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From: Tianyu Lan <>
To: Dave Hansen <>,
	"" <>,
	"" <>,
	"" <>,
	"" <>,
	"" <>,
	"" <>,
	"" <>,
	"" <>,
	"" <>,
	"" <>,
	"" <>,
	Michael Kelley <>,
	KY Srinivasan <>,
	"" <>
Cc: "" <>,
	vkuznets <>,
	"" <>
Subject: RE: [PATCH] mm/resource: Move child to new resource when release mem region.
Date: Fri, 11 Oct 2019 14:53:06 +0000
Message-ID: <KL1P15301MB0261260E5DD0E3BA4FD80BC092970@KL1P15301MB0261.APCP153.PROD.OUTLOOK.COM> (raw)
In-Reply-To: <>

On 10/10/2019 10:29 PM, Dave Hansen wrote:> On 10/10/19 12:28 AM, wrote:
>> When release mem region, old mem region may be splited to
>> two regions. Current allocate new struct resource for high
>> end mem region but not move child resources whose ranges are
>> in the high end range to new resource. When adjust old mem
>> region's range, adjust_resource() detects child region's range
>> is out of new range and return error. Move child resources to
>> high end resource before adjusting old mem range.
>  From the comment, it appears the old code intended to have the behavior
> that you are changing.  Could you explain _why_ this has become a
> problem for you?
Hi Dave:
    Thanks for your review. current code assumes that all children remain in
 the lower address entry for simplicity. For memory hot-remove, selecting
remove region via scanning system memory may hit case of child in the
higher address entry.

For example, the following output from /proc/iomem shows kernel code,
data and bss locate from 3a000000 to 3b5fffff and these resources are the
system ram resource's children. If the 39800000-39ffffff was selected as
remove range, the resource will be split into two ranges 00100000-397fffff
and 39800000-b87f1fff. Current code move kernel image related resources
under 00100000-397fffff resource. This will cause adjust_resource() return
error because children are not in the parent's range.

00100000-b87f1fff : System RAM
  3a000000-3ac00e80 : Kernel code
  3ac00e81-3b33883f : Kernel data
  3b4d3000-3b5fffff : Kernel bss

      reply index

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-10  7:28 lantianyu1986
2019-10-10 14:29 ` Dave Hansen
2019-10-11 14:53   ` Tianyu Lan [this message]

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