io_uring: mem-account pbuf buckets

Potentially, someone may create as many pbuf bucket as there are indexes
in an xarray without any other restrictions bounding our memory usage,
put memory needed for the buckets under memory accounting.

Cc: <[email protected]>
Signed-off-by: Pavel Begunkov <[email protected]>
Link: https://lore.kernel.org/r/d34c452e45793e978d26e2606211ec9070d329ea.1659622312.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <[email protected]>

Author: isilence

io_uring/kbuf.c

@@ -436,7 +436,7 @@ int io_provide_buffers(struct io_kiocb *req, unsigned int issue_flags)
 
 	bl = io_buffer_get_list(ctx, p->bgid);
 	if (unlikely(!bl)) {
-		bl = kzalloc(sizeof(*bl), GFP_KERNEL);
+		bl = kzalloc(sizeof(*bl), GFP_KERNEL_ACCOUNT);
 		if (!bl) {
 			ret = -ENOMEM;
 			goto err;