linux-kernel - Re: [PATCH v4 0/3] Optimize tlbflush path

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Message-ID: <alpine.DEB.2.21.9999.1908301939300.16731@viisi.sifive.com>
Date:   Fri, 30 Aug 2019 19:50:33 -0700 (PDT)
From:   Paul Walmsley <paul.walmsley@...ive.com>
To:     Atish Patra <atish.patra@....com>
cc:     linux-kernel@...r.kernel.org, Albert Ou <aou@...s.berkeley.edu>,
        linux-riscv@...ts.infradead.org,
        Palmer Dabbelt <palmer@...ive.com>,
        Christoph Hellwig <hch@....de>, Anup Patel <Anup.Patel@....com>
Subject: Re: [PATCH v4 0/3] Optimize tlbflush path

Hi Atish,

On Thu, 22 Aug 2019, Atish Patra wrote:

> This series adds few optimizations to reduce the trap cost in the tlb
> flush path. We should only make SBI calls to remote tlb flush only if
> absolutely required. 

The patches look great.  My understanding is that these optimization 
patches may actually be a partial workaround for the TLB flushing bug that 
we've been looking at for the last month or so, which can corrupt memory 
or crash the system.

If that's the case, let's first root-cause the underlying bug.  Otherwise 
we'll just be papering over the actual issue, which probably could still 
occur even with this series, correct?  Since it contains no explicit 
fixes?

- Paul