Re: RAID5 issue with UBUNTU 20.04.1 on my desktop

["Sung, KoWei" <winders@xxxxxxxxxx>]

Hi, Song:

Thanks a lot for your fix.
I've tested the patch by "v4.19.149" tag from Linux kernel stable tree (kernel/git/stable/linux.git).
The test runs over 1000 rounds in 24 hours without kernel crash, so the patch should fix this issue.

Best Regards,
Winder
________________________________________
From: Song Liu <song@xxxxxxxxxx>
Sent: Monday, October 5, 2020 3:40 PM
To: Sung, KoWei
Cc: linux-raid@xxxxxxxxxxxxxxx; Bshara, Saeed; Duan, HanShen; Tokoyo, Hiroshi; Fortin, Mike
Subject: RE: [EXTERNAL] RAID5 issue with UBUNTU 20.04.1 on my desktop

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Hi KoWei,

On Mon, Sep 28, 2020 at 10:15 AM Song Liu <song@xxxxxxxxxx> wrote:
>
> On Mon, Sep 21, 2020 at 5:34 PM Sung, KoWei <winders@xxxxxxxxxx> wrote:
> >
> > Hi, Song Liu:
> >
> > May I know if you're able to reproduce this issue? Thanks a lot for your help.
>

Could you please verify whether the following patch fixes it? If it
works well, please
reply with your Test-by tag.

Thanks,
Song

diff --git i/drivers/md/raid5.c w/drivers/md/raid5.c
index 66690b40818e7..39343479ac2a9 100644
--- i/drivers/md/raid5.c
+++ w/drivers/md/raid5.c
@@ -2585,8 +2585,6 @@ static int resize_stripes(struct r5conf *conf,
int newsize)
        } else
                err = -ENOMEM;

-       mutex_unlock(&conf->cache_size_mutex);
-
        conf->slab_cache = sc;
        conf->active_name = 1-conf->active_name;

@@ -2628,6 +2626,8 @@ static int resize_stripes(struct r5conf *conf,
int newsize)

        if (!err)
                conf->pool_size = newsize;
+       mutex_unlock(&conf->cache_size_mutex);
+
        return err;
 }