From 23baf831a32c04f9a968812511540b1b3e648bf5 Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Wed, 15 Mar 2023 14:31:33 +0300 Subject: mm, treewide: redefine MAX_ORDER sanely MAX_ORDER currently defined as number of orders page allocator supports: user can ask buddy allocator for page order between 0 and MAX_ORDER-1. This definition is counter-intuitive and lead to number of bugs all over the kernel. Change the definition of MAX_ORDER to be inclusive: the range of orders user can ask from buddy allocator is 0..MAX_ORDER now. [kirill@shutemov.name: fix min() warning] Link: https://lkml.kernel.org/r/20230315153800.32wib3n5rickolvh@box [akpm@linux-foundation.org: fix another min_t warning] [kirill@shutemov.name: fixups per Zi Yan] Link: https://lkml.kernel.org/r/20230316232144.b7ic4cif4kjiabws@box.shutemov.name [akpm@linux-foundation.org: fix underlining in docs] Link: https://lore.kernel.org/oe-kbuild-all/202303191025.VRCTk6mP-lkp@intel.com/ Link: https://lkml.kernel.org/r/20230315113133.11326-11-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov Reviewed-by: Michael Ellerman [powerpc] Cc: "Kirill A. Shutemov" Cc: Zi Yan Signed-off-by: Andrew Morton --- mm/page_alloc.c | 38 +++++++++++++++++++------------------- 1 file changed, 19 insertions(+), 19 deletions(-) (limited to 'mm/page_alloc.c') diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 0936bde1d486..c3e49d028a7a 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1063,7 +1063,7 @@ buddy_merge_likely(unsigned long pfn, unsigned long buddy_pfn, unsigned long higher_page_pfn; struct page *higher_page; - if (order >= MAX_ORDER - 2) + if (order >= MAX_ORDER - 1) return false; higher_page_pfn = buddy_pfn & pfn; @@ -1118,7 +1118,7 @@ static inline void __free_one_page(struct page *page, VM_BUG_ON_PAGE(pfn & ((1 << order) - 1), page); VM_BUG_ON_PAGE(bad_range(zone, page), page); - while (order < MAX_ORDER - 1) { + while (order < MAX_ORDER) { if (compaction_capture(capc, page, order, migratetype)) { __mod_zone_freepage_state(zone, -(1 << order), migratetype); @@ -2499,7 +2499,7 @@ struct page *__rmqueue_smallest(struct zone *zone, unsigned int order, struct page *page; /* Find a page of the appropriate size in the preferred list */ - for (current_order = order; current_order < MAX_ORDER; ++current_order) { + for (current_order = order; current_order <= MAX_ORDER; ++current_order) { area = &(zone->free_area[current_order]); page = get_page_from_free_area(area, migratetype); if (!page) @@ -2871,7 +2871,7 @@ static bool unreserve_highatomic_pageblock(const struct alloc_context *ac, continue; spin_lock_irqsave(&zone->lock, flags); - for (order = 0; order < MAX_ORDER; order++) { + for (order = 0; order <= MAX_ORDER; order++) { struct free_area *area = &(zone->free_area[order]); page = get_page_from_free_area(area, MIGRATE_HIGHATOMIC); @@ -2955,7 +2955,7 @@ __rmqueue_fallback(struct zone *zone, int order, int start_migratetype, * approximates finding the pageblock with the most free pages, which * would be too costly to do exactly. */ - for (current_order = MAX_ORDER - 1; current_order >= min_order; + for (current_order = MAX_ORDER; current_order >= min_order; --current_order) { area = &(zone->free_area[current_order]); fallback_mt = find_suitable_fallback(area, current_order, @@ -2981,7 +2981,7 @@ __rmqueue_fallback(struct zone *zone, int order, int start_migratetype, return false; find_smallest: - for (current_order = order; current_order < MAX_ORDER; + for (current_order = order; current_order <= MAX_ORDER; current_order++) { area = &(zone->free_area[current_order]); fallback_mt = find_suitable_fallback(area, current_order, @@ -2994,7 +2994,7 @@ find_smallest: * This should not happen - we already found a suitable fallback * when looking for the largest page. */ - VM_BUG_ON(current_order == MAX_ORDER); + VM_BUG_ON(current_order > MAX_ORDER); do_steal: page = get_page_from_free_area(area, fallback_mt); @@ -3955,7 +3955,7 @@ bool __zone_watermark_ok(struct zone *z, unsigned int order, unsigned long mark, return true; /* For a high-order request, check at least one suitable page is free */ - for (o = order; o < MAX_ORDER; o++) { + for (o = order; o <= MAX_ORDER; o++) { struct free_area *area = &z->free_area[o]; int mt; @@ -5475,7 +5475,7 @@ struct page *__alloc_pages(gfp_t gfp, unsigned int order, int preferred_nid, * There are several places where we assume that the order value is sane * so bail out early if the request is out of bound. */ - if (WARN_ON_ONCE_GFP(order >= MAX_ORDER, gfp)) + if (WARN_ON_ONCE_GFP(order > MAX_ORDER, gfp)) return NULL; gfp &= gfp_allowed_mask; @@ -6205,8 +6205,8 @@ void __show_free_areas(unsigned int filter, nodemask_t *nodemask, int max_zone_i for_each_populated_zone(zone) { unsigned int order; - unsigned long nr[MAX_ORDER], flags, total = 0; - unsigned char types[MAX_ORDER]; + unsigned long nr[MAX_ORDER + 1], flags, total = 0; + unsigned char types[MAX_ORDER + 1]; if (zone_idx(zone) > max_zone_idx) continue; @@ -6216,7 +6216,7 @@ void __show_free_areas(unsigned int filter, nodemask_t *nodemask, int max_zone_i printk(KERN_CONT "%s: ", zone->name); spin_lock_irqsave(&zone->lock, flags); - for (order = 0; order < MAX_ORDER; order++) { + for (order = 0; order <= MAX_ORDER; order++) { struct free_area *area = &zone->free_area[order]; int type; @@ -6230,7 +6230,7 @@ void __show_free_areas(unsigned int filter, nodemask_t *nodemask, int max_zone_i } } spin_unlock_irqrestore(&zone->lock, flags); - for (order = 0; order < MAX_ORDER; order++) { + for (order = 0; order <= MAX_ORDER; order++) { printk(KERN_CONT "%lu*%lukB ", nr[order], K(1UL) << order); if (nr[order]) @@ -7581,7 +7581,7 @@ static inline void setup_usemap(struct zone *zone) {} /* Initialise the number of pages represented by NR_PAGEBLOCK_BITS */ void __init set_pageblock_order(void) { - unsigned int order = MAX_ORDER - 1; + unsigned int order = MAX_ORDER; /* Check that pageblock_nr_pages has not already been setup */ if (pageblock_order) @@ -9076,7 +9076,7 @@ void *__init alloc_large_system_hash(const char *tablename, else table = memblock_alloc_raw(size, SMP_CACHE_BYTES); - } else if (get_order(size) >= MAX_ORDER || hashdist) { + } else if (get_order(size) > MAX_ORDER || hashdist) { table = vmalloc_huge(size, gfp_flags); virt = true; if (table) @@ -9290,7 +9290,7 @@ int alloc_contig_range(unsigned long start, unsigned long end, order = 0; outer_start = start; while (!PageBuddy(pfn_to_page(outer_start))) { - if (++order >= MAX_ORDER) { + if (++order > MAX_ORDER) { outer_start = start; break; } @@ -9540,7 +9540,7 @@ bool is_free_buddy_page(struct page *page) unsigned long pfn = page_to_pfn(page); unsigned int order; - for (order = 0; order < MAX_ORDER; order++) { + for (order = 0; order <= MAX_ORDER; order++) { struct page *page_head = page - (pfn & ((1 << order) - 1)); if (PageBuddy(page_head) && @@ -9548,7 +9548,7 @@ bool is_free_buddy_page(struct page *page) break; } - return order < MAX_ORDER; + return order <= MAX_ORDER; } EXPORT_SYMBOL(is_free_buddy_page); @@ -9599,7 +9599,7 @@ bool take_page_off_buddy(struct page *page) bool ret = false; spin_lock_irqsave(&zone->lock, flags); - for (order = 0; order < MAX_ORDER; order++) { + for (order = 0; order <= MAX_ORDER; order++) { struct page *page_head = page - (pfn & ((1 << order) - 1)); int page_order = buddy_order(page_head); -- cgit v1.2.3