Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Sun, 29 Aug 2021 02:40:59 +0100
From:   Matthew Wilcox <willy@infradead.org>
To:     Tony Luck <tony.luck@intel.com>
Cc:     Al Viro <viro@zeniv.linux.org.uk>,
        Thomas Gleixner <tglx@linutronix.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andreas Gruenbacher <agruenba@redhat.com>,
        Christoph Hellwig <hch@infradead.org>,
        "Darrick J. Wong" <djwong@kernel.org>, Jan Kara <jack@suse.cz>,
        cluster-devel <cluster-devel@redhat.com>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        ocfs2-devel@oss.oracle.com, Borislav Petkov <bp@alien8.de>,
        X86-ML <x86@kernel.org>
Subject: Re: [PATCH v7 05/19] iov_iter: Introduce fault_in_iov_iter_writeable
Message-ID: <YSrlq41Ytw7q8fCR@casper.infradead.org>
References: <YSk7xfcHVc7CxtQO@zeniv-ca.linux.org.uk>
 <CAHk-=wjMyZLH+ta5SohAViSc10iPj-hRnHc-KPDoj1XZCmxdBg@mail.gmail.com>
 <YSk+9cTMYi2+BFW7@zeniv-ca.linux.org.uk>
 <YSldx9uhMYhT/G8X@zeniv-ca.linux.org.uk>
 <YSlftta38M4FsWUq@zeniv-ca.linux.org.uk>
 <20210827232246.GA1668365@agluck-desk2.amr.corp.intel.com>
 <87r1edgs2w.ffs@tglx>
 <YSqy+U/3lnF6K0ia@zeniv-ca.linux.org.uk>
 <YSq0mPAIBfqFC/NE@zeniv-ca.linux.org.uk>
 <CA+8MBbLLze0siip=h-2hR3XiceBFQCN7uh5BPvqYRyBXgT318g@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CA+8MBbLLze0siip=h-2hR3XiceBFQCN7uh5BPvqYRyBXgT318g@mail.gmail.com>
Precedence: bulk

On Sat, Aug 28, 2021 at 03:20:58PM -0700, Tony Luck wrote:
> On Sat, Aug 28, 2021 at 3:12 PM Al Viro <viro@zeniv.linux.org.uk> wrote:
> > BTW, is #MC triggered on stored to a poisoned cacheline?  Existence of CLZERO
> > would seem to argue against that...
> 
> No #MC on stores. Just on loads. Note that you can't clear poison
> state with a series of small writes to the cache line. But a single
> 64-byte store might do it (architects didn't want to guarantee that
> it would work when I asked about avx512 stores to clear poison
> many years ago).

Dave Jiang thinks MOVDIR64B clears poison.

http://archive.lwn.net:8080/linux-kernel/157617505636.42350.1170110675242558018.stgit@djiang5-desk3.ch.intel.com/