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![Vlastimil Babka](/assets/img/avatar_default.png)
Compaction caches the migration and free scanner positions between
compaction invocations, so that the whole zone gets eventually scanned and
there is no bias towards the initial scanner positions at the
beginning/end of the zone.
The cached positions are continuously updated as scanners progress and the
updating stops as soon as a page is successfully isolated. The reasoning
behind this is that a pageblock where isolation succeeded is likely to
succeed again in near future and it should be worth revisiting it.
However, the downside is that potentially many pages are rescanned without
successful isolation. At worst, there might be a page where isolation
from LRU succeeds but migration fails (potentially always). So upon
encountering this page, cached position would always stop being updated
for no good reason. It might have been useful to let such page be
rescanned with sync compaction after async one failed, but this is now
handled by caching scanner position for async and sync mode separately
since commit 35979ef339
("mm, compaction: add per-zone migration pfn
cache for async compaction").
After this patch, cached positions are updated unconditionally. In
stress-highalloc benchmark, this has decreased the numbers of scanned
pages by few percent, without affecting allocation success rates.
To prevent free scanner from leaving free pages behind after they are
returned due to page migration failure, the cached scanner pfn is changed
to point to the pageblock of the returned free page with the highest pfn,
before leaving compact_zone().
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Christoph Lameter <cl@linux.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
410 lines
13 KiB
C
410 lines
13 KiB
C
/* internal.h: mm/ internal definitions
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*
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* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#ifndef __MM_INTERNAL_H
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#define __MM_INTERNAL_H
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#include <linux/fs.h>
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#include <linux/mm.h>
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void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *start_vma,
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unsigned long floor, unsigned long ceiling);
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static inline void set_page_count(struct page *page, int v)
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{
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atomic_set(&page->_count, v);
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}
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extern int __do_page_cache_readahead(struct address_space *mapping,
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struct file *filp, pgoff_t offset, unsigned long nr_to_read,
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unsigned long lookahead_size);
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/*
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* Submit IO for the read-ahead request in file_ra_state.
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*/
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static inline unsigned long ra_submit(struct file_ra_state *ra,
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struct address_space *mapping, struct file *filp)
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{
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return __do_page_cache_readahead(mapping, filp,
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ra->start, ra->size, ra->async_size);
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}
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/*
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* Turn a non-refcounted page (->_count == 0) into refcounted with
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* a count of one.
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*/
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static inline void set_page_refcounted(struct page *page)
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{
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VM_BUG_ON_PAGE(PageTail(page), page);
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VM_BUG_ON_PAGE(atomic_read(&page->_count), page);
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set_page_count(page, 1);
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}
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static inline void __get_page_tail_foll(struct page *page,
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bool get_page_head)
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{
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/*
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* If we're getting a tail page, the elevated page->_count is
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* required only in the head page and we will elevate the head
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* page->_count and tail page->_mapcount.
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*
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* We elevate page_tail->_mapcount for tail pages to force
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* page_tail->_count to be zero at all times to avoid getting
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* false positives from get_page_unless_zero() with
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* speculative page access (like in
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* page_cache_get_speculative()) on tail pages.
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*/
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VM_BUG_ON_PAGE(atomic_read(&page->first_page->_count) <= 0, page);
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if (get_page_head)
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atomic_inc(&page->first_page->_count);
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get_huge_page_tail(page);
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}
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/*
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* This is meant to be called as the FOLL_GET operation of
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* follow_page() and it must be called while holding the proper PT
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* lock while the pte (or pmd_trans_huge) is still mapping the page.
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*/
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static inline void get_page_foll(struct page *page)
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{
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if (unlikely(PageTail(page)))
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/*
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* This is safe only because
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* __split_huge_page_refcount() can't run under
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* get_page_foll() because we hold the proper PT lock.
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*/
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__get_page_tail_foll(page, true);
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else {
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/*
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* Getting a normal page or the head of a compound page
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* requires to already have an elevated page->_count.
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*/
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VM_BUG_ON_PAGE(atomic_read(&page->_count) <= 0, page);
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atomic_inc(&page->_count);
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}
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}
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extern unsigned long highest_memmap_pfn;
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/*
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* in mm/vmscan.c:
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*/
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extern int isolate_lru_page(struct page *page);
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extern void putback_lru_page(struct page *page);
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extern bool zone_reclaimable(struct zone *zone);
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/*
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* in mm/rmap.c:
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*/
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extern pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address);
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/*
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* in mm/page_alloc.c
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*/
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/*
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* Locate the struct page for both the matching buddy in our
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* pair (buddy1) and the combined O(n+1) page they form (page).
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*
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* 1) Any buddy B1 will have an order O twin B2 which satisfies
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* the following equation:
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* B2 = B1 ^ (1 << O)
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* For example, if the starting buddy (buddy2) is #8 its order
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* 1 buddy is #10:
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* B2 = 8 ^ (1 << 1) = 8 ^ 2 = 10
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*
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* 2) Any buddy B will have an order O+1 parent P which
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* satisfies the following equation:
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* P = B & ~(1 << O)
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*
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* Assumption: *_mem_map is contiguous at least up to MAX_ORDER
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*/
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static inline unsigned long
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__find_buddy_index(unsigned long page_idx, unsigned int order)
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{
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return page_idx ^ (1 << order);
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}
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extern int __isolate_free_page(struct page *page, unsigned int order);
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extern void __free_pages_bootmem(struct page *page, unsigned int order);
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extern void prep_compound_page(struct page *page, unsigned long order);
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#ifdef CONFIG_MEMORY_FAILURE
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extern bool is_free_buddy_page(struct page *page);
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#endif
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extern int user_min_free_kbytes;
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#if defined CONFIG_COMPACTION || defined CONFIG_CMA
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/*
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* in mm/compaction.c
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*/
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/*
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* compact_control is used to track pages being migrated and the free pages
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* they are being migrated to during memory compaction. The free_pfn starts
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* at the end of a zone and migrate_pfn begins at the start. Movable pages
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* are moved to the end of a zone during a compaction run and the run
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* completes when free_pfn <= migrate_pfn
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*/
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struct compact_control {
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struct list_head freepages; /* List of free pages to migrate to */
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struct list_head migratepages; /* List of pages being migrated */
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unsigned long nr_freepages; /* Number of isolated free pages */
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unsigned long nr_migratepages; /* Number of pages to migrate */
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unsigned long free_pfn; /* isolate_freepages search base */
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unsigned long migrate_pfn; /* isolate_migratepages search base */
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enum migrate_mode mode; /* Async or sync migration mode */
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bool ignore_skip_hint; /* Scan blocks even if marked skip */
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int order; /* order a direct compactor needs */
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const gfp_t gfp_mask; /* gfp mask of a direct compactor */
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const int alloc_flags; /* alloc flags of a direct compactor */
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const int classzone_idx; /* zone index of a direct compactor */
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struct zone *zone;
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int contended; /* Signal need_sched() or lock
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* contention detected during
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* compaction
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*/
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};
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unsigned long
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isolate_freepages_range(struct compact_control *cc,
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unsigned long start_pfn, unsigned long end_pfn);
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unsigned long
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isolate_migratepages_range(struct compact_control *cc,
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unsigned long low_pfn, unsigned long end_pfn);
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#endif
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/*
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* This function returns the order of a free page in the buddy system. In
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* general, page_zone(page)->lock must be held by the caller to prevent the
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* page from being allocated in parallel and returning garbage as the order.
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* If a caller does not hold page_zone(page)->lock, it must guarantee that the
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* page cannot be allocated or merged in parallel. Alternatively, it must
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* handle invalid values gracefully, and use page_order_unsafe() below.
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*/
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static inline unsigned long page_order(struct page *page)
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{
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/* PageBuddy() must be checked by the caller */
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return page_private(page);
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}
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/*
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* Like page_order(), but for callers who cannot afford to hold the zone lock.
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* PageBuddy() should be checked first by the caller to minimize race window,
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* and invalid values must be handled gracefully.
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*
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* ACCESS_ONCE is used so that if the caller assigns the result into a local
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* variable and e.g. tests it for valid range before using, the compiler cannot
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* decide to remove the variable and inline the page_private(page) multiple
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* times, potentially observing different values in the tests and the actual
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* use of the result.
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*/
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#define page_order_unsafe(page) ACCESS_ONCE(page_private(page))
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static inline bool is_cow_mapping(vm_flags_t flags)
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{
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return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
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}
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/* mm/util.c */
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void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma,
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struct vm_area_struct *prev, struct rb_node *rb_parent);
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#ifdef CONFIG_MMU
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extern long __mlock_vma_pages_range(struct vm_area_struct *vma,
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unsigned long start, unsigned long end, int *nonblocking);
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extern void munlock_vma_pages_range(struct vm_area_struct *vma,
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unsigned long start, unsigned long end);
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static inline void munlock_vma_pages_all(struct vm_area_struct *vma)
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{
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munlock_vma_pages_range(vma, vma->vm_start, vma->vm_end);
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}
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/*
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* must be called with vma's mmap_sem held for read or write, and page locked.
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*/
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extern void mlock_vma_page(struct page *page);
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extern unsigned int munlock_vma_page(struct page *page);
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/*
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* Clear the page's PageMlocked(). This can be useful in a situation where
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* we want to unconditionally remove a page from the pagecache -- e.g.,
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* on truncation or freeing.
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*
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* It is legal to call this function for any page, mlocked or not.
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* If called for a page that is still mapped by mlocked vmas, all we do
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* is revert to lazy LRU behaviour -- semantics are not broken.
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*/
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extern void clear_page_mlock(struct page *page);
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/*
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* mlock_migrate_page - called only from migrate_page_copy() to
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* migrate the Mlocked page flag; update statistics.
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*/
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static inline void mlock_migrate_page(struct page *newpage, struct page *page)
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{
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if (TestClearPageMlocked(page)) {
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unsigned long flags;
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int nr_pages = hpage_nr_pages(page);
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local_irq_save(flags);
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__mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages);
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SetPageMlocked(newpage);
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__mod_zone_page_state(page_zone(newpage), NR_MLOCK, nr_pages);
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local_irq_restore(flags);
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}
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}
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extern pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma);
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#ifdef CONFIG_TRANSPARENT_HUGEPAGE
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extern unsigned long vma_address(struct page *page,
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struct vm_area_struct *vma);
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#endif
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#else /* !CONFIG_MMU */
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static inline void clear_page_mlock(struct page *page) { }
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static inline void mlock_vma_page(struct page *page) { }
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static inline void mlock_migrate_page(struct page *new, struct page *old) { }
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#endif /* !CONFIG_MMU */
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/*
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* Return the mem_map entry representing the 'offset' subpage within
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* the maximally aligned gigantic page 'base'. Handle any discontiguity
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* in the mem_map at MAX_ORDER_NR_PAGES boundaries.
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*/
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static inline struct page *mem_map_offset(struct page *base, int offset)
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{
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if (unlikely(offset >= MAX_ORDER_NR_PAGES))
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return nth_page(base, offset);
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return base + offset;
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}
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/*
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* Iterator over all subpages within the maximally aligned gigantic
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* page 'base'. Handle any discontiguity in the mem_map.
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*/
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static inline struct page *mem_map_next(struct page *iter,
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struct page *base, int offset)
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{
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if (unlikely((offset & (MAX_ORDER_NR_PAGES - 1)) == 0)) {
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unsigned long pfn = page_to_pfn(base) + offset;
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if (!pfn_valid(pfn))
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return NULL;
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return pfn_to_page(pfn);
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}
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return iter + 1;
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}
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/*
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* FLATMEM and DISCONTIGMEM configurations use alloc_bootmem_node,
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* so all functions starting at paging_init should be marked __init
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* in those cases. SPARSEMEM, however, allows for memory hotplug,
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* and alloc_bootmem_node is not used.
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*/
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#ifdef CONFIG_SPARSEMEM
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#define __paginginit __meminit
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#else
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#define __paginginit __init
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#endif
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/* Memory initialisation debug and verification */
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enum mminit_level {
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MMINIT_WARNING,
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MMINIT_VERIFY,
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MMINIT_TRACE
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};
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#ifdef CONFIG_DEBUG_MEMORY_INIT
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extern int mminit_loglevel;
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#define mminit_dprintk(level, prefix, fmt, arg...) \
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do { \
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if (level < mminit_loglevel) { \
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printk(level <= MMINIT_WARNING ? KERN_WARNING : KERN_DEBUG); \
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printk(KERN_CONT "mminit::" prefix " " fmt, ##arg); \
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} \
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} while (0)
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extern void mminit_verify_pageflags_layout(void);
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extern void mminit_verify_page_links(struct page *page,
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enum zone_type zone, unsigned long nid, unsigned long pfn);
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extern void mminit_verify_zonelist(void);
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#else
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static inline void mminit_dprintk(enum mminit_level level,
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const char *prefix, const char *fmt, ...)
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{
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}
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static inline void mminit_verify_pageflags_layout(void)
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{
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}
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static inline void mminit_verify_page_links(struct page *page,
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enum zone_type zone, unsigned long nid, unsigned long pfn)
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{
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}
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static inline void mminit_verify_zonelist(void)
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{
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}
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#endif /* CONFIG_DEBUG_MEMORY_INIT */
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/* mminit_validate_memmodel_limits is independent of CONFIG_DEBUG_MEMORY_INIT */
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#if defined(CONFIG_SPARSEMEM)
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extern void mminit_validate_memmodel_limits(unsigned long *start_pfn,
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unsigned long *end_pfn);
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#else
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static inline void mminit_validate_memmodel_limits(unsigned long *start_pfn,
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unsigned long *end_pfn)
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{
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}
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#endif /* CONFIG_SPARSEMEM */
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#define ZONE_RECLAIM_NOSCAN -2
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#define ZONE_RECLAIM_FULL -1
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#define ZONE_RECLAIM_SOME 0
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#define ZONE_RECLAIM_SUCCESS 1
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extern int hwpoison_filter(struct page *p);
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extern u32 hwpoison_filter_dev_major;
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extern u32 hwpoison_filter_dev_minor;
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extern u64 hwpoison_filter_flags_mask;
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extern u64 hwpoison_filter_flags_value;
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extern u64 hwpoison_filter_memcg;
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extern u32 hwpoison_filter_enable;
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extern unsigned long vm_mmap_pgoff(struct file *, unsigned long,
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unsigned long, unsigned long,
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unsigned long, unsigned long);
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extern void set_pageblock_order(void);
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unsigned long reclaim_clean_pages_from_list(struct zone *zone,
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struct list_head *page_list);
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/* The ALLOC_WMARK bits are used as an index to zone->watermark */
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#define ALLOC_WMARK_MIN WMARK_MIN
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#define ALLOC_WMARK_LOW WMARK_LOW
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#define ALLOC_WMARK_HIGH WMARK_HIGH
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#define ALLOC_NO_WATERMARKS 0x04 /* don't check watermarks at all */
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/* Mask to get the watermark bits */
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#define ALLOC_WMARK_MASK (ALLOC_NO_WATERMARKS-1)
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#define ALLOC_HARDER 0x10 /* try to alloc harder */
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#define ALLOC_HIGH 0x20 /* __GFP_HIGH set */
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#define ALLOC_CPUSET 0x40 /* check for correct cpuset */
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#define ALLOC_CMA 0x80 /* allow allocations from CMA areas */
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#define ALLOC_FAIR 0x100 /* fair zone allocation */
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#endif /* __MM_INTERNAL_H */
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