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Miller" , Andreas Larsson Cc: sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org Date: Sat, 07 Nov 2026 22:13:51 +0100 In-Reply-To: <20261107195147.70084-1-kmehltretter@gmail.com> References: <20261107195147.70084-1-kmehltretter@gmail.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.62.1 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 X-Original-Sender: glaubitz@physik.fu-berlin.de X-ZEDAT-Hint: PO Hi Karl, On Sat, 2026-11-07 at 20:51 +0100, Karl Mehltretter wrote: > Fixes: ff7d37a50202 ("Break up monolithic iommu table/lock into finer gra= ularity pools and lock") > Signed-off-by: Karl Mehltretter > --- > Assisted by an LLM. >=20 > 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 --=20 .''`. John Paul Adrian Glaubitz : :' : Debian Developer `. `' Physicist `- GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913