io_uring: correct pinned_vm accounting

->mm_account should be released only after we free all registered
buffers, otherwise __io_sqe_buffers_unregister() will see a NULL
->mm_account and skip locked_vm accounting.

Cc: <Stable@vger.kernel.org>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/6d798f65ed4ab8db3664c4d3397d4af16ca98846.1664849932.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index 63f6ce5..ea5cee5 100644 (file)
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -2585,12 +2585,6 @@ static void io_req_caches_free(struct io_ring_ctx *ctx)
 static __cold void io_ring_ctx_free(struct io_ring_ctx *ctx)
 {
        io_sq_thread_finish(ctx);
-
-       if (ctx->mm_account) {
-               mmdrop(ctx->mm_account);
-               ctx->mm_account = NULL;
-       }
-
        io_rsrc_refs_drop(ctx);
        /* __io_rsrc_put_work() may need uring_lock to progress, wait w/o it */
        io_wait_rsrc_data(ctx->buf_data);
@@ -2633,6 +2627,10 @@ static __cold void io_ring_ctx_free(struct io_ring_ctx *ctx)
        WARN_ON_ONCE(!list_empty(&ctx->ltimeout_list));
        WARN_ON_ONCE(ctx->notif_slots || ctx->nr_notif_slots);
 
+       if (ctx->mm_account) {
+               mmdrop(ctx->mm_account);
+               ctx->mm_account = NULL;
+       }
        io_mem_free(ctx->rings);
        io_mem_free(ctx->sq_sqes);