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Date:   Mon, 24 Jun 2019 16:38:20 +0100
From:   Catalin Marinas <catalin.marinas@arm.com>
To:     Guo Ren <guoren@kernel.org>
Cc:     Julien Grall <julien.grall@arm.com>, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu,
        aou@eecs.berkeley.edu, gary@garyguo.net,
        Atish Patra <Atish.Patra@wdc.com>, hch@infradead.org,
        paul.walmsley@sifive.com, rppt@linux.ibm.com,
        linux-riscv@lists.infradead.org, Anup Patel <anup.Patel@wdc.com>,
        Palmer Dabbelt <palmer@sifive.com>, suzuki.poulose@arm.com,
        Marc Zyngier <marc.zyngier@arm.com>, julien.thierry@arm.com,
        Will Deacon <will.deacon@arm.com>, christoffer.dall@arm.com,
        james.morse@arm.com
Subject: Re: [PATCH RFC 11/14] arm64: Move the ASID allocator code in a
 separate file
Message-ID: <20190624153820.GH29120@arrakis.emea.arm.com>
References: <20190321163623.20219-1-julien.grall@arm.com>
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 <CAJF2gTTXHHgDboaexdHA284y6kNZVSjLis5-Q2rDnXCxr4RSmA@mail.gmail.com>
 <c871a5ae-914f-a8bb-9474-1dcfec5d45bf@arm.com>
 <CAJF2gTStSR7Jmu7=HaO5Wxz=Zn8A5-RD8ktori3oKEhM9vozAA@mail.gmail.com>
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On Mon, Jun 24, 2019 at 12:35:35AM +0800, Guo Ren wrote:
> On Fri, Jun 21, 2019 at 10:16 PM Catalin Marinas
> <catalin.marinas@arm.com> wrote:
> > BTW, if you find the algorithm fairly straightforward ;), see this
> > bug-fix which took a formal model to identify: a8ffaaa060b8 ("arm64:
> > asid: Do not replace active_asids if already 0").
[...]
> Btw, Is this detected by arm's aisd allocator TLA+ model ? Or a real
> bug report ?

This specific bug was found by the TLA+ model checker (at the time we
were actually tracking down another bug with multi-threaded CPU sharing
the TLB, bug also confirmed by the formal model).

-- 
Catalin