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Date: Mon, 18 Sep 2017 08:35:38 +0200 From: Michal Hocko <mhocko@...nel.org> To: YASUAKI ISHIMATSU <yasu.isimatu@...il.com> Cc: linux-mm@...ck.org, qiuxishi@...wei.com, arbab@...ux.vnet.ibm.com, vbabka@...e.cz, linux-kernel@...r.kernel.org Subject: Re: [PATCH 1/2] mm/memory_hotplug: Change pfn_to_section_nr/section_nr_to_pfn macro to inline function On Fri 15-09-17 22:52:20, YASUAKI ISHIMATSU wrote: > pfn_to_section_nr() and section_nr_to_pfn() are defined as macro. > pfn_to_section_nr() has no issue even if it is defined as macro. > But section_nr_to_pfn() has overflow issue if sec is defined as int. > > section_nr_to_pfn() just shifts sec by PFN_SECTION_SHIFT. If sec > is defined as unsigned long, section_nr_to_pfn() returns pfn as 64 > bit value. But if sec is defined as int, section_nr_to_pfn() returns > pfn as 32 bit value. > > __remove_section() calculates start_pfn using section_nr_to_pfn() and > scn_nr defined as int. So if hot-removed memory address is over 16TB, > overflow issue occurs and section_nr_to_pfn() does not calculate > correct pfn. > > To make callers use proper arg, the patch changes the macros to > inline functions. > I guess the following is due Fixes: 815121d2b5cd ("memory_hotplug: clear zone when removing the memory") > Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com> Acked-by: Michal Hocko <mhocko@...e.com> Thanks! > --- > include/linux/mmzone.h | 10 ++++++++-- > mm/memory_hotplug.c | 2 +- > 2 files changed, 9 insertions(+), 3 deletions(-) > > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index ef6a13b..6ae12b2 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -1073,8 +1073,14 @@ static inline unsigned long early_pfn_to_nid(unsigned long pfn) > #error Allocator MAX_ORDER exceeds SECTION_SIZE > #endif > > -#define pfn_to_section_nr(pfn) ((pfn) >> PFN_SECTION_SHIFT) > -#define section_nr_to_pfn(sec) ((sec) << PFN_SECTION_SHIFT) > +static inline unsigned long pfn_to_section_nr(unsigned long pfn) > +{ > + return pfn >> PFN_SECTION_SHIFT; > +} > +static inline unsigned long section_nr_to_pfn(unsigned long sec) > +{ > + return sec << PFN_SECTION_SHIFT; > +} > > #define SECTION_ALIGN_UP(pfn) (((pfn) + PAGES_PER_SECTION - 1) & PAGE_SECTION_MASK) > #define SECTION_ALIGN_DOWN(pfn) ((pfn) & PAGE_SECTION_MASK) > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index b63d7d1..38c3c37 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -798,7 +798,7 @@ static int __remove_section(struct zone *zone, struct mem_section *ms, > return ret; > > scn_nr = __section_nr(ms); > - start_pfn = section_nr_to_pfn(scn_nr); > + start_pfn = section_nr_to_pfn((unsigned long)scn_nr); > __remove_zone(zone, start_pfn); > > sparse_remove_one_section(zone, ms, map_offset); > -- > 1.8.3.1 -- Michal Hocko SUSE Labs
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