From: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
To: Karl Mehltretter <kmehltretter@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
Andreas Larsson <andreas@gaisler.com>
Cc: sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] sparc/iommu: Use raw_cpu_read() for iommu_hash_common in iommu_tbl_range_alloc()
Date: Sat, 07 Nov 2026 22:13:51 +0100 [thread overview]
Message-ID: <155ec5c6c5f6d4287a420191cb3927eba1d97526.camel@physik.fu-berlin.de> (raw)
In-Reply-To: <20261107195147.70084-1-kmehltretter@gmail.com>
Hi Karl,
On Sat, 2026-11-07 at 20:51 +0100, Karl Mehltretter wrote:
> Fixes: ff7d37a50202 ("Break up monolithic iommu table/lock into finer graularity pools and lock")
> Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
> ---
> Assisted by an LLM.
>
> Tested on v7.4-rc1 (d48723711bae) under QEMU sparc64 (sun4u, -smp 2)
> with PREEMPT and DEBUG_PREEMPT. Without this patch, two consecutive
> boots emit three "BUG: using __this_cpu_read() in preemptible
> [00000000] code: swapper/0/1" diagnostics in iommu_tbl_range_alloc().
> With this patch, two consecutive boots complete without the
> __this_cpu_read() preemption diagnostic.
According to your Fixes tag, this bug was introduced in 2015. However,
I have to admit I have never seen this message, neither on sun4u nor
on sun4v machines.
Is there a reliable way to reproduce this bug?
Adrian
--
.''`. John Paul Adrian Glaubitz
: :' : Debian Developer
`. `' Physicist
`- GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913
prev parent reply other threads:[~2026-11-07 21:14 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-07 19:51 Karl Mehltretter
2026-11-07 21:13 ` John Paul Adrian Glaubitz [this message]
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