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Subject: Re: [PATCH] xen/blkfront: When purging persistent grants, keep them
 in the buffer
To:     Juergen Gross <jgross@suse.com>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        konrad.wilk@oracle.com, roger.pau@citrix.com
Cc:     xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org
References: <20180922195549.27953-1-boris.ostrovsky@oracle.com>
 <28aa9249-7406-21c6-f509-65411828e2d7@suse.com>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <5bd1a695-50c6-e79f-38dd-c980fc2138ad@kernel.dk>
Date:   Thu, 27 Sep 2018 08:26:16 -0600
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On 9/27/18 1:12 AM, Juergen Gross wrote:
> On 22/09/18 21:55, Boris Ostrovsky wrote:
>> Commit a46b53672b2c ("xen/blkfront: cleanup stale persistent grants")
>> added support for purging persistent grants when they are not in use. As
>> part of the purge, the grants were removed from the grant buffer, This
>> eventually causes the buffer to become empty, with BUG_ON triggered in
>> get_free_grant(). This can be observed even on an idle system, within
>> 20-30 minutes.
>>
>> We should keep the grants in the buffer when purging, and only free the
>> grant ref.
>>
>> Fixes: a46b53672b2c ("xen/blkfront: cleanup stale persistent grants")
>> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> 
> Reviewed-by: Juergen Gross <jgross@suse.com>

Since Konrad is out, I'm going to queue this up for 4.19.

-- 
Jens Axboe