linux-kernel - Re: [PATCH] mmc: Fix tag set memory leak

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Message-ID: <CAPDyKFqNZeOZLgY4ntn=OPmP9Zo5S8HbtUtZ5MFVtz=BJ78LzQ@mail.gmail.com>
Date:   Fri, 3 May 2019 12:06:32 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Raul E Rangel <rrangel@...omium.org>
Cc:     "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        Avri Altman <avri.altman@....com>,
        Daniel Kurtz <djkurtz@...omium.org>, zwisler@...omium.org,
        Ming Lei <ming.lei@...hat.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Hannes Reinecke <hare@...e.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Jens Axboe <axboe@...nel.dk>, Omar Sandoval <osandov@...com>
Subject: Re: [PATCH] mmc: Fix tag set memory leak

On Thu, 2 May 2019 at 21:07, Raul E Rangel <rrangel@...omium.org> wrote:
>
> The tag set is allocated in mmc_init_queue but never freed. This results
> in a memory leak. This change makes sure we free the tag set when the
> queue is also freed.
>
> Signed-off-by: Raul E Rangel <rrangel@...omium.org>

Applied for fixes (it may not make it for v5.1 unless there is a rc8), thanks!

I also dropped the white space fixup, for the reasons explained by Adrian.

Kind regards
Uffe

> ---
> I found this using kmemleak and plugging and unplugging an SD card in a
> few times.
>
> Here is an example of the output of kmemleak:
> unreferenced object 0xffff888125be4ce8 (size 8):
>   comm "kworker/1:0", pid 17, jiffies 4294901575 (age 204.773s)
>   hex dump (first 8 bytes):
>     00 00 00 00 00 00 00 00                          ........
>   backtrace:
>     [<0000000061cb8887>] blk_mq_alloc_tag_set+0xe9/0x234
>     [<00000000cf532a0f>] mmc_init_queue+0xa9/0x2f0
>     [<000000001e085171>] mmc_blk_alloc_req+0x125/0x2f9
>     [<00000000eae1bd01>] mmc_blk_probe+0x1e2/0x6c1
>     [<00000000a0b4a87d>] really_probe+0x1bd/0x3b0
>     [<00000000e58f3eb9>] driver_probe_device+0xe1/0x115
>     [<00000000358f3b3c>] bus_for_each_drv+0x89/0xac
>     [<00000000ef52ccbe>] __device_attach+0xb0/0x14a
>     [<00000000c9daafa7>] bus_probe_device+0x33/0x9f
>     [<0000000008ac5779>] device_add+0x34b/0x5e2
>     [<00000000b42623cc>] mmc_add_card+0x1f5/0x20d
>     [<00000000f114ebc3>] mmc_attach_sd+0xc5/0x14b
>     [<000000006e915e0d>] mmc_rescan+0x261/0x2b6
>     [<00000000e5b49c26>] process_one_work+0x1d3/0x31f
>     [<0000000068c8cd3c>] worker_thread+0x1cd/0x2bf
>     [<00000000326e2e22>] kthread+0x14f/0x157
>
> Once I applied this patch the leak went away.
>
> p.s., I included a small white space fix. Hope that's ok.
>
>  drivers/mmc/core/queue.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c
> index 7c364a9c4eeb..176a08748cf1 100644
> --- a/drivers/mmc/core/queue.c
> +++ b/drivers/mmc/core/queue.c
> @@ -402,7 +402,7 @@ int mmc_init_queue(struct mmc_queue *mq, struct mmc_card *card)
>
>         mq->card = card;
>         mq->use_cqe = host->cqe_enabled;
> -
> +
>         spin_lock_init(&mq->lock);
>
>         memset(&mq->tag_set, 0, sizeof(mq->tag_set));
> @@ -472,6 +472,7 @@ void mmc_cleanup_queue(struct mmc_queue *mq)
>                 blk_mq_unquiesce_queue(q);
>
>         blk_cleanup_queue(q);
> +       blk_mq_free_tag_set(&mq->tag_set);
>
>         /*
>          * A request can be completed before the next request, potentially
> --
> 2.21.0.593.g511ec345e18-goog
>