linux-kernel - Re: [PATCH stable 5.10 1/1] mm/memory_hotplug: extend offline_and_remove_memory() to handle more than one memory block

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Date:   Mon, 19 Jun 2023 14:54:21 +0800
From:   mawupeng <mawupeng1@...wei.com>
To:     <gregkh@...uxfoundation.org>
CC:     <mawupeng1@...wei.com>, <akpm@...ux-foundation.org>,
        <david@...hat.com>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>, <stable@...r.kernel.org>,
        <richard.weiyang@...ux.alibaba.com>, <mst@...hat.com>,
        <jasowang@...hat.com>, <pankaj.gupta.linux@...il.com>,
        <mhocko@...nel.org>, <osalvador@...e.de>
Subject: Re: [PATCH stable 5.10 1/1] mm/memory_hotplug: extend
 offline_and_remove_memory() to handle more than one memory block



On 2023/6/19 14:20, Greg KH wrote:
> On Wed, Jun 14, 2023 at 02:45:58PM +0800, mawupeng wrote:
>>
>>
>> On 2023/6/14 14:35, Greg KH wrote:
>>> On Wed, Jun 14, 2023 at 02:19:00PM +0800, Wupeng Ma wrote:
>>>> From: David Hildenbrand <david@...hat.com>
>>>>
>>>> virtio-mem soon wants to use offline_and_remove_memory() memory that
>>>> exceeds a single Linux memory block (memory_block_size_bytes()). Let's
>>>> remove that restriction.
>>>>
>>>> Let's remember the old state and try to restore that if anything goes
>>>> wrong. While re-onlining can, in general, fail, it's highly unlikely to
>>>> happen (usually only when a notifier fails to allocate memory, and these
>>>> are rather rare).
>>>>
>>>> This will be used by virtio-mem to offline+remove memory ranges that are
>>>> bigger than a single memory block - for example, with a device block
>>>> size of 1 GiB (e.g., gigantic pages in the hypervisor) and a Linux memory
>>>> block size of 128MB.
>>>>
>>>> While we could compress the state into 2 bit, using 8 bit is much
>>>> easier.
>>>>
>>>> This handling is similar, but different to acpi_scan_try_to_offline():
>>>>
>>>> a) We don't try to offline twice. I am not sure if this CONFIG_MEMCG
>>>> optimization is still relevant - it should only apply to ZONE_NORMAL
>>>> (where we have no guarantees). If relevant, we can always add it.
>>>>
>>>> b) acpi_scan_try_to_offline() simply onlines all memory in case
>>>> something goes wrong. It doesn't restore previous online type. Let's do
>>>> that, so we won't overwrite what e.g., user space configured.
>>>>
>>>> Reviewed-by: Wei Yang <richard.weiyang@...ux.alibaba.com>
>>>> Cc: "Michael S. Tsirkin" <mst@...hat.com>
>>>> Cc: Jason Wang <jasowang@...hat.com>
>>>> Cc: Pankaj Gupta <pankaj.gupta.linux@...il.com>
>>>> Cc: Michal Hocko <mhocko@...nel.org>
>>>> Cc: Oscar Salvador <osalvador@...e.de>
>>>> Cc: Wei Yang <richard.weiyang@...ux.alibaba.com>
>>>> Cc: Andrew Morton <akpm@...ux-foundation.org>
>>>> Signed-off-by: David Hildenbrand <david@...hat.com>
>>>> Link: https://lore.kernel.org/r/20201112133815.13332-28-david@redhat.com
>>>> Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
>>>> Acked-by: Andrew Morton <akpm@...ux-foundation.org>
>>>> ---
>>>>  mm/memory_hotplug.c | 105 +++++++++++++++++++++++++++++++++++++-------
>>>>  1 file changed, 89 insertions(+), 16 deletions(-)
>>>
>>> As you forwarded this patch on, you too need to sign-off on it.
>>
>> Thanks for reminding me.
>>
>> Signed-off-by: Ma Wupeng <mawupeng1@...wei.com>
>>
>>>
>>> Also, what is the git id of the commit in Linus's tree?
>>
>> Sorry, here is the commit in Linus's tree.
>>
>> commit 8dc4bb58a146655eb057247d7c9d19e73928715b upstream.
> 
> Please resend the change with both of these things fixed up, so I don't
> have to manually do it :)

I have resend the patch but use the parent message id for in-reply-to.

Sorry.

> 
> thanks,
> 
> greg k-h