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authorJens Axboe <axboe@kernel.dk>2023-11-28 02:47:04 +0300
committerJens Axboe <axboe@kernel.dk>2023-11-28 17:56:16 +0300
commitc392cbecd8eca4c53f2bf508731257d9d0a21c2d (patch)
tree74054d568c3324dc69b65b037d9076466c2352af /io_uring/kbuf.c
parentedecf1689768452ba1a64b7aaf3a47a817da651a (diff)
downloadlinux-c392cbecd8eca4c53f2bf508731257d9d0a21c2d.tar.xz
io_uring/kbuf: defer release of mapped buffer rings
If a provided buffer ring is setup with IOU_PBUF_RING_MMAP, then the kernel allocates the memory for it and the application is expected to mmap(2) this memory. However, io_uring uses remap_pfn_range() for this operation, so we cannot rely on normal munmap/release on freeing them for us. Stash an io_buf_free entry away for each of these, if any, and provide a helper to free them post ->release(). Cc: stable@vger.kernel.org Fixes: c56e022c0a27 ("io_uring: add support for user mapped provided buffer ring") Reported-by: Jann Horn <jannh@google.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'io_uring/kbuf.c')
-rw-r--r--io_uring/kbuf.c44
1 files changed, 39 insertions, 5 deletions
diff --git a/io_uring/kbuf.c b/io_uring/kbuf.c
index a1e4239c7d75..85e680fc74ce 100644
--- a/io_uring/kbuf.c
+++ b/io_uring/kbuf.c
@@ -33,6 +33,11 @@ struct io_provide_buf {
__u16 bid;
};
+struct io_buf_free {
+ struct hlist_node list;
+ void *mem;
+};
+
static inline struct io_buffer_list *io_buffer_get_list(struct io_ring_ctx *ctx,
unsigned int bgid)
{
@@ -223,7 +228,10 @@ static int __io_remove_buffers(struct io_ring_ctx *ctx,
if (bl->is_mapped) {
i = bl->buf_ring->tail - bl->head;
if (bl->is_mmap) {
- folio_put(virt_to_folio(bl->buf_ring));
+ /*
+ * io_kbuf_list_free() will free the page(s) at
+ * ->release() time.
+ */
bl->buf_ring = NULL;
bl->is_mmap = 0;
} else if (bl->buf_nr_pages) {
@@ -531,18 +539,28 @@ error_unpin:
return -EINVAL;
}
-static int io_alloc_pbuf_ring(struct io_uring_buf_reg *reg,
+static int io_alloc_pbuf_ring(struct io_ring_ctx *ctx,
+ struct io_uring_buf_reg *reg,
struct io_buffer_list *bl)
{
- gfp_t gfp = GFP_KERNEL_ACCOUNT | __GFP_ZERO | __GFP_NOWARN | __GFP_COMP;
+ struct io_buf_free *ibf;
size_t ring_size;
void *ptr;
ring_size = reg->ring_entries * sizeof(struct io_uring_buf_ring);
- ptr = (void *) __get_free_pages(gfp, get_order(ring_size));
+ ptr = io_mem_alloc(ring_size);
if (!ptr)
return -ENOMEM;
+ /* Allocate and store deferred free entry */
+ ibf = kmalloc(sizeof(*ibf), GFP_KERNEL_ACCOUNT);
+ if (!ibf) {
+ io_mem_free(ptr);
+ return -ENOMEM;
+ }
+ ibf->mem = ptr;
+ hlist_add_head(&ibf->list, &ctx->io_buf_list);
+
bl->buf_ring = ptr;
bl->is_mapped = 1;
bl->is_mmap = 1;
@@ -599,7 +617,7 @@ int io_register_pbuf_ring(struct io_ring_ctx *ctx, void __user *arg)
if (!(reg.flags & IOU_PBUF_RING_MMAP))
ret = io_pin_pbuf_ring(&reg, bl);
else
- ret = io_alloc_pbuf_ring(&reg, bl);
+ ret = io_alloc_pbuf_ring(ctx, &reg, bl);
if (!ret) {
bl->nr_entries = reg.ring_entries;
@@ -649,3 +667,19 @@ void *io_pbuf_get_address(struct io_ring_ctx *ctx, unsigned long bgid)
return bl->buf_ring;
}
+
+/*
+ * Called at or after ->release(), free the mmap'ed buffers that we used
+ * for memory mapped provided buffer rings.
+ */
+void io_kbuf_mmap_list_free(struct io_ring_ctx *ctx)
+{
+ struct io_buf_free *ibf;
+ struct hlist_node *tmp;
+
+ hlist_for_each_entry_safe(ibf, tmp, &ctx->io_buf_list, list) {
+ hlist_del(&ibf->list);
+ io_mem_free(ibf->mem);
+ kfree(ibf);
+ }
+}