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Date:   Mon, 20 Nov 2023 09:23:46 +0100
From:   Christoph Hellwig <hch@lst.de>
To:     Keith Busch <kbusch@kernel.org>
Cc:     Christoph Hellwig <hch@lst.de>,
        Yuanyuan Zhong <yzhong@purestorage.com>,
        Jens Axboe <axboe@kernel.dk>, sagi@grimberg.me,
        linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org,
        randyj@purestorage.com, hcoutinho@purestorage.com
Subject: Re: [PATCH] nvme-core: remove head->effects to fix use-after-free
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References: <20231115185439.2616073-1-yzhong@purestorage.com> <69218380-45f0-41cc-8a65-50878d44219e@kernel.dk> <CA+AMecFkR0k9ofJt0_iHrPOvfMQ_ePv8QCPYy9m=U7xEjsNCKg@mail.gmail.com> <ZVUiLr3g1_i5YmRQ@kbusch-mbp.dhcp.thefacebook.com> <CA+AMecH1TZc3zVm0OF1VwwTBCrLp9mZnOa5zw59yr_W0WbH_uw@mail.gmail.com> <ZVWR4Rtr1N7IF6iQ@kbusch-mbp.dhcp.thefacebook.com> <20231117132846.GB7867@lst.de> <ZVeW-8cNNVOvNdaR@kbusch-mbp.dhcp.thefacebook.com>
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On Fri, Nov 17, 2023 at 09:38:19AM -0700, Keith Busch wrote:
> The effects log is per-CSI so different command sets won't create
> conflicts.

True.  But that wasn't the point anyway.  It is that different
controllers might expose very different namespaes with different
capabilities.  Maybe a controller with HDD namespaces vs flash might
be a better example.

> Namespaces that are not shared don't really matter here because this
> problem is unique to mulitpath.

Indeed.

> It doesn't make sense for effects logs to be different per-controller
> for the same shared namespace. The spec doesn't seem to explicitly
> prevent that, but hints that all hosts should be seeing the same thing
> no matter which controller they're connected to:

Also agreed as already indicated in the past mail.