From: Hugh Dickins <hugh@veritas.com>
To: Roland McGrath <roland@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-kernel@vger.kernel.org, "Kawai,
Hidehiro" <hidehiro.kawai.ez@hitachi.com>
Subject: Re: [PATCH] ELF core dump options
Date: Thu, 26 Jul 2007 17:57:36 +0100 (BST) [thread overview]
Message-ID: <Pine.LNX.4.64.0707261753030.370@blonde.wat.veritas.com> (raw)
In-Reply-To: <20070726113924.6017C4D058D@magilla.localdomain>
On Thu, 26 Jul 2007, Roland McGrath wrote:
>
> > hm, I'm now wondering whether testing i_nlink was the best (or official)
> > way of determining whether a MAP_SHARED vma is anonymous or file-backed.
> > Hugh will know.
>
> Well, it doesn't exactly test that it's not "file-backed". (Technically
> anything shared is file-backed, even if by a shmem virtual file.) It tests
> whether the backing file will probably ever be found on disk later. That
> gets shmem regions as well as originally-regular files that were deleted
> while mapped. I think we asked around when this test was put it and it was
> deemed proper at the time. (It doesn't really need to be a formal "what
> does the vm situation mean" guarantee, just a practical "you probably
> wanted that" test.)
Exactly, a rough heuristic which seemed to approximate what the coredump
people wanted when it went into 2.6.12. No absolute justification to it.
Hugh
prev parent reply other threads:[~2007-07-26 16:58 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-26 9:37 [PATCH] ELF core dump options Roland McGrath
2007-07-26 10:06 ` Andrew Morton
2007-07-26 11:39 ` Roland McGrath
2007-07-26 16:57 ` Hugh Dickins [this message]
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