From: Keith Busch <kbusch@kernel.org>
To: guzebing <guzebing1612@gmail.com>
Cc: axboe@kernel.dk, sagi@grimberg.me, leon@kernel.org,
linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org,
Guzebing <guzebing@bytedance.com>
Subject: Re: [PATCH] nvme-pci: unmap the full IOVA range on PRP setup failure
Date: Tue, 27 Oct 2026 09:10:41 -0600 [thread overview]
Message-ID: <auC-8UVAuj2KDb_S@kbusch-mbp> (raw)
In-Reply-To: <20261027115718.2241149-1-guzebing1612@gmail.com>
On Tue, Oct 27, 2026 at 07:57:18PM +0800, guzebing wrote:
> When using IOVA, blk_rq_dma_map_iter_start() maps the entire request
> before PRP construction begins. However, iod->total_len is accumulated
> as PRPs are populated. If a PRP list allocation fails, nvme_unmap_data()
> passes this partial length to blk_rq_dma_unmap(), leaving part of the
> request's DMA mapping intact.
>
> Use dma_iova_size() as the unmap length for IOVA mappings so that
> cleanup covers the full range mapped by blk_rq_dma_map_iter_start(),
> even when PRP construction fails.
I don't think this is right. The dma state's iova size was set when it
was allocated, but there are failure scenarios where we've only linked
part of the request. I think the iod's total_len is just not in sync
with the pinned mappings. We should update the total_len as we iterate
the blk_mq_dma_iter, not when we've assigned a PRP element.
prev parent reply other threads:[~2026-10-27 15:10 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-27 11:57 guzebing
2026-10-27 15:10 ` Keith Busch [this message]
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