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Date:   Wed, 6 Dec 2023 11:21:50 -0500
From:   Alan Stern <stern@rowland.harvard.edu>
To:     Ferry Toth <fntoth@gmail.com>
Cc:     Catalin Marinas <catalin.marinas@arm.com>,
        Christoph Hellwig <hch@lst.de>,
        Hamza Mahfooz <someguy@effective-light.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Andrew <travneff@gmail.com>,
        Andy Shevchenko <andy.shevchenko@gmail.com>,
        Thorsten Leemhuis <regressions@leemhuis.info>,
        iommu@lists.linux.dev,
        Kernel development list <linux-kernel@vger.kernel.org>,
        USB mailing list <linux-usb@vger.kernel.org>,
        Robin Murphy <robin.murphy@arm.com>,
        Will Deacon <will@kernel.org>
Subject: Re: Bug in add_dma_entry()'s debugging code
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On Wed, Dec 06, 2023 at 05:12:40PM +0100, Ferry Toth wrote:
> Hi
> 
> On 05-12-2023 19:28, Alan Stern wrote:
> > In the long run, it may turn out that trying to detect memory usage
> > patterns that could cause problems for architectures other than the one
> > currently running is not workable.  Certainly it is a bad idea to have a
> 
> Maybe. But while debugging code on your platform it is a good thing to get
> warnings for potential issues on other platforms.

Oh, absolutely!  It's definitely a good thing.  I'm just saying that 
doing it may not be practical -- there may be too many false positives 
(as in this bug report) and false negatives.

> In this case we (I) got misled by the warning message itself. That should be
> easy enough to improve.

I don't think so.  Issuing incorrect warnings that should be ignored is 
a very bad idea, no matter what the wording is.  After seeing a few 
messages like that, people learn to expect them -- and then they ignore 
the valid warnings along with the incorrect ones.

Alan Stern