From: Christoph Hellwig <hch@lst.de>
To: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>,
virtualization@lists.linux.dev, linux-kernel@vger.kernel.org,
Christoph Hellwig <hch@lst.de>,
Baokun Li <libaokun@linux.alibaba.com>
Subject: Re: [PATCH] virtio-pmem: use GFP_NOIO for flush bio allocation
Date: Wed, 8 Jul 2026 18:24:35 +0200 [thread overview]
Message-ID: <20260708162435.GB2502@lst.de> (raw)
In-Reply-To: <20260708124238.2817165-1-joseph.qi@linux.alibaba.com>
On Wed, Jul 08, 2026 at 08:42:38PM +0800, Joseph Qi wrote:
> diff --git a/drivers/nvdimm/nd_virtio.c b/drivers/nvdimm/nd_virtio.c
> index 4176046627beb..081370aac6317 100644
> --- a/drivers/nvdimm/nd_virtio.c
> +++ b/drivers/nvdimm/nd_virtio.c
> @@ -117,7 +117,7 @@ int async_pmem_flush(struct nd_region *nd_region, struct bio *bio)
> if (bio && bio->bi_iter.bi_sector != -1) {
> struct bio *child = bio_alloc(bio->bi_bdev, 0,
> REQ_OP_WRITE | REQ_PREFLUSH,
> - GFP_ATOMIC);
> + GFP_NOIO);
>
> if (!child)
> return -ENOMEM;
This NULL check can go away now, and probaby should to avoid confusion.
Also bio_alloc allocates from fs_bio_set, so if the incoming bio
is from that, we can still deadlock. We'll need a separate bio_set
for this to be deadlock free. disk->bio_split isn't otherwise
used for the drivers/nvdimm/ driverss, so you might be able to
repurpose that if you want to be creative.
next prev parent reply other threads:[~2026-07-08 16:24 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-08 12:42 [PATCH] virtio-pmem: use GFP_NOIO for flush bio allocation Joseph Qi
2026-07-08 16:24 ` Christoph Hellwig [this message]
2026-07-09 3:13 ` Joseph Qi
2026-07-09 10:58 ` Pankaj Gupta
2026-07-09 11:01 ` Joseph Qi
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