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From: Matthew Wilcox <willy@infradead.org>
Date: Sun, 29 Aug 2021 02:40:59 +0100
Subject: [Cluster-devel] [PATCH v7 05/19] iov_iter: Introduce
	fault_in_iov_iter_writeable
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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 at djiang5-desk3.ch.intel.com/