io_uring: return locked and pinned page accounting

Locked and pinned memory accounting in io_{,un}account_mem() depends on
having ->sqo_mm, which is NULL after a recent change for non SQPOLL'ed
io_ring. That disables the accounting.

Return ->sqo_mm initialisation back, and do __io_sq_thread_acquire_mm()
based on IORING_SETUP_SQPOLL flag.

Fixes: 8eb06d7e8dd85 ("io_uring: fix missing ->mm on exit")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index ba7ce103667b5dfdb3b5feb5b409e229770b4674..680b16f71a036f5f57ac4e90c66ae0ed07e572cb 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -981,7 +981,8 @@ static void io_sq_thread_drop_mm(void)
 static int __io_sq_thread_acquire_mm(struct io_ring_ctx *ctx)
 {
        if (!current->mm) {
-               if (unlikely(!ctx->sqo_mm || !mmget_not_zero(ctx->sqo_mm)))
+               if (unlikely(!(ctx->flags & IORING_SETUP_SQPOLL) ||
+                            !mmget_not_zero(ctx->sqo_mm)))
                        return -EFAULT;
                kthread_use_mm(ctx->sqo_mm);
        }
@@ -7259,10 +7260,10 @@ static int io_sq_offload_start(struct io_ring_ctx *ctx,
 {
        int ret;
 
-       if (ctx->flags & IORING_SETUP_SQPOLL) {
-               mmgrab(current->mm);
-               ctx->sqo_mm = current->mm;
+       mmgrab(current->mm);
+       ctx->sqo_mm = current->mm;
 
+       if (ctx->flags & IORING_SETUP_SQPOLL) {
                ret = -EPERM;
                if (!capable(CAP_SYS_ADMIN))
                        goto err;