linux-kernel - Re: WARNING: drivers/iommu/io-pgtable-arm.c:639

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Message-ID: <d1d76dcb-5241-4290-ae69-7d20e4461b9b@nvidia.com>
Date: Tue, 9 Dec 2025 17:29:09 +0000
From: Chaitanya Kulkarni <chaitanyak@...dia.com>
To: Robin Murphy <robin.murphy@....com>
CC: Jens Axboe <axboe@...com>, Christoph Hellwig <hch@....de>, Will Deacon
	<will@...nel.org>, Carlos Maiolino <cem@...nel.org>, "iommu@...ts.linux.dev"
	<iommu@...ts.linux.dev>, "linux-xfs@...r.kernel.org"
	<linux-xfs@...r.kernel.org>, "linux-nvme@...ts.infradead.org"
	<linux-nvme@...ts.infradead.org>, Sebastian Ott <sebott@...hat.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-block@...r.kernel.org" <linux-block@...r.kernel.org>
Subject: Re: WARNING: drivers/iommu/io-pgtable-arm.c:639

On 12/9/25 03:50, Robin Murphy wrote:
> On 2025-12-09 11:43 am, Sebastian Ott wrote:
>> Hi,
>>
>> got the following warning after a kernel update on Thurstday, leading 
>> to a
>> panic and fs corruption. I didn't capture the first warning but I'm 
>> pretty
>> sure it was the same. It's reproducible but I didn't bisect since it
>> borked my fs. The only hint I can give is that v6.18 worked. Is this a
>> known issue? Anything I should try?
>
> nvme_unmap_data() is attempting to unmap an IOVA that was never 
> mapped, or has already been unmapped by someone else. That's a usage bug.
>
> Thanks,
> Robin.

Ankit A. also reported this.

Apart from unmapping, by any chance do we need this ?

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index e6626004b323..05d63fe92e43 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -637,7 +637,7 @@ static size_t __arm_lpae_unmap(struct arm_lpae_io_pgtable *data,
  	pte = READ_ONCE(*ptep);
  	if (!pte) {
  		WARN_ON(!(data->iop.cfg.quirks & IO_PGTABLE_QUIRK_NO_WARN));
-		return -ENOENT;
+		return 0;
  	}
  
  	/* If the size matches this level, we're in the right place */
-- 
2.40.0

disclaimer :-

THIS PATCH IS COMPLETELY UNTESTED AND MAY BE INCORRECT.
PLEASE REVIEW CAREFULLY.

-ck