diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2023-02-24 04:09:35 +0300 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2023-02-24 04:09:35 +0300 |
commit | 3822a7c40997dc86b1458766a3f146d62393f084 (patch) | |
tree | 4473720ecbfaabeedfe58484425be77d0f89f736 /mm/migrate.c | |
parent | e4bc15889506723d7b93c053ad4a75cd58248d74 (diff) | |
parent | f9366f4c2a29d14f5992b195e268240c2deb116e (diff) | |
download | linux-3822a7c40997dc86b1458766a3f146d62393f084.tar.xz |
Merge tag 'mm-stable-2023-02-20-13-37' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
- Daniel Verkamp has contributed a memfd series ("mm/memfd: add
F_SEAL_EXEC") which permits the setting of the memfd execute bit at
memfd creation time, with the option of sealing the state of the X
bit.
- Peter Xu adds a patch series ("mm/hugetlb: Make huge_pte_offset()
thread-safe for pmd unshare") which addresses a rare race condition
related to PMD unsharing.
- Several folioification patch serieses from Matthew Wilcox, Vishal
Moola, Sidhartha Kumar and Lorenzo Stoakes
- Johannes Weiner has a series ("mm: push down lock_page_memcg()")
which does perform some memcg maintenance and cleanup work.
- SeongJae Park has added DAMOS filtering to DAMON, with the series
"mm/damon/core: implement damos filter".
These filters provide users with finer-grained control over DAMOS's
actions. SeongJae has also done some DAMON cleanup work.
- Kairui Song adds a series ("Clean up and fixes for swap").
- Vernon Yang contributed the series "Clean up and refinement for maple
tree".
- Yu Zhao has contributed the "mm: multi-gen LRU: memcg LRU" series. It
adds to MGLRU an LRU of memcgs, to improve the scalability of global
reclaim.
- David Hildenbrand has added some userfaultfd cleanup work in the
series "mm: uffd-wp + change_protection() cleanups".
- Christoph Hellwig has removed the generic_writepages() library
function in the series "remove generic_writepages".
- Baolin Wang has performed some maintenance on the compaction code in
his series "Some small improvements for compaction".
- Sidhartha Kumar is doing some maintenance work on struct page in his
series "Get rid of tail page fields".
- David Hildenbrand contributed some cleanup, bugfixing and
generalization of pte management and of pte debugging in his series
"mm: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE on all architectures with
swap PTEs".
- Mel Gorman and Neil Brown have removed the __GFP_ATOMIC allocation
flag in the series "Discard __GFP_ATOMIC".
- Sergey Senozhatsky has improved zsmalloc's memory utilization with
his series "zsmalloc: make zspage chain size configurable".
- Joey Gouly has added prctl() support for prohibiting the creation of
writeable+executable mappings.
The previous BPF-based approach had shortcomings. See "mm: In-kernel
support for memory-deny-write-execute (MDWE)".
- Waiman Long did some kmemleak cleanup and bugfixing in the series
"mm/kmemleak: Simplify kmemleak_cond_resched() & fix UAF".
- T.J. Alumbaugh has contributed some MGLRU cleanup work in his series
"mm: multi-gen LRU: improve".
- Jiaqi Yan has provided some enhancements to our memory error
statistics reporting, mainly by presenting the statistics on a
per-node basis. See the series "Introduce per NUMA node memory error
statistics".
- Mel Gorman has a second and hopefully final shot at fixing a CPU-hog
regression in compaction via his series "Fix excessive CPU usage
during compaction".
- Christoph Hellwig does some vmalloc maintenance work in the series
"cleanup vfree and vunmap".
- Christoph Hellwig has removed block_device_operations.rw_page() in
ths series "remove ->rw_page".
- We get some maple_tree improvements and cleanups in Liam Howlett's
series "VMA tree type safety and remove __vma_adjust()".
- Suren Baghdasaryan has done some work on the maintainability of our
vm_flags handling in the series "introduce vm_flags modifier
functions".
- Some pagemap cleanup and generalization work in Mike Rapoport's
series "mm, arch: add generic implementation of pfn_valid() for
FLATMEM" and "fixups for generic implementation of pfn_valid()"
- Baoquan He has done some work to make /proc/vmallocinfo and
/proc/kcore better represent the real state of things in his series
"mm/vmalloc.c: allow vread() to read out vm_map_ram areas".
- Jason Gunthorpe rationalized the GUP system's interface to the rest
of the kernel in the series "Simplify the external interface for
GUP".
- SeongJae Park wishes to migrate people from DAMON's debugfs interface
over to its sysfs interface. To support this, we'll temporarily be
printing warnings when people use the debugfs interface. See the
series "mm/damon: deprecate DAMON debugfs interface".
- Andrey Konovalov provided the accurately named "lib/stackdepot: fixes
and clean-ups" series.
- Huang Ying has provided a dramatic reduction in migration's TLB flush
IPI rates with the series "migrate_pages(): batch TLB flushing".
- Arnd Bergmann has some objtool fixups in "objtool warning fixes".
* tag 'mm-stable-2023-02-20-13-37' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (505 commits)
include/linux/migrate.h: remove unneeded externs
mm/memory_hotplug: cleanup return value handing in do_migrate_range()
mm/uffd: fix comment in handling pte markers
mm: change to return bool for isolate_movable_page()
mm: hugetlb: change to return bool for isolate_hugetlb()
mm: change to return bool for isolate_lru_page()
mm: change to return bool for folio_isolate_lru()
objtool: add UACCESS exceptions for __tsan_volatile_read/write
kmsan: disable ftrace in kmsan core code
kasan: mark addr_has_metadata __always_inline
mm: memcontrol: rename memcg_kmem_enabled()
sh: initialize max_mapnr
m68k/nommu: add missing definition of ARCH_PFN_OFFSET
mm: percpu: fix incorrect size in pcpu_obj_full_size()
maple_tree: reduce stack usage with gcc-9 and earlier
mm: page_alloc: call panic() when memoryless node allocation fails
mm: multi-gen LRU: avoid futile retries
migrate_pages: move THP/hugetlb migration support check to simplify code
migrate_pages: batch flushing TLB
migrate_pages: share more code between _unmap and _move
...
Diffstat (limited to 'mm/migrate.c')
-rw-r--r-- | mm/migrate.c | 934 |
1 files changed, 653 insertions, 281 deletions
diff --git a/mm/migrate.c b/mm/migrate.c index cc5455614e01..37865f85df6d 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -58,8 +58,9 @@ #include "internal.h" -int isolate_movable_page(struct page *page, isolate_mode_t mode) +bool isolate_movable_page(struct page *page, isolate_mode_t mode) { + struct folio *folio = folio_get_nontail_page(page); const struct movable_operations *mops; /* @@ -71,11 +72,11 @@ int isolate_movable_page(struct page *page, isolate_mode_t mode) * the put_page() at the end of this block will take care of * release this page, thus avoiding a nasty leakage. */ - if (unlikely(!get_page_unless_zero(page))) + if (!folio) goto out; - if (unlikely(PageSlab(page))) - goto out_putpage; + if (unlikely(folio_test_slab(folio))) + goto out_putfolio; /* Pairs with smp_wmb() in slab freeing, e.g. SLUB's __free_slab() */ smp_rmb(); /* @@ -83,12 +84,12 @@ int isolate_movable_page(struct page *page, isolate_mode_t mode) * we use non-atomic bitops on newly allocated page flags so * unconditionally grabbing the lock ruins page's owner side. */ - if (unlikely(!__PageMovable(page))) - goto out_putpage; + if (unlikely(!__folio_test_movable(folio))) + goto out_putfolio; /* Pairs with smp_wmb() in slab allocation, e.g. SLUB's alloc_slab_page() */ smp_rmb(); - if (unlikely(PageSlab(page))) - goto out_putpage; + if (unlikely(folio_test_slab(folio))) + goto out_putfolio; /* * As movable pages are not isolated from LRU lists, concurrent @@ -101,39 +102,39 @@ int isolate_movable_page(struct page *page, isolate_mode_t mode) * lets be sure we have the page lock * before proceeding with the movable page isolation steps. */ - if (unlikely(!trylock_page(page))) - goto out_putpage; + if (unlikely(!folio_trylock(folio))) + goto out_putfolio; - if (!PageMovable(page) || PageIsolated(page)) + if (!folio_test_movable(folio) || folio_test_isolated(folio)) goto out_no_isolated; - mops = page_movable_ops(page); - VM_BUG_ON_PAGE(!mops, page); + mops = folio_movable_ops(folio); + VM_BUG_ON_FOLIO(!mops, folio); - if (!mops->isolate_page(page, mode)) + if (!mops->isolate_page(&folio->page, mode)) goto out_no_isolated; /* Driver shouldn't use PG_isolated bit of page->flags */ - WARN_ON_ONCE(PageIsolated(page)); - SetPageIsolated(page); - unlock_page(page); + WARN_ON_ONCE(folio_test_isolated(folio)); + folio_set_isolated(folio); + folio_unlock(folio); - return 0; + return true; out_no_isolated: - unlock_page(page); -out_putpage: - put_page(page); + folio_unlock(folio); +out_putfolio: + folio_put(folio); out: - return -EBUSY; + return false; } -static void putback_movable_page(struct page *page) +static void putback_movable_folio(struct folio *folio) { - const struct movable_operations *mops = page_movable_ops(page); + const struct movable_operations *mops = folio_movable_ops(folio); - mops->putback_page(page); - ClearPageIsolated(page); + mops->putback_page(&folio->page); + folio_clear_isolated(folio); } /* @@ -146,33 +147,33 @@ static void putback_movable_page(struct page *page) */ void putback_movable_pages(struct list_head *l) { - struct page *page; - struct page *page2; + struct folio *folio; + struct folio *folio2; - list_for_each_entry_safe(page, page2, l, lru) { - if (unlikely(PageHuge(page))) { - putback_active_hugepage(page); + list_for_each_entry_safe(folio, folio2, l, lru) { + if (unlikely(folio_test_hugetlb(folio))) { + folio_putback_active_hugetlb(folio); continue; } - list_del(&page->lru); + list_del(&folio->lru); /* - * We isolated non-lru movable page so here we can use - * __PageMovable because LRU page's mapping cannot have + * We isolated non-lru movable folio so here we can use + * __PageMovable because LRU folio's mapping cannot have * PAGE_MAPPING_MOVABLE. */ - if (unlikely(__PageMovable(page))) { - VM_BUG_ON_PAGE(!PageIsolated(page), page); - lock_page(page); - if (PageMovable(page)) - putback_movable_page(page); + if (unlikely(__folio_test_movable(folio))) { + VM_BUG_ON_FOLIO(!folio_test_isolated(folio), folio); + folio_lock(folio); + if (folio_test_movable(folio)) + putback_movable_folio(folio); else - ClearPageIsolated(page); - unlock_page(page); - put_page(page); + folio_clear_isolated(folio); + folio_unlock(folio); + folio_put(folio); } else { - mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON + - page_is_file_lru(page), -thp_nr_pages(page)); - putback_lru_page(page); + node_stat_mod_folio(folio, NR_ISOLATED_ANON + + folio_is_file_lru(folio), -folio_nr_pages(folio)); + folio_putback_lru(folio); } } } @@ -267,7 +268,7 @@ static bool remove_migration_pte(struct folio *folio, set_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte); } if (vma->vm_flags & VM_LOCKED) - mlock_page_drain_local(); + mlock_drain_local(); trace_remove_migration_pte(pvmw.address, pte_val(pte), compound_order(new)); @@ -331,24 +332,41 @@ void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd, } #ifdef CONFIG_HUGETLB_PAGE -void __migration_entry_wait_huge(pte_t *ptep, spinlock_t *ptl) +/* + * The vma read lock must be held upon entry. Holding that lock prevents either + * the pte or the ptl from being freed. + * + * This function will release the vma lock before returning. + */ +void __migration_entry_wait_huge(struct vm_area_struct *vma, + pte_t *ptep, spinlock_t *ptl) { pte_t pte; + hugetlb_vma_assert_locked(vma); spin_lock(ptl); pte = huge_ptep_get(ptep); - if (unlikely(!is_hugetlb_entry_migration(pte))) + if (unlikely(!is_hugetlb_entry_migration(pte))) { spin_unlock(ptl); - else + hugetlb_vma_unlock_read(vma); + } else { + /* + * If migration entry existed, safe to release vma lock + * here because the pgtable page won't be freed without the + * pgtable lock released. See comment right above pgtable + * lock release in migration_entry_wait_on_locked(). + */ + hugetlb_vma_unlock_read(vma); migration_entry_wait_on_locked(pte_to_swp_entry(pte), NULL, ptl); + } } void migration_entry_wait_huge(struct vm_area_struct *vma, pte_t *pte) { spinlock_t *ptl = huge_pte_lockptr(hstate_vma(vma), vma->vm_mm, pte); - __migration_entry_wait_huge(pte, ptl); + __migration_entry_wait_huge(vma, pte, ptl); } #endif @@ -975,7 +993,7 @@ static int move_to_new_folio(struct folio *dst, struct folio *src, goto out; } - mops = page_movable_ops(&src->page); + mops = folio_movable_ops(src); rc = mops->migrate_page(&dst->page, &src->page, mode); WARN_ON_ONCE(rc == MIGRATEPAGE_SUCCESS && !folio_test_isolated(src)); @@ -1011,13 +1029,113 @@ out: return rc; } -static int __unmap_and_move(struct folio *src, struct folio *dst, - int force, enum migrate_mode mode) +/* + * To record some information during migration, we use some unused + * fields (mapping and private) of struct folio of the newly allocated + * destination folio. This is safe because nobody is using them + * except us. + */ +static void __migrate_folio_record(struct folio *dst, + unsigned long page_was_mapped, + struct anon_vma *anon_vma) +{ + dst->mapping = (void *)anon_vma; + dst->private = (void *)page_was_mapped; +} + +static void __migrate_folio_extract(struct folio *dst, + int *page_was_mappedp, + struct anon_vma **anon_vmap) +{ + *anon_vmap = (void *)dst->mapping; + *page_was_mappedp = (unsigned long)dst->private; + dst->mapping = NULL; + dst->private = NULL; +} + +/* Restore the source folio to the original state upon failure */ +static void migrate_folio_undo_src(struct folio *src, + int page_was_mapped, + struct anon_vma *anon_vma, + bool locked, + struct list_head *ret) +{ + if (page_was_mapped) + remove_migration_ptes(src, src, false); + /* Drop an anon_vma reference if we took one */ + if (anon_vma) + put_anon_vma(anon_vma); + if (locked) + folio_unlock(src); + if (ret) + list_move_tail(&src->lru, ret); +} + +/* Restore the destination folio to the original state upon failure */ +static void migrate_folio_undo_dst(struct folio *dst, + bool locked, + free_page_t put_new_page, + unsigned long private) +{ + if (locked) + folio_unlock(dst); + if (put_new_page) + put_new_page(&dst->page, private); + else + folio_put(dst); +} + +/* Cleanup src folio upon migration success */ +static void migrate_folio_done(struct folio *src, + enum migrate_reason reason) +{ + /* + * Compaction can migrate also non-LRU pages which are + * not accounted to NR_ISOLATED_*. They can be recognized + * as __PageMovable + */ + if (likely(!__folio_test_movable(src))) + mod_node_page_state(folio_pgdat(src), NR_ISOLATED_ANON + + folio_is_file_lru(src), -folio_nr_pages(src)); + + if (reason != MR_MEMORY_FAILURE) + /* We release the page in page_handle_poison. */ + folio_put(src); +} + +/* Obtain the lock on page, remove all ptes. */ +static int migrate_folio_unmap(new_page_t get_new_page, free_page_t put_new_page, + unsigned long private, struct folio *src, + struct folio **dstp, int force, bool avoid_force_lock, + enum migrate_mode mode, enum migrate_reason reason, + struct list_head *ret) { + struct folio *dst; int rc = -EAGAIN; - bool page_was_mapped = false; + struct page *newpage = NULL; + int page_was_mapped = 0; struct anon_vma *anon_vma = NULL; bool is_lru = !__PageMovable(&src->page); + bool locked = false; + bool dst_locked = false; + + if (folio_ref_count(src) == 1) { + /* Folio was freed from under us. So we are done. */ + folio_clear_active(src); + folio_clear_unevictable(src); + /* free_pages_prepare() will clear PG_isolated. */ + list_del(&src->lru); + migrate_folio_done(src, reason); + return MIGRATEPAGE_SUCCESS; + } + + newpage = get_new_page(&src->page, private); + if (!newpage) + return -ENOMEM; + dst = page_folio(newpage); + *dstp = dst; + + dst->private = NULL; if (!folio_trylock(src)) { if (!force || mode == MIGRATE_ASYNC) @@ -1039,8 +1157,20 @@ static int __unmap_and_move(struct folio *src, struct folio *dst, if (current->flags & PF_MEMALLOC) goto out; + /* + * We have locked some folios and are going to wait to lock + * this folio. To avoid a potential deadlock, let's bail + * out and not do that. The locked folios will be moved and + * unlocked, then we can wait to lock this folio. + */ + if (avoid_force_lock) { + rc = -EDEADLOCK; + goto out; + } + folio_lock(src); } + locked = true; if (folio_test_writeback(src)) { /* @@ -1055,10 +1185,10 @@ static int __unmap_and_move(struct folio *src, struct folio *dst, break; default: rc = -EBUSY; - goto out_unlock; + goto out; } if (!force) - goto out_unlock; + goto out; folio_wait_writeback(src); } @@ -1088,11 +1218,12 @@ static int __unmap_and_move(struct folio *src, struct folio *dst, * This is much like races on refcount of oldpage: just don't BUG(). */ if (unlikely(!folio_trylock(dst))) - goto out_unlock; + goto out; + dst_locked = true; if (unlikely(!is_lru)) { - rc = move_to_new_folio(dst, src, mode); - goto out_unlock_both; + __migrate_folio_record(dst, page_was_mapped, anon_vma); + return MIGRATEPAGE_UNMAP; } /* @@ -1110,18 +1241,57 @@ static int __unmap_and_move(struct folio *src, struct folio *dst, if (!src->mapping) { if (folio_test_private(src)) { try_to_free_buffers(src); - goto out_unlock_both; + goto out; } } else if (folio_mapped(src)) { /* Establish migration ptes */ VM_BUG_ON_FOLIO(folio_test_anon(src) && !folio_test_ksm(src) && !anon_vma, src); - try_to_migrate(src, 0); - page_was_mapped = true; + try_to_migrate(src, TTU_BATCH_FLUSH); + page_was_mapped = 1; } - if (!folio_mapped(src)) - rc = move_to_new_folio(dst, src, mode); + if (!folio_mapped(src)) { + __migrate_folio_record(dst, page_was_mapped, anon_vma); + return MIGRATEPAGE_UNMAP; + } + +out: + /* + * A folio that has not been unmapped will be restored to + * right list unless we want to retry. + */ + if (rc == -EAGAIN || rc == -EDEADLOCK) + ret = NULL; + + migrate_folio_undo_src(src, page_was_mapped, anon_vma, locked, ret); + migrate_folio_undo_dst(dst, dst_locked, put_new_page, private); + + return rc; +} + +/* Migrate the folio to the newly allocated folio in dst. */ +static int migrate_folio_move(free_page_t put_new_page, unsigned long private, + struct folio *src, struct folio *dst, + enum migrate_mode mode, enum migrate_reason reason, + struct list_head *ret) +{ + int rc; + int page_was_mapped = 0; + struct anon_vma *anon_vma = NULL; + bool is_lru = !__PageMovable(&src->page); + struct list_head *prev; + + __migrate_folio_extract(dst, &page_was_mapped, &anon_vma); + prev = dst->lru.prev; + list_del(&dst->lru); + + rc = move_to_new_folio(dst, src, mode); + if (rc) + goto out; + + if (unlikely(!is_lru)) + goto out_unlock_both; /* * When successful, push dst to LRU immediately: so that if it @@ -1132,111 +1302,49 @@ static int __unmap_and_move(struct folio *src, struct folio *dst, * unsuccessful, and other cases when a page has been temporarily * isolated from the unevictable LRU: but this case is the easiest. */ - if (rc == MIGRATEPAGE_SUCCESS) { - folio_add_lru(dst); - if (page_was_mapped) - lru_add_drain(); - } + folio_add_lru(dst); + if (page_was_mapped) + lru_add_drain(); if (page_was_mapped) - remove_migration_ptes(src, - rc == MIGRATEPAGE_SUCCESS ? dst : src, false); + remove_migration_ptes(src, dst, false); out_unlock_both: folio_unlock(dst); -out_unlock: - /* Drop an anon_vma reference if we took one */ - if (anon_vma) - put_anon_vma(anon_vma); - folio_unlock(src); -out: + set_page_owner_migrate_reason(&dst->page, reason); /* * If migration is successful, decrease refcount of dst, * which will not free the page because new page owner increased * refcounter. */ - if (rc == MIGRATEPAGE_SUCCESS) - folio_put(dst); - - return rc; -} - -/* - * Obtain the lock on folio, remove all ptes and migrate the folio - * to the newly allocated folio in dst. - */ -static int unmap_and_move(new_page_t get_new_page, - free_page_t put_new_page, - unsigned long private, struct folio *src, - int force, enum migrate_mode mode, - enum migrate_reason reason, - struct list_head *ret) -{ - struct folio *dst; - int rc = MIGRATEPAGE_SUCCESS; - struct page *newpage = NULL; - - if (!thp_migration_supported() && folio_test_transhuge(src)) - return -ENOSYS; - - if (folio_ref_count(src) == 1) { - /* Folio was freed from under us. So we are done. */ - folio_clear_active(src); - folio_clear_unevictable(src); - /* free_pages_prepare() will clear PG_isolated. */ - goto out; - } - - newpage = get_new_page(&src->page, private); - if (!newpage) - return -ENOMEM; - dst = page_folio(newpage); + folio_put(dst); - dst->private = NULL; - rc = __unmap_and_move(src, dst, force, mode); - if (rc == MIGRATEPAGE_SUCCESS) - set_page_owner_migrate_reason(&dst->page, reason); + /* + * A folio that has been migrated has all references removed + * and will be freed. + */ + list_del(&src->lru); + /* Drop an anon_vma reference if we took one */ + if (anon_vma) + put_anon_vma(anon_vma); + folio_unlock(src); + migrate_folio_done(src, reason); + return rc; out: - if (rc != -EAGAIN) { - /* - * A folio that has been migrated has all references - * removed and will be freed. A folio that has not been - * migrated will have kept its references and be restored. - */ - list_del(&src->lru); - } - /* - * If migration is successful, releases reference grabbed during - * isolation. Otherwise, restore the folio to right list unless - * we want to retry. + * A folio that has not been migrated will be restored to + * right list unless we want to retry. */ - if (rc == MIGRATEPAGE_SUCCESS) { - /* - * Compaction can migrate also non-LRU folios which are - * not accounted to NR_ISOLATED_*. They can be recognized - * as __folio_test_movable - */ - if (likely(!__folio_test_movable(src))) - mod_node_page_state(folio_pgdat(src), NR_ISOLATED_ANON + - folio_is_file_lru(src), -folio_nr_pages(src)); - - if (reason != MR_MEMORY_FAILURE) - /* - * We release the folio in page_handle_poison. - */ - folio_put(src); - } else { - if (rc != -EAGAIN) - list_add_tail(&src->lru, ret); - - if (put_new_page) - put_new_page(&dst->page, private); - else - folio_put(dst); + if (rc == -EAGAIN) { + list_add(&dst->lru, prev); + __migrate_folio_record(dst, page_was_mapped, anon_vma); + return rc; } + migrate_folio_undo_src(src, page_was_mapped, anon_vma, true, ret); + migrate_folio_undo_dst(dst, true, put_new_page, private); + return rc; } @@ -1271,19 +1379,9 @@ static int unmap_and_move_huge_page(new_page_t get_new_page, struct anon_vma *anon_vma = NULL; struct address_space *mapping = NULL; - /* - * Migratability of hugepages depends on architectures and their size. - * This check is necessary because some callers of hugepage migration - * like soft offline and memory hotremove don't walk through page - * tables or check whether the hugepage is pmd-based or not before - * kicking migration. - */ - if (!hugepage_migration_supported(page_hstate(hpage))) - return -ENOSYS; - if (folio_ref_count(src) == 1) { /* page was freed from under us. So we are done. */ - putback_active_hugepage(hpage); + folio_putback_active_hugetlb(src); return MIGRATEPAGE_SUCCESS; } @@ -1368,7 +1466,7 @@ out_unlock: folio_unlock(src); out: if (rc == MIGRATEPAGE_SUCCESS) - putback_active_hugepage(hpage); + folio_putback_active_hugetlb(src); else if (rc != -EAGAIN) list_move_tail(&src->lru, ret); @@ -1380,7 +1478,7 @@ out: if (put_new_page) put_new_page(new_hpage, private); else - putback_active_hugepage(new_hpage); + folio_putback_active_hugetlb(dst); return rc; } @@ -1398,61 +1496,153 @@ static inline int try_split_folio(struct folio *folio, struct list_head *split_f return rc; } +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +#define NR_MAX_BATCHED_MIGRATION HPAGE_PMD_NR +#else +#define NR_MAX_BATCHED_MIGRATION 512 +#endif +#define NR_MAX_MIGRATE_PAGES_RETRY 10 + +struct migrate_pages_stats { + int nr_succeeded; /* Normal and large folios migrated successfully, in + units of base pages */ + int nr_failed_pages; /* Normal and large folios failed to be migrated, in + units of base pages. Untried folios aren't counted */ + int nr_thp_succeeded; /* THP migrated successfully */ + int nr_thp_failed; /* THP failed to be migrated */ + int nr_thp_split; /* THP split before migrating */ +}; + /* - * migrate_pages - migrate the folios specified in a list, to the free folios - * supplied as the target for the page migration - * - * @from: The list of folios to be migrated. - * @get_new_page: The function used to allocate free folios to be used - * as the target of the folio migration. - * @put_new_page: The function used to free target folios if migration - * fails, or NULL if no special handling is necessary. - * @private: Private data to be passed on to get_new_page() - * @mode: The migration mode that specifies the constraints for - * folio migration, if any. - * @reason: The reason for folio migration. - * @ret_succeeded: Set to the number of folios migrated successfully if - * the caller passes a non-NULL pointer. - * - * The function returns after 10 attempts or if no folios are movable any more - * because the list has become empty or no retryable folios exist any more. - * It is caller's responsibility to call putback_movable_pages() to return folios - * to the LRU or free list only if ret != 0. - * - * Returns the number of {normal folio, large folio, hugetlb} that were not - * migrated, or an error code. The number of large folio splits will be - * considered as the number of non-migrated large folio, no matter how many - * split folios of the large folio are migrated successfully. + * Returns the number of hugetlb folios that were not migrated, or an error code + * after NR_MAX_MIGRATE_PAGES_RETRY attempts or if no hugetlb folios are movable + * any more because the list has become empty or no retryable hugetlb folios + * exist any more. It is caller's responsibility to call putback_movable_pages() + * only if ret != 0. */ -int migrate_pages(struct list_head *from, new_page_t get_new_page, - free_page_t put_new_page, unsigned long private, - enum migrate_mode mode, int reason, unsigned int *ret_succeeded) +static int migrate_hugetlbs(struct list_head *from, new_page_t get_new_page, + free_page_t put_new_page, unsigned long private, + enum migrate_mode mode, int reason, + struct migrate_pages_stats *stats, + struct list_head *ret_folios) { int retry = 1; + int nr_failed = 0; + int nr_retry_pages = 0; + int pass = 0; + struct folio *folio, *folio2; + int rc, nr_pages; + + for (pass = 0; pass < NR_MAX_MIGRATE_PAGES_RETRY && retry; pass++) { + retry = 0; + nr_retry_pages = 0; + + list_for_each_entry_safe(folio, folio2, from, lru) { + if (!folio_test_hugetlb(folio)) + continue; + + nr_pages = folio_nr_pages(folio); + + cond_resched(); + + /* + * Migratability of hugepages depends on architectures and + * their size. This check is necessary because some callers + * of hugepage migration like soft offline and memory + * hotremove don't walk through page tables or check whether + * the hugepage is pmd-based or not before kicking migration. + */ + if (!hugepage_migration_supported(folio_hstate(folio))) { + nr_failed++; + stats->nr_failed_pages += nr_pages; + list_move_tail(&folio->lru, ret_folios); + continue; + } + + rc = unmap_and_move_huge_page(get_new_page, + put_new_page, private, + &folio->page, pass > 2, mode, + reason, ret_folios); + /* + * The rules are: + * Success: hugetlb folio will be put back + * -EAGAIN: stay on the from list + * -ENOMEM: stay on the from list + * Other errno: put on ret_folios list + */ + switch(rc) { + case -ENOMEM: + /* + * When memory is low, don't bother to try to migrate + * other folios, just exit. + */ + stats->nr_failed_pages += nr_pages + nr_retry_pages; + return -ENOMEM; + case -EAGAIN: + retry++; + nr_retry_pages += nr_pages; + break; + case MIGRATEPAGE_SUCCESS: + stats->nr_succeeded += nr_pages; + break; + default: + /* + * Permanent failure (-EBUSY, etc.): + * unlike -EAGAIN case, the failed folio is + * removed from migration folio list and not + * retried in the next outer loop. + */ + nr_failed++; + stats->nr_failed_pages += nr_pages; + break; + } + } + } + /* + * nr_failed is number of hugetlb folios failed to be migrated. After + * NR_MAX_MIGRATE_PAGES_RETRY attempts, give up and count retried hugetlb + * folios as failed. + */ + nr_failed += retry; + stats->nr_failed_pages += nr_retry_pages; + + return nr_failed; +} + +/* + * migrate_pages_batch() first unmaps folios in the from list as many as + * possible, then move the unmapped folios. + */ +static int migrate_pages_batch(struct list_head *from, new_page_t get_new_page, + free_page_t put_new_page, unsigned long private, + enum migrate_mode mode, int reason, struct list_head *ret_folios, + struct migrate_pages_stats *stats) +{ + int retry; int large_retry = 1; int thp_retry = 1; int nr_failed = 0; - int nr_failed_pages = 0; int nr_retry_pages = 0; - int nr_succeeded = 0; - int nr_thp_succeeded = 0; int nr_large_failed = 0; - int nr_thp_failed = 0; - int nr_thp_split = 0; int pass = 0; bool is_large = false; bool is_thp = false; - struct folio *folio, *folio2; - int rc, nr_pages; - LIST_HEAD(ret_folios); + struct folio *folio, *folio2, *dst = NULL, *dst2; + int rc, rc_saved, nr_pages; LIST_HEAD(split_folios); + LIST_HEAD(unmap_folios); + LIST_HEAD(dst_folios); bool nosplit = (reason == MR_NUMA_MISPLACED); bool no_split_folio_counting = false; - - trace_mm_migrate_pages_start(mode, reason); - -split_folio_migration: - for (pass = 0; pass < 10 && (retry || large_retry); pass++) { + bool avoid_force_lock; + +retry: + rc_saved = 0; + avoid_force_lock = false; + retry = 1; + for (pass = 0; + pass < NR_MAX_MIGRATE_PAGES_RETRY && (retry || large_retry); + pass++) { retry = 0; large_retry = 0; thp_retry = 0; @@ -1464,35 +1654,15 @@ split_folio_migration: * folio. Capture required information that might get * lost during migration. */ - is_large = folio_test_large(folio) && !folio_test_hugetlb(folio); + is_large = folio_test_large(folio); is_thp = is_large && folio_test_pmd_mappable(folio); nr_pages = folio_nr_pages(folio); + cond_resched(); - if (folio_test_hugetlb(folio)) - rc = unmap_and_move_huge_page(get_new_page, - put_new_page, private, - &folio->page, pass > 2, mode, - reason, - &ret_folios); - else - rc = unmap_and_move(get_new_page, put_new_page, - private, folio, pass > 2, mode, - reason, &ret_folios); - /* - * The rules are: - * Success: non hugetlb folio will be freed, hugetlb - * folio will be put back - * -EAGAIN: stay on the from list - * -ENOMEM: stay on the from list - * -ENOSYS: stay on the from list - * Other errno: put on ret_folios list then splice to - * from list - */ - switch(rc) { /* * Large folio migration might be unsupported or - * the allocation could've failed so we should retry + * the allocation might be failed so we should retry * on the same folio with the large folio split * to normal folios. * @@ -1500,37 +1670,46 @@ split_folio_migration: * we will migrate them after the rest of the * list is processed. */ - case -ENOSYS: - /* Large folio migration is unsupported */ - if (is_large) { - nr_large_failed++; - nr_thp_failed += is_thp; - if (!try_split_folio(folio, &split_folios)) { - nr_thp_split += is_thp; - break; - } - /* Hugetlb migration is unsupported */ - } else if (!no_split_folio_counting) { - nr_failed++; + if (!thp_migration_supported() && is_thp) { + nr_large_failed++; + stats->nr_thp_failed++; + if (!try_split_folio(folio, &split_folios)) { + stats->nr_thp_split++; + continue; } + stats->nr_failed_pages += nr_pages; + list_move_tail(&folio->lru, ret_folios); + continue; + } - nr_failed_pages += nr_pages; - list_move_tail(&folio->lru, &ret_folios); - break; + rc = migrate_folio_unmap(get_new_page, put_new_page, private, + folio, &dst, pass > 2, avoid_force_lock, + mode, reason, ret_folios); + /* + * The rules are: + * Success: folio will be freed + * Unmap: folio will be put on unmap_folios list, + * dst folio put on dst_folios list + * -EAGAIN: stay on the from list + * -EDEADLOCK: stay on the from list + * -ENOMEM: stay on the from list + * Other errno: put on ret_folios list + */ + switch(rc) { case -ENOMEM: /* * When memory is low, don't bother to try to migrate - * other folios, just exit. + * other folios, move unmapped folios, then exit. */ if (is_large) { nr_large_failed++; - nr_thp_failed += is_thp; + stats->nr_thp_failed += is_thp; /* Large folio NUMA faulting doesn't split to retry. */ if (!nosplit) { int ret = try_split_folio(folio, &split_folios); if (!ret) { - nr_thp_split += is_thp; + stats->nr_thp_split += is_thp; break; } else if (reason == MR_LONGTERM_PIN && ret == -EAGAIN) { @@ -1548,18 +1727,30 @@ split_folio_migration: nr_failed++; } - nr_failed_pages += nr_pages + nr_retry_pages; + stats->nr_failed_pages += nr_pages + nr_retry_pages; /* * There might be some split folios of fail-to-migrate large - * folios left in split_folios list. Move them back to migration + * folios left in split_folios list. Move them to ret_folios * list so that they could be put back to the right list by * the caller otherwise the folio refcnt will be leaked. */ - list_splice_init(&split_folios, from); + list_splice_init(&split_folios, ret_folios); /* nr_failed isn't updated for not used */ nr_large_failed += large_retry; - nr_thp_failed += thp_retry; - goto out; + stats->nr_thp_failed += thp_retry; + rc_saved = rc; + if (list_empty(&unmap_folios)) + goto out; + else + goto move; + case -EDEADLOCK: + /* + * The folio cannot be locked for potential deadlock. + * Go move (and unlock) all locked folios. Then we can + * try again. + */ + rc_saved = rc; + goto move; case -EAGAIN: if (is_large) { large_retry++; @@ -1570,8 +1761,17 @@ split_folio_migration: nr_retry_pages += nr_pages; break; case MIGRATEPAGE_SUCCESS: - nr_succeeded += nr_pages; - nr_thp_succeeded += is_thp; + stats->nr_succeeded += nr_pages; + stats->nr_thp_succeeded += is_thp; + break; + case MIGRATEPAGE_UNMAP: + /* + * We have locked some folios, don't force lock + * to avoid deadlock. + */ + avoid_force_lock = true; + list_move_tail(&folio->lru, &unmap_folios); + list_add_tail(&dst->lru, &dst_folios); break; default: /* @@ -1582,38 +1782,204 @@ split_folio_migration: */ if (is_large) { nr_large_failed++; - nr_thp_failed += is_thp; + stats->nr_thp_failed += is_thp; + } else if (!no_split_folio_counting) { + nr_failed++; + } + + stats->nr_failed_pages += nr_pages; + break; + } + } + } + nr_failed += retry; + nr_large_failed += large_retry; + stats->nr_thp_failed += thp_retry; + stats->nr_failed_pages += nr_retry_pages; +move: + /* Flush TLBs for all unmapped folios */ + try_to_unmap_flush(); + + retry = 1; + for (pass = 0; + pass < NR_MAX_MIGRATE_PAGES_RETRY && (retry || large_retry); + pass++) { + retry = 0; + large_retry = 0; + thp_retry = 0; + nr_retry_pages = 0; + + dst = list_first_entry(&dst_folios, struct folio, lru); + dst2 = list_next_entry(dst, lru); + list_for_each_entry_safe(folio, folio2, &unmap_folios, lru) { + is_large = folio_test_large(folio); + is_thp = is_large && folio_test_pmd_mappable(folio); + nr_pages = folio_nr_pages(folio); + + cond_resched(); + + rc = migrate_folio_move(put_new_page, private, + folio, dst, mode, + reason, ret_folios); + /* + * The rules are: + * Success: folio will be freed + * -EAGAIN: stay on the unmap_folios list + * Other errno: put on ret_folios list + */ + switch(rc) { + case -EAGAIN: + if (is_large) { + large_retry++; + thp_retry += is_thp; + } else if (!no_split_folio_counting) { + retry++; + } + nr_retry_pages += nr_pages; + break; + case MIGRATEPAGE_SUCCESS: + stats->nr_succeeded += nr_pages; + stats->nr_thp_succeeded += is_thp; + break; + default: + if (is_large) { + nr_large_failed++; + stats->nr_thp_failed += is_thp; } else if (!no_split_folio_counting) { nr_failed++; } - nr_failed_pages += nr_pages; + stats->nr_failed_pages += nr_pages; break; } + dst = dst2; + dst2 = list_next_entry(dst, lru); } } nr_failed += retry; nr_large_failed += large_retry; - nr_thp_failed += thp_retry; - nr_failed_pages += nr_retry_pages; + stats->nr_thp_failed += thp_retry; + stats->nr_failed_pages += nr_retry_pages; + + if (rc_saved) + rc = rc_saved; + else + rc = nr_failed + nr_large_failed; +out: + /* Cleanup remaining folios */ + dst = list_first_entry(&dst_folios, struct folio, lru); + dst2 = list_next_entry(dst, lru); + list_for_each_entry_safe(folio, folio2, &unmap_folios, lru) { + int page_was_mapped = 0; + struct anon_vma *anon_vma = NULL; + + __migrate_folio_extract(dst, &page_was_mapped, &anon_vma); + migrate_folio_undo_src(folio, page_was_mapped, anon_vma, + true, ret_folios); + list_del(&dst->lru); + migrate_folio_undo_dst(dst, true, put_new_page, private); + dst = dst2; + dst2 = list_next_entry(dst, lru); + } + /* * Try to migrate split folios of fail-to-migrate large folios, no * nr_failed counting in this round, since all split folios of a * large folio is counted as 1 failure in the first round. */ - if (!list_empty(&split_folios)) { + if (rc >= 0 && !list_empty(&split_folios)) { /* - * Move non-migrated folios (after 10 retries) to ret_folios - * to avoid migrating them again. + * Move non-migrated folios (after NR_MAX_MIGRATE_PAGES_RETRY + * retries) to ret_folios to avoid migrating them again. */ - list_splice_init(from, &ret_folios); + list_splice_init(from, ret_folios); list_splice_init(&split_folios, from); no_split_folio_counting = true; - retry = 1; - goto split_folio_migration; + goto retry; } - rc = nr_failed + nr_large_failed; + /* + * We have unlocked all locked folios, so we can force lock now, let's + * try again. + */ + if (rc == -EDEADLOCK) + goto retry; + + return rc; +} + +/* + * migrate_pages - migrate the folios specified in a list, to the free folios + * supplied as the target for the page migration + * + * @from: The list of folios to be migrated. + * @get_new_page: The function used to allocate free folios to be used + * as the target of the folio migration. + * @put_new_page: The function used to free target folios if migration + * fails, or NULL if no special handling is necessary. + * @private: Private data to be passed on to get_new_page() + * @mode: The migration mode that specifies the constraints for + * folio migration, if any. + * @reason: The reason for folio migration. + * @ret_succeeded: Set to the number of folios migrated successfully if + * the caller passes a non-NULL pointer. + * + * The function returns after NR_MAX_MIGRATE_PAGES_RETRY attempts or if no folios + * are movable any more because the list has become empty or no retryable folios + * exist any more. It is caller's responsibility to call putback_movable_pages() + * only if ret != 0. + * + * Returns the number of {normal folio, large folio, hugetlb} that were not + * migrated, or an error code. The number of large folio splits will be + * considered as the number of non-migrated large folio, no matter how many + * split folios of the large folio are migrated successfully. + */ +int migrate_pages(struct list_head *from, new_page_t get_new_page, + free_page_t put_new_page, unsigned long private, + enum migrate_mode mode, int reason, unsigned int *ret_succeeded) +{ + int rc, rc_gather; + int nr_pages; + struct folio *folio, *folio2; + LIST_HEAD(folios); + LIST_HEAD(ret_folios); + struct migrate_pages_stats stats; + + trace_mm_migrate_pages_start(mode, reason); + + memset(&stats, 0, sizeof(stats)); + + rc_gather = migrate_hugetlbs(from, get_new_page, put_new_page, private, + mode, reason, &stats, &ret_folios); + if (rc_gather < 0) + goto out; +again: + nr_pages = 0; + list_for_each_entry_safe(folio, folio2, from, lru) { + /* Retried hugetlb folios will be kept in list */ + if (folio_test_hugetlb(folio)) { + list_move_tail(&folio->lru, &ret_folios); + continue; + } + + nr_pages += folio_nr_pages(folio); + if (nr_pages > NR_MAX_BATCHED_MIGRATION) + break; + } + if (nr_pages > NR_MAX_BATCHED_MIGRATION) + list_cut_before(&folios, from, &folio->lru); + else + list_splice_init(from, &folios); + rc = migrate_pages_batch(&folios, get_new_page, put_new_page, private, + mode, reason, &ret_folios, &stats); + list_splice_tail_init(&folios, &ret_folios); + if (rc < 0) { + rc_gather = rc; + goto out; + } + rc_gather += rc; + if (!list_empty(from)) + goto again; out: /* * Put the permanent failure folio back to migration list, they @@ -1626,20 +1992,21 @@ out: * are migrated successfully. */ if (list_empty(from)) - rc = 0; + rc_gather = 0; - count_vm_events(PGMIGRATE_SUCCESS, nr_succeeded); - count_vm_events(PGMIGRATE_FAIL, nr_failed_pages); - count_vm_events(THP_MIGRATION_SUCCESS, nr_thp_succeeded); - count_vm_events(THP_MIGRATION_FAIL, nr_thp_failed); - count_vm_events(THP_MIGRATION_SPLIT, nr_thp_split); - trace_mm_migrate_pages(nr_succeeded, nr_failed_pages, nr_thp_succeeded, - nr_thp_failed, nr_thp_split, mode, reason); + count_vm_events(PGMIGRATE_SUCCESS, stats.nr_succeeded); + count_vm_events(PGMIGRATE_FAIL, stats.nr_failed_pages); + count_vm_events(THP_MIGRATION_SUCCESS, stats.nr_thp_succeeded); + count_vm_events(THP_MIGRATION_FAIL, stats.nr_thp_failed); + count_vm_events(THP_MIGRATION_SPLIT, stats.nr_thp_split); + trace_mm_migrate_pages(stats.nr_succeeded, stats.nr_failed_pages, + stats.nr_thp_succeeded, stats.nr_thp_failed, + stats.nr_thp_split, mode, reason); if (ret_succeeded) - *ret_succeeded = nr_succeeded; + *ret_succeeded = stats.nr_succeeded; - return rc; + return rc_gather; } struct page *alloc_migration_target(struct page *page, unsigned long private) @@ -1648,6 +2015,7 @@ struct page *alloc_migration_target(struct page *page, unsigned long private) struct migration_target_control *mtc; gfp_t gfp_mask; unsigned int order = 0; + struct folio *hugetlb_folio = NULL; struct folio *new_folio = NULL; int nid; int zidx; @@ -1662,7 +2030,9 @@ struct page *alloc_migration_target(struct page *page, unsigned long private) struct hstate *h = folio_hstate(folio); gfp_mask = htlb_modify_alloc_mask(h, gfp_mask); - return alloc_huge_page_nodemask(h, nid, mtc->nmask, gfp_mask); + hugetlb_folio = alloc_hugetlb_folio_nodemask(h, nid, + mtc->nmask, gfp_mask); + return &hugetlb_folio->page; } if (folio_test_large(folio)) { @@ -1727,6 +2097,7 @@ static int add_page_for_migration(struct mm_struct *mm, unsigned long addr, struct vm_area_struct *vma; struct page *page; int err; + bool isolated; mmap_read_lock(mm); err = -EFAULT; @@ -1758,17 +2129,18 @@ static int add_page_for_migration(struct mm_struct *mm, unsigned long addr, if (PageHuge(page)) { if (PageHead(page)) { - err = isolate_hugetlb(page, pagelist); - if (!err) - err = 1; + isolated = isolate_hugetlb(page_folio(page), pagelist); + err = isolated ? 1 : -EBUSY; } } else { struct page *head; head = compound_head(page); - err = isolate_lru_page(head); - if (err) + isolated = isolate_lru_page(head); + if (!isolated) { + err = -EBUSY; goto out_putpage; + } err = 1; list_add_tail(&head->lru, pagelist); @@ -2173,7 +2545,7 @@ static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page) return 0; } - if (isolate_lru_page(page)) + if (!isolate_lru_page(page)) return 0; mod_node_page_state(page_pgdat(page), NR_ISOLATED_ANON + page_is_file_lru(page), |