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Date:   Tue, 19 Sep 2023 14:00:54 +0100
From:   Matthew Wilcox <willy@infradead.org>
To:     Thomas Gleixner <tglx@linutronix.de>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Ankur Arora <ankur.a.arora@oracle.com>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org,
        akpm@linux-foundation.org, luto@kernel.org, bp@alien8.de,
        dave.hansen@linux.intel.com, hpa@zytor.com, mingo@redhat.com,
        juri.lelli@redhat.com, vincent.guittot@linaro.org, mgorman@suse.de,
        rostedt@goodmis.org, jon.grimm@amd.com, bharata@amd.com,
        raghavendra.kt@amd.com, boris.ostrovsky@oracle.com,
        konrad.wilk@oracle.com, jgross@suse.com, andrew.cooper3@citrix.com,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        linux-m68k@lists.linux-m68k.org,
        Richard Weinberger <richard@nod.at>,
        Anton Ivanov <anton.ivanov@cambridgegreys.com>,
        Johannes Berg <johannes@sipsolutions.net>,
        linux-um@lists.infradead.org, Brian Cain <bcain@quicinc.com>,
        linux-hexagon@vger.kernel.org,
        Richard Henderson <richard.henderson@linaro.org>,
        Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
        Matt Turner <mattst88@gmail.com>, linux-alpha@vger.kernel.org
Subject: Arches that don't support PREEMPT
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On Tue, Sep 19, 2023 at 02:30:59PM +0200, Thomas Gleixner wrote:
> Though it just occured to me that there are dragons lurking:
> 
> arch/alpha/Kconfig:     select ARCH_NO_PREEMPT
> arch/hexagon/Kconfig:   select ARCH_NO_PREEMPT
> arch/m68k/Kconfig:      select ARCH_NO_PREEMPT if !COLDFIRE
> arch/um/Kconfig:        select ARCH_NO_PREEMPT

Sounds like three-and-a-half architectures which could be queued up for
removal right behind ia64 ...

I suspect none of these architecture maintainers have any idea there's a
problem.  Look at commit 87a4c375995e and the discussion in
https://lore.kernel.org/lkml/20180724175646.3621-1-hch@lst.de/

Let's cc those maintainers so they can remove this and fix whatever
breaks.