linux-kernel - Re: [PATCH 2/2 v2] core dump: add VM_NODUMP, MADV_NODUMP, MADV_CLEAR

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Message-Id: <20120308150505.c9c3d309.akpm@linux-foundation.org>
Date:	Thu, 8 Mar 2012 15:05:05 -0800
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Roland McGrath <roland@...k.frob.com>
Cc:	Jason Baron <jbaron@...hat.com>, torvalds@...ux-foundation.org,
	avi@...hat.com, cmetcalf@...era.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2 v2] core dump: add VM_NODUMP, MADV_NODUMP,
 MADV_CLEAR_NODUMP

On Thu,  8 Mar 2012 13:44:17 -0800 (PST)
Roland McGrath <roland@...k.frob.com> wrote:

> I'm vaguely dubious about the desireability of using this new feature.
> (I would hate to try to debug a qemu bug from a dump where half the
> interesting state was intentionally hidden from me.)

yup.  But the dumpability is fully controllable by userspace: one can
easily envisage large vma's full of data which just isn't interesting
for a dump.  Plus if you're a developer who is looking at a dump and
important data isn't there, you can often delete one line, rebuild and
run the test again.  

>  But I don't see
> any problem with the implementation.
> 
> As to the interface, I think the bits are OK but it would be more
> in keeping with the existing MADV_* names to call the new values
> MADV_DONTDUMP and MADV_DODUMP.

Yup.  I queued a patch to do that.
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