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Date:   Tue, 5 Jan 2021 15:26:48 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Nadav Amit <nadav.amit@gmail.com>
Cc:     Andrea Arcangeli <aarcange@redhat.com>,
        linux-mm <linux-mm@kvack.org>,
        lkml <linux-kernel@vger.kernel.org>, Yu Zhao <yuzhao@google.com>,
        Andy Lutomirski <luto@kernel.org>,
        Peter Xu <peterx@redhat.com>,
        Pavel Emelyanov <xemul@openvz.org>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Mike Rapoport <rppt@linux.vnet.ibm.com>,
        Minchan Kim <minchan@kernel.org>,
        Will Deacon <will@kernel.org>, Mel Gorman <mgorman@suse.de>
Subject: Re: [RFC PATCH v2 1/2] mm/userfaultfd: fix memory corruption due to
 writeprotect
Message-ID: <20210105142648.GJ3040@hirez.programming.kicks-ass.net>
References: <20201225092529.3228466-1-namit@vmware.com>
 <20201225092529.3228466-2-namit@vmware.com>
 <20210104122227.GL3021@hirez.programming.kicks-ass.net>
 <X/NrdnoDHgFd0Ku1@redhat.com>
 <20210105081325.GD3040@hirez.programming.kicks-ass.net>
 <C255B66E-C418-4B30-B363-76441266A0DC@gmail.com>
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On Tue, Jan 05, 2021 at 12:52:48AM -0800, Nadav Amit wrote:
> > On Jan 5, 2021, at 12:13 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> > 
> > On Mon, Jan 04, 2021 at 02:24:38PM -0500, Andrea Arcangeli wrote:
> >> The problematic one not pictured is the one of the wrprotect that has
> >> to be running in another CPU which is also isn't picture above. More
> >> accurate traces are posted later in the thread.
> > 
> > What thread? I don't seem to have discovered it yet, and the cover
> > letter from Nadav doesn't seem to have a msgid linking it either.
> 
> Sorry for that:
> 
> https://lore.kernel.org/lkml/X+K7JMrTEC9SpVIB@google.com/T/

Much reading later..

OK, go with the write-lock for now.