[PATCH 5.10 378/390] io_uring: correct pinned_vm accounting

[Greg Kroah-Hartman]

From: Pavel Begunkov <asml.silence@xxxxxxxxx>

[ upstream commit 42b6419d0aba47c5d8644cdc0b68502254671de5 ]

->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@xxxxxxxxxxxxxxx>
Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
Link: https://lore.kernel.org/r/6d798f65ed4ab8db3664c4d3397d4af16ca98846.1664849932.git.asml.silence@xxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 fs/io_uring.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -8436,8 +8436,6 @@ static void io_ring_ctx_free(struct io_r
 	if (ctx->sqo_task) {
 		put_task_struct(ctx->sqo_task);
 		ctx->sqo_task = NULL;
-		mmdrop(ctx->mm_account);
-		ctx->mm_account = NULL;
 	}
 
 #ifdef CONFIG_BLK_CGROUP
@@ -8456,6 +8454,11 @@ static void io_ring_ctx_free(struct io_r
 	}
 #endif
 
+	if (ctx->mm_account) {
+		mmdrop(ctx->mm_account);
+		ctx->mm_account = NULL;
+	}
+
 	io_mem_free(ctx->rings);
 	io_mem_free(ctx->sq_sqes);