Messages in this thread | | | Date | Fri, 15 Sep 2017 11:36:56 +0200 | From | Michal Hocko <> | Subject | Re: [PATCH] mm/memory_hotplug: fix wrong casting for __remove_section() |
| |
On Thu 14-09-17 11:43:10, YASUAKI ISHIMATSU wrote: > 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?
You are not wrong. We are talking about the same thing AFAICS. I was just less precise...
-- Michal Hocko SUSE Labs
| |