From: Yu Kuai <yukuai1@huaweicloud.com>
To: Dan Carpenter <dan.carpenter@linaro.org>
Cc: linux-raid@vger.kernel.org, "yukuai (C)" <yukuai3@huawei.com>
Subject: Re: [bug report] md: also clone new io if io accounting is disabled
Date: Thu, 1 Feb 2024 09:35:38 +0800 [thread overview]
Message-ID: <0efa13dc-f877-30b9-1f3f-e7ec500ad7f5@huaweicloud.com> (raw)
In-Reply-To: <2cf10b2e-3703-414b-99b6-457dd4b14177@moroto.mountain>
Hi,
在 2024/01/31 19:17, Dan Carpenter 写道:
> Hello Yu Kuai,
>
> The patch c687297b8845: "md: also clone new io if io accounting is
> disabled" from Jun 22, 2023 (linux-next), leads to the following
> Smatch static checker warning:
>
> drivers/md/md.c:8718 md_clone_bio()
> potential NULL container_of 'clone'
>
> drivers/md/md.c
> 8711 static void md_clone_bio(struct mddev *mddev, struct bio **bio)
> 8712 {
> 8713 struct block_device *bdev = (*bio)->bi_bdev;
> 8714 struct md_io_clone *md_io_clone;
> 8715 struct bio *clone =
> 8716 bio_alloc_clone(bdev, *bio, GFP_NOIO, &mddev->io_clone_set);
If you ever look at the comment, you'll know that this will never fail.
* If %__GFP_DIRECT_RECLAIM is set then bio_alloc will always be able to
* allocate a bio. This is due to the mempool guarantees.
Thanks,
Kuai
>
> Generally in the kernel, you have to check for allocation failure. In
> this case if the allocation fails it leads to a NULL dereference.
>
> 8717
> --> 8718 md_io_clone = container_of(clone, struct md_io_clone, bio_clone);
> 8719 md_io_clone->orig_bio = *bio;
> 8720 md_io_clone->mddev = mddev;
> 8721 if (blk_queue_io_stat(bdev->bd_disk->queue))
> 8722 md_io_clone->start_time = bio_start_io_acct(*bio);
> 8723
> 8724 clone->bi_end_io = md_end_clone_io;
> 8725 clone->bi_private = md_io_clone;
> 8726 *bio = clone;
> 8727 }
>
> regards,
> dan carpenter
> .
>
prev parent reply other threads:[~2024-02-01 1:35 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-31 11:17 [bug report] md: also clone new io if io accounting is disabled Dan Carpenter
2024-02-01 1:35 ` Yu Kuai [this message]
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