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059ab7be09
Removes two unnecessary conversions from folio to page. Should be no difference in behaviour. Link: https://lkml.kernel.org/r/20240215205307.674707-1-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2724 lines
79 KiB
C
2724 lines
79 KiB
C
/*
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* mm/rmap.c - physical to virtual reverse mappings
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*
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* Copyright 2001, Rik van Riel <riel@conectiva.com.br>
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* Released under the General Public License (GPL).
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*
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* Simple, low overhead reverse mapping scheme.
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* Please try to keep this thing as modular as possible.
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*
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* Provides methods for unmapping each kind of mapped page:
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* the anon methods track anonymous pages, and
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* the file methods track pages belonging to an inode.
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*
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* Original design by Rik van Riel <riel@conectiva.com.br> 2001
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* File methods by Dave McCracken <dmccr@us.ibm.com> 2003, 2004
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* Anonymous methods by Andrea Arcangeli <andrea@suse.de> 2004
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* Contributions by Hugh Dickins 2003, 2004
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*/
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/*
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* Lock ordering in mm:
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*
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* inode->i_rwsem (while writing or truncating, not reading or faulting)
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* mm->mmap_lock
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* mapping->invalidate_lock (in filemap_fault)
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* page->flags PG_locked (lock_page)
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* hugetlbfs_i_mmap_rwsem_key (in huge_pmd_share, see hugetlbfs below)
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* vma_start_write
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* mapping->i_mmap_rwsem
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* anon_vma->rwsem
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* mm->page_table_lock or pte_lock
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* swap_lock (in swap_duplicate, swap_info_get)
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* mmlist_lock (in mmput, drain_mmlist and others)
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* mapping->private_lock (in block_dirty_folio)
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* folio_lock_memcg move_lock (in block_dirty_folio)
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* i_pages lock (widely used)
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* lruvec->lru_lock (in folio_lruvec_lock_irq)
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* inode->i_lock (in set_page_dirty's __mark_inode_dirty)
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* bdi.wb->list_lock (in set_page_dirty's __mark_inode_dirty)
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* sb_lock (within inode_lock in fs/fs-writeback.c)
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* i_pages lock (widely used, in set_page_dirty,
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* in arch-dependent flush_dcache_mmap_lock,
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* within bdi.wb->list_lock in __sync_single_inode)
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*
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* anon_vma->rwsem,mapping->i_mmap_rwsem (memory_failure, collect_procs_anon)
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* ->tasklist_lock
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* pte map lock
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*
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* hugetlbfs PageHuge() take locks in this order:
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* hugetlb_fault_mutex (hugetlbfs specific page fault mutex)
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* vma_lock (hugetlb specific lock for pmd_sharing)
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* mapping->i_mmap_rwsem (also used for hugetlb pmd sharing)
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* page->flags PG_locked (lock_page)
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*/
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#include <linux/mm.h>
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#include <linux/sched/mm.h>
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#include <linux/sched/task.h>
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#include <linux/pagemap.h>
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#include <linux/swap.h>
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#include <linux/swapops.h>
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/ksm.h>
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#include <linux/rmap.h>
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#include <linux/rcupdate.h>
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#include <linux/export.h>
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#include <linux/memcontrol.h>
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#include <linux/mmu_notifier.h>
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#include <linux/migrate.h>
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#include <linux/hugetlb.h>
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#include <linux/huge_mm.h>
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#include <linux/backing-dev.h>
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#include <linux/page_idle.h>
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#include <linux/memremap.h>
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#include <linux/userfaultfd_k.h>
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#include <linux/mm_inline.h>
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#include <asm/tlbflush.h>
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#define CREATE_TRACE_POINTS
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#include <trace/events/tlb.h>
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#include <trace/events/migrate.h>
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#include "internal.h"
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static struct kmem_cache *anon_vma_cachep;
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static struct kmem_cache *anon_vma_chain_cachep;
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static inline struct anon_vma *anon_vma_alloc(void)
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{
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struct anon_vma *anon_vma;
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anon_vma = kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL);
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if (anon_vma) {
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atomic_set(&anon_vma->refcount, 1);
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anon_vma->num_children = 0;
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anon_vma->num_active_vmas = 0;
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anon_vma->parent = anon_vma;
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/*
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* Initialise the anon_vma root to point to itself. If called
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* from fork, the root will be reset to the parents anon_vma.
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*/
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anon_vma->root = anon_vma;
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}
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return anon_vma;
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}
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static inline void anon_vma_free(struct anon_vma *anon_vma)
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{
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VM_BUG_ON(atomic_read(&anon_vma->refcount));
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/*
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* Synchronize against folio_lock_anon_vma_read() such that
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* we can safely hold the lock without the anon_vma getting
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* freed.
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*
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* Relies on the full mb implied by the atomic_dec_and_test() from
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* put_anon_vma() against the acquire barrier implied by
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* down_read_trylock() from folio_lock_anon_vma_read(). This orders:
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*
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* folio_lock_anon_vma_read() VS put_anon_vma()
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* down_read_trylock() atomic_dec_and_test()
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* LOCK MB
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* atomic_read() rwsem_is_locked()
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*
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* LOCK should suffice since the actual taking of the lock must
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* happen _before_ what follows.
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*/
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might_sleep();
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if (rwsem_is_locked(&anon_vma->root->rwsem)) {
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anon_vma_lock_write(anon_vma);
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anon_vma_unlock_write(anon_vma);
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}
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kmem_cache_free(anon_vma_cachep, anon_vma);
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}
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static inline struct anon_vma_chain *anon_vma_chain_alloc(gfp_t gfp)
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{
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return kmem_cache_alloc(anon_vma_chain_cachep, gfp);
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}
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static void anon_vma_chain_free(struct anon_vma_chain *anon_vma_chain)
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{
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kmem_cache_free(anon_vma_chain_cachep, anon_vma_chain);
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}
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static void anon_vma_chain_link(struct vm_area_struct *vma,
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struct anon_vma_chain *avc,
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struct anon_vma *anon_vma)
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{
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avc->vma = vma;
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avc->anon_vma = anon_vma;
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list_add(&avc->same_vma, &vma->anon_vma_chain);
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anon_vma_interval_tree_insert(avc, &anon_vma->rb_root);
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}
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/**
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* __anon_vma_prepare - attach an anon_vma to a memory region
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* @vma: the memory region in question
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*
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* This makes sure the memory mapping described by 'vma' has
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* an 'anon_vma' attached to it, so that we can associate the
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* anonymous pages mapped into it with that anon_vma.
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*
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* The common case will be that we already have one, which
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* is handled inline by anon_vma_prepare(). But if
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* not we either need to find an adjacent mapping that we
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* can re-use the anon_vma from (very common when the only
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* reason for splitting a vma has been mprotect()), or we
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* allocate a new one.
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*
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* Anon-vma allocations are very subtle, because we may have
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* optimistically looked up an anon_vma in folio_lock_anon_vma_read()
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* and that may actually touch the rwsem even in the newly
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* allocated vma (it depends on RCU to make sure that the
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* anon_vma isn't actually destroyed).
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*
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* As a result, we need to do proper anon_vma locking even
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* for the new allocation. At the same time, we do not want
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* to do any locking for the common case of already having
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* an anon_vma.
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*
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* This must be called with the mmap_lock held for reading.
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*/
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int __anon_vma_prepare(struct vm_area_struct *vma)
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{
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struct mm_struct *mm = vma->vm_mm;
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struct anon_vma *anon_vma, *allocated;
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struct anon_vma_chain *avc;
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might_sleep();
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avc = anon_vma_chain_alloc(GFP_KERNEL);
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if (!avc)
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goto out_enomem;
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anon_vma = find_mergeable_anon_vma(vma);
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allocated = NULL;
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if (!anon_vma) {
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anon_vma = anon_vma_alloc();
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if (unlikely(!anon_vma))
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goto out_enomem_free_avc;
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anon_vma->num_children++; /* self-parent link for new root */
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allocated = anon_vma;
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}
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anon_vma_lock_write(anon_vma);
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/* page_table_lock to protect against threads */
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spin_lock(&mm->page_table_lock);
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if (likely(!vma->anon_vma)) {
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vma->anon_vma = anon_vma;
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anon_vma_chain_link(vma, avc, anon_vma);
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anon_vma->num_active_vmas++;
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allocated = NULL;
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avc = NULL;
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}
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spin_unlock(&mm->page_table_lock);
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anon_vma_unlock_write(anon_vma);
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if (unlikely(allocated))
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put_anon_vma(allocated);
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if (unlikely(avc))
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anon_vma_chain_free(avc);
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return 0;
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out_enomem_free_avc:
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anon_vma_chain_free(avc);
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out_enomem:
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return -ENOMEM;
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}
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/*
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* This is a useful helper function for locking the anon_vma root as
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* we traverse the vma->anon_vma_chain, looping over anon_vma's that
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* have the same vma.
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*
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* Such anon_vma's should have the same root, so you'd expect to see
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* just a single mutex_lock for the whole traversal.
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*/
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static inline struct anon_vma *lock_anon_vma_root(struct anon_vma *root, struct anon_vma *anon_vma)
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{
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struct anon_vma *new_root = anon_vma->root;
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if (new_root != root) {
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if (WARN_ON_ONCE(root))
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up_write(&root->rwsem);
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root = new_root;
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down_write(&root->rwsem);
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}
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return root;
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}
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static inline void unlock_anon_vma_root(struct anon_vma *root)
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{
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if (root)
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up_write(&root->rwsem);
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}
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/*
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* Attach the anon_vmas from src to dst.
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* Returns 0 on success, -ENOMEM on failure.
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*
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* anon_vma_clone() is called by vma_expand(), vma_merge(), __split_vma(),
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* copy_vma() and anon_vma_fork(). The first four want an exact copy of src,
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* while the last one, anon_vma_fork(), may try to reuse an existing anon_vma to
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* prevent endless growth of anon_vma. Since dst->anon_vma is set to NULL before
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* call, we can identify this case by checking (!dst->anon_vma &&
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* src->anon_vma).
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*
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* If (!dst->anon_vma && src->anon_vma) is true, this function tries to find
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* and reuse existing anon_vma which has no vmas and only one child anon_vma.
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* This prevents degradation of anon_vma hierarchy to endless linear chain in
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* case of constantly forking task. On the other hand, an anon_vma with more
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* than one child isn't reused even if there was no alive vma, thus rmap
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* walker has a good chance of avoiding scanning the whole hierarchy when it
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* searches where page is mapped.
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*/
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int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src)
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{
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struct anon_vma_chain *avc, *pavc;
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struct anon_vma *root = NULL;
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list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) {
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struct anon_vma *anon_vma;
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avc = anon_vma_chain_alloc(GFP_NOWAIT | __GFP_NOWARN);
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if (unlikely(!avc)) {
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unlock_anon_vma_root(root);
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root = NULL;
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avc = anon_vma_chain_alloc(GFP_KERNEL);
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if (!avc)
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goto enomem_failure;
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}
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anon_vma = pavc->anon_vma;
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root = lock_anon_vma_root(root, anon_vma);
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anon_vma_chain_link(dst, avc, anon_vma);
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/*
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* Reuse existing anon_vma if it has no vma and only one
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* anon_vma child.
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*
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* Root anon_vma is never reused:
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* it has self-parent reference and at least one child.
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*/
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if (!dst->anon_vma && src->anon_vma &&
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anon_vma->num_children < 2 &&
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anon_vma->num_active_vmas == 0)
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dst->anon_vma = anon_vma;
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}
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if (dst->anon_vma)
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dst->anon_vma->num_active_vmas++;
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unlock_anon_vma_root(root);
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return 0;
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enomem_failure:
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/*
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* dst->anon_vma is dropped here otherwise its num_active_vmas can
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* be incorrectly decremented in unlink_anon_vmas().
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* We can safely do this because callers of anon_vma_clone() don't care
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* about dst->anon_vma if anon_vma_clone() failed.
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*/
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dst->anon_vma = NULL;
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unlink_anon_vmas(dst);
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return -ENOMEM;
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}
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/*
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* Attach vma to its own anon_vma, as well as to the anon_vmas that
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* the corresponding VMA in the parent process is attached to.
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* Returns 0 on success, non-zero on failure.
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*/
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int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma)
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{
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struct anon_vma_chain *avc;
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struct anon_vma *anon_vma;
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int error;
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/* Don't bother if the parent process has no anon_vma here. */
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if (!pvma->anon_vma)
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return 0;
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/* Drop inherited anon_vma, we'll reuse existing or allocate new. */
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vma->anon_vma = NULL;
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/*
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* First, attach the new VMA to the parent VMA's anon_vmas,
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* so rmap can find non-COWed pages in child processes.
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*/
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error = anon_vma_clone(vma, pvma);
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if (error)
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return error;
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/* An existing anon_vma has been reused, all done then. */
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if (vma->anon_vma)
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return 0;
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/* Then add our own anon_vma. */
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anon_vma = anon_vma_alloc();
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if (!anon_vma)
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goto out_error;
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anon_vma->num_active_vmas++;
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avc = anon_vma_chain_alloc(GFP_KERNEL);
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if (!avc)
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goto out_error_free_anon_vma;
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/*
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* The root anon_vma's rwsem is the lock actually used when we
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* lock any of the anon_vmas in this anon_vma tree.
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*/
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anon_vma->root = pvma->anon_vma->root;
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anon_vma->parent = pvma->anon_vma;
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/*
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* With refcounts, an anon_vma can stay around longer than the
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* process it belongs to. The root anon_vma needs to be pinned until
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* this anon_vma is freed, because the lock lives in the root.
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*/
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get_anon_vma(anon_vma->root);
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/* Mark this anon_vma as the one where our new (COWed) pages go. */
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vma->anon_vma = anon_vma;
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anon_vma_lock_write(anon_vma);
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anon_vma_chain_link(vma, avc, anon_vma);
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anon_vma->parent->num_children++;
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anon_vma_unlock_write(anon_vma);
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return 0;
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|
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out_error_free_anon_vma:
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put_anon_vma(anon_vma);
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out_error:
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unlink_anon_vmas(vma);
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return -ENOMEM;
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}
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|
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void unlink_anon_vmas(struct vm_area_struct *vma)
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{
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struct anon_vma_chain *avc, *next;
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struct anon_vma *root = NULL;
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|
|
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/*
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* Unlink each anon_vma chained to the VMA. This list is ordered
|
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* from newest to oldest, ensuring the root anon_vma gets freed last.
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*/
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list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) {
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struct anon_vma *anon_vma = avc->anon_vma;
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|
|
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root = lock_anon_vma_root(root, anon_vma);
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anon_vma_interval_tree_remove(avc, &anon_vma->rb_root);
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|
|
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/*
|
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* Leave empty anon_vmas on the list - we'll need
|
|
* to free them outside the lock.
|
|
*/
|
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if (RB_EMPTY_ROOT(&anon_vma->rb_root.rb_root)) {
|
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anon_vma->parent->num_children--;
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continue;
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}
|
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|
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list_del(&avc->same_vma);
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anon_vma_chain_free(avc);
|
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}
|
|
if (vma->anon_vma) {
|
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vma->anon_vma->num_active_vmas--;
|
|
|
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/*
|
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* vma would still be needed after unlink, and anon_vma will be prepared
|
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* when handle fault.
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*/
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vma->anon_vma = NULL;
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}
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unlock_anon_vma_root(root);
|
|
|
|
/*
|
|
* Iterate the list once more, it now only contains empty and unlinked
|
|
* anon_vmas, destroy them. Could not do before due to __put_anon_vma()
|
|
* needing to write-acquire the anon_vma->root->rwsem.
|
|
*/
|
|
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->num_children);
|
|
VM_WARN_ON(anon_vma->num_active_vmas);
|
|
put_anon_vma(anon_vma);
|
|
|
|
list_del(&avc->same_vma);
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|
anon_vma_chain_free(avc);
|
|
}
|
|
}
|
|
|
|
static void anon_vma_ctor(void *data)
|
|
{
|
|
struct anon_vma *anon_vma = data;
|
|
|
|
init_rwsem(&anon_vma->rwsem);
|
|
atomic_set(&anon_vma->refcount, 0);
|
|
anon_vma->rb_root = RB_ROOT_CACHED;
|
|
}
|
|
|
|
void __init anon_vma_init(void)
|
|
{
|
|
anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma),
|
|
0, SLAB_TYPESAFE_BY_RCU|SLAB_PANIC|SLAB_ACCOUNT,
|
|
anon_vma_ctor);
|
|
anon_vma_chain_cachep = KMEM_CACHE(anon_vma_chain,
|
|
SLAB_PANIC|SLAB_ACCOUNT);
|
|
}
|
|
|
|
/*
|
|
* 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 folio_remove_rmap_*()
|
|
* 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).
|
|
*
|
|
* In case it was remapped to a different anon_vma, the new anon_vma will be a
|
|
* child of the old anon_vma, and the anon_vma lifetime rules will therefore
|
|
* ensure that any anon_vma obtained from the page will still be valid for as
|
|
* long as we observe page_mapped() [ hence all those page_mapped() tests ].
|
|
*
|
|
* All users of this function must be very careful when walking the anon_vma
|
|
* chain and verify that the page in question is indeed mapped in it
|
|
* [ something equivalent to page_mapped_in_vma() ].
|
|
*
|
|
* Since anon_vma's slab is SLAB_TYPESAFE_BY_RCU and we know from
|
|
* folio_remove_rmap_*() that the anon_vma pointer from page->mapping is valid
|
|
* if there is a mapcount, we can dereference the anon_vma after observing
|
|
* those.
|
|
*
|
|
* NOTE: the caller should normally hold folio lock when calling this. If
|
|
* not, the caller needs to double check the anon_vma didn't change after
|
|
* taking the anon_vma lock for either read or write (UFFDIO_MOVE can modify it
|
|
* concurrently without folio lock protection). See folio_lock_anon_vma_read()
|
|
* which has already covered that, and comment above remap_pages().
|
|
*/
|
|
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(folio->mapping);
|
|
if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
|
|
goto out;
|
|
if (!folio_mapped(folio))
|
|
goto out;
|
|
|
|
anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
|
|
if (!atomic_inc_not_zero(&anon_vma->refcount)) {
|
|
anon_vma = NULL;
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* 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 (!folio_mapped(folio)) {
|
|
rcu_read_unlock();
|
|
put_anon_vma(anon_vma);
|
|
return NULL;
|
|
}
|
|
out:
|
|
rcu_read_unlock();
|
|
|
|
return 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 folio_get_anon_vma() and then block on the mutex
|
|
* on !rwc->try_lock case.
|
|
*/
|
|
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;
|
|
|
|
retry:
|
|
rcu_read_lock();
|
|
anon_mapping = (unsigned long)READ_ONCE(folio->mapping);
|
|
if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
|
|
goto out;
|
|
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)) {
|
|
/*
|
|
* folio_move_anon_rmap() might have changed the anon_vma as we
|
|
* might not hold the folio lock here.
|
|
*/
|
|
if (unlikely((unsigned long)READ_ONCE(folio->mapping) !=
|
|
anon_mapping)) {
|
|
up_read(&root_anon_vma->rwsem);
|
|
rcu_read_unlock();
|
|
goto retry;
|
|
}
|
|
|
|
/*
|
|
* 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 (!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 (!folio_mapped(folio)) {
|
|
rcu_read_unlock();
|
|
put_anon_vma(anon_vma);
|
|
return NULL;
|
|
}
|
|
|
|
/* we pinned the anon_vma, its safe to sleep */
|
|
rcu_read_unlock();
|
|
anon_vma_lock_read(anon_vma);
|
|
|
|
/*
|
|
* folio_move_anon_rmap() might have changed the anon_vma as we might
|
|
* not hold the folio lock here.
|
|
*/
|
|
if (unlikely((unsigned long)READ_ONCE(folio->mapping) !=
|
|
anon_mapping)) {
|
|
anon_vma_unlock_read(anon_vma);
|
|
put_anon_vma(anon_vma);
|
|
anon_vma = NULL;
|
|
goto retry;
|
|
}
|
|
|
|
if (atomic_dec_and_test(&anon_vma->refcount)) {
|
|
/*
|
|
* Oops, we held the last refcount, release the lock
|
|
* and bail -- can't simply use put_anon_vma() because
|
|
* we'll deadlock on the anon_vma_lock_write() recursion.
|
|
*/
|
|
anon_vma_unlock_read(anon_vma);
|
|
__put_anon_vma(anon_vma);
|
|
anon_vma = NULL;
|
|
}
|
|
|
|
return anon_vma;
|
|
|
|
out:
|
|
rcu_read_unlock();
|
|
return anon_vma;
|
|
}
|
|
|
|
#ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
|
|
/*
|
|
* Flush TLB entries for recently unmapped pages from remote CPUs. It is
|
|
* important if a PTE was dirty when it was unmapped that it's flushed
|
|
* before any IO is initiated on the page to prevent lost writes. Similarly,
|
|
* it must be flushed before freeing to prevent data leakage.
|
|
*/
|
|
void try_to_unmap_flush(void)
|
|
{
|
|
struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc;
|
|
|
|
if (!tlb_ubc->flush_required)
|
|
return;
|
|
|
|
arch_tlbbatch_flush(&tlb_ubc->arch);
|
|
tlb_ubc->flush_required = false;
|
|
tlb_ubc->writable = false;
|
|
}
|
|
|
|
/* Flush iff there are potentially writable TLB entries that can race with IO */
|
|
void try_to_unmap_flush_dirty(void)
|
|
{
|
|
struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc;
|
|
|
|
if (tlb_ubc->writable)
|
|
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, pte_t pteval,
|
|
unsigned long uaddr)
|
|
{
|
|
struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc;
|
|
int batch;
|
|
bool writable = pte_dirty(pteval);
|
|
|
|
if (!pte_accessible(mm, pteval))
|
|
return;
|
|
|
|
arch_tlbbatch_add_pending(&tlb_ubc->arch, mm, uaddr);
|
|
tlb_ubc->flush_required = true;
|
|
|
|
/*
|
|
* Ensure compiler does not re-order the setting of tlb_flush_batched
|
|
* before the PTE is cleared.
|
|
*/
|
|
barrier();
|
|
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.
|
|
*/
|
|
if (!atomic_try_cmpxchg(&mm->tlb_flush_batched, &batch, 1))
|
|
goto retry;
|
|
} else {
|
|
atomic_inc(&mm->tlb_flush_batched);
|
|
}
|
|
|
|
/*
|
|
* If the PTE was dirty then it's best to assume it's writable. The
|
|
* caller must use try_to_unmap_flush_dirty() or try_to_unmap_flush()
|
|
* before the page is queued for IO.
|
|
*/
|
|
if (writable)
|
|
tlb_ubc->writable = true;
|
|
}
|
|
|
|
/*
|
|
* Returns true if the TLB flush should be deferred to the end of a batch of
|
|
* unmap operations to reduce IPIs.
|
|
*/
|
|
static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags)
|
|
{
|
|
if (!(flags & TTU_BATCH_FLUSH))
|
|
return false;
|
|
|
|
return arch_tlbbatch_should_defer(mm);
|
|
}
|
|
|
|
/*
|
|
* Reclaim unmaps pages under the PTL but do not flush the TLB prior to
|
|
* releasing the PTL if TLB flushes are batched. It's possible for a parallel
|
|
* operation such as mprotect or munmap to race between reclaim unmapping
|
|
* the page and flushing the page. If this race occurs, it potentially allows
|
|
* access to data via a stale TLB entry. Tracking all mm's that have TLB
|
|
* batching in flight would be expensive during reclaim so instead track
|
|
* whether TLB batching occurred in the past and if so then do a flush here
|
|
* if required. This will cost one additional flush per reclaim cycle paid
|
|
* by the first operation at risk such as mprotect and mumap.
|
|
*
|
|
* This must be called under the PTL so that an access to tlb_flush_batched
|
|
* that is potentially a "reclaim vs mprotect/munmap/etc" race will synchronise
|
|
* via the PTL.
|
|
*/
|
|
void flush_tlb_batched_pending(struct mm_struct *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) {
|
|
arch_flush_tlb_batched_pending(mm);
|
|
/*
|
|
* If the new TLB flushing is pending during flushing, leave
|
|
* mm->tlb_flush_batched as is, to avoid losing flushing.
|
|
*/
|
|
atomic_cmpxchg(&mm->tlb_flush_batched, batch,
|
|
pending | (pending << TLB_FLUSH_BATCH_FLUSHED_SHIFT));
|
|
}
|
|
}
|
|
#else
|
|
static void set_tlb_ubc_flush_pending(struct mm_struct *mm, pte_t pteval,
|
|
unsigned long uaddr)
|
|
{
|
|
}
|
|
|
|
static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags)
|
|
{
|
|
return false;
|
|
}
|
|
#endif /* CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH */
|
|
|
|
/*
|
|
* At what user virtual address is page expected in vma?
|
|
* Caller should check the page is actually part of the vma.
|
|
*/
|
|
unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
|
|
{
|
|
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.
|
|
*/
|
|
if (!vma->anon_vma || !page__anon_vma ||
|
|
vma->anon_vma->root != page__anon_vma->root)
|
|
return -EFAULT;
|
|
} else if (!vma->vm_file) {
|
|
return -EFAULT;
|
|
} else if (vma->vm_file->f_mapping != folio->mapping) {
|
|
return -EFAULT;
|
|
}
|
|
|
|
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;
|
|
|
|
pgd = pgd_offset(mm, address);
|
|
if (!pgd_present(*pgd))
|
|
goto out;
|
|
|
|
p4d = p4d_offset(pgd, address);
|
|
if (!p4d_present(*p4d))
|
|
goto out;
|
|
|
|
pud = pud_offset(p4d, address);
|
|
if (!pud_present(*pud))
|
|
goto out;
|
|
|
|
pmd = pmd_offset(pud, address);
|
|
out:
|
|
return pmd;
|
|
}
|
|
|
|
struct folio_referenced_arg {
|
|
int mapcount;
|
|
int referenced;
|
|
unsigned long vm_flags;
|
|
struct mem_cgroup *memcg;
|
|
};
|
|
|
|
/*
|
|
* arg: folio_referenced_arg will be passed
|
|
*/
|
|
static bool folio_referenced_one(struct folio *folio,
|
|
struct vm_area_struct *vma, unsigned long address, void *arg)
|
|
{
|
|
struct folio_referenced_arg *pra = arg;
|
|
DEFINE_FOLIO_VMA_WALK(pvmw, folio, vma, address, 0);
|
|
int referenced = 0;
|
|
unsigned long start = address, ptes = 0;
|
|
|
|
while (page_vma_mapped_walk(&pvmw)) {
|
|
address = pvmw.address;
|
|
|
|
if (vma->vm_flags & VM_LOCKED) {
|
|
if (!folio_test_large(folio) || !pvmw.pte) {
|
|
/* Restore the mlock which got missed */
|
|
mlock_vma_folio(folio, vma);
|
|
page_vma_mapped_walk_done(&pvmw);
|
|
pra->vm_flags |= VM_LOCKED;
|
|
return false; /* To break the loop */
|
|
}
|
|
/*
|
|
* For large folio fully mapped to VMA, will
|
|
* be handled after the pvmw loop.
|
|
*
|
|
* For large folio cross VMA boundaries, it's
|
|
* expected to be picked by page reclaim. But
|
|
* should skip reference of pages which are in
|
|
* the range of VM_LOCKED vma. As page reclaim
|
|
* should just count the reference of pages out
|
|
* the range of VM_LOCKED vma.
|
|
*/
|
|
ptes++;
|
|
pra->mapcount--;
|
|
continue;
|
|
}
|
|
|
|
if (pvmw.pte) {
|
|
if (lru_gen_enabled() &&
|
|
pte_young(ptep_get(pvmw.pte))) {
|
|
lru_gen_look_around(&pvmw);
|
|
referenced++;
|
|
}
|
|
|
|
if (ptep_clear_flush_young_notify(vma, address,
|
|
pvmw.pte))
|
|
referenced++;
|
|
} else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
|
|
if (pmdp_clear_flush_young_notify(vma, address,
|
|
pvmw.pmd))
|
|
referenced++;
|
|
} else {
|
|
/* unexpected pmd-mapped folio? */
|
|
WARN_ON_ONCE(1);
|
|
}
|
|
|
|
pra->mapcount--;
|
|
}
|
|
|
|
if ((vma->vm_flags & VM_LOCKED) &&
|
|
folio_test_large(folio) &&
|
|
folio_within_vma(folio, vma)) {
|
|
unsigned long s_align, e_align;
|
|
|
|
s_align = ALIGN_DOWN(start, PMD_SIZE);
|
|
e_align = ALIGN_DOWN(start + folio_size(folio) - 1, PMD_SIZE);
|
|
|
|
/* folio doesn't cross page table boundary and fully mapped */
|
|
if ((s_align == e_align) && (ptes == folio_nr_pages(folio))) {
|
|
/* Restore the mlock which got missed */
|
|
mlock_vma_folio(folio, vma);
|
|
pra->vm_flags |= VM_LOCKED;
|
|
return false; /* To break the loop */
|
|
}
|
|
}
|
|
|
|
if (referenced)
|
|
folio_clear_idle(folio);
|
|
if (folio_test_clear_young(folio))
|
|
referenced++;
|
|
|
|
if (referenced) {
|
|
pra->referenced++;
|
|
pra->vm_flags |= vma->vm_flags & ~VM_LOCKED;
|
|
}
|
|
|
|
if (!pra->mapcount)
|
|
return false; /* To break the loop */
|
|
|
|
return true;
|
|
}
|
|
|
|
static bool invalid_folio_referenced_vma(struct vm_area_struct *vma, void *arg)
|
|
{
|
|
struct folio_referenced_arg *pra = arg;
|
|
struct mem_cgroup *memcg = pra->memcg;
|
|
|
|
/*
|
|
* Ignore references from this mapping if it has no recency. 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 the
|
|
* referenced flag or activated the folio in zap_pte_range().
|
|
*/
|
|
if (!vma_has_recency(vma))
|
|
return true;
|
|
|
|
/*
|
|
* If we are reclaiming on behalf of a cgroup, skip counting on behalf
|
|
* of references from different cgroups.
|
|
*/
|
|
if (memcg && !mm_match_cgroup(vma->vm_mm, memcg))
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
/**
|
|
* 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: A combination of all the vma->vm_flags which referenced the folio.
|
|
*
|
|
* Quick test_and_clear_referenced for all mappings of a folio,
|
|
*
|
|
* Return: The number of mappings which referenced the folio. Return -1 if
|
|
* the function bailed out due to rmap lock contention.
|
|
*/
|
|
int folio_referenced(struct folio *folio, int is_locked,
|
|
struct mem_cgroup *memcg, unsigned long *vm_flags)
|
|
{
|
|
int we_locked = 0;
|
|
struct folio_referenced_arg pra = {
|
|
.mapcount = folio_mapcount(folio),
|
|
.memcg = memcg,
|
|
};
|
|
struct rmap_walk_control rwc = {
|
|
.rmap_one = folio_referenced_one,
|
|
.arg = (void *)&pra,
|
|
.anon_lock = folio_lock_anon_vma_read,
|
|
.try_lock = true,
|
|
.invalid_vma = invalid_folio_referenced_vma,
|
|
};
|
|
|
|
*vm_flags = 0;
|
|
if (!pra.mapcount)
|
|
return 0;
|
|
|
|
if (!folio_raw_mapping(folio))
|
|
return 0;
|
|
|
|
if (!is_locked && (!folio_test_anon(folio) || folio_test_ksm(folio))) {
|
|
we_locked = folio_trylock(folio);
|
|
if (!we_locked)
|
|
return 1;
|
|
}
|
|
|
|
rmap_walk(folio, &rwc);
|
|
*vm_flags = pra.vm_flags;
|
|
|
|
if (we_locked)
|
|
folio_unlock(folio);
|
|
|
|
return rwc.contended ? -1 : pra.referenced;
|
|
}
|
|
|
|
static int page_vma_mkclean_one(struct page_vma_mapped_walk *pvmw)
|
|
{
|
|
int cleaned = 0;
|
|
struct vm_area_struct *vma = pvmw->vma;
|
|
struct mmu_notifier_range range;
|
|
unsigned long address = pvmw->address;
|
|
|
|
/*
|
|
* We have to assume the worse case ie pmd for invalidation. Note that
|
|
* the folio can not be freed from this function.
|
|
*/
|
|
mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_PAGE, 0,
|
|
vma->vm_mm, address, vma_address_end(pvmw));
|
|
mmu_notifier_invalidate_range_start(&range);
|
|
|
|
while (page_vma_mapped_walk(pvmw)) {
|
|
int ret = 0;
|
|
|
|
address = pvmw->address;
|
|
if (pvmw->pte) {
|
|
pte_t *pte = pvmw->pte;
|
|
pte_t entry = ptep_get(pte);
|
|
|
|
if (!pte_dirty(entry) && !pte_write(entry))
|
|
continue;
|
|
|
|
flush_cache_page(vma, address, pte_pfn(entry));
|
|
entry = ptep_clear_flush(vma, address, pte);
|
|
entry = pte_wrprotect(entry);
|
|
entry = pte_mkclean(entry);
|
|
set_pte_at(vma->vm_mm, address, pte, entry);
|
|
ret = 1;
|
|
} else {
|
|
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
|
|
pmd_t *pmd = pvmw->pmd;
|
|
pmd_t entry;
|
|
|
|
if (!pmd_dirty(*pmd) && !pmd_write(*pmd))
|
|
continue;
|
|
|
|
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 folio? */
|
|
WARN_ON_ONCE(1);
|
|
#endif
|
|
}
|
|
|
|
if (ret)
|
|
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;
|
|
}
|
|
|
|
static bool invalid_mkclean_vma(struct vm_area_struct *vma, void *arg)
|
|
{
|
|
if (vma->vm_flags & VM_SHARED)
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
int folio_mkclean(struct folio *folio)
|
|
{
|
|
int cleaned = 0;
|
|
struct address_space *mapping;
|
|
struct rmap_walk_control rwc = {
|
|
.arg = (void *)&cleaned,
|
|
.rmap_one = page_mkclean_one,
|
|
.invalid_vma = invalid_mkclean_vma,
|
|
};
|
|
|
|
BUG_ON(!folio_test_locked(folio));
|
|
|
|
if (!folio_mapped(folio))
|
|
return 0;
|
|
|
|
mapping = folio_mapping(folio);
|
|
if (!mapping)
|
|
return 0;
|
|
|
|
rmap_walk(folio, &rwc);
|
|
|
|
return cleaned;
|
|
}
|
|
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);
|
|
}
|
|
|
|
int folio_total_mapcount(struct folio *folio)
|
|
{
|
|
int mapcount = folio_entire_mapcount(folio);
|
|
int nr_pages;
|
|
int i;
|
|
|
|
/* In the common case, avoid the loop when no pages mapped by PTE */
|
|
if (folio_nr_pages_mapped(folio) == 0)
|
|
return mapcount;
|
|
/*
|
|
* Add all the PTE mappings of those pages mapped by PTE.
|
|
* Limit the loop to folio_nr_pages_mapped()?
|
|
* Perhaps: given all the raciness, that may be a good or a bad idea.
|
|
*/
|
|
nr_pages = folio_nr_pages(folio);
|
|
for (i = 0; i < nr_pages; i++)
|
|
mapcount += atomic_read(&folio_page(folio, i)->_mapcount);
|
|
|
|
/* But each of those _mapcounts was based on -1 */
|
|
mapcount += nr_pages;
|
|
return mapcount;
|
|
}
|
|
|
|
static __always_inline unsigned int __folio_add_rmap(struct folio *folio,
|
|
struct page *page, int nr_pages, enum rmap_level level,
|
|
int *nr_pmdmapped)
|
|
{
|
|
atomic_t *mapped = &folio->_nr_pages_mapped;
|
|
int first, nr = 0;
|
|
|
|
__folio_rmap_sanity_checks(folio, page, nr_pages, level);
|
|
|
|
switch (level) {
|
|
case RMAP_LEVEL_PTE:
|
|
do {
|
|
first = atomic_inc_and_test(&page->_mapcount);
|
|
if (first && folio_test_large(folio)) {
|
|
first = atomic_inc_return_relaxed(mapped);
|
|
first = (first < ENTIRELY_MAPPED);
|
|
}
|
|
|
|
if (first)
|
|
nr++;
|
|
} while (page++, --nr_pages > 0);
|
|
break;
|
|
case RMAP_LEVEL_PMD:
|
|
first = atomic_inc_and_test(&folio->_entire_mapcount);
|
|
if (first) {
|
|
nr = atomic_add_return_relaxed(ENTIRELY_MAPPED, mapped);
|
|
if (likely(nr < ENTIRELY_MAPPED + ENTIRELY_MAPPED)) {
|
|
*nr_pmdmapped = folio_nr_pages(folio);
|
|
nr = *nr_pmdmapped - (nr & FOLIO_PAGES_MAPPED);
|
|
/* Raced ahead of a remove and another add? */
|
|
if (unlikely(nr < 0))
|
|
nr = 0;
|
|
} else {
|
|
/* Raced ahead of a remove of ENTIRELY_MAPPED */
|
|
nr = 0;
|
|
}
|
|
}
|
|
break;
|
|
}
|
|
return nr;
|
|
}
|
|
|
|
/**
|
|
* folio_move_anon_rmap - move a folio to our anon_vma
|
|
* @folio: The folio to move to our anon_vma
|
|
* @vma: The vma the folio belongs to
|
|
*
|
|
* When a folio belongs exclusively to one process after a COW event,
|
|
* that folio can be moved into the anon_vma that belongs to just that
|
|
* process, so the rmap code will not search the parent or sibling processes.
|
|
*/
|
|
void folio_move_anon_rmap(struct folio *folio, struct vm_area_struct *vma)
|
|
{
|
|
void *anon_vma = vma->anon_vma;
|
|
|
|
VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
|
|
VM_BUG_ON_VMA(!anon_vma, vma);
|
|
|
|
anon_vma += PAGE_MAPPING_ANON;
|
|
/*
|
|
* Ensure that anon_vma and the PAGE_MAPPING_ANON bit are written
|
|
* simultaneously, so a concurrent reader (eg folio_referenced()'s
|
|
* folio_test_anon()) will not see one without the other.
|
|
*/
|
|
WRITE_ONCE(folio->mapping, anon_vma);
|
|
}
|
|
|
|
/**
|
|
* __folio_set_anon - set up a new anonymous rmap for a folio
|
|
* @folio: The folio to set up the new anonymous rmap for.
|
|
* @vma: VM area to add the folio to.
|
|
* @address: User virtual address of the mapping
|
|
* @exclusive: Whether the folio is exclusive to the process.
|
|
*/
|
|
static void __folio_set_anon(struct folio *folio, struct vm_area_struct *vma,
|
|
unsigned long address, bool exclusive)
|
|
{
|
|
struct anon_vma *anon_vma = vma->anon_vma;
|
|
|
|
BUG_ON(!anon_vma);
|
|
|
|
/*
|
|
* If the folio isn't exclusive to this vma, we must use the _oldest_
|
|
* possible anon_vma for the folio mapping!
|
|
*/
|
|
if (!exclusive)
|
|
anon_vma = anon_vma->root;
|
|
|
|
/*
|
|
* page_idle does a lockless/optimistic rmap scan on folio->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;
|
|
WRITE_ONCE(folio->mapping, (struct address_space *) anon_vma);
|
|
folio->index = linear_page_index(vma, address);
|
|
}
|
|
|
|
/**
|
|
* __page_check_anon_rmap - sanity check anonymous rmap addition
|
|
* @folio: The folio containing @page.
|
|
* @page: the page to check the mapping of
|
|
* @vma: the vm area in which the mapping is added
|
|
* @address: the user virtual address mapped
|
|
*/
|
|
static void __page_check_anon_rmap(struct folio *folio, struct page *page,
|
|
struct vm_area_struct *vma, unsigned long address)
|
|
{
|
|
/*
|
|
* The page's anon-rmap details (mapping and index) are guaranteed to
|
|
* be set up correctly at this point.
|
|
*
|
|
* We have exclusion against folio_add_anon_rmap_*() because the caller
|
|
* always holds the page locked.
|
|
*
|
|
* We have exclusion against folio_add_new_anon_rmap because those pages
|
|
* are initially only visible via the pagetables, and the pte is locked
|
|
* over the call to folio_add_new_anon_rmap.
|
|
*/
|
|
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);
|
|
}
|
|
|
|
static __always_inline void __folio_add_anon_rmap(struct folio *folio,
|
|
struct page *page, int nr_pages, struct vm_area_struct *vma,
|
|
unsigned long address, rmap_t flags, enum rmap_level level)
|
|
{
|
|
int i, nr, nr_pmdmapped = 0;
|
|
|
|
nr = __folio_add_rmap(folio, page, nr_pages, level, &nr_pmdmapped);
|
|
if (nr_pmdmapped)
|
|
__lruvec_stat_mod_folio(folio, NR_ANON_THPS, nr_pmdmapped);
|
|
if (nr)
|
|
__lruvec_stat_mod_folio(folio, NR_ANON_MAPPED, nr);
|
|
|
|
if (unlikely(!folio_test_anon(folio))) {
|
|
VM_WARN_ON_FOLIO(!folio_test_locked(folio), folio);
|
|
/*
|
|
* For a PTE-mapped large folio, we only know that the single
|
|
* PTE is exclusive. Further, __folio_set_anon() might not get
|
|
* folio->index right when not given the address of the head
|
|
* page.
|
|
*/
|
|
VM_WARN_ON_FOLIO(folio_test_large(folio) &&
|
|
level != RMAP_LEVEL_PMD, folio);
|
|
__folio_set_anon(folio, vma, address,
|
|
!!(flags & RMAP_EXCLUSIVE));
|
|
} else if (likely(!folio_test_ksm(folio))) {
|
|
__page_check_anon_rmap(folio, page, vma, address);
|
|
}
|
|
|
|
if (flags & RMAP_EXCLUSIVE) {
|
|
switch (level) {
|
|
case RMAP_LEVEL_PTE:
|
|
for (i = 0; i < nr_pages; i++)
|
|
SetPageAnonExclusive(page + i);
|
|
break;
|
|
case RMAP_LEVEL_PMD:
|
|
SetPageAnonExclusive(page);
|
|
break;
|
|
}
|
|
}
|
|
for (i = 0; i < nr_pages; i++) {
|
|
struct page *cur_page = page + i;
|
|
|
|
/* While PTE-mapping a THP we have a PMD and a PTE mapping. */
|
|
VM_WARN_ON_FOLIO((atomic_read(&cur_page->_mapcount) > 0 ||
|
|
(folio_test_large(folio) &&
|
|
folio_entire_mapcount(folio) > 1)) &&
|
|
PageAnonExclusive(cur_page), folio);
|
|
}
|
|
|
|
/*
|
|
* For large folio, only mlock it if it's fully mapped to VMA. It's
|
|
* not easy to check whether the large folio is fully mapped to VMA
|
|
* here. Only mlock normal 4K folio and leave page reclaim to handle
|
|
* large folio.
|
|
*/
|
|
if (!folio_test_large(folio))
|
|
mlock_vma_folio(folio, vma);
|
|
}
|
|
|
|
/**
|
|
* folio_add_anon_rmap_ptes - add PTE mappings to a page range of an anon folio
|
|
* @folio: The folio to add the mappings to
|
|
* @page: The first page to add
|
|
* @nr_pages: The number of pages which will be mapped
|
|
* @vma: The vm area in which the mappings are added
|
|
* @address: The user virtual address of the first page to map
|
|
* @flags: The rmap flags
|
|
*
|
|
* The page range of folio is defined by [first_page, first_page + nr_pages)
|
|
*
|
|
* The caller needs to hold the page table lock, and the page must be locked in
|
|
* the anon_vma case: to serialize mapping,index checking after setting,
|
|
* and to ensure that an anon folio is not being upgraded racily to a KSM folio
|
|
* (but KSM folios are never downgraded).
|
|
*/
|
|
void folio_add_anon_rmap_ptes(struct folio *folio, struct page *page,
|
|
int nr_pages, struct vm_area_struct *vma, unsigned long address,
|
|
rmap_t flags)
|
|
{
|
|
__folio_add_anon_rmap(folio, page, nr_pages, vma, address, flags,
|
|
RMAP_LEVEL_PTE);
|
|
}
|
|
|
|
/**
|
|
* folio_add_anon_rmap_pmd - add a PMD mapping to a page range of an anon folio
|
|
* @folio: The folio to add the mapping to
|
|
* @page: The first page to add
|
|
* @vma: The vm area in which the mapping is added
|
|
* @address: The user virtual address of the first page to map
|
|
* @flags: The rmap flags
|
|
*
|
|
* The page range of folio is defined by [first_page, first_page + HPAGE_PMD_NR)
|
|
*
|
|
* The caller needs to hold the page table lock, and the page must be locked in
|
|
* the anon_vma case: to serialize mapping,index checking after setting.
|
|
*/
|
|
void folio_add_anon_rmap_pmd(struct folio *folio, struct page *page,
|
|
struct vm_area_struct *vma, unsigned long address, rmap_t flags)
|
|
{
|
|
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
|
|
__folio_add_anon_rmap(folio, page, HPAGE_PMD_NR, vma, address, flags,
|
|
RMAP_LEVEL_PMD);
|
|
#else
|
|
WARN_ON_ONCE(true);
|
|
#endif
|
|
}
|
|
|
|
/**
|
|
* folio_add_new_anon_rmap - Add mapping to a new anonymous folio.
|
|
* @folio: The folio to add the mapping to.
|
|
* @vma: the vm area in which the mapping is added
|
|
* @address: the user virtual address mapped
|
|
*
|
|
* Like folio_add_anon_rmap_*() but must only be called on *new* folios.
|
|
* This means the inc-and-test can be bypassed.
|
|
* The folio does not have to be locked.
|
|
*
|
|
* If the folio is pmd-mappable, it is accounted as a THP. As the folio
|
|
* is new, it's assumed to be mapped exclusively by a single process.
|
|
*/
|
|
void folio_add_new_anon_rmap(struct folio *folio, struct vm_area_struct *vma,
|
|
unsigned long address)
|
|
{
|
|
int nr = folio_nr_pages(folio);
|
|
|
|
VM_WARN_ON_FOLIO(folio_test_hugetlb(folio), folio);
|
|
VM_BUG_ON_VMA(address < vma->vm_start ||
|
|
address + (nr << PAGE_SHIFT) > vma->vm_end, vma);
|
|
__folio_set_swapbacked(folio);
|
|
__folio_set_anon(folio, vma, address, true);
|
|
|
|
if (likely(!folio_test_large(folio))) {
|
|
/* increment count (starts at -1) */
|
|
atomic_set(&folio->_mapcount, 0);
|
|
SetPageAnonExclusive(&folio->page);
|
|
} else if (!folio_test_pmd_mappable(folio)) {
|
|
int i;
|
|
|
|
for (i = 0; i < nr; i++) {
|
|
struct page *page = folio_page(folio, i);
|
|
|
|
/* increment count (starts at -1) */
|
|
atomic_set(&page->_mapcount, 0);
|
|
SetPageAnonExclusive(page);
|
|
}
|
|
|
|
atomic_set(&folio->_nr_pages_mapped, nr);
|
|
} else {
|
|
/* increment count (starts at -1) */
|
|
atomic_set(&folio->_entire_mapcount, 0);
|
|
atomic_set(&folio->_nr_pages_mapped, ENTIRELY_MAPPED);
|
|
SetPageAnonExclusive(&folio->page);
|
|
__lruvec_stat_mod_folio(folio, NR_ANON_THPS, nr);
|
|
}
|
|
|
|
__lruvec_stat_mod_folio(folio, NR_ANON_MAPPED, nr);
|
|
}
|
|
|
|
static __always_inline void __folio_add_file_rmap(struct folio *folio,
|
|
struct page *page, int nr_pages, struct vm_area_struct *vma,
|
|
enum rmap_level level)
|
|
{
|
|
int nr, nr_pmdmapped = 0;
|
|
|
|
VM_WARN_ON_FOLIO(folio_test_anon(folio), folio);
|
|
|
|
nr = __folio_add_rmap(folio, page, nr_pages, level, &nr_pmdmapped);
|
|
if (nr_pmdmapped)
|
|
__lruvec_stat_mod_folio(folio, folio_test_swapbacked(folio) ?
|
|
NR_SHMEM_PMDMAPPED : NR_FILE_PMDMAPPED, nr_pmdmapped);
|
|
if (nr)
|
|
__lruvec_stat_mod_folio(folio, NR_FILE_MAPPED, nr);
|
|
|
|
/* See comments in folio_add_anon_rmap_*() */
|
|
if (!folio_test_large(folio))
|
|
mlock_vma_folio(folio, vma);
|
|
}
|
|
|
|
/**
|
|
* folio_add_file_rmap_ptes - add PTE mappings to a page range of a folio
|
|
* @folio: The folio to add the mappings to
|
|
* @page: The first page to add
|
|
* @nr_pages: The number of pages that will be mapped using PTEs
|
|
* @vma: The vm area in which the mappings are added
|
|
*
|
|
* The page range of the folio is defined by [page, page + nr_pages)
|
|
*
|
|
* The caller needs to hold the page table lock.
|
|
*/
|
|
void folio_add_file_rmap_ptes(struct folio *folio, struct page *page,
|
|
int nr_pages, struct vm_area_struct *vma)
|
|
{
|
|
__folio_add_file_rmap(folio, page, nr_pages, vma, RMAP_LEVEL_PTE);
|
|
}
|
|
|
|
/**
|
|
* folio_add_file_rmap_pmd - add a PMD mapping to a page range of a folio
|
|
* @folio: The folio to add the mapping to
|
|
* @page: The first page to add
|
|
* @vma: The vm area in which the mapping is added
|
|
*
|
|
* The page range of the folio is defined by [page, page + HPAGE_PMD_NR)
|
|
*
|
|
* The caller needs to hold the page table lock.
|
|
*/
|
|
void folio_add_file_rmap_pmd(struct folio *folio, struct page *page,
|
|
struct vm_area_struct *vma)
|
|
{
|
|
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
|
|
__folio_add_file_rmap(folio, page, HPAGE_PMD_NR, vma, RMAP_LEVEL_PMD);
|
|
#else
|
|
WARN_ON_ONCE(true);
|
|
#endif
|
|
}
|
|
|
|
static __always_inline void __folio_remove_rmap(struct folio *folio,
|
|
struct page *page, int nr_pages, struct vm_area_struct *vma,
|
|
enum rmap_level level)
|
|
{
|
|
atomic_t *mapped = &folio->_nr_pages_mapped;
|
|
int last, nr = 0, nr_pmdmapped = 0;
|
|
enum node_stat_item idx;
|
|
|
|
__folio_rmap_sanity_checks(folio, page, nr_pages, level);
|
|
|
|
switch (level) {
|
|
case RMAP_LEVEL_PTE:
|
|
do {
|
|
last = atomic_add_negative(-1, &page->_mapcount);
|
|
if (last && folio_test_large(folio)) {
|
|
last = atomic_dec_return_relaxed(mapped);
|
|
last = (last < ENTIRELY_MAPPED);
|
|
}
|
|
|
|
if (last)
|
|
nr++;
|
|
} while (page++, --nr_pages > 0);
|
|
break;
|
|
case RMAP_LEVEL_PMD:
|
|
last = atomic_add_negative(-1, &folio->_entire_mapcount);
|
|
if (last) {
|
|
nr = atomic_sub_return_relaxed(ENTIRELY_MAPPED, mapped);
|
|
if (likely(nr < ENTIRELY_MAPPED)) {
|
|
nr_pmdmapped = folio_nr_pages(folio);
|
|
nr = nr_pmdmapped - (nr & FOLIO_PAGES_MAPPED);
|
|
/* Raced ahead of another remove and an add? */
|
|
if (unlikely(nr < 0))
|
|
nr = 0;
|
|
} else {
|
|
/* An add of ENTIRELY_MAPPED raced ahead */
|
|
nr = 0;
|
|
}
|
|
}
|
|
break;
|
|
}
|
|
|
|
if (nr_pmdmapped) {
|
|
if (folio_test_anon(folio))
|
|
idx = NR_ANON_THPS;
|
|
else if (folio_test_swapbacked(folio))
|
|
idx = NR_SHMEM_PMDMAPPED;
|
|
else
|
|
idx = NR_FILE_PMDMAPPED;
|
|
__lruvec_stat_mod_folio(folio, idx, -nr_pmdmapped);
|
|
}
|
|
if (nr) {
|
|
idx = folio_test_anon(folio) ? NR_ANON_MAPPED : NR_FILE_MAPPED;
|
|
__lruvec_stat_mod_folio(folio, idx, -nr);
|
|
|
|
/*
|
|
* Queue anon large folio for deferred split if at least one
|
|
* page of the folio is unmapped and at least one page
|
|
* is still mapped.
|
|
*/
|
|
if (folio_test_large(folio) && folio_test_anon(folio))
|
|
if (level == RMAP_LEVEL_PTE || nr < nr_pmdmapped)
|
|
deferred_split_folio(folio);
|
|
}
|
|
|
|
/*
|
|
* It would be tidy to reset folio_test_anon mapping when fully
|
|
* unmapped, but that might overwrite a racing folio_add_anon_rmap_*()
|
|
* which increments mapcount after us but sets mapping before us:
|
|
* so leave the reset to free_pages_prepare, and remember that
|
|
* it's only reliable while mapped.
|
|
*/
|
|
|
|
munlock_vma_folio(folio, vma);
|
|
}
|
|
|
|
/**
|
|
* folio_remove_rmap_ptes - remove PTE mappings from a page range of a folio
|
|
* @folio: The folio to remove the mappings from
|
|
* @page: The first page to remove
|
|
* @nr_pages: The number of pages that will be removed from the mapping
|
|
* @vma: The vm area from which the mappings are removed
|
|
*
|
|
* The page range of the folio is defined by [page, page + nr_pages)
|
|
*
|
|
* The caller needs to hold the page table lock.
|
|
*/
|
|
void folio_remove_rmap_ptes(struct folio *folio, struct page *page,
|
|
int nr_pages, struct vm_area_struct *vma)
|
|
{
|
|
__folio_remove_rmap(folio, page, nr_pages, vma, RMAP_LEVEL_PTE);
|
|
}
|
|
|
|
/**
|
|
* folio_remove_rmap_pmd - remove a PMD mapping from a page range of a folio
|
|
* @folio: The folio to remove the mapping from
|
|
* @page: The first page to remove
|
|
* @vma: The vm area from which the mapping is removed
|
|
*
|
|
* The page range of the folio is defined by [page, page + HPAGE_PMD_NR)
|
|
*
|
|
* The caller needs to hold the page table lock.
|
|
*/
|
|
void folio_remove_rmap_pmd(struct folio *folio, struct page *page,
|
|
struct vm_area_struct *vma)
|
|
{
|
|
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
|
|
__folio_remove_rmap(folio, page, HPAGE_PMD_NR, vma, RMAP_LEVEL_PMD);
|
|
#else
|
|
WARN_ON_ONCE(true);
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* @arg: enum ttu_flags will be passed to this argument
|
|
*/
|
|
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;
|
|
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;
|
|
unsigned long pfn;
|
|
unsigned long hsz = 0;
|
|
|
|
/*
|
|
* When racing against e.g. zap_pte_range() on another cpu,
|
|
* in between its ptep_get_and_clear_full() and folio_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, 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 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->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);
|
|
|
|
/* We need the huge page size for set_huge_pte_at() */
|
|
hsz = huge_page_size(hstate_vma(vma));
|
|
}
|
|
mmu_notifier_invalidate_range_start(&range);
|
|
|
|
while (page_vma_mapped_walk(&pvmw)) {
|
|
/* Unexpected PMD-mapped THP? */
|
|
VM_BUG_ON_FOLIO(!pvmw.pte, folio);
|
|
|
|
/*
|
|
* If the folio is in an mlock()d vma, we must not swap it out.
|
|
*/
|
|
if (!(flags & TTU_IGNORE_MLOCK) &&
|
|
(vma->vm_flags & VM_LOCKED)) {
|
|
/* Restore the mlock which got missed */
|
|
if (!folio_test_large(folio))
|
|
mlock_vma_folio(folio, vma);
|
|
page_vma_mapped_walk_done(&pvmw);
|
|
ret = false;
|
|
break;
|
|
}
|
|
|
|
pfn = pte_pfn(ptep_get(pvmw.pte));
|
|
subpage = folio_page(folio, pfn - 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);
|
|
|
|
/*
|
|
* The try_to_unmap() is only passed a hugetlb page
|
|
* in the case where the hugetlb page is poisoned.
|
|
*/
|
|
VM_BUG_ON_PAGE(!PageHWPoison(subpage), subpage);
|
|
/*
|
|
* 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);
|
|
/*
|
|
* 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 {
|
|
flush_cache_page(vma, address, pfn);
|
|
/* 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, pteval, address);
|
|
} else {
|
|
pteval = ptep_clear_flush(vma, address, pvmw.pte);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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))
|
|
folio_mark_dirty(folio);
|
|
|
|
/* Update high watermark before we lower rss */
|
|
update_hiwater_rss(mm);
|
|
|
|
if (PageHWPoison(subpage) && (flags & TTU_HWPOISON)) {
|
|
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,
|
|
hsz);
|
|
} else {
|
|
dec_mm_counter(mm, mm_counter(folio));
|
|
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));
|
|
} else if (folio_test_anon(folio)) {
|
|
swp_entry_t entry = page_swap_entry(subpage);
|
|
pte_t swp_pte;
|
|
/*
|
|
* Store the swap location in the pte.
|
|
* See handle_pte_fault() ...
|
|
*/
|
|
if (unlikely(folio_test_swapbacked(folio) !=
|
|
folio_test_swapcache(folio))) {
|
|
WARN_ON_ONCE(1);
|
|
ret = false;
|
|
page_vma_mapped_walk_done(&pvmw);
|
|
break;
|
|
}
|
|
|
|
/* MADV_FREE page check */
|
|
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)) {
|
|
dec_mm_counter(mm, MM_ANONPAGES);
|
|
goto discard;
|
|
}
|
|
|
|
/*
|
|
* If the folio was redirtied, it cannot be
|
|
* discarded. Remap the page to page table.
|
|
*/
|
|
set_pte_at(mm, address, pvmw.pte, pteval);
|
|
folio_set_swapbacked(folio);
|
|
ret = false;
|
|
page_vma_mapped_walk_done(&pvmw);
|
|
break;
|
|
}
|
|
|
|
if (swap_duplicate(entry) < 0) {
|
|
set_pte_at(mm, address, pvmw.pte, pteval);
|
|
ret = false;
|
|
page_vma_mapped_walk_done(&pvmw);
|
|
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 folio_try_share_anon_rmap(): clear PTE first. */
|
|
if (anon_exclusive &&
|
|
folio_try_share_anon_rmap_pte(folio, subpage)) {
|
|
swap_free(entry);
|
|
set_pte_at(mm, address, pvmw.pte, pteval);
|
|
ret = false;
|
|
page_vma_mapped_walk_done(&pvmw);
|
|
break;
|
|
}
|
|
if (list_empty(&mm->mmlist)) {
|
|
spin_lock(&mmlist_lock);
|
|
if (list_empty(&mm->mmlist))
|
|
list_add(&mm->mmlist, &init_mm.mmlist);
|
|
spin_unlock(&mmlist_lock);
|
|
}
|
|
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);
|
|
} else {
|
|
/*
|
|
* 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/mm/mmu_notifier.rst
|
|
*/
|
|
dec_mm_counter(mm, mm_counter_file(folio));
|
|
}
|
|
discard:
|
|
if (unlikely(folio_test_hugetlb(folio)))
|
|
hugetlb_remove_rmap(folio);
|
|
else
|
|
folio_remove_rmap_pte(folio, subpage, vma);
|
|
if (vma->vm_flags & VM_LOCKED)
|
|
mlock_drain_local();
|
|
folio_put(folio);
|
|
}
|
|
|
|
mmu_notifier_invalidate_range_end(&range);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static bool invalid_migration_vma(struct vm_area_struct *vma, void *arg)
|
|
{
|
|
return vma_is_temporary_stack(vma);
|
|
}
|
|
|
|
static int folio_not_mapped(struct folio *folio)
|
|
{
|
|
return !folio_mapped(folio);
|
|
}
|
|
|
|
/**
|
|
* 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
|
|
* folio. It is the caller's responsibility to check if the folio is
|
|
* still mapped if needed (use TTU_SYNC to prevent accounting races).
|
|
*
|
|
* Context: Caller must hold the folio lock.
|
|
*/
|
|
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 = folio_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;
|
|
unsigned long pfn;
|
|
unsigned long hsz = 0;
|
|
|
|
/*
|
|
* When racing against e.g. zap_pte_range() on another cpu,
|
|
* in between its ptep_get_and_clear_full() and folio_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->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);
|
|
|
|
/* We need the huge page size for set_huge_pte_at() */
|
|
hsz = huge_page_size(hstate_vma(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) {
|
|
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);
|
|
|
|
pfn = pte_pfn(ptep_get(pvmw.pte));
|
|
|
|
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, pfn - 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);
|
|
|
|
/*
|
|
* 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, pfn);
|
|
/* 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, pteval, address);
|
|
} else {
|
|
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)
|
|
WARN_ON_ONCE(folio_try_share_anon_rmap_pte(folio,
|
|
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),
|
|
folio_order(folio));
|
|
/*
|
|
* 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,
|
|
hsz);
|
|
} else {
|
|
dec_mm_counter(mm, mm_counter(folio));
|
|
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));
|
|
} 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, hsz);
|
|
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 folio_try_share_anon_rmap_pte(): clear PTE first. */
|
|
if (folio_test_hugetlb(folio)) {
|
|
if (anon_exclusive &&
|
|
hugetlb_try_share_anon_rmap(folio)) {
|
|
set_huge_pte_at(mm, address, pvmw.pte,
|
|
pteval, hsz);
|
|
ret = false;
|
|
page_vma_mapped_walk_done(&pvmw);
|
|
break;
|
|
}
|
|
} else if (anon_exclusive &&
|
|
folio_try_share_anon_rmap_pte(folio, subpage)) {
|
|
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,
|
|
hsz);
|
|
else
|
|
set_pte_at(mm, address, pvmw.pte, swp_pte);
|
|
trace_set_migration_pte(address, pte_val(swp_pte),
|
|
folio_order(folio));
|
|
/*
|
|
* No need to invalidate here it will synchronize on
|
|
* against the special swap migration pte.
|
|
*/
|
|
}
|
|
|
|
if (unlikely(folio_test_hugetlb(folio)))
|
|
hugetlb_remove_rmap(folio);
|
|
else
|
|
folio_remove_rmap_pte(folio, subpage, vma);
|
|
if (vma->vm_flags & VM_LOCKED)
|
|
mlock_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 = folio_not_mapped,
|
|
.anon_lock = folio_lock_anon_vma_read,
|
|
};
|
|
|
|
/*
|
|
* Migration always ignores mlock and only supports TTU_RMAP_LOCKED and
|
|
* TTU_SPLIT_HUGE_PMD, TTU_SYNC, and TTU_BATCH_FLUSH flags.
|
|
*/
|
|
if (WARN_ON_ONCE(flags & ~(TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD |
|
|
TTU_SYNC | TTU_BATCH_FLUSH)))
|
|
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
|
|
* page tables leading to a race where migration cannot
|
|
* find the migration ptes. Rather than increasing the
|
|
* locking requirements of exec(), migration skips
|
|
* temporary VMAs until after exec() completes.
|
|
*/
|
|
if (!folio_test_ksm(folio) && folio_test_anon(folio))
|
|
rwc.invalid_vma = invalid_migration_vma;
|
|
|
|
if (flags & TTU_RMAP_LOCKED)
|
|
rmap_walk_locked(folio, &rwc);
|
|
else
|
|
rmap_walk(folio, &rwc);
|
|
}
|
|
|
|
#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;
|
|
pte_t ptent;
|
|
|
|
mmu_notifier_range_init_owner(&range, MMU_NOTIFY_EXCLUSIVE, 0,
|
|
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);
|
|
|
|
ptent = ptep_get(pvmw.pte);
|
|
if (!pte_present(ptent)) {
|
|
ret = false;
|
|
page_vma_mapped_walk_done(&pvmw);
|
|
break;
|
|
}
|
|
|
|
subpage = folio_page(folio,
|
|
pte_pfn(ptent) - folio_pfn(folio));
|
|
address = pvmw.address;
|
|
|
|
/* Nuke the page table entry. */
|
|
flush_cache_page(vma, address, pte_pfn(ptent));
|
|
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.
|
|
*/
|
|
folio_remove_rmap_pte(folio, subpage, vma);
|
|
}
|
|
|
|
mmu_notifier_invalidate_range_end(&range);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* 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.
|
|
*
|
|
* 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).
|
|
*/
|
|
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 = page_make_device_exclusive_one,
|
|
.done = folio_not_mapped,
|
|
.anon_lock = folio_lock_anon_vma_read,
|
|
.arg = &args,
|
|
};
|
|
|
|
/*
|
|
* Restrict to anonymous folios for now to avoid potential writeback
|
|
* issues.
|
|
*/
|
|
if (!folio_test_anon(folio))
|
|
return false;
|
|
|
|
rmap_walk(folio, &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);
|
|
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;
|
|
|
|
anon_vma_free(anon_vma);
|
|
if (root != anon_vma && atomic_dec_and_test(&root->refcount))
|
|
anon_vma_free(root);
|
|
}
|
|
|
|
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(folio, rwc);
|
|
|
|
/*
|
|
* 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_lock. Users without mmap_lock are required to
|
|
* take a reference count to prevent the anon_vma disappearing
|
|
*/
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* rmap_walk_anon - do something to anonymous page using the object-based
|
|
* rmap method
|
|
* @folio: the folio to be handled
|
|
* @rwc: control variable according to each walk type
|
|
* @locked: caller holds relevant rmap lock
|
|
*
|
|
* Find all the mappings of a folio using the mapping pointer and the vma
|
|
* chains contained in the anon_vma struct it points to.
|
|
*/
|
|
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 = folio_anon_vma(folio);
|
|
/* anon_vma disappear under us? */
|
|
VM_BUG_ON_FOLIO(!anon_vma, folio);
|
|
} else {
|
|
anon_vma = rmap_walk_anon_lock(folio, rwc);
|
|
}
|
|
if (!anon_vma)
|
|
return;
|
|
|
|
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(&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(folio, vma, address, rwc->arg))
|
|
break;
|
|
if (rwc->done && rwc->done(folio))
|
|
break;
|
|
}
|
|
|
|
if (!locked)
|
|
anon_vma_unlock_read(anon_vma);
|
|
}
|
|
|
|
/*
|
|
* rmap_walk_file - do something to file page using the object-based rmap method
|
|
* @folio: the folio to be handled
|
|
* @rwc: control variable according to each walk type
|
|
* @locked: caller holds relevant rmap lock
|
|
*
|
|
* Find all the mappings of a folio using the mapping pointer and the vma chains
|
|
* contained in the address_space struct it points to.
|
|
*/
|
|
static void rmap_walk_file(struct folio *folio,
|
|
struct rmap_walk_control *rwc, bool locked)
|
|
{
|
|
struct address_space *mapping = folio_mapping(folio);
|
|
pgoff_t pgoff_start, pgoff_end;
|
|
struct vm_area_struct *vma;
|
|
|
|
/*
|
|
* The page lock not only makes sure that page->mapping cannot
|
|
* suddenly be NULLified by truncation, it makes sure that the
|
|
* structure at mapping cannot be freed and reused yet,
|
|
* so we can safely take mapping->i_mmap_rwsem.
|
|
*/
|
|
VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
|
|
|
|
if (!mapping)
|
|
return;
|
|
|
|
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(&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(folio, vma, address, rwc->arg))
|
|
goto done;
|
|
if (rwc->done && rwc->done(folio))
|
|
goto done;
|
|
}
|
|
|
|
done:
|
|
if (!locked)
|
|
i_mmap_unlock_read(mapping);
|
|
}
|
|
|
|
void rmap_walk(struct folio *folio, struct rmap_walk_control *rwc)
|
|
{
|
|
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(folio, rwc, false);
|
|
}
|
|
|
|
/* Like rmap_walk, but caller holds relevant rmap lock */
|
|
void rmap_walk_locked(struct folio *folio, struct rmap_walk_control *rwc)
|
|
{
|
|
/* no ksm support for now */
|
|
VM_BUG_ON_FOLIO(folio_test_ksm(folio), folio);
|
|
if (folio_test_anon(folio))
|
|
rmap_walk_anon(folio, rwc, true);
|
|
else
|
|
rmap_walk_file(folio, rwc, true);
|
|
}
|
|
|
|
#ifdef CONFIG_HUGETLB_PAGE
|
|
/*
|
|
* 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.
|
|
*/
|
|
void hugetlb_add_anon_rmap(struct folio *folio, struct vm_area_struct *vma,
|
|
unsigned long address, rmap_t flags)
|
|
{
|
|
VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio);
|
|
VM_WARN_ON_FOLIO(!folio_test_anon(folio), folio);
|
|
|
|
atomic_inc(&folio->_entire_mapcount);
|
|
if (flags & RMAP_EXCLUSIVE)
|
|
SetPageAnonExclusive(&folio->page);
|
|
VM_WARN_ON_FOLIO(folio_entire_mapcount(folio) > 1 &&
|
|
PageAnonExclusive(&folio->page), folio);
|
|
}
|
|
|
|
void hugetlb_add_new_anon_rmap(struct folio *folio,
|
|
struct vm_area_struct *vma, unsigned long address)
|
|
{
|
|
VM_WARN_ON_FOLIO(!folio_test_hugetlb(folio), folio);
|
|
|
|
BUG_ON(address < vma->vm_start || address >= vma->vm_end);
|
|
/* increment count (starts at -1) */
|
|
atomic_set(&folio->_entire_mapcount, 0);
|
|
folio_clear_hugetlb_restore_reserve(folio);
|
|
__folio_set_anon(folio, vma, address, true);
|
|
SetPageAnonExclusive(&folio->page);
|
|
}
|
|
#endif /* CONFIG_HUGETLB_PAGE */
|