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Re: vvar, gup && coredump
- From: Oleg Nesterov <oleg at redhat dot com>
- To: Sergio Durigan Junior <sergiodj at redhat dot com>
- Cc: Andy Lutomirski <luto at amacapital dot net>, Jan Kratochvil <jan dot kratochvil at redhat dot com>, GDB Patches <gdb-patches at sourceware dot org>, Pedro Alves <palves at redhat dot com>, "linux-kernel at vger dot kernel dot org" <linux-kernel at vger dot kernel dot org>
- Date: Thu, 12 Mar 2015 19:02:29 +0100
- Subject: Re: vvar, gup && coredump
- Authentication-results: sourceware.org; auth=none
- References: <20150305154827 dot GA9441 at host1 dot jankratochvil dot net> <87zj7r5fpz dot fsf at redhat dot com> <20150305205744 dot GA13165 at host1 dot jankratochvil dot net> <20150311200052 dot GA22654 at redhat dot com> <20150312143438 dot GA4338 at redhat dot com> <CALCETrW5rmAHutzm_OwK2LTd_J0XByV3pvWGyW=AmC=v7rLfhQ at mail dot gmail dot com> <20150312165423 dot GA10073 at redhat dot com> <CALCETrUGu5Wc7BbbQ4_tn29JGbyotUJay67EHBEgSa8-bz01Jg at mail dot gmail dot com> <20150312173901 dot GA12225 at redhat dot com> <874mpqp0sm dot fsf at redhat dot com>
On 03/12, Sergio Durigan Junior wrote:
> On Thursday, March 12 2015, Oleg Nesterov wrote:
> >> gdb will still need changes, though, right?
> > This is up to gdb developers. To me, it should simply skip this
> > VM_DONTDUMP vma.
> If I understood this discussion correctly (and thanks Andy and Oleg for,
> *ahem*, dumping all this useful information for us!), GDB will not need
> modifications in the Linux kernel in this area. In fact, my patch
> already implements the "ignore VM_DONTDUMP mappings" part, so we're
> pretty much covered.
And it seems that we all agree that the kernel should not dump this vma
too. Could you confirm that this is fine from gdb pov just in case?
However. Even if we do not want it in the coredump, this can confuse gdb
users which might want to read this memory during debugging. So perhaps
we still can add ->access() to "fix" PTRACE_PEEK/access_remote_vm later.
But I see another email from Andy, so lets forget about this for now.