kernel/linux.git/include/linux/pageblock-flags.h, branch v6.6.132

minmax: avoid overly complicated constant expressions in VM code

2025-09-25T09:00:10+00:00

[ Upstream commit 3a7e02c040b130b5545e4b115aada7bacd80a2b6 ] The minmax infrastructure is overkill for simple constants, and can cause huge expansions because those simple constants are then used by other things. For example, 'pageblock_order' is a core VM constant, but because it was implemented using 'min_t()' and all the type-checking that involves, it actually expanded to something like 2.5kB of preprocessor noise. And when that simple constant was then used inside other expansions: #define pageblock_nr_pages (1UL << pageblock_order) #define pageblock_start_pfn(pfn) ALIGN_DOWN((pfn), pageblock_nr_pages) and we then use that inside a 'max()' macro: case ISOLATE_SUCCESS: update_cached = false; last_migrated_pfn = max(cc->zone->zone_start_pfn, pageblock_start_pfn(cc->migrate_pfn - 1)); the end result was that one statement expanding to 253kB in size. There are probably other cases of this, but this one case certainly stood out. I've added 'MIN_T()' and 'MAX_T()' macros for this kind of "core simple constant with specific type" use. These macros skip the type checking, and as such need to be very sparingly used only for obvious cases that have active issues like this. Reported-by: Lorenzo Stoakes Link: https://lore.kernel.org/all/36aa2cad-1db1-4abf-8dd2-fb20484aabc3@lucifer.local/ Cc: David Laight Signed-off-by: Linus Torvalds Signed-off-by: Eliav Farber Signed-off-by: Greg Kroah-Hartman

mm, treewide: redefine MAX_ORDER sanely

2023-04-06T02:42:46+00:00

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: add pageblock_aligned() macro

2022-10-03T21:03:04+00:00

Add pageblock_aligned() and use it to simplify code. Link: https://lkml.kernel.org/r/20220907060844.126891-3-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang Acked-by: Mike Rapoport Cc: David Hildenbrand Cc: Oscar Salvador Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm: add pageblock_align() macro

2022-10-03T21:03:04+00:00

Add pageblock_align() macro and use it to simplify code. Link: https://lkml.kernel.org/r/20220907060844.126891-2-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang Acked-by: Mike Rapoport Reviewed-by: David Hildenbrand Cc: Oscar Salvador Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm: reuse pageblock_start/end_pfn() macro

2022-10-03T21:03:03+00:00

Move pageblock_start_pfn/pageblock_end_pfn() into pageblock-flags.h, then they could be used somewhere else, not only in compaction, also use ALIGN_DOWN() instead of round_down() to be pair with ALIGN(), which should be same for pageblock usage. Link: https://lkml.kernel.org/r/20220907060844.126891-1-wangkefeng.wang@huawei.com Signed-off-by: Kefeng Wang Acked-by: Mike Rapoport Reviewed-by: David Hildenbrand Cc: Oscar Salvador Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm: enforce pageblock_order < MAX_ORDER

2022-03-22T22:57:06+00:00

Some places in the kernel don't really expect pageblock_order >= MAX_ORDER, and it looks like this is only possible in corner cases: 1) CONFIG_DEFERRED_STRUCT_PAGE_INIT we'll end up freeing pageblock_order pages via __free_pages_core(), which cannot possibly work. 2) find_zone_movable_pfns_for_nodes() will roundup the ZONE_MOVABLE start PFN to MAX_ORDER_NR_PAGES. Consequently with a bigger pageblock_order, we could have a single pageblock partially managed by two zones. 3) compaction code runs into __fragmentation_index() with order >= MAX_ORDER, when checking WARN_ON_ONCE(order >= MAX_ORDER). [1] 4) mm/page_reporting.c won't be reporting any pages with default page_reporting_order == pageblock_order, as we'll be skipping the reporting loop inside page_reporting_process_zone(). 5) __rmqueue_fallback() will never be able to steal with ALLOC_NOFRAGMENT. pageblock_order >= MAX_ORDER is weird either way: it's a pure optimization for making alloc_contig_range(), as used for allcoation of gigantic pages, a little more reliable to succeed. However, if there is demand for somewhat reliable allocation of gigantic pages, affected setups should be using CMA or boottime allocations instead. So let's make sure that pageblock_order < MAX_ORDER and simplify. [1] https://lkml.kernel.org/r/87r189a2ks.fsf@linux.ibm.com Link: https://lkml.kernel.org/r/20220214174132.219303-3-david@redhat.com Signed-off-by: David Hildenbrand Reviewed-by: Zi Yan Cc: Aneesh Kumar K.V Cc: Benjamin Herrenschmidt Cc: Christoph Hellwig Cc: Frank Rowand Cc: John Garry via iommu Cc: Marek Szyprowski Cc: Michael Ellerman Cc: Michael S. Tsirkin Cc: Minchan Kim Cc: Paul Mackerras Cc: Rob Herring Cc: Robin Murphy Cc: Vlastimil Babka Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: constify get_pfnblock_flags_mask and get_pfnblock_migratetype

2021-06-29T17:53:53+00:00

The struct page is not modified by these routines, so it can be marked const. Link: https://lkml.kernel.org/r/20210416231531.2521383-6-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Vlastimil Babka Reviewed-by: Anshuman Khandual Reviewed-by: William Kucharski Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/page_alloc.c: remove unnecessary end_bitidx for [set|get]_pfnblock_flags_mask()

2020-08-07T18:33:29+00:00

After previous cleanup, the end_bitidx is not necessary any more. Signed-off-by: Wei Yang Signed-off-by: Andrew Morton Cc: Mel Gorman Link: http://lkml.kernel.org/r/20200623124201.8199-4-richard.weiyang@linux.alibaba.com Signed-off-by: Linus Torvalds

mm/page_alloc.c: simplify pageblock bitmap access

2020-08-07T18:33:29+00:00

Due to commit e58469bafd05 ("mm: page_alloc: use word-based accesses for get/set pageblock bitmaps"), pageblock bitmap is accessed with word-based access. This operation could be simplified a little. Intuitively, if we want to get a bit range [start_idx, end_idx] in a word, we can do like this: mask = (1 << (end_bitidx - start_bitidx + 1)) - 1; ret = (word >> start_idx) & mask; And also if we want to set a bit range [start_idx, end_idx] with flags, we can do the same by just shift start_bitidx. By doing so we reduce some instructions for these two helper functions: Before Patched set_pfnblock_flags_mask 209 198(-5%) get_pfnblock_flags_mask 101 87(-13%) Since the syntax is changed a little, we need to check the whole 4-bit migrate_type instead of part of it. Signed-off-by: Wei Yang Signed-off-by: Andrew Morton Cc: Mel Gorman Link: http://lkml.kernel.org/r/20200623124201.8199-3-richard.weiyang@linux.alibaba.com Signed-off-by: Linus Torvalds

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 167

2019-05-30T18:26:39+00:00

Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation version 2 of the license this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details you should have received a copy of the gnu general public license along with this program if not write to the free software foundation inc 59 temple place suite 330 boston ma 02111 1307 usa extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 83 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Richard Fontana Reviewed-by: Kate Stewart Reviewed-by: Allison Randal Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070034.021731668@linutronix.de Signed-off-by: Greg Kroah-Hartman