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[68.160.176.52]) by smtp.gmail.com with ESMTPSA id z8sm8208376qth.62.2019.05.13.18.37.17 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 13 May 2019 18:37:17 -0700 (PDT) Date: Mon, 13 May 2019 21:37:16 -0400 From: Mike Snitzer To: Helen Koike Cc: dm-devel@redhat.com, kernel@collabora.com, linux-kernel@vger.kernel.org, Alasdair Kergon Subject: Re: dm ioctl: fix hang in early create error condition Message-ID: <20190514013716.GA10260@lobo> References: <20190513192530.1167-1-helen.koike@collabora.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190513192530.1167-1-helen.koike@collabora.com> User-Agent: Mutt/1.11.4 (2019-03-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 13 2019 at 3:25P -0400, Helen Koike 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@vger.kernel.org > Signed-off-by: Helen Koike > > --- > Hi, > > I tested this patch by adding a new test case in the following test > script: > > https://gitlab.collabora.com/koike/dm-cmdline-test/commit/d2d7a0ee4a49931cdb59f08a837b516c2d5d743d > > This test was failing, but with this patch it works correctly. > > Thanks > Helen Thanks for the patch but I'd prefer the following simpler fix. What do you think? 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 --- a/drivers/md/dm-ioctl.c +++ b/drivers/md/dm-ioctl.c @@ -2117,6 +2117,7 @@ int __init dm_early_create(struct dm_ioctl *dmi, err_destroy_table: dm_table_destroy(t); err_destroy_dm: + (void) __hash_remove(__find_device_hash_cell(dmi)); dm_put(md); dm_destroy(md); return r;