On Wed 22-05-13 12:49:37, Michal Hocko wrote: > On Wed 22-05-13 17:29:27, Wanpeng Li wrote: > > Logic memory-remove code fails to correctly account the Total High Memory > > when a memory block which contains High Memory is offlined as shown in the > > example below. The following patch fixes it. > > > > cat /proc/meminfo > > MemTotal: 7079452 kB > > MemFree: 5805976 kB > > Buffers: 94372 kB > > Cached: 872000 kB > > SwapCached: 0 kB > > Active: 626936 kB > > Inactive: 519236 kB > > Active(anon): 180780 kB > > Inactive(anon): 222944 kB > > Active(file): 446156 kB > > Inactive(file): 296292 kB > > Unevictable: 0 kB > > Mlocked: 0 kB > > HighTotal: 7294672 kB > > HighFree: 5181024 kB > > LowTotal: 4294752076 kB > > LowFree: 624952 kB > > Ok, so the HighTotal is higher than MemTotal but it would have been more > straightforward to show number of HighTotal before hotremove, show how > much memory has been removed and the number after. > > It is not clear which stable kernels need this fix as well. > > > > > Signed-off-by: Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx> > > Anyway > Reviewed-by: Michal Hocko <mhocko@xxxxxxx> > > with a nit pick bellow > > > --- > > mm/page_alloc.c | 4 ++++ > > 1 file changed, 4 insertions(+) > > > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index 98cbdf6..80474b2 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -6140,6 +6140,10 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn) > > list_del(&page->lru); > > rmv_page_order(page); > > zone->free_area[order].nr_free--; > > +#ifdef CONFIG_HIGHMEM > > + if (PageHighMem(page)) > > + totalhigh_pages -= 1 << order; > > +#endif Hmm, it seems that my old gcc (4.3.4) doesn't like this. mm/page_alloc.c:6202: error: lvalue required as left operand of assignment I am not sure this is a compiler bug because PAGEFLAG_FALSE is clearly returning 0 which should make the whole if a no-op... But maybe we shouldn't be more clever than compiler. Andrew, could you fold this follow up fix for mm-memory-hotplug-fix-lowmem-count-overflow-when-offline-pages.patch Sorr about the confusion I brought to this. --- diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 717286e..c164e5f 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -6198,8 +6198,10 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn) list_del(&page->lru); rmv_page_order(page); zone->free_area[order].nr_free--; +#ifdef CONFIG_HIGHMEM if (PageHighMem(page)) totalhigh_pages -= 1 << order; +#endif for (i = 0; i < (1 << order); i++) SetPageReserved((page+i)); pfn += (1 << order); -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>