxx>
---
io_uring/io_uring.c | 134 +++++++++++++++++++++++++++++++++++++++++---
io_uring/io_uring.h | 2 +
2 files changed, 128 insertions(+), 8 deletions(-)
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 585fbc363eaf..29d0c1764aab 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -2601,6 +2601,27 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
return READ_ONCE(rings->cq.head) == READ_ONCE(rings->cq.tail) ? ret : 0;
}
+static void io_pages_unmap(void *ptr, struct page ***pages,
+ unsigned short *npages)
+{
+ bool do_vunmap = false;
+
+ if (*npages) {
+ struct page **to_free = *pages;
+ int i;
+
+ /* only did vmap for non-compound and multiple pages */
+ do_vunmap = !PageCompound(to_free[0]) && *npages > 1;
+ for (i = 0; i < *npages; i++)
+ put_page(to_free[i]);
+ }
+ if (do_vunmap)
+ vunmap(ptr);
+ kvfree(*pages);
+ *pages = NULL;
+ *npages = 0;
+}
+
void io_mem_free(void *ptr)
{
if (!ptr)
@@ -2701,8 +2722,8 @@ static void *io_sqes_map(struct io_ring_ctx *ctx, unsigned long uaddr,
static void io_rings_free(struct io_ring_ctx *ctx)
{
if (!(ctx->flags & IORING_SETUP_NO_MMAP)) {
- io_mem_free(ctx->rings);
- io_mem_free(ctx->sq_sqes);
+ io_pages_unmap(ctx->rings, &ctx->ring_pages, &ctx->n_ring_pages);
+ io_pages_unmap(ctx->sq_sqes, &ctx->sqe_pages, &ctx->n_sqe_pages);
} else {
io_pages_free(&ctx->ring_pages, ctx->n_ring_pages);
ctx->n_ring_pages = 0;
@@ -2714,6 +2735,84 @@ static void io_rings_free(struct io_ring_ctx *ctx)
ctx->sq_sqes = NULL;
}
+static void *io_mem_alloc_compound(struct page **pages, int nr_pages,
+ size_t size, gfp_t gfp)
+{
+ struct page *page;
+ int i, order;
+
+ order = get_order(size);
+ if (order > MAX_PAGE_ORDER)
+ return NULL;
+ else if (order)
+ gfp |= __GFP_COMP;
+
+ page = alloc_pages(gfp, order);
+ if (!page)
+ return NULL;
+
+ /* add pages, grab a ref to tail pages */
+ for (i = 0; i < nr_pages; i++) {
+ pages[i] = page + i;
+ if (i)
+ get_page(pages[i]);
+ }
+
+ return page_address(page);
+}
+
+static void *io_mem_alloc_single(struct page **pages, int nr_pages, size_t size,
+ gfp_t gfp)
+{
+ void *ret;
+ int i;
+
+ for (i = 0; i < nr_pages; i++) {
+ pages[i] = alloc_page(gfp);
+ if (!pages[i])
+ goto err;
+ }
+
+ ret = vmap(pages, nr_pages, VM_MAP | VM_ALLOW_HUGE_VMAP, PAGE_KERNEL);
+ if (ret)
+ return ret;
+err:
+ while (i--)
+ put_page(pages[i]);
+ return ERR_PTR(-ENOMEM);
+}
+
+static void *io_pages_map(struct page ***out_pages, unsigned short *npages,
+ size_t size)
+{
+ gfp_t gfp = GFP_KERNEL_ACCOUNT | __GFP_ZERO | __GFP_NOWARN;
+ struct page **pages;
+ int nr_pages;
+ void *ret;
+
+ nr_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ pages = kvmalloc_array(nr_pages, sizeof(struct page *), gfp);
+ if (!pages)
+ return ERR_PTR(-ENOMEM);
+
+ ret = io_mem_alloc_compound(pages, nr_pages, size, gfp);
+ if (ret)
+ goto done;
+
+ ret = io_mem_alloc_single(pages, nr_pages, size, gfp);
+ if (ret) {
+done:
+ *out_pages = pages;
+ *npages = nr_pages;
+ return ret;
+ }
+
+ kvfree(pages);
+ *out_pages = NULL;
+ *npages = 0;
+ return ERR_PTR(-ENOMEM);
+}
+
void *io_mem_alloc(size_t size)
{
gfp_t gfp = GFP_KERNEL_ACCOUNT | __GFP_ZERO | __GFP_NOWARN | __GFP_COMP;
@@ -3301,14 +3400,12 @@ static void *io_uring_validate_mmap_request(struct file *file,
/* Don't allow mmap if the ring was setup without it */
if (ctx->flags & IORING_SETUP_NO_MMAP)
return ERR_PTR(-EINVAL);
- ptr = ctx->rings;
- break;
+ return ctx->rings;
case IORING_OFF_SQES:
/* Don't allow mmap if the ring was setup without it */
if (ctx->flags & IORING_SETUP_NO_MMAP)
return ERR_PTR(-EINVAL);
- ptr = ctx->sq_sqes;
- break;
+ return ctx->sq_sqes;
case IORING_OFF_PBUF_RING: {
unsigned int bgid;
@@ -3331,11 +3428,22 @@ static void *io_uring_validate_mmap_request(struct file *file,
return ptr;
}
+int io_uring_mmap_pages(struct io_ring_ctx *ctx, struct vm_area_struct *vma,
+ struct page **pages, int npages)
+{
+ unsigned long nr_pages = npages;
+
+ vm_flags_set(vma, VM_DONTEXPAND);
+ return vm_insert_pages(vma, vma->vm_start, pages, &nr_pages);
+}
+
#ifdef CONFIG_MMU
static __cold int io_uring_mmap(struct file *file, struct vm_area_struct *vma)
{
+ struct io_ring_ctx *ctx = file->private_data;
size_t sz = vma->vm_end - vma->vm_start;
+ long offset = vma->vm_pgoff << PAGE_SHIFT;
unsigned long pfn;
void *ptr;
@@ -3343,6 +3451,16 @@ static __cold int io_uring_mmap(struct file *file, struct vm_area_struct *vma)
if (IS_ERR(ptr))
return PTR_ERR(ptr);
+ switch (offset & IORING_OFF_MMAP_MASK) {
+ case IORING_OFF_SQ_RING:
+ case IORING_OFF_CQ_RING:
+ return io_uring_mmap_pages(ctx, vma, ctx->ring_pages,
+ ctx->n_ring_pages);
+ case IORING_OFF_SQES:
+ return io_uring_mmap_pages(ctx, vma, ctx->sqe_pages,
+ ctx->n_sqe_pages);
+ }
+
pfn = virt_to_phys(ptr) >> PAGE_SHIFT;
return remap_pfn_range(vma, vma->vm_start, pfn, sz, vma->vm_page_prot);
}
@@ -3632,7 +3750,7 @@ static __cold int io_allocate_scq_urings(struct io_ring_ctx *ctx,
return -EOVERFLOW;
if (!(ctx->flags & IORING_SETUP_NO_MMAP))
- rings = io_mem_alloc(size);
+ rings = io_pages_map(&ctx->ring_pages, &ctx->n_ring_pages, size);
else
rings = io_rings_map(ctx, p->cq_off.user_addr, size);
@@ -3657,7 +3775,7 @@ static __cold int io_allocate_scq_urings(struct io_ring_ctx *ctx,
}
if (!(ctx->flags & IORING_SETUP_NO_MMAP))
- ptr = io_mem_alloc(size);
+ ptr = io_pages_map(&ctx->sqe_pages, &ctx->n_sqe_pages, size);
else
ptr = io_sqes_map(ctx, p->sq_off.user_addr, size);
diff --git a/io_uring/io_uring.h b/io_uring/io_uring.h
index 7654dfb34c2e..ac2a84542417 100644
--- a/io_uring/io_uring.h
+++ b/io_uring/io_uring.h
@@ -70,6 +70,8 @@ bool io_req_post_cqe(struct io_kiocb *req, s32 res, u32 cflags);
void __io_commit_cqring_flush(struct io_ring_ctx *ctx);
struct page **io_pin_pages(unsigned long ubuf, unsigned long len, int *npages);
+int io_uring_mmap_pages(struct io_ring_ctx *ctx, struct vm_area_struct *vma,
+ struct page **pages, int npages);
struct file *io_file_get_normal(struct io_kiocb *req, int fd);
struct file *io_file_get_fixed(struct io_kiocb *req, int fd,
--
2.43.0
