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Date:   Fri, 17 Apr 2020 14:59:29 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Kai-Heng Feng <kai.heng.feng@canonical.com>
Cc:     kbusch@kernel.org, axboe@fb.com, hch@lst.de, sagi@grimberg.me,
        linux-stable <stable@vger.kernel.org>,
        "open list:NVM EXPRESS DRIVER" <linux-nvme@lists.infradead.org>,
        open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] nvme/pci: Use Discard instead of Write Zeroes on SK
 hynix SC300
Message-ID: <20200417125929.GA5053@lst.de>
References: <20200417083641.28205-1-kai.heng.feng@canonical.com>
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On Fri, Apr 17, 2020 at 04:36:41PM +0800, Kai-Heng Feng wrote:
> After commit 6e02318eaea5 ("nvme: add support for the Write Zeroes
> command"), SK hynix SC300 becomes very slow with the following error
> message:
> [  224.567695] blk_update_request: operation not supported error, dev nvme1n1, sector 499384320 op 0x9:(WRITE_ZEROES) flags 0x1000000 phys_seg 0 prio class 0]
> 
> Use quirk NVME_QUIRK_DEALLOCATE_ZEROES to workaround this issue.

Do you have a written guarantee from SK Hynix that it will always zero
all blocks discarded?