diff options
Diffstat (limited to '')
| -rw-r--r-- | mm/rmap.c | 1688 |
1 files changed, 1143 insertions, 545 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index b3e381919835..2ec925e5fa6a 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -20,29 +20,36 @@ /* * Lock ordering in mm: * - * inode->i_mutex (while writing or truncating, not reading or faulting) - * mm->mmap_sem - * page->flags PG_locked (lock_page) - * hugetlbfs_i_mmap_rwsem_key (in huge_pmd_share) - * mapping->i_mmap_rwsem - * anon_vma->rwsem - * mm->page_table_lock or pte_lock - * pgdat->lru_lock (in mark_page_accessed, isolate_lru_page) - * swap_lock (in swap_duplicate, swap_info_get) - * mmlist_lock (in mmput, drain_mmlist and others) - * mapping->private_lock (in __set_page_dirty_buffers) - * mem_cgroup_{begin,end}_page_stat (memcg->move_lock) - * i_pages lock (widely used) - * inode->i_lock (in set_page_dirty's __mark_inode_dirty) - * bdi.wb->list_lock (in set_page_dirty's __mark_inode_dirty) - * sb_lock (within inode_lock in fs/fs-writeback.c) - * i_pages lock (widely used, in set_page_dirty, - * in arch-dependent flush_dcache_mmap_lock, - * within bdi.wb->list_lock in __sync_single_inode) + * inode->i_rwsem (while writing or truncating, not reading or faulting) + * mm->mmap_lock + * mapping->invalidate_lock (in filemap_fault) + * page->flags PG_locked (lock_page) + * hugetlbfs_i_mmap_rwsem_key (in huge_pmd_share, see hugetlbfs below) + * mapping->i_mmap_rwsem + * anon_vma->rwsem + * mm->page_table_lock or pte_lock + * swap_lock (in swap_duplicate, swap_info_get) + * mmlist_lock (in mmput, drain_mmlist and others) + * mapping->private_lock (in block_dirty_folio) + * folio_lock_memcg move_lock (in block_dirty_folio) + * i_pages lock (widely used) + * lruvec->lru_lock (in folio_lruvec_lock_irq) + * inode->i_lock (in set_page_dirty's __mark_inode_dirty) + * bdi.wb->list_lock (in set_page_dirty's __mark_inode_dirty) + * sb_lock (within inode_lock in fs/fs-writeback.c) + * i_pages lock (widely used, in set_page_dirty, + * in arch-dependent flush_dcache_mmap_lock, + * within bdi.wb->list_lock in __sync_single_inode) * - * anon_vma->rwsem,mapping->i_mutex (memory_failure, collect_procs_anon) + * anon_vma->rwsem,mapping->i_mmap_rwsem (memory_failure, collect_procs_anon) * ->tasklist_lock * pte map lock + * + * hugetlbfs PageHuge() take locks in this order: + * hugetlb_fault_mutex (hugetlbfs specific page fault mutex) + * vma_lock (hugetlb specific lock for pmd_sharing) + * mapping->i_mmap_rwsem (also used for hugetlb pmd sharing) + * page->flags PG_locked (lock_page) */ #include <linux/mm.h> @@ -66,10 +73,13 @@ #include <linux/page_idle.h> #include <linux/memremap.h> #include <linux/userfaultfd_k.h> +#include <linux/mm_inline.h> #include <asm/tlbflush.h> +#define CREATE_TRACE_POINTS #include <trace/events/tlb.h> +#include <trace/events/migrate.h> #include "internal.h" @@ -83,7 +93,8 @@ static inline struct anon_vma *anon_vma_alloc(void) anon_vma = kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL); if (anon_vma) { atomic_set(&anon_vma->refcount, 1); - anon_vma->degree = 1; /* Reference for first vma */ + anon_vma->num_children = 0; + anon_vma->num_active_vmas = 0; anon_vma->parent = anon_vma; /* * Initialise the anon_vma root to point to itself. If called @@ -100,15 +111,15 @@ static inline void anon_vma_free(struct anon_vma *anon_vma) VM_BUG_ON(atomic_read(&anon_vma->refcount)); /* - * Synchronize against page_lock_anon_vma_read() such that + * Synchronize against folio_lock_anon_vma_read() such that * we can safely hold the lock without the anon_vma getting * freed. * * Relies on the full mb implied by the atomic_dec_and_test() from * put_anon_vma() against the acquire barrier implied by - * down_read_trylock() from page_lock_anon_vma_read(). This orders: + * down_read_trylock() from folio_lock_anon_vma_read(). This orders: * - * page_lock_anon_vma_read() VS put_anon_vma() + * folio_lock_anon_vma_read() VS put_anon_vma() * down_read_trylock() atomic_dec_and_test() * LOCK MB * atomic_read() rwsem_is_locked() @@ -161,8 +172,8 @@ static void anon_vma_chain_link(struct vm_area_struct *vma, * allocate a new one. * * Anon-vma allocations are very subtle, because we may have - * optimistically looked up an anon_vma in page_lock_anon_vma_read() - * and that may actually touch the spinlock even in the newly + * optimistically looked up an anon_vma in folio_lock_anon_vma_read() + * and that may actually touch the rwsem even in the newly * allocated vma (it depends on RCU to make sure that the * anon_vma isn't actually destroyed). * @@ -171,7 +182,7 @@ static void anon_vma_chain_link(struct vm_area_struct *vma, * to do any locking for the common case of already having * an anon_vma. * - * This must be called with the mmap_sem held for reading. + * This must be called with the mmap_lock held for reading. */ int __anon_vma_prepare(struct vm_area_struct *vma) { @@ -191,6 +202,7 @@ int __anon_vma_prepare(struct vm_area_struct *vma) anon_vma = anon_vma_alloc(); if (unlikely(!anon_vma)) goto out_enomem_free_avc; + anon_vma->num_children++; /* self-parent link for new root */ allocated = anon_vma; } @@ -200,8 +212,7 @@ int __anon_vma_prepare(struct vm_area_struct *vma) if (likely(!vma->anon_vma)) { vma->anon_vma = anon_vma; anon_vma_chain_link(vma, avc, anon_vma); - /* vma reference or self-parent link for new root */ - anon_vma->degree++; + anon_vma->num_active_vmas++; allocated = NULL; avc = NULL; } @@ -251,7 +262,7 @@ static inline void unlock_anon_vma_root(struct anon_vma *root) * Attach the anon_vmas from src to dst. * Returns 0 on success, -ENOMEM on failure. * - * anon_vma_clone() is called by __vma_split(), __split_vma(), copy_vma() and + * anon_vma_clone() is called by __vma_adjust(), __split_vma(), copy_vma() and * anon_vma_fork(). The first three want an exact copy of src, while the last * one, anon_vma_fork(), may try to reuse an existing anon_vma to prevent * endless growth of anon_vma. Since dst->anon_vma is set to NULL before call, @@ -269,19 +280,6 @@ int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src) { struct anon_vma_chain *avc, *pavc; struct anon_vma *root = NULL; - struct vm_area_struct *prev = dst->vm_prev, *pprev = src->vm_prev; - - /* - * If parent share anon_vma with its vm_prev, keep this sharing in in - * child. - * - * 1. Parent has vm_prev, which implies we have vm_prev. - * 2. Parent and its vm_prev have the same anon_vma. - */ - if (!dst->anon_vma && src->anon_vma && - pprev && pprev->anon_vma == src->anon_vma) - dst->anon_vma = prev->anon_vma; - list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) { struct anon_vma *anon_vma; @@ -299,19 +297,19 @@ int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src) anon_vma_chain_link(dst, avc, anon_vma); /* - * Reuse existing anon_vma if its degree lower than two, - * that means it has no vma and only one anon_vma child. + * Reuse existing anon_vma if it has no vma and only one + * anon_vma child. * - * Do not chose parent anon_vma, otherwise first child - * will always reuse it. Root anon_vma is never reused: + * Root anon_vma is never reused: * it has self-parent reference and at least one child. */ if (!dst->anon_vma && src->anon_vma && - anon_vma != src->anon_vma && anon_vma->degree < 2) + anon_vma->num_children < 2 && + anon_vma->num_active_vmas == 0) dst->anon_vma = anon_vma; } if (dst->anon_vma) - dst->anon_vma->degree++; + dst->anon_vma->num_active_vmas++; unlock_anon_vma_root(root); return 0; @@ -361,12 +359,13 @@ int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma) anon_vma = anon_vma_alloc(); if (!anon_vma) goto out_error; + anon_vma->num_active_vmas++; avc = anon_vma_chain_alloc(GFP_KERNEL); if (!avc) goto out_error_free_anon_vma; /* - * The root anon_vma's spinlock is the lock actually used when we + * The root anon_vma's rwsem is the lock actually used when we * lock any of the anon_vmas in this anon_vma tree. */ anon_vma->root = pvma->anon_vma->root; @@ -381,7 +380,7 @@ int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma) vma->anon_vma = anon_vma; anon_vma_lock_write(anon_vma); anon_vma_chain_link(vma, avc, anon_vma); - anon_vma->parent->degree++; + anon_vma->parent->num_children++; anon_vma_unlock_write(anon_vma); return 0; @@ -413,15 +412,22 @@ void unlink_anon_vmas(struct vm_area_struct *vma) * to free them outside the lock. */ if (RB_EMPTY_ROOT(&anon_vma->rb_root.rb_root)) { - anon_vma->parent->degree--; + anon_vma->parent->num_children--; continue; } list_del(&avc->same_vma); anon_vma_chain_free(avc); } - if (vma->anon_vma) - vma->anon_vma->degree--; + if (vma->anon_vma) { + vma->anon_vma->num_active_vmas--; + + /* + * vma would still be needed after unlink, and anon_vma will be prepared + * when handle fault. + */ + vma->anon_vma = NULL; + } unlock_anon_vma_root(root); /* @@ -432,7 +438,8 @@ void unlink_anon_vmas(struct vm_area_struct *vma) list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) { struct anon_vma *anon_vma = avc->anon_vma; - VM_WARN_ON(anon_vma->degree); + VM_WARN_ON(anon_vma->num_children); + VM_WARN_ON(anon_vma->num_active_vmas); put_anon_vma(anon_vma); list_del(&avc->same_vma); @@ -462,8 +469,8 @@ void __init anon_vma_init(void) * Getting a lock on a stable anon_vma from a page off the LRU is tricky! * * Since there is no serialization what so ever against page_remove_rmap() - * the best this function can do is return a locked anon_vma that might - * have been relevant to this page. + * the best this function can do is return a refcount increased anon_vma + * that might have been relevant to this page. * * The page might have been remapped to a different anon_vma or the anon_vma * returned may already be freed (and even reused). @@ -482,16 +489,16 @@ void __init anon_vma_init(void) * if there is a mapcount, we can dereference the anon_vma after observing * those. */ -struct anon_vma *page_get_anon_vma(struct page *page) +struct anon_vma *folio_get_anon_vma(struct folio *folio) { struct anon_vma *anon_vma = NULL; unsigned long anon_mapping; rcu_read_lock(); - anon_mapping = (unsigned long)READ_ONCE(page->mapping); + anon_mapping = (unsigned long)READ_ONCE(folio->mapping); if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON) goto out; - if (!page_mapped(page)) + if (!folio_mapped(folio)) goto out; anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); @@ -501,13 +508,13 @@ struct anon_vma *page_get_anon_vma(struct page *page) } /* - * If this page is still mapped, then its anon_vma cannot have been + * If this folio is still mapped, then its anon_vma cannot have been * freed. But if it has been unmapped, we have no security against the * anon_vma structure being freed and reused (for another anon_vma: * SLAB_TYPESAFE_BY_RCU guarantees that - so the atomic_inc_not_zero() * above cannot corrupt). */ - if (!page_mapped(page)) { + if (!folio_mapped(folio)) { rcu_read_unlock(); put_anon_vma(anon_vma); return NULL; @@ -519,47 +526,55 @@ out: } /* - * Similar to page_get_anon_vma() except it locks the anon_vma. + * Similar to folio_get_anon_vma() except it locks the anon_vma. * * Its a little more complex as it tries to keep the fast path to a single * atomic op -- the trylock. If we fail the trylock, we fall back to getting a - * reference like with page_get_anon_vma() and then block on the mutex. + * reference like with folio_get_anon_vma() and then block on the mutex + * on !rwc->try_lock case. */ -struct anon_vma *page_lock_anon_vma_read(struct page *page) +struct anon_vma *folio_lock_anon_vma_read(struct folio *folio, + struct rmap_walk_control *rwc) { struct anon_vma *anon_vma = NULL; struct anon_vma *root_anon_vma; unsigned long anon_mapping; rcu_read_lock(); - anon_mapping = (unsigned long)READ_ONCE(page->mapping); + anon_mapping = (unsigned long)READ_ONCE(folio->mapping); if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON) goto out; - if (!page_mapped(page)) + if (!folio_mapped(folio)) goto out; anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); root_anon_vma = READ_ONCE(anon_vma->root); if (down_read_trylock(&root_anon_vma->rwsem)) { /* - * If the page is still mapped, then this anon_vma is still + * If the folio is still mapped, then this anon_vma is still * its anon_vma, and holding the mutex ensures that it will * not go away, see anon_vma_free(). */ - if (!page_mapped(page)) { + if (!folio_mapped(folio)) { up_read(&root_anon_vma->rwsem); anon_vma = NULL; } goto out; } + if (rwc && rwc->try_lock) { + anon_vma = NULL; + rwc->contended = true; + goto out; + } + /* trylock failed, we got to sleep */ if (!atomic_inc_not_zero(&anon_vma->refcount)) { anon_vma = NULL; goto out; } - if (!page_mapped(page)) { + if (!folio_mapped(folio)) { rcu_read_unlock(); put_anon_vma(anon_vma); return NULL; @@ -587,11 +602,6 @@ out: return anon_vma; } -void page_unlock_anon_vma_read(struct anon_vma *anon_vma) -{ - anon_vma_unlock_read(anon_vma); -} - #ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH /* * Flush TLB entries for recently unmapped pages from remote CPUs. It is @@ -620,9 +630,20 @@ void try_to_unmap_flush_dirty(void) try_to_unmap_flush(); } +/* + * Bits 0-14 of mm->tlb_flush_batched record pending generations. + * Bits 16-30 of mm->tlb_flush_batched bit record flushed generations. + */ +#define TLB_FLUSH_BATCH_FLUSHED_SHIFT 16 +#define TLB_FLUSH_BATCH_PENDING_MASK \ + ((1 << (TLB_FLUSH_BATCH_FLUSHED_SHIFT - 1)) - 1) +#define TLB_FLUSH_BATCH_PENDING_LARGE \ + (TLB_FLUSH_BATCH_PENDING_MASK / 2) + static void set_tlb_ubc_flush_pending(struct mm_struct *mm, bool writable) { struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc; + int batch, nbatch; arch_tlbbatch_add_mm(&tlb_ubc->arch, mm); tlb_ubc->flush_required = true; @@ -632,7 +653,22 @@ static void set_tlb_ubc_flush_pending(struct mm_struct *mm, bool writable) * before the PTE is cleared. */ barrier(); - mm->tlb_flush_batched = true; + batch = atomic_read(&mm->tlb_flush_batched); +retry: + if ((batch & TLB_FLUSH_BATCH_PENDING_MASK) > TLB_FLUSH_BATCH_PENDING_LARGE) { + /* + * Prevent `pending' from catching up with `flushed' because of + * overflow. Reset `pending' and `flushed' to be 1 and 0 if + * `pending' becomes large. + */ + nbatch = atomic_cmpxchg(&mm->tlb_flush_batched, batch, 1); + if (nbatch != batch) { + batch = nbatch; + goto retry; + } + } else { + atomic_inc(&mm->tlb_flush_batched); + } /* * If the PTE was dirty then it's best to assume it's writable. The @@ -679,15 +715,18 @@ static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags) */ void flush_tlb_batched_pending(struct mm_struct *mm) { - if (mm->tlb_flush_batched) { - flush_tlb_mm(mm); + int batch = atomic_read(&mm->tlb_flush_batched); + int pending = batch & TLB_FLUSH_BATCH_PENDING_MASK; + int flushed = batch >> TLB_FLUSH_BATCH_FLUSHED_SHIFT; + if (pending != flushed) { + flush_tlb_mm(mm); /* - * Do not allow the compiler to re-order the clearing of - * tlb_flush_batched before the tlb is flushed. + * If the new TLB flushing is pending during flushing, leave + * mm->tlb_flush_batched as is, to avoid losing flushing. */ - barrier(); - mm->tlb_flush_batched = false; + atomic_cmpxchg(&mm->tlb_flush_batched, batch, + pending | (pending << TLB_FLUSH_BATCH_FLUSHED_SHIFT)); } } #else @@ -707,9 +746,9 @@ static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags) */ unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma) { - unsigned long address; - if (PageAnon(page)) { - struct anon_vma *page__anon_vma = page_anon_vma(page); + struct folio *folio = page_folio(page); + if (folio_test_anon(folio)) { + struct anon_vma *page__anon_vma = folio_anon_vma(folio); /* * Note: swapoff's unuse_vma() is more efficient with this * check, and needs it to match anon_vma when KSM is active. @@ -717,24 +756,26 @@ unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma) if (!vma->anon_vma || !page__anon_vma || vma->anon_vma->root != page__anon_vma->root) return -EFAULT; - } else if (page->mapping) { - if (!vma->vm_file || vma->vm_file->f_mapping != page->mapping) - return -EFAULT; - } else + } else if (!vma->vm_file) { return -EFAULT; - address = __vma_address(page, vma); - if (unlikely(address < vma->vm_start || address >= vma->vm_end)) + } else if (vma->vm_file->f_mapping != folio->mapping) { return -EFAULT; - return address; + } + + return vma_address(page, vma); } +/* + * Returns the actual pmd_t* where we expect 'address' to be mapped from, or + * NULL if it doesn't exist. No guarantees / checks on what the pmd_t* + * represents. + */ pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address) { pgd_t *pgd; p4d_t *p4d; pud_t *pud; pmd_t *pmd = NULL; - pmd_t pmde; pgd = pgd_offset(mm, address); if (!pgd_present(*pgd)) @@ -749,58 +790,54 @@ pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address) goto out; pmd = pmd_offset(pud, address); - /* - * Some THP functions use the sequence pmdp_huge_clear_flush(), set_pmd_at() - * without holding anon_vma lock for write. So when looking for a - * genuine pmde (in which to find pte), test present and !THP together. - */ - pmde = *pmd; - barrier(); - if (!pmd_present(pmde) || pmd_trans_huge(pmde)) - pmd = NULL; out: return pmd; } -struct page_referenced_arg { +struct folio_referenced_arg { int mapcount; int referenced; unsigned long vm_flags; struct mem_cgroup *memcg; }; /* - * arg: page_referenced_arg will be passed + * arg: folio_referenced_arg will be passed */ -static bool page_referenced_one(struct page *page, struct vm_area_struct *vma, - unsigned long address, void *arg) +static bool folio_referenced_one(struct folio *folio, + struct vm_area_struct *vma, unsigned long address, void *arg) { - struct page_referenced_arg *pra = arg; - struct page_vma_mapped_walk pvmw = { - .page = page, - .vma = vma, - .address = address, - }; + struct folio_referenced_arg *pra = arg; + DEFINE_FOLIO_VMA_WALK(pvmw, folio, vma, address, 0); int referenced = 0; while (page_vma_mapped_walk(&pvmw)) { address = pvmw.address; - if (vma->vm_flags & VM_LOCKED) { + if ((vma->vm_flags & VM_LOCKED) && + (!folio_test_large(folio) || !pvmw.pte)) { + /* Restore the mlock which got missed */ + mlock_vma_folio(folio, vma, !pvmw.pte); page_vma_mapped_walk_done(&pvmw); pra->vm_flags |= VM_LOCKED; return false; /* To break the loop */ } if (pvmw.pte) { + if (lru_gen_enabled() && pte_young(*pvmw.pte) && + !(vma->vm_flags & (VM_SEQ_READ | VM_RAND_READ))) { + lru_gen_look_around(&pvmw); + referenced++; + } + if (ptep_clear_flush_young_notify(vma, address, pvmw.pte)) { /* * Don't treat a reference through * a sequentially read mapping as such. - * If the page has been used in another mapping, + * If the folio has been used in another mapping, * we will catch it; if this other mapping is * already gone, the unmap path will have set - * PG_referenced or activated the page. + * the referenced flag or activated the folio. */ if (likely(!(vma->vm_flags & VM_SEQ_READ))) referenced++; @@ -810,7 +847,7 @@ static bool page_referenced_one(struct page *page, struct vm_area_struct *vma, pvmw.pmd)) referenced++; } else { - /* unexpected pmd-mapped page? */ + /* unexpected pmd-mapped folio? */ WARN_ON_ONCE(1); } @@ -818,13 +855,13 @@ static bool page_referenced_one(struct page *page, struct vm_area_struct *vma, } if (referenced) - clear_page_idle(page); - if (test_and_clear_page_young(page)) + folio_clear_idle(folio); + if (folio_test_clear_young(folio)) referenced++; if (referenced) { pra->referenced++; - pra->vm_flags |= vma->vm_flags; + pra->vm_flags |= vma->vm_flags & ~VM_LOCKED; } if (!pra->mapcount) @@ -833,9 +870,9 @@ static bool page_referenced_one(struct page *page, struct vm_area_struct *vma, return true; } -static bool invalid_page_referenced_vma(struct vm_area_struct *vma, void *arg) +static bool invalid_folio_referenced_vma(struct vm_area_struct *vma, void *arg) { - struct page_referenced_arg *pra = arg; + struct folio_referenced_arg *pra = arg; struct mem_cgroup *memcg = pra->memcg; if (!mm_match_cgroup(vma->vm_mm, memcg)) @@ -845,40 +882,41 @@ static bool invalid_page_referenced_vma(struct vm_area_struct *vma, void *arg) } /** - * page_referenced - test if the page was referenced - * @page: the page to test - * @is_locked: caller holds lock on the page + * folio_referenced() - Test if the folio was referenced. + * @folio: The folio to test. + * @is_locked: Caller holds lock on the folio. * @memcg: target memory cgroup - * @vm_flags: collect encountered vma->vm_flags who actually referenced the page + * @vm_flags: A combination of all the vma->vm_flags which referenced the folio. + * + * Quick test_and_clear_referenced for all mappings of a folio, * - * Quick test_and_clear_referenced for all mappings to a page, - * returns the number of ptes which referenced the page. + * Return: The number of mappings which referenced the folio. Return -1 if + * the function bailed out due to rmap lock contention. */ -int page_referenced(struct page *page, - int is_locked, - struct mem_cgroup *memcg, - unsigned long *vm_flags) +int folio_referenced(struct folio *folio, int is_locked, + struct mem_cgroup *memcg, unsigned long *vm_flags) { int we_locked = 0; - struct page_referenced_arg pra = { - .mapcount = total_mapcount(page), + struct folio_referenced_arg pra = { + .mapcount = folio_mapcount(folio), .memcg = memcg, }; struct rmap_walk_control rwc = { - .rmap_one = page_referenced_one, + .rmap_one = folio_referenced_one, .arg = (void *)&pra, - .anon_lock = page_lock_anon_vma_read, + .anon_lock = folio_lock_anon_vma_read, + .try_lock = true, }; *vm_flags = 0; if (!pra.mapcount) return 0; - if (!page_rmapping(page)) + if (!folio_raw_mapping(folio)) return 0; - if (!is_locked && (!PageAnon(page) || PageKsm(page))) { - we_locked = trylock_page(page); + if (!is_locked && (!folio_test_anon(folio) || folio_test_ksm(folio))) { + we_locked = folio_trylock(folio); if (!we_locked) return 1; } @@ -889,46 +927,41 @@ int page_referenced(struct page *page, * cgroups */ if (memcg) { - rwc.invalid_vma = invalid_page_referenced_vma; + rwc.invalid_vma = invalid_folio_referenced_vma; } - rmap_walk(page, &rwc); + rmap_walk(folio, &rwc); *vm_flags = pra.vm_flags; if (we_locked) - unlock_page(page); + folio_unlock(folio); - return pra.referenced; + return rwc.contended ? -1 : pra.referenced; } -static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma, - unsigned long address, void *arg) +static int page_vma_mkclean_one(struct page_vma_mapped_walk *pvmw) { - struct page_vma_mapped_walk pvmw = { - .page = page, - .vma = vma, - .address = address, - .flags = PVMW_SYNC, - }; + int cleaned = 0; + struct vm_area_struct *vma = pvmw->vma; struct mmu_notifier_range range; - int *cleaned = arg; + unsigned long address = pvmw->address; /* * We have to assume the worse case ie pmd for invalidation. Note that - * the page can not be free from this function. + * the folio can not be freed from this function. */ mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_PAGE, 0, vma, vma->vm_mm, address, - min(vma->vm_end, address + page_size(page))); + vma_address_end(pvmw)); mmu_notifier_invalidate_range_start(&range); - while (page_vma_mapped_walk(&pvmw)) { + while (page_vma_mapped_walk(pvmw)) { int ret = 0; - address = pvmw.address; - if (pvmw.pte) { + address = pvmw->address; + if (pvmw->pte) { pte_t entry; - pte_t *pte = pvmw.pte; + pte_t *pte = pvmw->pte; if (!pte_dirty(*pte) && !pte_write(*pte)) continue; @@ -940,21 +973,22 @@ static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma, set_pte_at(vma->vm_mm, address, pte, entry); ret = 1; } else { -#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE - pmd_t *pmd = pvmw.pmd; +#ifdef CONFIG_TRANSPARENT_HUGEPAGE + pmd_t *pmd = pvmw->pmd; pmd_t entry; if (!pmd_dirty(*pmd) && !pmd_write(*pmd)) continue; - flush_cache_page(vma, address, page_to_pfn(page)); + flush_cache_range(vma, address, + address + HPAGE_PMD_SIZE); entry = pmdp_invalidate(vma, address, pmd); entry = pmd_wrprotect(entry); entry = pmd_mkclean(entry); set_pmd_at(vma->vm_mm, address, pmd, entry); ret = 1; #else - /* unexpected pmd-mapped page? */ + /* unexpected pmd-mapped folio? */ WARN_ON_ONCE(1); #endif } @@ -964,14 +998,25 @@ static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma, * downgrading page table protection not changing it to point * to a new page. * - * See Documentation/vm/mmu_notifier.rst + * See Documentation/mm/mmu_notifier.rst */ if (ret) - (*cleaned)++; + cleaned++; } mmu_notifier_invalidate_range_end(&range); + return cleaned; +} + +static bool page_mkclean_one(struct folio *folio, struct vm_area_struct *vma, + unsigned long address, void *arg) +{ + DEFINE_FOLIO_VMA_WALK(pvmw, folio, vma, address, PVMW_SYNC); + int *cleaned = arg; + + *cleaned += page_vma_mkclean_one(&pvmw); + return true; } @@ -983,7 +1028,7 @@ static bool invalid_mkclean_vma(struct vm_area_struct *vma, void *arg) return true; } -int page_mkclean(struct page *page) +int folio_mkclean(struct folio *folio) { int cleaned = 0; struct address_space *mapping; @@ -993,20 +1038,52 @@ int page_mkclean(struct page *page) .invalid_vma = invalid_mkclean_vma, }; - BUG_ON(!PageLocked(page)); + BUG_ON(!folio_test_locked(folio)); - if (!page_mapped(page)) + if (!folio_mapped(folio)) return 0; - mapping = page_mapping(page); + mapping = folio_mapping(folio); if (!mapping) return 0; - rmap_walk(page, &rwc); + rmap_walk(folio, &rwc); return cleaned; } -EXPORT_SYMBOL_GPL(page_mkclean); +EXPORT_SYMBOL_GPL(folio_mkclean); + +/** + * pfn_mkclean_range - Cleans the PTEs (including PMDs) mapped with range of + * [@pfn, @pfn + @nr_pages) at the specific offset (@pgoff) + * within the @vma of shared mappings. And since clean PTEs + * should also be readonly, write protects them too. + * @pfn: start pfn. + * @nr_pages: number of physically contiguous pages srarting with @pfn. + * @pgoff: page offset that the @pfn mapped with. + * @vma: vma that @pfn mapped within. + * + * Returns the number of cleaned PTEs (including PMDs). + */ +int pfn_mkclean_range(unsigned long pfn, unsigned long nr_pages, pgoff_t pgoff, + struct vm_area_struct *vma) +{ + struct page_vma_mapped_walk pvmw = { + .pfn = pfn, + .nr_pages = nr_pages, + .pgoff = pgoff, + .vma = vma, + .flags = PVMW_SYNC, + }; + + if (invalid_mkclean_vma(vma, NULL)) + return 0; + + pvmw.address = vma_pgoff_address(pgoff, nr_pages, vma); + VM_BUG_ON_VMA(pvmw.address == -EFAULT, vma); + + return page_vma_mkclean_one(&pvmw); +} /** * page_move_anon_rmap - move a page to our anon_vma @@ -1020,20 +1097,20 @@ EXPORT_SYMBOL_GPL(page_mkclean); */ void page_move_anon_rmap(struct page *page, struct vm_area_struct *vma) { - struct anon_vma *anon_vma = vma->anon_vma; - - page = compound_head(page); + void *anon_vma = vma->anon_vma; + struct folio *folio = page_folio(page); - VM_BUG_ON_PAGE(!PageLocked(page), page); + VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); VM_BUG_ON_VMA(!anon_vma, vma); - anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; + anon_vma += PAGE_MAPPING_ANON; /* * Ensure that anon_vma and the PAGE_MAPPING_ANON bit are written - * simultaneously, so a concurrent reader (eg page_referenced()'s - * PageAnon()) will not see one without the other. + * simultaneously, so a concurrent reader (eg folio_referenced()'s + * folio_test_anon()) will not see one without the other. */ - WRITE_ONCE(page->mapping, (struct address_space *) anon_vma); + WRITE_ONCE(folio->mapping, anon_vma); + SetPageAnonExclusive(page); } /** @@ -1051,7 +1128,7 @@ static void __page_set_anon_rmap(struct page *page, BUG_ON(!anon_vma); if (PageAnon(page)) - return; + goto out; /* * If the page isn't exclusively mapped into this vma, @@ -1061,9 +1138,18 @@ static void __page_set_anon_rmap(struct page *page, if (!exclusive) anon_vma = anon_vma->root; + /* + * page_idle does a lockless/optimistic rmap scan on page->mapping. + * Make sure the compiler doesn't split the stores of anon_vma and + * the PAGE_MAPPING_ANON type identifier, otherwise the rmap code + * could mistake the mapping for a struct address_space and crash. + */ anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; - page->mapping = (struct address_space *) anon_vma; + WRITE_ONCE(page->mapping, (struct address_space *) anon_vma); page->index = linear_page_index(vma, address); +out: + if (exclusive) + SetPageAnonExclusive(page); } /** @@ -1075,19 +1161,20 @@ static void __page_set_anon_rmap(struct page *page, static void __page_check_anon_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address) { + struct folio *folio = page_folio(page); /* * The page's anon-rmap details (mapping and index) are guaranteed to * be set up correctly at this point. * * We have exclusion against page_add_anon_rmap because the caller - * always holds the page locked, except if called from page_dup_rmap, - * in which case the page is already known to be setup. + * always holds the page locked. * * We have exclusion against page_add_new_anon_rmap because those pages * are initially only visible via the pagetables, and the pte is locked * over the call to page_add_new_anon_rmap. */ - VM_BUG_ON_PAGE(page_anon_vma(page)->root != vma->anon_vma->root, page); + VM_BUG_ON_FOLIO(folio_anon_vma(folio)->root != vma->anon_vma->root, + folio); VM_BUG_ON_PAGE(page_to_pgoff(page) != linear_page_index(vma, address), page); } @@ -1097,7 +1184,7 @@ static void __page_check_anon_rmap(struct page *page, * @page: the page to add the mapping to * @vma: the vm area in which the mapping is added * @address: the user virtual address mapped - * @compound: charge the page as compound or small page + * @flags: the rmap flags * * The caller needs to hold the pte lock, and the page must be locked in * the anon_vma case: to serialize mapping,index checking after setting, @@ -1105,22 +1192,16 @@ static void __page_check_anon_rmap(struct page *page, * (but PageKsm is never downgraded to PageAnon). */ void page_add_anon_rmap(struct page *page, - struct vm_area_struct *vma, unsigned long address, bool compound) -{ - do_page_add_anon_rmap(page, vma, address, compound ? RMAP_COMPOUND : 0); -} - -/* - * Special version of the above for do_swap_page, which often runs - * into pages that are exclusively owned by the current process. - * Everybody else should continue to use page_add_anon_rmap above. - */ -void do_page_add_anon_rmap(struct page *page, - struct vm_area_struct *vma, unsigned long address, int flags) + struct vm_area_struct *vma, unsigned long address, rmap_t flags) { bool compound = flags & RMAP_COMPOUND; bool first; + if (unlikely(PageKsm(page))) + lock_page_memcg(page); + else + VM_BUG_ON_PAGE(!PageLocked(page), page); + if (compound) { atomic_t *mapcount; VM_BUG_ON_PAGE(!PageLocked(page), page); @@ -1130,9 +1211,11 @@ void do_page_add_anon_rmap(struct page *page, } else { first = atomic_inc_and_test(&page->_mapcount); } + VM_BUG_ON_PAGE(!first && (flags & RMAP_EXCLUSIVE), page); + VM_BUG_ON_PAGE(!first && PageAnonExclusive(page), page); if (first) { - int nr = compound ? hpage_nr_pages(page) : 1; + int nr = compound ? thp_nr_pages(page) : 1; /* * We use the irq-unsafe __{inc|mod}_zone_page_stat because * these counters are not modified in interrupt context, and @@ -1140,37 +1223,41 @@ void do_page_add_anon_rmap(struct page *page, * disabled. */ if (compound) - __inc_node_page_state(page, NR_ANON_THPS); - __mod_node_page_state(page_pgdat(page), NR_ANON_MAPPED, nr); + __mod_lruvec_page_state(page, NR_ANON_THPS, nr); + __mod_lruvec_page_state(page, NR_ANON_MAPPED, nr); } - if (unlikely(PageKsm(page))) - return; - VM_BUG_ON_PAGE(!PageLocked(page), page); + if (unlikely(PageKsm(page))) + unlock_page_memcg(page); /* address might be in next vma when migration races vma_adjust */ - if (first) + else if (first) __page_set_anon_rmap(page, vma, address, - flags & RMAP_EXCLUSIVE); + !!(flags & RMAP_EXCLUSIVE)); else __page_check_anon_rmap(page, vma, address); + + mlock_vma_page(page, vma, compound); } /** - * page_add_new_anon_rmap - add pte mapping to a new anonymous page + * page_add_new_anon_rmap - add mapping to a new anonymous page * @page: the page to add the mapping to * @vma: the vm area in which the mapping is added * @address: the user virtual address mapped - * @compound: charge the page as compound or small page + * + * If it's a compound page, it is accounted as a compound page. As the page + * is new, it's assume to get mapped exclusively by a single process. * * Same as page_add_anon_rmap but must only be called on *new* pages. * This means the inc-and-test can be bypassed. * Page does not have to be locked. */ void page_add_new_anon_rmap(struct page *page, - struct vm_area_struct *vma, unsigned long address, bool compound) + struct vm_area_struct *vma, unsigned long address) { - int nr = compound ? hpage_nr_pages(page) : 1; + const bool compound = PageCompound(page); + int nr = compound ? thp_nr_pages(page) : 1; VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma); __SetPageSwapBacked(page); @@ -1178,99 +1265,110 @@ void page_add_new_anon_rmap(struct page *page, VM_BUG_ON_PAGE(!PageTransHuge(page), page); /* increment count (starts at -1) */ atomic_set(compound_mapcount_ptr(page), 0); - __inc_node_page_state(page, NR_ANON_THPS); + atomic_set(compound_pincount_ptr(page), 0); + + __mod_lruvec_page_state(page, NR_ANON_THPS, nr); } else { - /* Anon THP always mapped first with PMD */ - VM_BUG_ON_PAGE(PageTransCompound(page), page); /* increment count (starts at -1) */ atomic_set(&page->_mapcount, 0); } - __mod_node_page_state(page_pgdat(page), NR_ANON_MAPPED, nr); + __mod_lruvec_page_state(page, NR_ANON_MAPPED, nr); __page_set_anon_rmap(page, vma, address, 1); } /** * page_add_file_rmap - add pte mapping to a file page - * @page: the page to add the mapping to - * @compound: charge the page as compound or small page + * @page: the page to add the mapping to + * @vma: the vm area in which the mapping is added + * @compound: charge the page as compound or small page * * The caller needs to hold the pte lock. */ -void page_add_file_rmap(struct page *page, bool compound) +void page_add_file_rmap(struct page *page, + struct vm_area_struct *vma, bool compound) { - int i, nr = 1; + int i, nr = 0; VM_BUG_ON_PAGE(compound && !PageTransHuge(page), page); lock_page_memcg(page); if (compound && PageTransHuge(page)) { - for (i = 0, nr = 0; i < HPAGE_PMD_NR; i++) { + int nr_pages = thp_nr_pages(page); + + for (i = 0; i < nr_pages; i++) { if (atomic_inc_and_test(&page[i]._mapcount)) nr++; } if (!atomic_inc_and_test(compound_mapcount_ptr(page))) goto out; + + /* + * It is racy to ClearPageDoubleMap in page_remove_file_rmap(); + * but page lock is held by all page_add_file_rmap() compound + * callers, and SetPageDoubleMap below warns if !PageLocked: + * so here is a place that DoubleMap can be safely cleared. + */ + VM_WARN_ON_ONCE(!PageLocked(page)); + if (nr == nr_pages && PageDoubleMap(page)) + ClearPageDoubleMap(page); + if (PageSwapBacked(page)) - __inc_node_page_state(page, NR_SHMEM_PMDMAPPED); + __mod_lruvec_page_state(page, NR_SHMEM_PMDMAPPED, + nr_pages); else - __inc_node_page_state(page, NR_FILE_PMDMAPPED); + __mod_lruvec_page_state(page, NR_FILE_PMDMAPPED, + nr_pages); } else { if (PageTransCompound(page) && page_mapping(page)) { VM_WARN_ON_ONCE(!PageLocked(page)); - SetPageDoubleMap(compound_head(page)); - if (PageMlocked(page)) - clear_page_mlock(compound_head(page)); } - if (!atomic_inc_and_test(&page->_mapcount)) - goto out; + if (atomic_inc_and_test(&page->_mapcount)) + nr++; } - __mod_lruvec_page_state(page, NR_FILE_MAPPED, nr); out: + if (nr) + __mod_lruvec_page_state(page, NR_FILE_MAPPED, nr); unlock_page_memcg(page); + + mlock_vma_page(page, vma, compound); } static void page_remove_file_rmap(struct page *page, bool compound) { - int i, nr = 1; + int i, nr = 0; VM_BUG_ON_PAGE(compound && !PageHead(page), page); - lock_page_memcg(page); /* Hugepages are not counted in NR_FILE_MAPPED for now. */ if (unlikely(PageHuge(page))) { /* hugetlb pages are always mapped with pmds */ atomic_dec(compound_mapcount_ptr(page)); - goto out; + return; } /* page still mapped by someone else? */ if (compound && PageTransHuge(page)) { - for (i = 0, nr = 0; i < HPAGE_PMD_NR; i++) { + int nr_pages = thp_nr_pages(page); + + for (i = 0; i < nr_pages; i++) { if (atomic_add_negative(-1, &page[i]._mapcount)) nr++; } if (!atomic_add_negative(-1, compound_mapcount_ptr(page))) goto out; if (PageSwapBacked(page)) - __dec_node_page_state(page, NR_SHMEM_PMDMAPPED); + __mod_lruvec_page_state(page, NR_SHMEM_PMDMAPPED, + -nr_pages); else - __dec_node_page_state(page, NR_FILE_PMDMAPPED); + __mod_lruvec_page_state(page, NR_FILE_PMDMAPPED, + -nr_pages); } else { - if (!atomic_add_negative(-1, &page->_mapcount)) - goto out; + if (atomic_add_negative(-1, &page->_mapcount)) + nr++; } - - /* - * We use the irq-unsafe __{inc|mod}_lruvec_page_state because - * these counters are not modified in interrupt context, and - * pte lock(a spinlock) is held, which implies preemption disabled. - */ - __mod_lruvec_page_state(page, NR_FILE_MAPPED, -nr); - - if (unlikely(PageMlocked(page))) - clear_page_mlock(page); out: - unlock_page_memcg(page); + if (nr) + __mod_lruvec_page_state(page, NR_FILE_MAPPED, -nr); } static void page_remove_anon_compound_rmap(struct page *page) @@ -1287,14 +1385,14 @@ static void page_remove_anon_compound_rmap(struct page *page) if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) return; - __dec_node_page_state(page, NR_ANON_THPS); + __mod_lruvec_page_state(page, NR_ANON_THPS, -thp_nr_pages(page)); if (TestClearPageDoubleMap(page)) { /* * Subpages can be mapped with PTEs too. Check how many of * them are still mapped. */ - for (i = 0, nr = 0; i < HPAGE_PMD_NR; i++) { + for (i = 0, nr = 0; i < thp_nr_pages(page); i++) { if (atomic_add_negative(-1, &page[i]._mapcount)) nr++; } @@ -1304,47 +1402,49 @@ static void page_remove_anon_compound_rmap(struct page *page) * page of the compound page is unmapped, but at least one * small page is still mapped. */ - if (nr && nr < HPAGE_PMD_NR) + if (nr && nr < thp_nr_pages(page)) deferred_split_huge_page(page); } else { - nr = HPAGE_PMD_NR; + nr = thp_nr_pages(page); } - if (unlikely(PageMlocked(page))) - clear_page_mlock(page); - if (nr) - __mod_node_page_state(page_pgdat(page), NR_ANON_MAPPED, -nr); + __mod_lruvec_page_state(page, NR_ANON_MAPPED, -nr); } /** * page_remove_rmap - take down pte mapping from a page * @page: page to remove mapping from + * @vma: the vm area from which the mapping is removed * @compound: uncharge the page as compound or small page * * The caller needs to hold the pte lock. */ -void page_remove_rmap(struct page *page, bool compound) +void page_remove_rmap(struct page *page, + struct vm_area_struct *vma, bool compound) { - if (!PageAnon(page)) - return page_remove_file_rmap(page, compound); + lock_page_memcg(page); - if (compound) - return page_remove_anon_compound_rmap(page); + if (!PageAnon(page)) { + page_remove_file_rmap(page, compound); + goto out; + } + + if (compound) { + page_remove_anon_compound_rmap(page); + goto out; + } /* page still mapped by someone else? */ if (!atomic_add_negative(-1, &page->_mapcount)) - return; + goto out; /* * We use the irq-unsafe __{inc|mod}_zone_page_stat because * these counters are not modified in interrupt context, and * pte lock(a spinlock) is held, which implies preemption disabled. */ - __dec_node_page_state(page, NR_ANON_MAPPED); - - if (unlikely(PageMlocked(page))) - clear_page_mlock(page); + __dec_lruvec_page_state(page, NR_ANON_MAPPED); if (PageTransCompound(page)) deferred_split_huge_page(compound_head(page)); @@ -1358,51 +1458,50 @@ void page_remove_rmap(struct page *page, bool compound) * Leaving it set also helps swapoff to reinstate ptes * faster for those pages still in swapcache. */ +out: + unlock_page_memcg(page); + + munlock_vma_page(page, vma, compound); } /* * @arg: enum ttu_flags will be passed to this argument */ -static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma, +static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, unsigned long address, void *arg) { struct mm_struct *mm = vma->vm_mm; - struct page_vma_mapped_walk pvmw = { - .page = page, - .vma = vma, - .address = address, - }; + DEFINE_FOLIO_VMA_WALK(pvmw, folio, vma, address, 0); pte_t pteval; struct page *subpage; - bool ret = true; + bool anon_exclusive, ret = true; struct mmu_notifier_range range; - enum ttu_flags flags = (enum ttu_flags)arg; - - /* munlock has nothing to gain from examining un-locked vmas */ - if ((flags & TTU_MUNLOCK) && !(vma->vm_flags & VM_LOCKED)) - return true; + enum ttu_flags flags = (enum ttu_flags)(long)arg; - if (IS_ENABLED(CONFIG_MIGRATION) && (flags & TTU_MIGRATION) && - is_zone_device_page(page) && !is_device_private_page(page)) - return true; + /* + * When racing against e.g. zap_pte_range() on another cpu, + * in between its ptep_get_and_clear_full() and page_remove_rmap(), + * try_to_unmap() may return before page_mapped() has become false, + * if page table locking is skipped: use TTU_SYNC to wait for that. + */ + if (flags & TTU_SYNC) + pvmw.flags = PVMW_SYNC; - if (flags & TTU_SPLIT_HUGE_PMD) { - split_huge_pmd_address(vma, address, - flags & TTU_SPLIT_FREEZE, page); - } + if (flags & TTU_SPLIT_HUGE_PMD) + split_huge_pmd_address(vma, address, false, folio); /* * For THP, we have to assume the worse case ie pmd for invalidation. * For hugetlb, it could be much worse if we need to do pud * invalidation in the case of pmd sharing. * - * Note that the page can not be free in this function as call of - * try_to_unmap() must hold a reference on the page. + * Note that the folio can not be freed in this function as call of + * try_to_unmap() must hold a reference on the folio. */ + range.end = vma_address_end(&pvmw); mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, - address, - min(vma->vm_end, address + page_size(page))); - if (PageHuge(page)) { + address, range.end); + if (folio_test_hugetlb(folio)) { /* * If sharing is possible, start and end will be adjusted * accordingly. @@ -1413,149 +1512,124 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma, mmu_notifier_invalidate_range_start(&range); while (page_vma_mapped_walk(&pvmw)) { -#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION - /* PMD-mapped THP migration entry */ - if (!pvmw.pte && (flags & TTU_MIGRATION)) { - VM_BUG_ON_PAGE(PageHuge(page) || !PageTransCompound(page), page); - - set_pmd_migration_entry(&pvmw, page); - continue; - } -#endif + /* Unexpected PMD-mapped THP? */ + VM_BUG_ON_FOLIO(!pvmw.pte, folio); /* - * If the page is mlock()d, we cannot swap it out. - * If it's recently referenced (perhaps page_referenced - * skipped over this mm) then we should reactivate it. + * If the folio is in an mlock()d vma, we must not swap it out. */ - if (!(flags & TTU_IGNORE_MLOCK)) { - if (vma->vm_flags & VM_LOCKED) { - /* PTE-mapped THP are never mlocked */ - if (!PageTransCompound(page)) { - /* - * Holding pte lock, we do *not* need - * mmap_sem here - */ - mlock_vma_page(page); - } - ret = false; - page_vma_mapped_walk_done(&pvmw); - break; - } - if (flags & TTU_MUNLOCK) - continue; + if (!(flags & TTU_IGNORE_MLOCK) && + (vma->vm_flags & VM_LOCKED)) { + /* Restore the mlock which got missed */ + mlock_vma_folio(folio, vma, false); + page_vma_mapped_walk_done(&pvmw); + ret = false; + break; } - /* Unexpected PMD-mapped THP? */ - VM_BUG_ON_PAGE(!pvmw.pte, page); - - subpage = page - page_to_pfn(page) + pte_pfn(*pvmw.pte); + subpage = folio_page(folio, + pte_pfn(*pvmw.pte) - folio_pfn(folio)); address = pvmw.address; + anon_exclusive = folio_test_anon(folio) && + PageAnonExclusive(subpage); - if (PageHuge(page)) { - if (huge_pmd_unshare(mm, &address, pvmw.pte)) { - /* - * huge_pmd_unshare unmapped an entire PMD - * page. There is no way of knowing exactly - * which PMDs may be cached for this mm, so - * we must flush them all. start/end were - * already adjusted above to cover this range. - */ - flush_cache_range(vma, range.start, range.end); - flush_tlb_range(vma, range.start, range.end); - mmu_notifier_invalidate_range(mm, range.start, - range.end); - - /* - * The ref count of the PMD page was dropped - * which is part of the way map counting - * is done for shared PMDs. Return 'true' - * here. When there is no other sharing, - * huge_pmd_unshare returns false and we will - * unmap the actual page and drop map count - * to zero. - */ - page_vma_mapped_walk_done(&pvmw); - break; - } - } - - if (IS_ENABLED(CONFIG_MIGRATION) && - (flags & TTU_MIGRATION) && - is_zone_device_page(page)) { - swp_entry_t entry; - pte_t swp_pte; - - pteval = ptep_get_and_clear(mm, pvmw.address, pvmw.pte); + if (folio_test_hugetlb(folio)) { + bool anon = folio_test_anon(folio); /* - * Store the pfn of the page in a special migration - * pte. do_swap_page() will wait until the migration - * pte is removed and then restart fault handling. + * The try_to_unmap() is only passed a hugetlb page + * in the case where the hugetlb page is poisoned. */ - entry = make_migration_entry(page, 0); - swp_pte = swp_entry_to_pte(entry); - if (pte_soft_dirty(pteval)) - swp_pte = pte_swp_mksoft_dirty(swp_pte); - set_pte_at(mm, pvmw.address, pvmw.pte, swp_pte); + VM_BUG_ON_PAGE(!PageHWPoison(subpage), subpage); /* - * No need to invalidate here it will synchronize on - * against the special swap migration pte. - * - * The assignment to subpage above was computed from a - * swap PTE which results in an invalid pointer. - * Since only PAGE_SIZE pages can currently be - * migrated, just set it to page. This will need to be - * changed when hugepage migrations to device private - * memory are supported. + * huge_pmd_unshare may unmap an entire PMD page. + * There is no way of knowing exactly which PMDs may + * be cached for this mm, so we must flush them all. + * start/end were already adjusted above to cover this + * range. */ - subpage = page; - goto discard; - } - - if (!(flags & TTU_IGNORE_ACCESS)) { - if (ptep_clear_flush_young_notify(vma, address, - pvmw.pte)) { - ret = false; - page_vma_mapped_walk_done(&pvmw); - break; - } - } + flush_cache_range(vma, range.start, range.end); - /* Nuke the page table entry. */ - flush_cache_page(vma, address, pte_pfn(*pvmw.pte)); - if (should_defer_flush(mm, flags)) { /* - * We clear the PTE but do not flush so potentially - * a remote CPU could still be writing to the page. - * If the entry was previously clean then the - * architecture must guarantee that a clear->dirty - * transition on a cached TLB entry is written through - * and traps if the PTE is unmapped. + * To call huge_pmd_unshare, i_mmap_rwsem must be + * held in write mode. Caller needs to explicitly + * do this outside rmap routines. + * + * We also must hold hugetlb vma_lock in write mode. + * Lock order dictates acquiring vma_lock BEFORE + * i_mmap_rwsem. We can only try lock here and fail + * if unsuccessful. */ - pteval = ptep_get_and_clear(mm, address, pvmw.pte); - - set_tlb_ubc_flush_pending(mm, pte_dirty(pteval)); + if (!anon) { + VM_BUG_ON(!(flags & TTU_RMAP_LOCKED)); + if (!hugetlb_vma_trylock_write(vma)) { + page_vma_mapped_walk_done(&pvmw); + ret = false; + break; + } + if (huge_pmd_unshare(mm, vma, address, pvmw.pte)) { + hugetlb_vma_unlock_write(vma); + flush_tlb_range(vma, + range.start, range.end); + mmu_notifier_invalidate_range(mm, + range.start, range.end); + /* + * The ref count of the PMD page was + * dropped which is part of the way map + * counting is done for shared PMDs. + * Return 'true' here. When there is + * no other sharing, huge_pmd_unshare + * returns false and we will unmap the + * actual page and drop map count + * to zero. + */ + page_vma_mapped_walk_done(&pvmw); + break; + } + hugetlb_vma_unlock_write(vma); + } + pteval = huge_ptep_clear_flush(vma, address, pvmw.pte); } else { - pteval = ptep_clear_flush(vma, address, pvmw.pte); + flush_cache_page(vma, address, pte_pfn(*pvmw.pte)); + /* Nuke the page table entry. */ + if (should_defer_flush(mm, flags)) { + /* + * We clear the PTE but do not flush so potentially + * a remote CPU could still be writing to the folio. + * If the entry was previously clean then the + * architecture must guarantee that a clear->dirty + * transition on a cached TLB entry is written through + * and traps if the PTE is unmapped. + */ + pteval = ptep_get_and_clear(mm, address, pvmw.pte); + + set_tlb_ubc_flush_pending(mm, pte_dirty(pteval)); + } else { + pteval = ptep_clear_flush(vma, address, pvmw.pte); + } } - /* Move the dirty bit to the page. Now the pte is gone. */ + /* + * Now the pte is cleared. If this pte was uffd-wp armed, + * we may want to replace a none pte with a marker pte if + * it's file-backed, so we don't lose the tracking info. + */ + pte_install_uffd_wp_if_needed(vma, address, pvmw.pte, pteval); + + /* Set the dirty flag on the folio now the pte is gone. */ if (pte_dirty(pteval)) - set_page_dirty(page); + folio_mark_dirty(folio); /* Update high watermark before we lower rss */ update_hiwater_rss(mm); - if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) { + if (PageHWPoison(subpage) && !(flags & TTU_IGNORE_HWPOISON)) { pteval = swp_entry_to_pte(make_hwpoison_entry(subpage)); - if (PageHuge(page)) { - hugetlb_count_sub(compound_nr(page), mm); - set_huge_swap_pte_at(mm, address, - pvmw.pte, pteval, - vma_mmu_pagesize(vma)); + if (folio_test_hugetlb(folio)) { + hugetlb_count_sub(folio_nr_pages(folio), mm); + set_huge_pte_at(mm, address, pvmw.pte, pteval); } else { - dec_mm_counter(mm, mm_counter(page)); + dec_mm_counter(mm, mm_counter(&folio->page)); set_pte_at(mm, address, pvmw.pte, pteval); } @@ -1570,45 +1644,19 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma, * migration) will not expect userfaults on already * copied pages. */ - dec_mm_counter(mm, mm_counter(page)); + dec_mm_counter(mm, mm_counter(&folio->page)); /* We have to invalidate as we cleared the pte */ mmu_notifier_invalidate_range(mm, address, address + PAGE_SIZE); - } else if (IS_ENABLED(CONFIG_MIGRATION) && - (flags & (TTU_MIGRATION|TTU_SPLIT_FREEZE))) { - swp_entry_t entry; - pte_t swp_pte; - - if (arch_unmap_one(mm, vma, address, pteval) < 0) { - set_pte_at(mm, address, pvmw.pte, pteval); - ret = false; - page_vma_mapped_walk_done(&pvmw); - break; - } - - /* - * Store the pfn of the page in a special migration - * pte. do_swap_page() will wait until the migration - * pte is removed and then restart fault handling. - */ - entry = make_migration_entry(subpage, - pte_write(pteval)); - swp_pte = swp_entry_to_pte(entry); - if (pte_soft_dirty(pteval)) - swp_pte = pte_swp_mksoft_dirty(swp_pte); - set_pte_at(mm, address, pvmw.pte, swp_pte); - /* - * No need to invalidate here it will synchronize on - * against the special swap migration pte. - */ - } else if (PageAnon(page)) { + } else if (folio_test_anon(folio)) { swp_entry_t entry = { .val = page_private(subpage) }; pte_t swp_pte; /* * Store the swap location in the pte. * See handle_pte_fault() ... */ - if (unlikely(PageSwapBacked(page) != PageSwapCache(page))) { + if (unlikely(folio_test_swapbacked(folio) != + folio_test_swapcache(folio))) { WARN_ON_ONCE(1); ret = false; /* We have to invalidate as we cleared the pte */ @@ -1619,8 +1667,31 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma, } /* MADV_FREE page check */ - if (!PageSwapBacked(page)) { - if (!PageDirty(page)) { + if (!folio_test_swapbacked(folio)) { + int ref_count, map_count; + + /* + * Synchronize with gup_pte_range(): + * - clear PTE; barrier; read refcount + * - inc refcount; barrier; read PTE + */ + smp_mb(); + + ref_count = folio_ref_count(folio); + map_count = folio_mapcount(folio); + + /* + * Order reads for page refcount and dirty flag + * (see comments in __remove_mapping()). + */ + smp_rmb(); + + /* + * The only page refs must be one from isolation + * plus the rmap(s) (dropped by discard:). + */ + if (ref_count == 1 + map_count && + !folio_test_dirty(folio)) { /* Invalidate as we cleared the pte */ mmu_notifier_invalidate_range(mm, address, address + PAGE_SIZE); @@ -1629,11 +1700,11 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma, } /* - * If the page was redirtied, it cannot be + * If the folio was redirtied, it cannot be * discarded. Remap the page to page table. */ set_pte_at(mm, address, pvmw.pte, pteval); - SetPageSwapBacked(page); + folio_set_swapbacked(folio); ret = false; page_vma_mapped_walk_done(&pvmw); break; @@ -1646,11 +1717,33 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma, break; } if (arch_unmap_one(mm, vma, address, pteval) < 0) { + swap_free(entry); + set_pte_at(mm, address, pvmw.pte, pteval); + ret = false; + page_vma_mapped_walk_done(&pvmw); + break; + } + + /* See page_try_share_anon_rmap(): clear PTE first. */ + if (anon_exclusive && + page_try_share_anon_rmap(subpage)) { + swap_free(entry); set_pte_at(mm, address, pvmw.pte, pteval); ret = false; page_vma_mapped_walk_done(&pvmw); break; } + /* + * Note: We *don't* remember if the page was mapped + * exclusively in the swap pte if the architecture + * doesn't support __HAVE_ARCH_PTE_SWP_EXCLUSIVE. In + * that case, swapin code has to re-determine that + * manually and might detect the page as possibly + * shared, for example, if there are other references on + * the page or if the page is under writeback. We made + * sure that there are no GUP pins on the page that + * would rely on it, so for GUP pins this is fine. + */ if (list_empty(&mm->mmlist)) { spin_lock(&mmlist_lock); if (list_empty(&mm->mmlist)) @@ -1660,24 +1753,29 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma, dec_mm_counter(mm, MM_ANONPAGES); inc_mm_counter(mm, MM_SWAPENTS); swp_pte = swp_entry_to_pte(entry); + if (anon_exclusive) + swp_pte = pte_swp_mkexclusive(swp_pte); if (pte_soft_dirty(pteval)) swp_pte = pte_swp_mksoft_dirty(swp_pte); + if (pte_uffd_wp(pteval)) + swp_pte = pte_swp_mkuffd_wp(swp_pte); set_pte_at(mm, address, pvmw.pte, swp_pte); /* Invalidate as we cleared the pte */ mmu_notifier_invalidate_range(mm, address, address + PAGE_SIZE); } else { /* - * This is a locked file-backed page, thus it cannot - * be removed from the page cache and replaced by a new - * page before mmu_notifier_invalidate_range_end, so no - * concurrent thread might update its page table to - * point at new page while a device still is using this - * page. + * This is a locked file-backed folio, + * so it cannot be removed from the page + * cache and replaced by a new folio before + * mmu_notifier_invalidate_range_end, so no + * concurrent thread might update its page table + * to point at a new folio while a device is + * still using this folio. * - * See Documentation/vm/mmu_notifier.rst + * See Documentation/mm/mmu_notifier.rst */ - dec_mm_counter(mm, mm_counter_file(page)); + dec_mm_counter(mm, mm_counter_file(&folio->page)); } discard: /* @@ -1685,10 +1783,12 @@ discard: * done above for all cases requiring it to happen under page * table lock before mmu_notifier_invalidate_range_end() * - * See Documentation/vm/mmu_notifier.rst + * See Documentation/mm/mmu_notifier.rst */ - page_remove_rmap(subpage, PageHuge(page)); - put_page(page); + page_remove_rmap(subpage, vma, folio_test_hugetlb(folio)); + if (vma->vm_flags & VM_LOCKED) + mlock_page_drain_local(); + folio_put(folio); } mmu_notifier_invalidate_range_end(&range); @@ -1696,49 +1796,376 @@ discard: return ret; } -bool is_vma_temporary_stack(struct vm_area_struct *vma) -{ - int maybe_stack = vma->vm_flags & (VM_GROWSDOWN | VM_GROWSUP); - - if (!maybe_stack) - return false; - - if ((vma->vm_flags & VM_STACK_INCOMPLETE_SETUP) == - VM_STACK_INCOMPLETE_SETUP) - return true; - - return false; -} - static bool invalid_migration_vma(struct vm_area_struct *vma, void *arg) { - return is_vma_temporary_stack(vma); + return vma_is_temporary_stack(vma); } -static int page_mapcount_is_zero(struct page *page) +static int page_not_mapped(struct folio *folio) { - return !total_mapcount(page); + return !folio_mapped(folio); } /** - * try_to_unmap - try to remove all page table mappings to a page - * @page: the page to get unmapped + * try_to_unmap - Try to remove all page table mappings to a folio. + * @folio: The folio to unmap. * @flags: action and flags * * Tries to remove all the page table entries which are mapping this - * page, used in the pageout path. Caller must hold the page lock. + * folio. It is the caller's responsibility to check if the folio is + * still mapped if needed (use TTU_SYNC to prevent accounting races). * - * If unmap is successful, return true. Otherwise, false. + * Context: Caller must hold the folio lock. */ -bool try_to_unmap(struct page *page, enum ttu_flags flags) +void try_to_unmap(struct folio *folio, enum ttu_flags flags) { struct rmap_walk_control rwc = { .rmap_one = try_to_unmap_one, .arg = (void *)flags, - .done = page_mapcount_is_zero, - .anon_lock = page_lock_anon_vma_read, + .done = page_not_mapped, + .anon_lock = folio_lock_anon_vma_read, }; + if (flags & TTU_RMAP_LOCKED) + rmap_walk_locked(folio, &rwc); + else + rmap_walk(folio, &rwc); +} + +/* + * @arg: enum ttu_flags will be passed to this argument. + * + * If TTU_SPLIT_HUGE_PMD is specified any PMD mappings will be split into PTEs + * containing migration entries. + */ +static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma, + unsigned long address, void *arg) +{ + struct mm_struct *mm = vma->vm_mm; + DEFINE_FOLIO_VMA_WALK(pvmw, folio, vma, address, 0); + pte_t pteval; + struct page *subpage; + bool anon_exclusive, ret = true; + struct mmu_notifier_range range; + enum ttu_flags flags = (enum ttu_flags)(long)arg; + + /* + * When racing against e.g. zap_pte_range() on another cpu, + * in between its ptep_get_and_clear_full() and page_remove_rmap(), + * try_to_migrate() may return before page_mapped() has become false, + * if page table locking is skipped: use TTU_SYNC to wait for that. + */ + if (flags & TTU_SYNC) + pvmw.flags = PVMW_SYNC; + + /* + * unmap_page() in mm/huge_memory.c is the only user of migration with + * TTU_SPLIT_HUGE_PMD and it wants to freeze. + */ + if (flags & TTU_SPLIT_HUGE_PMD) + split_huge_pmd_address(vma, address, true, folio); + + /* + * For THP, we have to assume the worse case ie pmd for invalidation. + * For hugetlb, it could be much worse if we need to do pud + * invalidation in the case of pmd sharing. + * + * Note that the page can not be free in this function as call of + * try_to_unmap() must hold a reference on the page. + */ + range.end = vma_address_end(&pvmw); + mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, + address, range.end); + if (folio_test_hugetlb(folio)) { + /* + * If sharing is possible, start and end will be adjusted + * accordingly. + */ + adjust_range_if_pmd_sharing_possible(vma, &range.start, + &range.end); + } + mmu_notifier_invalidate_range_start(&range); + + while (page_vma_mapped_walk(&pvmw)) { +#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION + /* PMD-mapped THP migration entry */ + if (!pvmw.pte) { + subpage = folio_page(folio, + pmd_pfn(*pvmw.pmd) - folio_pfn(folio)); + VM_BUG_ON_FOLIO(folio_test_hugetlb(folio) || + !folio_test_pmd_mappable(folio), folio); + + if (set_pmd_migration_entry(&pvmw, subpage)) { + ret = false; + page_vma_mapped_walk_done(&pvmw); + break; + } + continue; + } +#endif + + /* Unexpected PMD-mapped THP? */ + VM_BUG_ON_FOLIO(!pvmw.pte, folio); + + if (folio_is_zone_device(folio)) { + /* + * Our PTE is a non-present device exclusive entry and + * calculating the subpage as for the common case would + * result in an invalid pointer. + * + * Since only PAGE_SIZE pages can currently be + * migrated, just set it to page. This will need to be + * changed when hugepage migrations to device private + * memory are supported. + */ + VM_BUG_ON_FOLIO(folio_nr_pages(folio) > 1, folio); + subpage = &folio->page; + } else { + subpage = folio_page(folio, + pte_pfn(*pvmw.pte) - folio_pfn(folio)); + } + address = pvmw.address; + anon_exclusive = folio_test_anon(folio) && + PageAnonExclusive(subpage); + + if (folio_test_hugetlb(folio)) { + bool anon = folio_test_anon(folio); + + /* + * huge_pmd_unshare may unmap an entire PMD page. + * There is no way of knowing exactly which PMDs may + * be cached for this mm, so we must flush them all. + * start/end were already adjusted above to cover this + * range. + */ + flush_cache_range(vma, range.start, range.end); + + /* + * To call huge_pmd_unshare, i_mmap_rwsem must be + * held in write mode. Caller needs to explicitly + * do this outside rmap routines. + * + * We also must hold hugetlb vma_lock in write mode. + * Lock order dictates acquiring vma_lock BEFORE + * i_mmap_rwsem. We can only try lock here and + * fail if unsuccessful. + */ + if (!anon) { + VM_BUG_ON(!(flags & TTU_RMAP_LOCKED)); + if (!hugetlb_vma_trylock_write(vma)) { + page_vma_mapped_walk_done(&pvmw); + ret = false; + break; + } + if (huge_pmd_unshare(mm, vma, address, pvmw.pte)) { + hugetlb_vma_unlock_write(vma); + flush_tlb_range(vma, + range.start, range.end); + mmu_notifier_invalidate_range(mm, + range.start, range.end); + + /* + * The ref count of the PMD page was + * dropped which is part of the way map + * counting is done for shared PMDs. + * Return 'true' here. When there is + * no other sharing, huge_pmd_unshare + * returns false and we will unmap the + * actual page and drop map count + * to zero. + */ + page_vma_mapped_walk_done(&pvmw); + break; + } + hugetlb_vma_unlock_write(vma); + } + /* Nuke the hugetlb page table entry */ + pteval = huge_ptep_clear_flush(vma, address, pvmw.pte); + } else { + flush_cache_page(vma, address, pte_pfn(*pvmw.pte)); + /* Nuke the page table entry. */ + pteval = ptep_clear_flush(vma, address, pvmw.pte); + } + + /* Set the dirty flag on the folio now the pte is gone. */ + if (pte_dirty(pteval)) + folio_mark_dirty(folio); + + /* Update high watermark before we lower rss */ + update_hiwater_rss(mm); + + if (folio_is_device_private(folio)) { + unsigned long pfn = folio_pfn(folio); + swp_entry_t entry; + pte_t swp_pte; + + if (anon_exclusive) + BUG_ON(page_try_share_anon_rmap(subpage)); + + /* + * Store the pfn of the page in a special migration + * pte. do_swap_page() will wait until the migration + * pte is removed and then restart fault handling. + */ + entry = pte_to_swp_entry(pteval); + if (is_writable_device_private_entry(entry)) + entry = make_writable_migration_entry(pfn); + else if (anon_exclusive) + entry = make_readable_exclusive_migration_entry(pfn); + else + entry = make_readable_migration_entry(pfn); + swp_pte = swp_entry_to_pte(entry); + + /* + * pteval maps a zone device page and is therefore + * a swap pte. + */ + if (pte_swp_soft_dirty(pteval)) + swp_pte = pte_swp_mksoft_dirty(swp_pte); + if (pte_swp_uffd_wp(pteval)) + swp_pte = pte_swp_mkuffd_wp(swp_pte); + set_pte_at(mm, pvmw.address, pvmw.pte, swp_pte); + trace_set_migration_pte(pvmw.address, pte_val(swp_pte), + compound_order(&folio->page)); + /* + * No need to invalidate here it will synchronize on + * against the special swap migration pte. + */ + } else if (PageHWPoison(subpage)) { + pteval = swp_entry_to_pte(make_hwpoison_entry(subpage)); + if (folio_test_hugetlb(folio)) { + hugetlb_count_sub(folio_nr_pages(folio), mm); + set_huge_pte_at(mm, address, pvmw.pte, pteval); + } else { + dec_mm_counter(mm, mm_counter(&folio->page)); + set_pte_at(mm, address, pvmw.pte, pteval); + } + + } else if (pte_unused(pteval) && !userfaultfd_armed(vma)) { + /* + * The guest indicated that the page content is of no + * interest anymore. Simply discard the pte, vmscan + * will take care of the rest. + * A future reference will then fault in a new zero + * page. When userfaultfd is active, we must not drop + * this page though, as its main user (postcopy + * migration) will not expect userfaults on already + * copied pages. + */ + dec_mm_counter(mm, mm_counter(&folio->page)); + /* We have to invalidate as we cleared the pte */ + mmu_notifier_invalidate_range(mm, address, + address + PAGE_SIZE); + } else { + swp_entry_t entry; + pte_t swp_pte; + + if (arch_unmap_one(mm, vma, address, pteval) < 0) { + if (folio_test_hugetlb(folio)) + set_huge_pte_at(mm, address, pvmw.pte, pteval); + else + set_pte_at(mm, address, pvmw.pte, pteval); + ret = false; + page_vma_mapped_walk_done(&pvmw); + break; + } + VM_BUG_ON_PAGE(pte_write(pteval) && folio_test_anon(folio) && + !anon_exclusive, subpage); + + /* See page_try_share_anon_rmap(): clear PTE first. */ + if (anon_exclusive && + page_try_share_anon_rmap(subpage)) { + if (folio_test_hugetlb(folio)) + set_huge_pte_at(mm, address, pvmw.pte, pteval); + else + set_pte_at(mm, address, pvmw.pte, pteval); + ret = false; + page_vma_mapped_walk_done(&pvmw); + break; + } + + /* + * Store the pfn of the page in a special migration + * pte. do_swap_page() will wait until the migration + * pte is removed and then restart fault handling. + */ + if (pte_write(pteval)) + entry = make_writable_migration_entry( + page_to_pfn(subpage)); + else if (anon_exclusive) + entry = make_readable_exclusive_migration_entry( + page_to_pfn(subpage)); + else + entry = make_readable_migration_entry( + page_to_pfn(subpage)); + if (pte_young(pteval)) + entry = make_migration_entry_young(entry); + if (pte_dirty(pteval)) + entry = make_migration_entry_dirty(entry); + swp_pte = swp_entry_to_pte(entry); + if (pte_soft_dirty(pteval)) + swp_pte = pte_swp_mksoft_dirty(swp_pte); + if (pte_uffd_wp(pteval)) + swp_pte = pte_swp_mkuffd_wp(swp_pte); + if (folio_test_hugetlb(folio)) + set_huge_pte_at(mm, address, pvmw.pte, swp_pte); + else + set_pte_at(mm, address, pvmw.pte, swp_pte); + trace_set_migration_pte(address, pte_val(swp_pte), + compound_order(&folio->page)); + /* + * No need to invalidate here it will synchronize on + * against the special swap migration pte. + */ + } + + /* + * No need to call mmu_notifier_invalidate_range() it has be + * done above for all cases requiring it to happen under page + * table lock before mmu_notifier_invalidate_range_end() + * + * See Documentation/mm/mmu_notifier.rst + */ + page_remove_rmap(subpage, vma, folio_test_hugetlb(folio)); + if (vma->vm_flags & VM_LOCKED) + mlock_page_drain_local(); + folio_put(folio); + } + + mmu_notifier_invalidate_range_end(&range); + + return ret; +} + +/** + * try_to_migrate - try to replace all page table mappings with swap entries + * @folio: the folio to replace page table entries for + * @flags: action and flags + * + * Tries to remove all the page table entries which are mapping this folio and + * replace them with special swap entries. Caller must hold the folio lock. + */ +void try_to_migrate(struct folio *folio, enum ttu_flags flags) +{ + struct rmap_walk_control rwc = { + .rmap_one = try_to_migrate_one, + .arg = (void *)flags, + .done = page_not_mapped, + .anon_lock = folio_lock_anon_vma_read, + }; + + /* + * Migration always ignores mlock and only supports TTU_RMAP_LOCKED and + * TTU_SPLIT_HUGE_PMD and TTU_SYNC flags. + */ + if (WARN_ON_ONCE(flags & ~(TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD | + TTU_SYNC))) + return; + + if (folio_is_zone_device(folio) && + (!folio_is_device_private(folio) && !folio_is_device_coherent(folio))) + return; + /* * During exec, a temporary VMA is setup and later moved. * The VMA is moved under the anon_vma lock but not the @@ -1747,48 +2174,200 @@ bool try_to_unmap(struct page *page, enum ttu_flags flags) * locking requirements of exec(), migration skips * temporary VMAs until after exec() completes. */ - if ((flags & (TTU_MIGRATION|TTU_SPLIT_FREEZE)) - && !PageKsm(page) && PageAnon(page)) + if (!folio_test_ksm(folio) && folio_test_anon(folio)) rwc.invalid_vma = invalid_migration_vma; if (flags & TTU_RMAP_LOCKED) - rmap_walk_locked(page, &rwc); + rmap_walk_locked(folio, &rwc); else - rmap_walk(page, &rwc); - - return !page_mapcount(page) ? true : false; + rmap_walk(folio, &rwc); } -static int page_not_mapped(struct page *page) -{ - return !page_mapped(page); +#ifdef CONFIG_DEVICE_PRIVATE +struct make_exclusive_args { + struct mm_struct *mm; + unsigned long address; + void *owner; + bool valid; }; +static bool page_make_device_exclusive_one(struct folio *folio, + struct vm_area_struct *vma, unsigned long address, void *priv) +{ + struct mm_struct *mm = vma->vm_mm; + DEFINE_FOLIO_VMA_WALK(pvmw, folio, vma, address, 0); + struct make_exclusive_args *args = priv; + pte_t pteval; + struct page *subpage; + bool ret = true; + struct mmu_notifier_range range; + swp_entry_t entry; + pte_t swp_pte; + + mmu_notifier_range_init_owner(&range, MMU_NOTIFY_EXCLUSIVE, 0, vma, + vma->vm_mm, address, min(vma->vm_end, + address + folio_size(folio)), + args->owner); + mmu_notifier_invalidate_range_start(&range); + + while (page_vma_mapped_walk(&pvmw)) { + /* Unexpected PMD-mapped THP? */ + VM_BUG_ON_FOLIO(!pvmw.pte, folio); + + if (!pte_present(*pvmw.pte)) { + ret = false; + page_vma_mapped_walk_done(&pvmw); + break; + } + + subpage = folio_page(folio, + pte_pfn(*pvmw.pte) - folio_pfn(folio)); + address = pvmw.address; + + /* Nuke the page table entry. */ + flush_cache_page(vma, address, pte_pfn(*pvmw.pte)); + pteval = ptep_clear_flush(vma, address, pvmw.pte); + + /* Set the dirty flag on the folio now the pte is gone. */ + if (pte_dirty(pteval)) + folio_mark_dirty(folio); + + /* + * Check that our target page is still mapped at the expected + * address. + */ + if (args->mm == mm && args->address == address && + pte_write(pteval)) + args->valid = true; + + /* + * Store the pfn of the page in a special migration + * pte. do_swap_page() will wait until the migration + * pte is removed and then restart fault handling. + */ + if (pte_write(pteval)) + entry = make_writable_device_exclusive_entry( + page_to_pfn(subpage)); + else + entry = make_readable_device_exclusive_entry( + page_to_pfn(subpage)); + swp_pte = swp_entry_to_pte(entry); + if (pte_soft_dirty(pteval)) + swp_pte = pte_swp_mksoft_dirty(swp_pte); + if (pte_uffd_wp(pteval)) + swp_pte = pte_swp_mkuffd_wp(swp_pte); + + set_pte_at(mm, address, pvmw.pte, swp_pte); + + /* + * There is a reference on the page for the swap entry which has + * been removed, so shouldn't take another. + */ + page_remove_rmap(subpage, vma, false); + } + + mmu_notifier_invalidate_range_end(&range); + + return ret; +} + /** - * try_to_munlock - try to munlock a page - * @page: the page to be munlocked + * folio_make_device_exclusive - Mark the folio exclusively owned by a device. + * @folio: The folio to replace page table entries for. + * @mm: The mm_struct where the folio is expected to be mapped. + * @address: Address where the folio is expected to be mapped. + * @owner: passed to MMU_NOTIFY_EXCLUSIVE range notifier callbacks + * + * Tries to remove all the page table entries which are mapping this + * folio and replace them with special device exclusive swap entries to + * grant a device exclusive access to the folio. * - * Called from munlock code. Checks all of the VMAs mapping the page - * to make sure nobody else has this page mlocked. The page will be - * returned with PG_mlocked cleared if no other vmas have it mlocked. + * Context: Caller must hold the folio lock. + * Return: false if the page is still mapped, or if it could not be unmapped + * from the expected address. Otherwise returns true (success). */ - -void try_to_munlock(struct page *page) +static bool folio_make_device_exclusive(struct folio *folio, + struct mm_struct *mm, unsigned long address, void *owner) { + struct make_exclusive_args args = { + .mm = mm, + .address = address, + .owner = owner, + .valid = false, + }; struct rmap_walk_control rwc = { - .rmap_one = try_to_unmap_one, - .arg = (void *)TTU_MUNLOCK, + .rmap_one = page_make_device_exclusive_one, .done = page_not_mapped, - .anon_lock = page_lock_anon_vma_read, - + .anon_lock = folio_lock_anon_vma_read, + .arg = &args, }; - VM_BUG_ON_PAGE(!PageLocked(page) || PageLRU(page), page); - VM_BUG_ON_PAGE(PageCompound(page) && PageDoubleMap(page), page); + /* + * Restrict to anonymous folios for now to avoid potential writeback + * issues. + */ + if (!folio_test_anon(folio)) + return false; + + rmap_walk(folio, &rwc); - rmap_walk(page, &rwc); + return args.valid && !folio_mapcount(folio); } +/** + * make_device_exclusive_range() - Mark a range for exclusive use by a device + * @mm: mm_struct of associated target process + * @start: start of the region to mark for exclusive device access + * @end: end address of region + * @pages: returns the pages which were successfully marked for exclusive access + * @owner: passed to MMU_NOTIFY_EXCLUSIVE range notifier to allow filtering + * + * Returns: number of pages found in the range by GUP. A page is marked for + * exclusive access only if the page pointer is non-NULL. + * + * This function finds ptes mapping page(s) to the given address range, locks + * them and replaces mappings with special swap entries preventing userspace CPU + * access. On fault these entries are replaced with the original mapping after + * calling MMU notifiers. + * + * A driver using this to program access from a device must use a mmu notifier + * critical section to hold a device specific lock during programming. Once + * programming is complete it should drop the page lock and reference after + * which point CPU access to the page will revoke the exclusive access. + */ +int make_device_exclusive_range(struct mm_struct *mm, unsigned long start, + unsigned long end, struct page **pages, + void *owner) +{ + long npages = (end - start) >> PAGE_SHIFT; + long i; + + npages = get_user_pages_remote(mm, start, npages, + FOLL_GET | FOLL_WRITE | FOLL_SPLIT_PMD, + pages, NULL, NULL); + if (npages < 0) + return npages; + + for (i = 0; i < npages; i++, start += PAGE_SIZE) { + struct folio *folio = page_folio(pages[i]); + if (PageTail(pages[i]) || !folio_trylock(folio)) { + folio_put(folio); + pages[i] = NULL; + continue; + } + + if (!folio_make_device_exclusive(folio, mm, start, owner)) { + folio_unlock(folio); + folio_put(folio); + pages[i] = NULL; + } + } + + return npages; +} +EXPORT_SYMBOL_GPL(make_device_exclusive_range); +#endif + void __put_anon_vma(struct anon_vma *anon_vma) { struct anon_vma *root = anon_vma->root; @@ -1798,25 +2377,35 @@ void __put_anon_vma(struct anon_vma *anon_vma) anon_vma_free(root); } -static struct anon_vma *rmap_walk_anon_lock(struct page *page, - struct rmap_walk_control *rwc) +static struct anon_vma *rmap_walk_anon_lock(struct folio *folio, + struct rmap_walk_control *rwc) { struct anon_vma *anon_vma; if (rwc->anon_lock) - return rwc->anon_lock(page); + return rwc->anon_lock(folio, rwc); /* - * Note: remove_migration_ptes() cannot use page_lock_anon_vma_read() + * Note: remove_migration_ptes() cannot use folio_lock_anon_vma_read() * because that depends on page_mapped(); but not all its usages - * are holding mmap_sem. Users without mmap_sem are required to + * are holding mmap_lock. Users without mmap_lock are required to * take a reference count to prevent the anon_vma disappearing */ - anon_vma = page_anon_vma(page); + anon_vma = folio_anon_vma(folio); if (!anon_vma) return NULL; + if (anon_vma_trylock_read(anon_vma)) + goto out; + + if (rwc->try_lock) { + anon_vma = NULL; + rwc->contended = true; + goto out; + } + anon_vma_lock_read(anon_vma); +out: return anon_vma; } @@ -1828,44 +2417,40 @@ static struct anon_vma *rmap_walk_anon_lock(struct page *page, * * Find all the mappings of a page using the mapping pointer and the vma chains * contained in the anon_vma struct it points to. - * - * When called from try_to_munlock(), the mmap_sem of the mm containing the vma - * where the page was found will be held for write. So, we won't recheck - * vm_flags for that VMA. That should be OK, because that vma shouldn't be - * LOCKED. */ -static void rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc, - bool locked) +static void rmap_walk_anon(struct folio *folio, + struct rmap_walk_control *rwc, bool locked) { struct anon_vma *anon_vma; pgoff_t pgoff_start, pgoff_end; struct anon_vma_chain *avc; if (locked) { - anon_vma = page_anon_vma(page); + anon_vma = folio_anon_vma(folio); /* anon_vma disappear under us? */ - VM_BUG_ON_PAGE(!anon_vma, page); + VM_BUG_ON_FOLIO(!anon_vma, folio); } else { - anon_vma = rmap_walk_anon_lock(page, rwc); + anon_vma = rmap_walk_anon_lock(folio, rwc); } if (!anon_vma) return; - pgoff_start = page_to_pgoff(page); - pgoff_end = pgoff_start + hpage_nr_pages(page) - 1; + pgoff_start = folio_pgoff(folio); + pgoff_end = pgoff_start + folio_nr_pages(folio) - 1; anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff_start, pgoff_end) { struct vm_area_struct *vma = avc->vma; - unsigned long address = vma_address(page, vma); + unsigned long address = vma_address(&folio->page, vma); + VM_BUG_ON_VMA(address == -EFAULT, vma); cond_resched(); if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg)) continue; - if (!rwc->rmap_one(page, vma, address, rwc->arg)) + if (!rwc->rmap_one(folio, vma, address, rwc->arg)) break; - if (rwc->done && rwc->done(page)) + if (rwc->done && rwc->done(folio)) break; } @@ -1880,16 +2465,11 @@ static void rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc, * * Find all the mappings of a page using the mapping pointer and the vma chains * contained in the address_space struct it points to. - * - * When called from try_to_munlock(), the mmap_sem of the mm containing the vma - * where the page was found will be held for write. So, we won't recheck - * vm_flags for that VMA. That should be OK, because that vma shouldn't be - * LOCKED. */ -static void rmap_walk_file(struct page *page, struct rmap_walk_control *rwc, - bool locked) +static void rmap_walk_file(struct folio *folio, + struct rmap_walk_control *rwc, bool locked) { - struct address_space *mapping = page_mapping(page); + struct address_space *mapping = folio_mapping(folio); pgoff_t pgoff_start, pgoff_end; struct vm_area_struct *vma; @@ -1899,27 +2479,38 @@ static void rmap_walk_file(struct page *page, struct rmap_walk_control *rwc, * structure at mapping cannot be freed and reused yet, * so we can safely take mapping->i_mmap_rwsem. */ - VM_BUG_ON_PAGE(!PageLocked(page), page); + VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); if (!mapping) return; - pgoff_start = page_to_pgoff(page); - pgoff_end = pgoff_start + hpage_nr_pages(page) - 1; - if (!locked) + pgoff_start = folio_pgoff(folio); + pgoff_end = pgoff_start + folio_nr_pages(folio) - 1; + if (!locked) { + if (i_mmap_trylock_read(mapping)) + goto lookup; + + if (rwc->try_lock) { + rwc->contended = true; + return; + } + i_mmap_lock_read(mapping); + } +lookup: vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff_start, pgoff_end) { - unsigned long address = vma_address(page, vma); + unsigned long address = vma_address(&folio->page, vma); + VM_BUG_ON_VMA(address == -EFAULT, vma); cond_resched(); if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg)) continue; - if (!rwc->rmap_one(page, vma, address, rwc->arg)) + if (!rwc->rmap_one(folio, vma, address, rwc->arg)) goto done; - if (rwc->done && rwc->done(page)) + if (rwc->done && rwc->done(folio)) goto done; } @@ -1928,25 +2519,25 @@ done: i_mmap_unlock_read(mapping); } -void rmap_walk(struct page *page, struct rmap_walk_control *rwc) +void rmap_walk(struct folio *folio, struct rmap_walk_control *rwc) { - if (unlikely(PageKsm(page))) - rmap_walk_ksm(page, rwc); - else if (PageAnon(page)) - rmap_walk_anon(page, rwc, false); + if (unlikely(folio_test_ksm(folio))) + rmap_walk_ksm(folio, rwc); + else if (folio_test_anon(folio)) + rmap_walk_anon(folio, rwc, false); else - rmap_walk_file(page, rwc, false); + rmap_walk_file(folio, rwc, false); } /* Like rmap_walk, but caller holds relevant rmap lock */ -void rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc) +void rmap_walk_locked(struct folio *folio, struct rmap_walk_control *rwc) { /* no ksm support for now */ - VM_BUG_ON_PAGE(PageKsm(page), page); - if (PageAnon(page)) - rmap_walk_anon(page, rwc, true); + VM_BUG_ON_FOLIO(folio_test_ksm(folio), folio); + if (folio_test_anon(folio)) + rmap_walk_anon(folio, rwc, true); else - rmap_walk_file(page, rwc, true); + rmap_walk_file(folio, rwc, true); } #ifdef CONFIG_HUGETLB_PAGE @@ -1954,9 +2545,11 @@ void rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc) * The following two functions are for anonymous (private mapped) hugepages. * Unlike common anonymous pages, anonymous hugepages have no accounting code * and no lru code, because we handle hugepages differently from common pages. + * + * RMAP_COMPOUND is ignored. */ -void hugepage_add_anon_rmap(struct page *page, - struct vm_area_struct *vma, unsigned long address) +void hugepage_add_anon_rmap(struct page *page, struct vm_area_struct *vma, + unsigned long address, rmap_t flags) { struct anon_vma *anon_vma = vma->anon_vma; int first; @@ -1965,8 +2558,11 @@ void hugepage_add_anon_rmap(struct page *page, BUG_ON(!anon_vma); /* address might be in next vma when migration races vma_adjust */ first = atomic_inc_and_test(compound_mapcount_ptr(page)); + VM_BUG_ON_PAGE(!first && (flags & RMAP_EXCLUSIVE), page); + VM_BUG_ON_PAGE(!first && PageAnonExclusive(page), page); if (first) - __page_set_anon_rmap(page, vma, address, 0); + __page_set_anon_rmap(page, vma, address, + !!(flags & RMAP_EXCLUSIVE)); } void hugepage_add_new_anon_rmap(struct page *page, @@ -1974,6 +2570,8 @@ void hugepage_add_new_anon_rmap(struct page *page, { BUG_ON(address < vma->vm_start || address >= vma->vm_end); atomic_set(compound_mapcount_ptr(page), 0); + atomic_set(compound_pincount_ptr(page), 0); + __page_set_anon_rmap(page, vma, address, 1); } #endif /* CONFIG_HUGETLB_PAGE */ |