From: Christoph Hellwig <hch@lst.de>
To: Robin Murphy <robin.murphy@arm.com>
Cc: Ming Lei <ming.lei@redhat.com>, Christoph Hellwig <hch@lst.de>,
Hannes Reinecke <hare@suse.de>,
Hamza Mahfooz <someguy@effective-light.com>,
Dan Williams <dan.j.williams@intel.com>,
linux-block@vger.kernel.org, io-uring@vger.kernel.org,
linux-raid@vger.kernel.org, iommu@lists.linux.dev,
linux-kernel@vger.kernel.org
Subject: Re: [Report] annoyed dma debug warning "cacheline tracking EEXIST, overlapping mappings aren't supported"
Date: Tue, 15 Oct 2024 06:54:13 +0200 [thread overview]
Message-ID: <20241015045413.GA18058@lst.de> (raw)
In-Reply-To: <7411ae1d-5e36-46da-99cf-c485ebdb31bc@arm.com>
On Mon, Oct 14, 2024 at 07:09:08PM +0100, Robin Murphy wrote:
>>> The only case I fully understand without looking into the details
>>> is raid1, and that will obviously map the same data multiple times
>>
>> The other cases should be concurrent DIOs on same userspace buffer.
>
> active_cacheline_insert() does already bail out for DMA_TO_DEVICE, so it
> returning -EEXIST to tickle the warning would seem to genuinely imply these
> are DMA mappings requesting to *write* the same cacheline concurrently,
> which is indeed broken in general.
Yes, active_cacheline_insert only complains for FROM_DEVICE or
BIDIRECTIONAL mappings. I can't see how raid 1 would trigger that
given that it only reads from one leg at a time.
Ming, can you look a bit more into what is happening here?
next prev parent reply other threads:[~2024-10-15 4:54 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-14 1:27 [Report] annoyed dma debug warning "cacheline tracking EEXIST, overlapping mappings aren't supported" Ming Lei
2024-10-14 7:23 ` Hannes Reinecke
2024-10-14 7:41 ` Christoph Hellwig
2024-10-14 7:58 ` Ming Lei
2024-10-14 18:09 ` Robin Murphy
2024-10-15 1:59 ` Ming Lei
2024-10-15 2:22 ` Dan Williams
2024-10-15 4:54 ` Christoph Hellwig [this message]
2024-10-15 7:40 ` Ming Lei
2024-10-15 7:54 ` Christoph Hellwig
2024-10-15 2:31 ` Ming Lei
2024-10-14 15:17 ` Jens Axboe
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20241015045413.GA18058@lst.de \
--to=hch@lst.de \
--cc=dan.j.williams@intel.com \
--cc=hare@suse.de \
--cc=io-uring@vger.kernel.org \
--cc=iommu@lists.linux.dev \
--cc=linux-block@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-raid@vger.kernel.org \
--cc=ming.lei@redhat.com \
--cc=robin.murphy@arm.com \
--cc=someguy@effective-light.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.