From: Dave Young <dyoung@redhat.com>
To: James Morse <james.morse@arm.com>
Cc: Baoquan He <bhe@redhat.com>,
Anshuman Khandual <anshuman.khandual@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Bhupesh Sharma <bhsharma@redhat.com>,
kexec@lists.infradead.org, linux-mm@kvack.org,
Eric Biederman <ebiederm@xmission.com>,
Andrew Morton <akpm@linux-foundation.org>,
Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 0/3] kexec/memory_hotplug: Prevent removal and accidental use
Date: Tue, 31 Mar 2020 11:46:12 +0800 [thread overview]
Message-ID: <20200331034612.GB83248@dhcp-128-65.nay.redhat.com> (raw)
In-Reply-To: <2bdfbb1c-49da-d476-4a38-f91937105ae3@arm.com>
Hi James,
On 03/30/20 at 06:17pm, James Morse wrote:
> Hi Baoquan,
>
> On 3/30/20 2:55 PM, Baoquan He wrote:
> > On 03/26/20 at 06:07pm, James Morse wrote:
> >> arm64 recently queued support for memory hotremove, which led to some
> >> new corner cases for kexec.
> >>
> >> If the kexec segments are loaded for a removable region, that region may
> >> be removed before kexec actually occurs. This causes the first kernel to
> >> lockup when applying the relocations. (I've triggered this on x86 too).
> >>
> >> The first patch adds a memory notifier for kexec so that it can refuse
> >> to allow in-use regions to be taken offline.
> >
> > I talked about this with Dave Young. Currently, we tend to use
> > kexec_file_load more in the future since most of its implementation is
> > in kernel, we can get information about kernel more easilier. For the
> > kexec kernel loaded into hotpluggable area, we can fix it in
> > kexec_file_load side, we know the MOVABLE zone's start and end. As for
> > the old kexec_load, we would like to keep it for back compatibility. At
> > least in our distros, we have switched to kexec_file_load, will
> > gradually obsolete kexec_load.
>
> > So for this one, I suggest avoiding those
> > MOVZBLE memory region when searching place for kexec kernel.
>
> How does today's user-space know?
>
>
> > Not sure if arm64 will still have difficulty.
>
> arm64 added support for kexec_load first, then kexec_file_load. (evidently a
> mistake).
> kexec_file_load support was only added in the last year or so, I'd hazard most
> people using this, are using the regular load kind. (and probably don't know or
> care).
I agreed that file load is still not widely used, but in the long run
we should not maintain both of them all the future time. Especially
when some kernel-userspace interfaces need to be introduced, file load
will have the natural advantage. We may keep the kexec_load for other
misc usecases, but we can use file load for the major modern
linux-to-linux loading. I'm not saying we can do it immediately, just
thought we should reduce the duplicate effort and try to avoid hacking if
possible.
Anyway about this particular issue, I wonder if we can just reload with
a udev rule as replied in another mail.
Thanks
Dave
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next prev parent reply other threads:[~2020-03-31 3:46 UTC|newest]
Thread overview: 92+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-26 18:07 [PATCH 0/3] kexec/memory_hotplug: Prevent removal and accidental use James Morse
2020-03-26 18:07 ` [PATCH 1/3] kexec: Prevent removal of memory in use by a loaded kexec image James Morse
2020-03-27 0:43 ` Anshuman Khandual
2020-03-27 2:54 ` Baoquan He
2020-03-27 15:46 ` James Morse
2020-03-27 2:34 ` Baoquan He
2020-03-27 9:30 ` David Hildenbrand
2020-03-27 16:56 ` James Morse
2020-03-27 17:06 ` David Hildenbrand
2020-03-27 18:07 ` James Morse
2020-03-27 18:52 ` David Hildenbrand
2020-03-30 13:00 ` James Morse
2020-03-30 13:13 ` David Hildenbrand
2020-03-30 17:17 ` James Morse
2020-03-30 18:14 ` David Hildenbrand
2020-04-10 19:10 ` Andrew Morton
2020-04-11 3:44 ` Baoquan He
2020-04-11 9:30 ` Russell King - ARM Linux admin
2020-04-11 9:58 ` David Hildenbrand
2020-04-12 5:35 ` Baoquan He
2020-04-12 8:08 ` Russell King - ARM Linux admin
2020-04-12 19:52 ` Eric W. Biederman
2020-04-12 20:37 ` Bhupesh SHARMA
2020-04-13 2:37 ` Baoquan He
2020-04-13 13:15 ` Eric W. Biederman
2020-04-13 23:01 ` Andrew Morton
2020-04-14 6:13 ` Eric W. Biederman
2020-04-14 6:40 ` Baoquan He
2020-04-14 6:51 ` Baoquan He
2020-04-14 8:00 ` David Hildenbrand
2020-04-14 9:22 ` Baoquan He
2020-04-14 9:37 ` David Hildenbrand
2020-04-14 14:39 ` Baoquan He
2020-04-14 14:49 ` David Hildenbrand
2020-04-15 2:35 ` Baoquan He
2020-04-16 13:31 ` David Hildenbrand
2020-04-16 14:02 ` Baoquan He
2020-04-16 14:09 ` David Hildenbrand
2020-04-16 14:36 ` Baoquan He
2020-04-16 14:47 ` David Hildenbrand
2020-04-21 13:29 ` David Hildenbrand
2020-04-21 13:57 ` David Hildenbrand
2020-04-21 13:59 ` Eric W. Biederman
2020-04-21 14:30 ` David Hildenbrand
2020-04-22 9:17 ` Baoquan He
2020-04-22 9:24 ` David Hildenbrand
2020-04-22 9:57 ` Baoquan He
2020-04-22 10:05 ` David Hildenbrand
2020-04-22 10:36 ` Baoquan He
2020-04-14 9:16 ` Dave Young
2020-04-14 9:38 ` Dave Young
2020-04-14 7:05 ` David Hildenbrand
2020-04-14 16:55 ` James Morse
2020-04-14 17:41 ` David Hildenbrand
2020-04-15 20:33 ` Eric W. Biederman
2020-04-22 12:28 ` James Morse
2020-04-22 15:25 ` Eric W. Biederman
2020-04-22 16:40 ` David Hildenbrand
2020-04-23 16:29 ` Eric W. Biederman
2020-04-24 7:39 ` David Hildenbrand
2020-04-24 7:41 ` David Hildenbrand
2020-05-01 16:55 ` James Morse
2020-03-26 18:07 ` [PATCH 2/3] mm/memory_hotplug: Allow arch override of non boot memory resource names James Morse
2020-03-27 9:59 ` David Hildenbrand
2020-03-27 15:39 ` James Morse
2020-03-30 13:23 ` David Hildenbrand
2020-03-30 17:17 ` James Morse
2020-04-02 5:49 ` Dave Young
2020-04-02 6:12 ` piliu
2020-04-14 17:21 ` James Morse
2020-04-15 20:36 ` Eric W. Biederman
2020-04-22 12:14 ` James Morse
2020-05-09 0:45 ` Andrew Morton
2020-05-11 8:35 ` David Hildenbrand
2020-03-26 18:07 ` [PATCH 3/3] arm64: memory: Give hotplug memory a different resource name James Morse
2020-03-30 19:01 ` David Hildenbrand
2020-04-15 20:37 ` Eric W. Biederman
2020-04-22 12:14 ` James Morse
2020-03-27 2:11 ` [PATCH 0/3] kexec/memory_hotplug: Prevent removal and accidental use Baoquan He
2020-03-27 15:40 ` James Morse
2020-03-27 9:27 ` David Hildenbrand
2020-03-27 15:42 ` James Morse
2020-03-30 13:18 ` David Hildenbrand
2020-03-30 13:55 ` Baoquan He
2020-03-30 17:17 ` James Morse
2020-03-31 3:46 ` Dave Young [this message]
2020-04-14 17:31 ` James Morse
2020-03-31 3:38 ` Dave Young
2020-04-15 20:29 ` Eric W. Biederman
2020-04-22 12:14 ` James Morse
2020-04-22 13:04 ` Eric W. Biederman
2020-04-22 15:40 ` James Morse
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