Messages in this thread | | | Subject | Re: [PATCH] mm/memory_hotplug: fix wrong casting for __remove_section() | From | YASUAKI ISHIMATSU <> | Date | Thu, 14 Sep 2017 11:43:10 -0400 |
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Hi Michal,
On 09/13/2017 01:59 AM, Michal Hocko wrote: > On Tue 12-09-17 13:05:39, YASUAKI ISHIMATSU wrote: >> Hi Michal, >> >> Thanks you for reviewing my patch. >> >> On 09/12/2017 08:49 AM, Michal Hocko wrote: >>> On Fri 08-09-17 16:43:04, YASUAKI ISHIMATSU wrote: >>>> __remove_section() calls __remove_zone() to shrink zone and pgdat. >>>> But due to wrong castings, __remvoe_zone() cannot shrink zone >>>> and pgdat correctly if pfn is over 0xffffffff. >>>> >>>> So the patch fixes the following 3 wrong castings. >>>> >>>> 1. find_smallest_section_pfn() returns 0 or start_pfn which defined >>>> as unsigned long. But the function always returns 32bit value >>>> since the function is defined as int. >>>> >>>> 2. find_biggest_section_pfn() returns 0 or pfn which defined as >>>> unsigned long. the function always returns 32bit value >>>> since the function is defined as int. >>> >>> this is indeed wrong. Pfns over would be really broken 15TB. Not that >>> unrealistic these days >> >> Why 15TB? > > 0xffffffff>>28 >
Even thought I see your explanation, I cannot understand.
In my understanding, find_{smallest|biggest}_section_pfn() return integer. So the functions always return 0x00000000 - 0xffffffff. Therefore if pfn is over 0xffffffff (under 16TB), then the function cannot work correctly.
What am I wrong?
Thanks, Yasuaki Ishimatsu
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