Re: dm ioctl: fix hang in early create error condition
From: Mike Snitzer
Date: Mon May 13 2019 - 21:38:58 EST
On Mon, May 13 2019 at 3:25P -0400,
Helen Koike <helen.koike@xxxxxxxxxxxxx> wrote:
> The dm_early_create() function (which deals with "dm-mod.create=" kernel
> command line option) calls dm_hash_insert() who gets an extra reference
> to the md object.
> In case of failure, this reference wasn't being released, causing
> dm_destroy() to hang, thus hanging the whole boot process.
> Fix this by calling __hash_remove() in the error path.
> Fixes: 6bbc923dfcf57d ("dm: add support to directly boot to a mapped device")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Helen Koike <helen.koike@xxxxxxxxxxxxx>
> I tested this patch by adding a new test case in the following test
> This test was failing, but with this patch it works correctly.
Thanks for the patch but I'd prefer the following simpler fix. What do
That said, I can provide a follow-on patch (inspired by the patch you
provided) that encourages more code sharing between dm_early_create()
and dev_create() by factoring out __dev_create().
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index c740153b4e52..0eb0b462c736 100644
@@ -2117,6 +2117,7 @@ int __init dm_early_create(struct dm_ioctl *dmi,
+ (void) __hash_remove(__find_device_hash_cell(dmi));