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Re: vvar, gup && coredump
- From: Andy Lutomirski <luto at amacapital dot net>
- To: Oleg Nesterov <oleg at redhat dot com>
- Cc: Jan Kratochvil <jan dot kratochvil at redhat dot com>, Sergio Durigan Junior <sergiodj 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 10:55:46 -0700
- Subject: Re: vvar, gup && coredump
- Authentication-results: sourceware.org; auth=none
- References: <878ufc9kau dot fsf at redhat dot com> <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>
On Thu, Mar 12, 2015 at 10:39 AM, Oleg Nesterov <email@example.com> wrote:
> On 03/12, Andy Lutomirski wrote:
>> On Thu, Mar 12, 2015 at 9:54 AM, Oleg Nesterov <firstname.lastname@example.org> wrote:
>> > On 03/12, Andy Lutomirski wrote:
>> > As for 32-bit applications. Yes, this can't work because 32-bit simply
>> > can't access this "high" memory. But you know, it would be very nice to
>> > have the fixmap-like "global" area in init_mm which is also visible to
>> > compat applications. If we had it, uprobes could work without xol vma's.
>> It could work for 32-bit native, but not for 32-bit compat.
> Yes, yes, I meant 32-bit compat apps. Once again, it would be nice if we
> had the "low" fixmaps in init_mm. But unlikely this is possible...
>> On a related note, I'm hoping to rework the mm part pretty heavily:
> OK... not that I really understand this email.
> Well. Speaking of vdso. I understand that unlikely we can do this, but
> for uprobes it would be nice to have a anon-inode file behind this mapping,
> so that vma_interval_tree_foreach() could work, etc. OK, this is completely
> off-topic, please forget.
Couldn't you do that directly in the uprobes code? That is, create an
anon_inode file and just map it the old-fashioned way?
> And I noticed that I didn't read your previous email carefully enough...
>> That sounds reasonable to me. I'll write the patch later today.
> Sure, please send a patch if you want to do this.
>> gdb will still need changes, though, right?
> This is up to gdb developers. To me, it should simply skip this
> VM_DONTDUMP vma.
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