At 11/19/2012 04:45 PM, Bob Liu Wrote: > zone->present_pages shoule be: > spanned pages - absent pages - bootmem pages(including memmap pages), > but now it's: > spanned pages - absent pages - memmap pages. > And it didn't consider whether the memmap pages is actully allocated from the > zone or not which may cause problem when memory hotplug is improved recently. > > For example: > numa node 1 has ZONE_NORMAL and ZONE_MOVABLE, it's memmap and other bootmem > allocated from ZONE_MOVABLE. > So ZONE_NORMAL's present_pages should be spanned pages - absent pages, but now > it also minus memmap pages, which are actually allocated from ZONE_MOVABLE. > This is wrong and when offlining all memory of this zone: > (zone->present_pages -= offline_pages) will less than 0. > Since present_pages is unsigned long type, that is actually a very large > integer which will cause zone->watermark[WMARK_MIN] becomes a large > integer too(see setup_per_zone_wmarks()). > As a result, totalreserve_pages become a large integer also and finally memory > allocating will fail in __vm_enough_memory(). > > Related discuss: > http://lkml.org/lkml/2012/11/5/866 > https://patchwork.kernel.org/patch/1346751/ > > Related patches in mmotm: > mm: fix-up zone present pages(7f1290f2f2a4d2c) (sometimes cause egression) > mm: fix a regression with HIGHMEM(fe2cebd5a259eec) (Andrew have some feedback) > > Jiang Liu have sent a series patches to fix this issue by adding a > managed_pages area to zone struct: > [RFT PATCH v1 0/5] fix up inaccurate zone->present_pages > > But i think it's too complicated. > Mine is based on the two related patches already in mmotm(need to revert them > first) > It fix the calculation of zone->present_pages by: > 1. Reset the zone->present_pages to zero before > free_all_bootmem(),free_all_bootmem_node() and free_low_memory_core_early(). > I think these should already included all path in all arch. > > 2. If there is a page freed to buddy system in __free_pages_bootmem(), > add zone->present_pages accrodingly. > > Note this patch assumes that bootmem won't use memory above ZONE_HIGHMEM, so Hmm, on x86_64 box, bootmem uses the memory in ZONE_MOVABLE and ZONE_MOVABLE > ZONE_HIGHMEM. > only zones below ZONE_HIGHMEM are reset/fixed. If not, some update is needed. > For ZONE_HIGHMEM, only fix it's init value to: > panned_pages - absent_pages in free_area_init_core(). > > Only did some simple test currently. > > Signed-off-by: Jianguo Wu <wujianguo@xxxxxxxxxx> > Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxx> > Signed-off-by: Bob Liu <lliubbo@xxxxxxxxx> > --- > include/linux/mm.h | 3 +++ > mm/bootmem.c | 2 ++ > mm/nobootmem.c | 1 + > mm/page_alloc.c | 49 +++++++++++++++++++++++++++++++++++++------------ > 4 files changed, 43 insertions(+), 12 deletions(-) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 7b03cab..3b40eb6 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -1763,5 +1763,8 @@ static inline unsigned int debug_guardpage_minorder(void) { return 0; } > static inline bool page_is_guard(struct page *page) { return false; } > #endif /* CONFIG_DEBUG_PAGEALLOC */ > > +extern void reset_lowmem_zone_present_pages_pernode(pg_data_t *pgdat); > +extern void reset_lowmem_zone_present_pages(void); > + > #endif /* __KERNEL__ */ > #endif /* _LINUX_MM_H */ > diff --git a/mm/bootmem.c b/mm/bootmem.c > index 26d057a..661775b 100644 > --- a/mm/bootmem.c > +++ b/mm/bootmem.c > @@ -238,6 +238,7 @@ static unsigned long __init free_all_bootmem_core(bootmem_data_t *bdata) > unsigned long __init free_all_bootmem_node(pg_data_t *pgdat) > { > register_page_bootmem_info_node(pgdat); > + reset_lowmem_zone_present_pages_pernode(pgdat); > return free_all_bootmem_core(pgdat->bdata); > } > > @@ -251,6 +252,7 @@ unsigned long __init free_all_bootmem(void) > unsigned long total_pages = 0; > bootmem_data_t *bdata; > > + reset_lowmem_zone_present_pages(); > list_for_each_entry(bdata, &bdata_list, list) > total_pages += free_all_bootmem_core(bdata); > > diff --git a/mm/nobootmem.c b/mm/nobootmem.c > index bd82f6b..378d50a 100644 > --- a/mm/nobootmem.c > +++ b/mm/nobootmem.c > @@ -126,6 +126,7 @@ unsigned long __init free_low_memory_core_early(int nodeid) > phys_addr_t start, end, size; > u64 i; > > + reset_lowmem_zone_present_pages(); > for_each_free_mem_range(i, MAX_NUMNODES, &start, &end, NULL) > count += __free_memory_core(start, end); > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 07425a7..76d37f0 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -735,6 +735,7 @@ void __meminit __free_pages_bootmem(struct page *page, unsigned int order) > { > unsigned int nr_pages = 1 << order; > unsigned int loop; > + struct zone *zone; > > prefetchw(page); > for (loop = 0; loop < nr_pages; loop++) { > @@ -748,6 +749,9 @@ void __meminit __free_pages_bootmem(struct page *page, unsigned int order) > > set_page_refcounted(page); > __free_pages(page, order); > + zone = page_zone(page); > + WARN_ON(!(is_normal(zone) || is_dma(zone) || is_dma32(zone))); > + zone->present_pages += nr_pages; > } > > #ifdef CONFIG_CMA > @@ -4547,18 +4551,20 @@ static void __paginginit free_area_init_core(struct pglist_data *pgdat, > * is used by this zone for memmap. This affects the watermark > * and per-cpu initialisations > */ > - memmap_pages = > - PAGE_ALIGN(size * sizeof(struct page)) >> PAGE_SHIFT; > - if (realsize >= memmap_pages) { > - realsize -= memmap_pages; > - if (memmap_pages) > - printk(KERN_DEBUG > - " %s zone: %lu pages used for memmap\n", > - zone_names[j], memmap_pages); > - } else > - printk(KERN_WARNING > - " %s zone: %lu pages exceeds realsize %lu\n", > - zone_names[j], memmap_pages, realsize); > + if (j < ZONE_HIGHMEM) { > + memmap_pages = > + PAGE_ALIGN(size * sizeof(struct page)) >> PAGE_SHIFT; > + if (realsize >= memmap_pages) { > + realsize -= memmap_pages; > + if (memmap_pages) > + printk(KERN_DEBUG > + " %s zone: %lu pages used for memmap\n", > + zone_names[j], memmap_pages); > + } else > + printk(KERN_WARNING > + " %s zone: %lu pages exceeds realsize %lu\n", > + zone_names[j], memmap_pages, realsize); > + } > > /* Account for reserved pages */ > if (j == 0 && realsize > dma_reserve) { > @@ -6143,3 +6149,22 @@ void dump_page(struct page *page) > dump_page_flags(page->flags); > mem_cgroup_print_bad_page(page); > } > + > +/* reset zone->present_pages to 0 for zones below ZONE_HIGHMEM */ > +void reset_lowmem_zone_present_pages_pernode(pg_data_t *pgdat) > +{ > + int i; > + struct zone *z; > + for (i = 0; i < ZONE_HIGHMEM; i++) { And if CONFIG_HIGHMEM is no, ZONE_NORMAL == ZONE_HIGHMEM. So, you don't reset ZONE_NORMAL here. > + z = pgdat->node_zones + i; > + z->present_pages = 0; > + } > +} > + > +void reset_lowmem_zone_present_pages(void) > +{ > + int nid; > + > + for_each_node_state(nid, N_HIGH_MEMORY) > + reset_lowmem_zone_present_pages_pernode(NODE_DATA(nid)); > +} -- 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>