Linux-mm Archive on lore.kernel.org
 help / color / Atom feed
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: Eric Biederman <ebiederm@xmission.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	Bhupesh Sharma <bhsharma@redhat.com>
Subject: Re: [PATCH 2/3] mm/memory_hotplug: Allow arch override of non boot memory resource names
Date: Fri, 27 Mar 2020 10:59:47 +0100
Message-ID: <52d6fd33-c15d-b842-84ed-b4a74265199f@redhat.com> (raw)
In-Reply-To: <20200326180730.4754-3-james.morse@arm.com>

On 26.03.20 19:07, James Morse wrote:
> Memory added to the system by hotplug has a 'System RAM' resource created
> for it. This is exposed to user-space via /proc/iomem.
> 
> This poses problems for kexec on arm64. If kexec decides to place the
> kernel in one of these newly onlined regions, the new kernel will find
> itself booting from a region not described as memory in the firmware
> tables.
> 
> Arm64 doesn't have a structure like the e820 memory map that can be
> re-written when memory is brought online. Instead arm64 uses the UEFI
> memory map, or the memory node from the DT, sometimes both. We never
> rewrite these.
> 
> Allow an architecture to specify a different name for these hotplug
> regions.
> 
> Signed-off-by: James Morse <james.morse@arm.com>
> ---
>  mm/memory_hotplug.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 0a54ffac8c68..69b03dd7fc74 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -42,6 +42,10 @@
>  #include "internal.h"
>  #include "shuffle.h"
>  
> +#ifndef MEMORY_HOTPLUG_RES_NAME
> +#define MEMORY_HOTPLUG_RES_NAME "System RAM"
> +#endif

So I assume changing this for all architectures would result in some
user space tool breaking? Are we aware of any?

I do wonder if we should simply change it for all architectures if possible.


> +
>  /*
>   * online_page_callback contains pointer to current page onlining function.
>   * Initially it is generic_online_page(). If it is required it could be
> @@ -103,7 +107,7 @@ static struct resource *register_memory_resource(u64 start, u64 size)
>  {
>  	struct resource *res;
>  	unsigned long flags =  IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
> -	char *resource_name = "System RAM";
> +	char *resource_name = MEMORY_HOTPLUG_RES_NAME;
>  
>  	if (start + size > max_mem_size)
>  		return ERR_PTR(-E2BIG);
> 


-- 
Thanks,

David / dhildenb



  reply index

Thread overview: 33+ 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
2020-03-26 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 [this message]
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
2020-03-26 18:07 ` [PATCH 3/3] arm64: memory: Give hotplug memory a different resource name James Morse
2020-03-30 19:01   ` David Hildenbrand
2020-03-27  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
2020-03-31  3:38 ` Dave Young

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=52d6fd33-c15d-b842-84ed-b4a74265199f@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

Linux-mm Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-mm/0 linux-mm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-mm linux-mm/ https://lore.kernel.org/linux-mm \
		linux-mm@kvack.org
	public-inbox-index linux-mm

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kvack.linux-mm


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git