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From: Jeff Moyer <jmoyer@redhat.com>
To: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
        Peter Zijlstra <peterz@infradead.org>,
        Jonathan Corbet <corbet@lwn.net>, linux-nvdimm@ml01.01.org,
        Ingo Molnar <mingo@redhat.com>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        linux-fsdevel@vger.kernel.org,
        Matthew Wilcox <matthew.r.wilcox@intel.com>
Subject: Re: [PATCH 0/2] Add explicit coredump filtering for DAX mappings
References: <1444084417-19192-1-git-send-email-ross.zwisler@linux.intel.com>
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Date: Thu, 15 Oct 2015 16:01:30 -0400
In-Reply-To: <1444084417-19192-1-git-send-email-ross.zwisler@linux.intel.com>
	(Ross Zwisler's message of "Mon, 5 Oct 2015 16:33:35 -0600")
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Ross Zwisler <ross.zwisler@linux.intel.com> writes:

> Add two new flags to the existing coredump mechanism for ELF files to allow
> us to explicitly filter DAX mappings.  This is desirable because DAX
> mappings, like hugetlb mappings, have the potential to be very large.
>
> The coredump code relies on get_user_page() to populate the coredump file
> with the appropriate data, and for DAX mappings this currently fails.  This
> results in a hole being placed in the coredump file, so you end up reading
> back zeros.  Once the get_user_pages() patch series from Dan Williams [1]
> is merged, DAX core dumps will give real data.
>
> I have a patch ready for core(5) to update the documentation on the new
> filtering flags.  I'll send it out once this gets merged.

Looks straight-forward.

Acked-by: Jeff Moyer <jmoyer@redhat.com>