From: David Hildenbrand <david@redhat.com>
To: James Morse <james.morse@arm.com>,
kexec@lists.infradead.org, linux-mm@kvack.org,
linux-arm-kernel@lists.infradead.org
Cc: Anshuman Khandual <anshuman.khandual@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Bhupesh Sharma <bhsharma@redhat.com>,
Eric Biederman <ebiederm@xmission.com>,
Andrew Morton <akpm@linux-foundation.org>,
Will Deacon <will@kernel.org>
Subject: Re: [PATCH 3/3] arm64: memory: Give hotplug memory a different resource name
Date: Mon, 30 Mar 2020 21:01:01 +0200 [thread overview]
Message-ID: <25e2f1ea-412a-f03e-7544-1b217fdc8160@redhat.com> (raw)
In-Reply-To: <20200326180730.4754-4-james.morse@arm.com>
On 26.03.20 19:07, James Morse wrote:
> If kexec chooses to place the kernel in a memory region that was
> added after boot, we fail to boot as the kernel is running from a
> location that is not described as memory by the UEFI memory map or
> the original DT.
>
> To prevent unaware user-space kexec from doing this accidentally,
> give these regions a different name.
>
> Signed-off-by: James Morse <james.morse@arm.com>
> ---
> This is a change in behaviour as seen by user-space, because memory hot-add
> has already been merged.
>
> arch/arm64/include/asm/memory.h | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
> index 2be67b232499..ef1686518469 100644
> --- a/arch/arm64/include/asm/memory.h
> +++ b/arch/arm64/include/asm/memory.h
> @@ -166,6 +166,17 @@
> #define IOREMAP_MAX_ORDER (PMD_SHIFT)
> #endif
>
> +/*
> + * Memory hotplug allows new regions of 'System RAM' to be added to the system.
> + * These aren't described as memory by the UEFI memory map, or DT memory node.
> + * If we kexec from one of these regions, the new kernel boots from a location
> + * that isn't described as RAM.
> + *
> + * Give these resources a different name, so unaware kexec doesn't do this by
> + * accident.
> + */
> +#define MEMORY_HOTPLUG_RES_NAME "System RAM (hotplug)"
> +
> #ifndef __ASSEMBLY__
> extern u64 vabits_actual;
> #define PAGE_END (_PAGE_END(vabits_actual))
>
(While I am familiar with makedumpfile in the crash kernel, I am not yet
familiar with kexec, so bare with me)
Looking at kexec:arch/arm64/crashdump-arm64.c
load_crashdump_segments() -> crash_get_memory_ranges() ->
kexec_iomem_for_each_line() -> iomem_range_callback()
#define SYSTEM_RAM "System RAM\n"
...
} else if (strncmp(str, SYSTEM_RAM, strlen(SYSTEM_RAM)) == 0) {
return mem_regions_add(&system_memory_rgns, ...);
}
The hotplugged memory will no longer be detected as a crashdump segment,
consequently (AFAIU) not be described in the elf header, and therefore
also no longer dumped (e.g., by makedumpfile).
I assume you'll have to adapt kexec-tools to still consider this memory
for dumping, correct? Or am I missing something?
--
Thanks,
David / dhildenb
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-03-30 19:01 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 [this message]
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
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=25e2f1ea-412a-f03e-7544-1b217fdc8160@redhat.com \
--to=david@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=anshuman.khandual@arm.com \
--cc=bhsharma@redhat.com \
--cc=catalin.marinas@arm.com \
--cc=ebiederm@xmission.com \
--cc=james.morse@arm.com \
--cc=kexec@lists.infradead.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-mm@kvack.org \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).