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Date:   Tue, 3 Jul 2018 10:47:41 -0600
From:   Ross Zwisler <ross.zwisler@linux.intel.com>
To:     Dan Williams <dan.j.williams@intel.com>
Cc:     mingo@kernel.org, Al Viro <viro@zeniv.linux.org.uk>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andy Lutomirski <luto@amacapital.net>,
        Borislav Petkov <bp@alien8.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Tony Luck <tony.luck@intel.com>,
        Ross Zwisler <ross.zwisler@linux.intel.com>,
        linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH] lib/iov_iter: Fix pipe handling in _copy_to_iter_mcsafe
Message-ID: <20180703164741.GA30451@linux.intel.com>
Mail-Followup-To: Ross Zwisler <ross.zwisler@linux.intel.com>,
        Dan Williams <dan.j.williams@intel.com>, mingo@kernel.org,
        Al Viro <viro@zeniv.linux.org.uk>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andy Lutomirski <luto@amacapital.net>,
        Borislav Petkov <bp@alien8.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Tony Luck <tony.luck@intel.com>, linux-kernel@vger.kernel.org,
        linux-fsdevel@vger.kernel.org
References: <153046008813.2019.6356018879675062644.stgit@dwillia2-desk3.amr.corp.intel.com>
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On Sun, Jul 01, 2018 at 08:52:20AM -0700, Dan Williams wrote:
> By mistake the ITER_PIPE early-exit / warning from copy_from_iter() was
> cargo-culted in _copy_to_iter_mcsafe() rather than a machine-check-safe
> version of copy_to_iter_pipe().
> 
> Implement copy_pipe_to_iter_mcsafe() being careful to return the
> indication of short copies due to a CPU exception.
> 
> Without this regression-fix all splice reads to dax-mode files fail.
> 
> Fixes: 8780356ef630 ("x86/asm/memcpy_mcsafe: Define copy_to_iter_mcsafe()")
> Cc: Al Viro <viro@zeniv.linux.org.uk>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Andy Lutomirski <luto@amacapital.net>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Tony Luck <tony.luck@intel.com>
> Reported-by: Ross Zwisler <ross.zwisler@linux.intel.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Tested-by: Ross Zwisler <ross.zwisler@linux.intel.com>