mirror of https://gitee.com/openkylin/linux.git
1795 lines
49 KiB
C
1795 lines
49 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_mutex (while writing or truncating, not reading or faulting)
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* mm->mmap_sem
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* page->flags PG_locked (lock_page)
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* hugetlbfs_i_mmap_rwsem_key (in huge_pmd_share)
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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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* zone_lru_lock (in mark_page_accessed, isolate_lru_page)
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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 __set_page_dirty_buffers)
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* mem_cgroup_{begin,end}_page_stat (memcg->move_lock)
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* mapping->tree_lock (widely used)
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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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* mapping->tree_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_mutex (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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#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/backing-dev.h>
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#include <linux/page_idle.h>
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#include <asm/tlbflush.h>
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#include <trace/events/tlb.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->degree = 1; /* Reference for first vma */
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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 page_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 page_lock_anon_vma_read(). This orders:
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*
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* page_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 page_lock_anon_vma_read()
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* and that may actually touch the spinlock 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_sem 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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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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/* vma reference or self-parent link for new root */
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anon_vma->degree++;
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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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* If dst->anon_vma is NULL this function tries to find and reuse existing
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* anon_vma which has no vmas and only one child anon_vma. This prevents
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* degradation of anon_vma hierarchy to endless linear chain in case of
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* constantly forking task. On the other hand, an anon_vma with more than one
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* child isn't reused even if there was no alive vma, thus rmap walker has a
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* good chance of avoiding scanning the whole hierarchy when it searches where
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* 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 its degree lower than two,
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* that means it has no vma and only one anon_vma child.
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*
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* Do not chose parent anon_vma, otherwise first child
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* will always reuse it. 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 && anon_vma != src->anon_vma &&
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anon_vma->degree < 2)
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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->degree++;
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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 degree can be incorrectly
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* 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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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 spinlock 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->degree++;
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anon_vma_unlock_write(anon_vma);
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return 0;
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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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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
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* to free them outside the lock.
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*/
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if (RB_EMPTY_ROOT(&anon_vma->rb_root)) {
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anon_vma->parent->degree--;
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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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}
|
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if (vma->anon_vma)
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vma->anon_vma->degree--;
|
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unlock_anon_vma_root(root);
|
|
|
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/*
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* Iterate the list once more, it now only contains empty and unlinked
|
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* anon_vmas, destroy them. Could not do before due to __put_anon_vma()
|
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* needing to write-acquire the anon_vma->root->rwsem.
|
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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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VM_WARN_ON(anon_vma->degree);
|
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put_anon_vma(anon_vma);
|
|
|
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list_del(&avc->same_vma);
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anon_vma_chain_free(avc);
|
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}
|
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}
|
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|
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static void anon_vma_ctor(void *data)
|
|
{
|
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struct anon_vma *anon_vma = data;
|
|
|
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init_rwsem(&anon_vma->rwsem);
|
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atomic_set(&anon_vma->refcount, 0);
|
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anon_vma->rb_root = RB_ROOT;
|
|
}
|
|
|
|
void __init anon_vma_init(void)
|
|
{
|
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anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma),
|
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0, SLAB_TYPESAFE_BY_RCU|SLAB_PANIC|SLAB_ACCOUNT,
|
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anon_vma_ctor);
|
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anon_vma_chain_cachep = KMEM_CACHE(anon_vma_chain,
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SLAB_PANIC|SLAB_ACCOUNT);
|
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}
|
|
|
|
/*
|
|
* Getting a lock on a stable anon_vma from a page off the LRU is tricky!
|
|
*
|
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* Since there is no serialization what so ever against page_remove_rmap()
|
|
* the best this function can do is return a locked anon_vma that might
|
|
* have been relevant to this page.
|
|
*
|
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* 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 DESTROY_BY_RCU and we know from page_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.
|
|
*/
|
|
struct anon_vma *page_get_anon_vma(struct page *page)
|
|
{
|
|
struct anon_vma *anon_vma = NULL;
|
|
unsigned long anon_mapping;
|
|
|
|
rcu_read_lock();
|
|
anon_mapping = (unsigned long)READ_ONCE(page->mapping);
|
|
if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
|
|
goto out;
|
|
if (!page_mapped(page))
|
|
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 page is still mapped, then its anon_vma cannot have been
|
|
* freed. But if it has been unmapped, we have no security against the
|
|
* anon_vma structure being freed and reused (for another anon_vma:
|
|
* SLAB_TYPESAFE_BY_RCU guarantees that - so the atomic_inc_not_zero()
|
|
* above cannot corrupt).
|
|
*/
|
|
if (!page_mapped(page)) {
|
|
rcu_read_unlock();
|
|
put_anon_vma(anon_vma);
|
|
return NULL;
|
|
}
|
|
out:
|
|
rcu_read_unlock();
|
|
|
|
return anon_vma;
|
|
}
|
|
|
|
/*
|
|
* Similar to page_get_anon_vma() except it locks the anon_vma.
|
|
*
|
|
* Its a little more complex as it tries to keep the fast path to a single
|
|
* atomic op -- the trylock. If we fail the trylock, we fall back to getting a
|
|
* reference like with page_get_anon_vma() and then block on the mutex.
|
|
*/
|
|
struct anon_vma *page_lock_anon_vma_read(struct page *page)
|
|
{
|
|
struct anon_vma *anon_vma = NULL;
|
|
struct anon_vma *root_anon_vma;
|
|
unsigned long anon_mapping;
|
|
|
|
rcu_read_lock();
|
|
anon_mapping = (unsigned long)READ_ONCE(page->mapping);
|
|
if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
|
|
goto out;
|
|
if (!page_mapped(page))
|
|
goto out;
|
|
|
|
anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
|
|
root_anon_vma = READ_ONCE(anon_vma->root);
|
|
if (down_read_trylock(&root_anon_vma->rwsem)) {
|
|
/*
|
|
* If the page is still mapped, then this anon_vma is still
|
|
* its anon_vma, and holding the mutex ensures that it will
|
|
* not go away, see anon_vma_free().
|
|
*/
|
|
if (!page_mapped(page)) {
|
|
up_read(&root_anon_vma->rwsem);
|
|
anon_vma = NULL;
|
|
}
|
|
goto out;
|
|
}
|
|
|
|
/* trylock failed, we got to sleep */
|
|
if (!atomic_inc_not_zero(&anon_vma->refcount)) {
|
|
anon_vma = NULL;
|
|
goto out;
|
|
}
|
|
|
|
if (!page_mapped(page)) {
|
|
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);
|
|
|
|
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;
|
|
}
|
|
|
|
void page_unlock_anon_vma_read(struct anon_vma *anon_vma)
|
|
{
|
|
anon_vma_unlock_read(anon_vma);
|
|
}
|
|
|
|
#ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
|
|
/*
|
|
* Flush TLB entries for recently unmapped pages from remote CPUs. It is
|
|
* 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();
|
|
}
|
|
|
|
static void set_tlb_ubc_flush_pending(struct mm_struct *mm, bool writable)
|
|
{
|
|
struct tlbflush_unmap_batch *tlb_ubc = ¤t->tlb_ubc;
|
|
|
|
arch_tlbbatch_add_mm(&tlb_ubc->arch, mm);
|
|
tlb_ubc->flush_required = true;
|
|
|
|
/*
|
|
* Ensure compiler does not re-order the setting of tlb_flush_batched
|
|
* before the PTE is cleared.
|
|
*/
|
|
barrier();
|
|
mm->tlb_flush_batched = true;
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
bool should_defer = false;
|
|
|
|
if (!(flags & TTU_BATCH_FLUSH))
|
|
return false;
|
|
|
|
/* If remote CPUs need to be flushed then defer batch the flush */
|
|
if (cpumask_any_but(mm_cpumask(mm), get_cpu()) < nr_cpu_ids)
|
|
should_defer = true;
|
|
put_cpu();
|
|
|
|
return should_defer;
|
|
}
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
if (mm->tlb_flush_batched) {
|
|
flush_tlb_mm(mm);
|
|
|
|
/*
|
|
* Do not allow the compiler to re-order the clearing of
|
|
* tlb_flush_batched before the tlb is flushed.
|
|
*/
|
|
barrier();
|
|
mm->tlb_flush_batched = false;
|
|
}
|
|
}
|
|
#else
|
|
static void set_tlb_ubc_flush_pending(struct mm_struct *mm, bool writable)
|
|
{
|
|
}
|
|
|
|
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)
|
|
{
|
|
unsigned long address;
|
|
if (PageAnon(page)) {
|
|
struct anon_vma *page__anon_vma = page_anon_vma(page);
|
|
/*
|
|
* 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 (page->mapping) {
|
|
if (!vma->vm_file || vma->vm_file->f_mapping != page->mapping)
|
|
return -EFAULT;
|
|
} else
|
|
return -EFAULT;
|
|
address = __vma_address(page, vma);
|
|
if (unlikely(address < vma->vm_start || address >= vma->vm_end))
|
|
return -EFAULT;
|
|
return address;
|
|
}
|
|
|
|
pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address)
|
|
{
|
|
pgd_t *pgd;
|
|
p4d_t *p4d;
|
|
pud_t *pud;
|
|
pmd_t *pmd = NULL;
|
|
pmd_t pmde;
|
|
|
|
pgd = pgd_offset(mm, address);
|
|
if (!pgd_present(*pgd))
|
|
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);
|
|
/*
|
|
* Some THP functions use the sequence pmdp_huge_clear_flush(), set_pmd_at()
|
|
* without holding anon_vma lock for write. So when looking for a
|
|
* genuine pmde (in which to find pte), test present and !THP together.
|
|
*/
|
|
pmde = *pmd;
|
|
barrier();
|
|
if (!pmd_present(pmde) || pmd_trans_huge(pmde))
|
|
pmd = NULL;
|
|
out:
|
|
return pmd;
|
|
}
|
|
|
|
struct page_referenced_arg {
|
|
int mapcount;
|
|
int referenced;
|
|
unsigned long vm_flags;
|
|
struct mem_cgroup *memcg;
|
|
};
|
|
/*
|
|
* arg: page_referenced_arg will be passed
|
|
*/
|
|
static bool page_referenced_one(struct page *page, struct vm_area_struct *vma,
|
|
unsigned long address, void *arg)
|
|
{
|
|
struct page_referenced_arg *pra = arg;
|
|
struct page_vma_mapped_walk pvmw = {
|
|
.page = page,
|
|
.vma = vma,
|
|
.address = address,
|
|
};
|
|
int referenced = 0;
|
|
|
|
while (page_vma_mapped_walk(&pvmw)) {
|
|
address = pvmw.address;
|
|
|
|
if (vma->vm_flags & VM_LOCKED) {
|
|
page_vma_mapped_walk_done(&pvmw);
|
|
pra->vm_flags |= VM_LOCKED;
|
|
return false; /* To break the loop */
|
|
}
|
|
|
|
if (pvmw.pte) {
|
|
if (ptep_clear_flush_young_notify(vma, address,
|
|
pvmw.pte)) {
|
|
/*
|
|
* Don't treat a reference through
|
|
* a sequentially read mapping as such.
|
|
* If the page has been used in another mapping,
|
|
* we will catch it; if this other mapping is
|
|
* already gone, the unmap path will have set
|
|
* PG_referenced or activated the page.
|
|
*/
|
|
if (likely(!(vma->vm_flags & VM_SEQ_READ)))
|
|
referenced++;
|
|
}
|
|
} else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
|
|
if (pmdp_clear_flush_young_notify(vma, address,
|
|
pvmw.pmd))
|
|
referenced++;
|
|
} else {
|
|
/* unexpected pmd-mapped page? */
|
|
WARN_ON_ONCE(1);
|
|
}
|
|
|
|
pra->mapcount--;
|
|
}
|
|
|
|
if (referenced)
|
|
clear_page_idle(page);
|
|
if (test_and_clear_page_young(page))
|
|
referenced++;
|
|
|
|
if (referenced) {
|
|
pra->referenced++;
|
|
pra->vm_flags |= vma->vm_flags;
|
|
}
|
|
|
|
if (!pra->mapcount)
|
|
return false; /* To break the loop */
|
|
|
|
return true;
|
|
}
|
|
|
|
static bool invalid_page_referenced_vma(struct vm_area_struct *vma, void *arg)
|
|
{
|
|
struct page_referenced_arg *pra = arg;
|
|
struct mem_cgroup *memcg = pra->memcg;
|
|
|
|
if (!mm_match_cgroup(vma->vm_mm, memcg))
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
/**
|
|
* page_referenced - test if the page was referenced
|
|
* @page: the page to test
|
|
* @is_locked: caller holds lock on the page
|
|
* @memcg: target memory cgroup
|
|
* @vm_flags: collect encountered vma->vm_flags who actually referenced the page
|
|
*
|
|
* Quick test_and_clear_referenced for all mappings to a page,
|
|
* returns the number of ptes which referenced the page.
|
|
*/
|
|
int page_referenced(struct page *page,
|
|
int is_locked,
|
|
struct mem_cgroup *memcg,
|
|
unsigned long *vm_flags)
|
|
{
|
|
int we_locked = 0;
|
|
struct page_referenced_arg pra = {
|
|
.mapcount = total_mapcount(page),
|
|
.memcg = memcg,
|
|
};
|
|
struct rmap_walk_control rwc = {
|
|
.rmap_one = page_referenced_one,
|
|
.arg = (void *)&pra,
|
|
.anon_lock = page_lock_anon_vma_read,
|
|
};
|
|
|
|
*vm_flags = 0;
|
|
if (!page_mapped(page))
|
|
return 0;
|
|
|
|
if (!page_rmapping(page))
|
|
return 0;
|
|
|
|
if (!is_locked && (!PageAnon(page) || PageKsm(page))) {
|
|
we_locked = trylock_page(page);
|
|
if (!we_locked)
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* If we are reclaiming on behalf of a cgroup, skip
|
|
* counting on behalf of references from different
|
|
* cgroups
|
|
*/
|
|
if (memcg) {
|
|
rwc.invalid_vma = invalid_page_referenced_vma;
|
|
}
|
|
|
|
rmap_walk(page, &rwc);
|
|
*vm_flags = pra.vm_flags;
|
|
|
|
if (we_locked)
|
|
unlock_page(page);
|
|
|
|
return pra.referenced;
|
|
}
|
|
|
|
static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma,
|
|
unsigned long address, void *arg)
|
|
{
|
|
struct page_vma_mapped_walk pvmw = {
|
|
.page = page,
|
|
.vma = vma,
|
|
.address = address,
|
|
.flags = PVMW_SYNC,
|
|
};
|
|
int *cleaned = arg;
|
|
|
|
while (page_vma_mapped_walk(&pvmw)) {
|
|
int ret = 0;
|
|
address = pvmw.address;
|
|
if (pvmw.pte) {
|
|
pte_t entry;
|
|
pte_t *pte = pvmw.pte;
|
|
|
|
if (!pte_dirty(*pte) && !pte_write(*pte))
|
|
continue;
|
|
|
|
flush_cache_page(vma, address, pte_pfn(*pte));
|
|
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_HUGE_PAGECACHE
|
|
pmd_t *pmd = pvmw.pmd;
|
|
pmd_t entry;
|
|
|
|
if (!pmd_dirty(*pmd) && !pmd_write(*pmd))
|
|
continue;
|
|
|
|
flush_cache_page(vma, address, page_to_pfn(page));
|
|
entry = pmdp_huge_clear_flush(vma, address, pmd);
|
|
entry = pmd_wrprotect(entry);
|
|
entry = pmd_mkclean(entry);
|
|
set_pmd_at(vma->vm_mm, address, pmd, entry);
|
|
ret = 1;
|
|
#else
|
|
/* unexpected pmd-mapped page? */
|
|
WARN_ON_ONCE(1);
|
|
#endif
|
|
}
|
|
|
|
if (ret) {
|
|
mmu_notifier_invalidate_page(vma->vm_mm, address);
|
|
(*cleaned)++;
|
|
}
|
|
}
|
|
|
|
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 page_mkclean(struct page *page)
|
|
{
|
|
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(!PageLocked(page));
|
|
|
|
if (!page_mapped(page))
|
|
return 0;
|
|
|
|
mapping = page_mapping(page);
|
|
if (!mapping)
|
|
return 0;
|
|
|
|
rmap_walk(page, &rwc);
|
|
|
|
return cleaned;
|
|
}
|
|
EXPORT_SYMBOL_GPL(page_mkclean);
|
|
|
|
/**
|
|
* page_move_anon_rmap - move a page to our anon_vma
|
|
* @page: the page to move to our anon_vma
|
|
* @vma: the vma the page belongs to
|
|
*
|
|
* When a page belongs exclusively to one process after a COW event,
|
|
* that page 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 page_move_anon_rmap(struct page *page, struct vm_area_struct *vma)
|
|
{
|
|
struct anon_vma *anon_vma = vma->anon_vma;
|
|
|
|
page = compound_head(page);
|
|
|
|
VM_BUG_ON_PAGE(!PageLocked(page), page);
|
|
VM_BUG_ON_VMA(!anon_vma, vma);
|
|
|
|
anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
|
|
/*
|
|
* Ensure that anon_vma and the PAGE_MAPPING_ANON bit are written
|
|
* simultaneously, so a concurrent reader (eg page_referenced()'s
|
|
* PageAnon()) will not see one without the other.
|
|
*/
|
|
WRITE_ONCE(page->mapping, (struct address_space *) anon_vma);
|
|
}
|
|
|
|
/**
|
|
* __page_set_anon_rmap - set up new anonymous rmap
|
|
* @page: Page to add to rmap
|
|
* @vma: VM area to add page to.
|
|
* @address: User virtual address of the mapping
|
|
* @exclusive: the page is exclusively owned by the current process
|
|
*/
|
|
static void __page_set_anon_rmap(struct page *page,
|
|
struct vm_area_struct *vma, unsigned long address, int exclusive)
|
|
{
|
|
struct anon_vma *anon_vma = vma->anon_vma;
|
|
|
|
BUG_ON(!anon_vma);
|
|
|
|
if (PageAnon(page))
|
|
return;
|
|
|
|
/*
|
|
* If the page isn't exclusively mapped into this vma,
|
|
* we must use the _oldest_ possible anon_vma for the
|
|
* page mapping!
|
|
*/
|
|
if (!exclusive)
|
|
anon_vma = anon_vma->root;
|
|
|
|
anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
|
|
page->mapping = (struct address_space *) anon_vma;
|
|
page->index = linear_page_index(vma, address);
|
|
}
|
|
|
|
/**
|
|
* __page_check_anon_rmap - sanity check anonymous rmap addition
|
|
* @page: the page to add the mapping to
|
|
* @vma: the vm area in which the mapping is added
|
|
* @address: the user virtual address mapped
|
|
*/
|
|
static void __page_check_anon_rmap(struct page *page,
|
|
struct vm_area_struct *vma, unsigned long address)
|
|
{
|
|
#ifdef CONFIG_DEBUG_VM
|
|
/*
|
|
* The page's anon-rmap details (mapping and index) are guaranteed to
|
|
* be set up correctly at this point.
|
|
*
|
|
* We have exclusion against page_add_anon_rmap because the caller
|
|
* always holds the page locked, except if called from page_dup_rmap,
|
|
* in which case the page is already known to be setup.
|
|
*
|
|
* We have exclusion against page_add_new_anon_rmap because those pages
|
|
* are initially only visible via the pagetables, and the pte is locked
|
|
* over the call to page_add_new_anon_rmap.
|
|
*/
|
|
BUG_ON(page_anon_vma(page)->root != vma->anon_vma->root);
|
|
BUG_ON(page_to_pgoff(page) != linear_page_index(vma, address));
|
|
#endif
|
|
}
|
|
|
|
/**
|
|
* page_add_anon_rmap - add pte mapping to an anonymous page
|
|
* @page: the page to add the mapping to
|
|
* @vma: the vm area in which the mapping is added
|
|
* @address: the user virtual address mapped
|
|
* @compound: charge the page as compound or small page
|
|
*
|
|
* The caller needs to hold the pte lock, and the page must be locked in
|
|
* the anon_vma case: to serialize mapping,index checking after setting,
|
|
* and to ensure that PageAnon is not being upgraded racily to PageKsm
|
|
* (but PageKsm is never downgraded to PageAnon).
|
|
*/
|
|
void page_add_anon_rmap(struct page *page,
|
|
struct vm_area_struct *vma, unsigned long address, bool compound)
|
|
{
|
|
do_page_add_anon_rmap(page, vma, address, compound ? RMAP_COMPOUND : 0);
|
|
}
|
|
|
|
/*
|
|
* Special version of the above for do_swap_page, which often runs
|
|
* into pages that are exclusively owned by the current process.
|
|
* Everybody else should continue to use page_add_anon_rmap above.
|
|
*/
|
|
void do_page_add_anon_rmap(struct page *page,
|
|
struct vm_area_struct *vma, unsigned long address, int flags)
|
|
{
|
|
bool compound = flags & RMAP_COMPOUND;
|
|
bool first;
|
|
|
|
if (compound) {
|
|
atomic_t *mapcount;
|
|
VM_BUG_ON_PAGE(!PageLocked(page), page);
|
|
VM_BUG_ON_PAGE(!PageTransHuge(page), page);
|
|
mapcount = compound_mapcount_ptr(page);
|
|
first = atomic_inc_and_test(mapcount);
|
|
} else {
|
|
first = atomic_inc_and_test(&page->_mapcount);
|
|
}
|
|
|
|
if (first) {
|
|
int nr = compound ? hpage_nr_pages(page) : 1;
|
|
/*
|
|
* We use the irq-unsafe __{inc|mod}_zone_page_stat because
|
|
* these counters are not modified in interrupt context, and
|
|
* pte lock(a spinlock) is held, which implies preemption
|
|
* disabled.
|
|
*/
|
|
if (compound)
|
|
__inc_node_page_state(page, NR_ANON_THPS);
|
|
__mod_node_page_state(page_pgdat(page), NR_ANON_MAPPED, nr);
|
|
}
|
|
if (unlikely(PageKsm(page)))
|
|
return;
|
|
|
|
VM_BUG_ON_PAGE(!PageLocked(page), page);
|
|
|
|
/* address might be in next vma when migration races vma_adjust */
|
|
if (first)
|
|
__page_set_anon_rmap(page, vma, address,
|
|
flags & RMAP_EXCLUSIVE);
|
|
else
|
|
__page_check_anon_rmap(page, vma, address);
|
|
}
|
|
|
|
/**
|
|
* page_add_new_anon_rmap - add pte mapping to a new anonymous page
|
|
* @page: the page to add the mapping to
|
|
* @vma: the vm area in which the mapping is added
|
|
* @address: the user virtual address mapped
|
|
* @compound: charge the page as compound or small page
|
|
*
|
|
* Same as page_add_anon_rmap but must only be called on *new* pages.
|
|
* This means the inc-and-test can be bypassed.
|
|
* Page does not have to be locked.
|
|
*/
|
|
void page_add_new_anon_rmap(struct page *page,
|
|
struct vm_area_struct *vma, unsigned long address, bool compound)
|
|
{
|
|
int nr = compound ? hpage_nr_pages(page) : 1;
|
|
|
|
VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);
|
|
__SetPageSwapBacked(page);
|
|
if (compound) {
|
|
VM_BUG_ON_PAGE(!PageTransHuge(page), page);
|
|
/* increment count (starts at -1) */
|
|
atomic_set(compound_mapcount_ptr(page), 0);
|
|
__inc_node_page_state(page, NR_ANON_THPS);
|
|
} else {
|
|
/* Anon THP always mapped first with PMD */
|
|
VM_BUG_ON_PAGE(PageTransCompound(page), page);
|
|
/* increment count (starts at -1) */
|
|
atomic_set(&page->_mapcount, 0);
|
|
}
|
|
__mod_node_page_state(page_pgdat(page), NR_ANON_MAPPED, nr);
|
|
__page_set_anon_rmap(page, vma, address, 1);
|
|
}
|
|
|
|
/**
|
|
* page_add_file_rmap - add pte mapping to a file page
|
|
* @page: the page to add the mapping to
|
|
*
|
|
* The caller needs to hold the pte lock.
|
|
*/
|
|
void page_add_file_rmap(struct page *page, bool compound)
|
|
{
|
|
int i, nr = 1;
|
|
|
|
VM_BUG_ON_PAGE(compound && !PageTransHuge(page), page);
|
|
lock_page_memcg(page);
|
|
if (compound && PageTransHuge(page)) {
|
|
for (i = 0, nr = 0; i < HPAGE_PMD_NR; i++) {
|
|
if (atomic_inc_and_test(&page[i]._mapcount))
|
|
nr++;
|
|
}
|
|
if (!atomic_inc_and_test(compound_mapcount_ptr(page)))
|
|
goto out;
|
|
VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
|
|
__inc_node_page_state(page, NR_SHMEM_PMDMAPPED);
|
|
} else {
|
|
if (PageTransCompound(page) && page_mapping(page)) {
|
|
VM_WARN_ON_ONCE(!PageLocked(page));
|
|
|
|
SetPageDoubleMap(compound_head(page));
|
|
if (PageMlocked(page))
|
|
clear_page_mlock(compound_head(page));
|
|
}
|
|
if (!atomic_inc_and_test(&page->_mapcount))
|
|
goto out;
|
|
}
|
|
__mod_lruvec_page_state(page, NR_FILE_MAPPED, nr);
|
|
out:
|
|
unlock_page_memcg(page);
|
|
}
|
|
|
|
static void page_remove_file_rmap(struct page *page, bool compound)
|
|
{
|
|
int i, nr = 1;
|
|
|
|
VM_BUG_ON_PAGE(compound && !PageHead(page), page);
|
|
lock_page_memcg(page);
|
|
|
|
/* Hugepages are not counted in NR_FILE_MAPPED for now. */
|
|
if (unlikely(PageHuge(page))) {
|
|
/* hugetlb pages are always mapped with pmds */
|
|
atomic_dec(compound_mapcount_ptr(page));
|
|
goto out;
|
|
}
|
|
|
|
/* page still mapped by someone else? */
|
|
if (compound && PageTransHuge(page)) {
|
|
for (i = 0, nr = 0; i < HPAGE_PMD_NR; i++) {
|
|
if (atomic_add_negative(-1, &page[i]._mapcount))
|
|
nr++;
|
|
}
|
|
if (!atomic_add_negative(-1, compound_mapcount_ptr(page)))
|
|
goto out;
|
|
VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
|
|
__dec_node_page_state(page, NR_SHMEM_PMDMAPPED);
|
|
} else {
|
|
if (!atomic_add_negative(-1, &page->_mapcount))
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* We use the irq-unsafe __{inc|mod}_lruvec_page_state because
|
|
* these counters are not modified in interrupt context, and
|
|
* pte lock(a spinlock) is held, which implies preemption disabled.
|
|
*/
|
|
__mod_lruvec_page_state(page, NR_FILE_MAPPED, -nr);
|
|
|
|
if (unlikely(PageMlocked(page)))
|
|
clear_page_mlock(page);
|
|
out:
|
|
unlock_page_memcg(page);
|
|
}
|
|
|
|
static void page_remove_anon_compound_rmap(struct page *page)
|
|
{
|
|
int i, nr;
|
|
|
|
if (!atomic_add_negative(-1, compound_mapcount_ptr(page)))
|
|
return;
|
|
|
|
/* Hugepages are not counted in NR_ANON_PAGES for now. */
|
|
if (unlikely(PageHuge(page)))
|
|
return;
|
|
|
|
if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
|
|
return;
|
|
|
|
__dec_node_page_state(page, NR_ANON_THPS);
|
|
|
|
if (TestClearPageDoubleMap(page)) {
|
|
/*
|
|
* Subpages can be mapped with PTEs too. Check how many of
|
|
* themi are still mapped.
|
|
*/
|
|
for (i = 0, nr = 0; i < HPAGE_PMD_NR; i++) {
|
|
if (atomic_add_negative(-1, &page[i]._mapcount))
|
|
nr++;
|
|
}
|
|
} else {
|
|
nr = HPAGE_PMD_NR;
|
|
}
|
|
|
|
if (unlikely(PageMlocked(page)))
|
|
clear_page_mlock(page);
|
|
|
|
if (nr) {
|
|
__mod_node_page_state(page_pgdat(page), NR_ANON_MAPPED, -nr);
|
|
deferred_split_huge_page(page);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* page_remove_rmap - take down pte mapping from a page
|
|
* @page: page to remove mapping from
|
|
* @compound: uncharge the page as compound or small page
|
|
*
|
|
* The caller needs to hold the pte lock.
|
|
*/
|
|
void page_remove_rmap(struct page *page, bool compound)
|
|
{
|
|
if (!PageAnon(page))
|
|
return page_remove_file_rmap(page, compound);
|
|
|
|
if (compound)
|
|
return page_remove_anon_compound_rmap(page);
|
|
|
|
/* page still mapped by someone else? */
|
|
if (!atomic_add_negative(-1, &page->_mapcount))
|
|
return;
|
|
|
|
/*
|
|
* We use the irq-unsafe __{inc|mod}_zone_page_stat because
|
|
* these counters are not modified in interrupt context, and
|
|
* pte lock(a spinlock) is held, which implies preemption disabled.
|
|
*/
|
|
__dec_node_page_state(page, NR_ANON_MAPPED);
|
|
|
|
if (unlikely(PageMlocked(page)))
|
|
clear_page_mlock(page);
|
|
|
|
if (PageTransCompound(page))
|
|
deferred_split_huge_page(compound_head(page));
|
|
|
|
/*
|
|
* It would be tidy to reset the PageAnon mapping here,
|
|
* but that might overwrite a racing page_add_anon_rmap
|
|
* which increments mapcount after us but sets mapping
|
|
* before us: so leave the reset to free_hot_cold_page,
|
|
* and remember that it's only reliable while mapped.
|
|
* Leaving it set also helps swapoff to reinstate ptes
|
|
* faster for those pages still in swapcache.
|
|
*/
|
|
}
|
|
|
|
/*
|
|
* @arg: enum ttu_flags will be passed to this argument
|
|
*/
|
|
static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
|
|
unsigned long address, void *arg)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
struct page_vma_mapped_walk pvmw = {
|
|
.page = page,
|
|
.vma = vma,
|
|
.address = address,
|
|
};
|
|
pte_t pteval;
|
|
struct page *subpage;
|
|
bool ret = true;
|
|
enum ttu_flags flags = (enum ttu_flags)arg;
|
|
|
|
/* munlock has nothing to gain from examining un-locked vmas */
|
|
if ((flags & TTU_MUNLOCK) && !(vma->vm_flags & VM_LOCKED))
|
|
return true;
|
|
|
|
if (flags & TTU_SPLIT_HUGE_PMD) {
|
|
split_huge_pmd_address(vma, address,
|
|
flags & TTU_MIGRATION, page);
|
|
}
|
|
|
|
while (page_vma_mapped_walk(&pvmw)) {
|
|
/*
|
|
* If the page is mlock()d, we cannot swap it out.
|
|
* If it's recently referenced (perhaps page_referenced
|
|
* skipped over this mm) then we should reactivate it.
|
|
*/
|
|
if (!(flags & TTU_IGNORE_MLOCK)) {
|
|
if (vma->vm_flags & VM_LOCKED) {
|
|
/* PTE-mapped THP are never mlocked */
|
|
if (!PageTransCompound(page)) {
|
|
/*
|
|
* Holding pte lock, we do *not* need
|
|
* mmap_sem here
|
|
*/
|
|
mlock_vma_page(page);
|
|
}
|
|
ret = false;
|
|
page_vma_mapped_walk_done(&pvmw);
|
|
break;
|
|
}
|
|
if (flags & TTU_MUNLOCK)
|
|
continue;
|
|
}
|
|
|
|
/* Unexpected PMD-mapped THP? */
|
|
VM_BUG_ON_PAGE(!pvmw.pte, page);
|
|
|
|
subpage = page - page_to_pfn(page) + pte_pfn(*pvmw.pte);
|
|
address = pvmw.address;
|
|
|
|
|
|
if (!(flags & TTU_IGNORE_ACCESS)) {
|
|
if (ptep_clear_flush_young_notify(vma, address,
|
|
pvmw.pte)) {
|
|
ret = false;
|
|
page_vma_mapped_walk_done(&pvmw);
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* Nuke the page table entry. */
|
|
flush_cache_page(vma, address, pte_pfn(*pvmw.pte));
|
|
if (should_defer_flush(mm, flags)) {
|
|
/*
|
|
* We clear the PTE but do not flush so potentially
|
|
* a remote CPU could still be writing to the page.
|
|
* If the entry was previously clean then the
|
|
* architecture must guarantee that a clear->dirty
|
|
* transition on a cached TLB entry is written through
|
|
* and traps if the PTE is unmapped.
|
|
*/
|
|
pteval = ptep_get_and_clear(mm, address, pvmw.pte);
|
|
|
|
set_tlb_ubc_flush_pending(mm, pte_dirty(pteval));
|
|
} else {
|
|
pteval = ptep_clear_flush(vma, address, pvmw.pte);
|
|
}
|
|
|
|
/* Move the dirty bit to the page. Now the pte is gone. */
|
|
if (pte_dirty(pteval))
|
|
set_page_dirty(page);
|
|
|
|
/* Update high watermark before we lower rss */
|
|
update_hiwater_rss(mm);
|
|
|
|
if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) {
|
|
pteval = swp_entry_to_pte(make_hwpoison_entry(subpage));
|
|
if (PageHuge(page)) {
|
|
int nr = 1 << compound_order(page);
|
|
hugetlb_count_sub(nr, mm);
|
|
set_huge_swap_pte_at(mm, address,
|
|
pvmw.pte, pteval,
|
|
vma_mmu_pagesize(vma));
|
|
} else {
|
|
dec_mm_counter(mm, mm_counter(page));
|
|
set_pte_at(mm, address, pvmw.pte, pteval);
|
|
}
|
|
|
|
} else if (pte_unused(pteval)) {
|
|
/*
|
|
* The guest indicated that the page content is of no
|
|
* interest anymore. Simply discard the pte, vmscan
|
|
* will take care of the rest.
|
|
*/
|
|
dec_mm_counter(mm, mm_counter(page));
|
|
} else if (IS_ENABLED(CONFIG_MIGRATION) &&
|
|
(flags & TTU_MIGRATION)) {
|
|
swp_entry_t entry;
|
|
pte_t swp_pte;
|
|
/*
|
|
* Store the pfn of the page in a special migration
|
|
* pte. do_swap_page() will wait until the migration
|
|
* pte is removed and then restart fault handling.
|
|
*/
|
|
entry = make_migration_entry(subpage,
|
|
pte_write(pteval));
|
|
swp_pte = swp_entry_to_pte(entry);
|
|
if (pte_soft_dirty(pteval))
|
|
swp_pte = pte_swp_mksoft_dirty(swp_pte);
|
|
set_pte_at(mm, address, pvmw.pte, swp_pte);
|
|
} else if (PageAnon(page)) {
|
|
swp_entry_t entry = { .val = page_private(subpage) };
|
|
pte_t swp_pte;
|
|
/*
|
|
* Store the swap location in the pte.
|
|
* See handle_pte_fault() ...
|
|
*/
|
|
if (unlikely(PageSwapBacked(page) != PageSwapCache(page))) {
|
|
WARN_ON_ONCE(1);
|
|
ret = false;
|
|
page_vma_mapped_walk_done(&pvmw);
|
|
break;
|
|
}
|
|
|
|
/* MADV_FREE page check */
|
|
if (!PageSwapBacked(page)) {
|
|
if (!PageDirty(page)) {
|
|
dec_mm_counter(mm, MM_ANONPAGES);
|
|
goto discard;
|
|
}
|
|
|
|
/*
|
|
* If the page was redirtied, it cannot be
|
|
* discarded. Remap the page to page table.
|
|
*/
|
|
set_pte_at(mm, address, pvmw.pte, pteval);
|
|
SetPageSwapBacked(page);
|
|
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 (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 (pte_soft_dirty(pteval))
|
|
swp_pte = pte_swp_mksoft_dirty(swp_pte);
|
|
set_pte_at(mm, address, pvmw.pte, swp_pte);
|
|
} else
|
|
dec_mm_counter(mm, mm_counter_file(page));
|
|
discard:
|
|
page_remove_rmap(subpage, PageHuge(page));
|
|
put_page(page);
|
|
mmu_notifier_invalidate_page(mm, address);
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
bool is_vma_temporary_stack(struct vm_area_struct *vma)
|
|
{
|
|
int maybe_stack = vma->vm_flags & (VM_GROWSDOWN | VM_GROWSUP);
|
|
|
|
if (!maybe_stack)
|
|
return false;
|
|
|
|
if ((vma->vm_flags & VM_STACK_INCOMPLETE_SETUP) ==
|
|
VM_STACK_INCOMPLETE_SETUP)
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
static bool invalid_migration_vma(struct vm_area_struct *vma, void *arg)
|
|
{
|
|
return is_vma_temporary_stack(vma);
|
|
}
|
|
|
|
static int page_mapcount_is_zero(struct page *page)
|
|
{
|
|
return !total_mapcount(page);
|
|
}
|
|
|
|
/**
|
|
* try_to_unmap - try to remove all page table mappings to a page
|
|
* @page: the page to get unmapped
|
|
* @flags: action and flags
|
|
*
|
|
* Tries to remove all the page table entries which are mapping this
|
|
* page, used in the pageout path. Caller must hold the page lock.
|
|
*
|
|
* If unmap is successful, return true. Otherwise, false.
|
|
*/
|
|
bool try_to_unmap(struct page *page, enum ttu_flags flags)
|
|
{
|
|
struct rmap_walk_control rwc = {
|
|
.rmap_one = try_to_unmap_one,
|
|
.arg = (void *)flags,
|
|
.done = page_mapcount_is_zero,
|
|
.anon_lock = page_lock_anon_vma_read,
|
|
};
|
|
|
|
/*
|
|
* 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 ((flags & TTU_MIGRATION) && !PageKsm(page) && PageAnon(page))
|
|
rwc.invalid_vma = invalid_migration_vma;
|
|
|
|
if (flags & TTU_RMAP_LOCKED)
|
|
rmap_walk_locked(page, &rwc);
|
|
else
|
|
rmap_walk(page, &rwc);
|
|
|
|
return !page_mapcount(page) ? true : false;
|
|
}
|
|
|
|
static int page_not_mapped(struct page *page)
|
|
{
|
|
return !page_mapped(page);
|
|
};
|
|
|
|
/**
|
|
* try_to_munlock - try to munlock a page
|
|
* @page: the page to be munlocked
|
|
*
|
|
* Called from munlock code. Checks all of the VMAs mapping the page
|
|
* to make sure nobody else has this page mlocked. The page will be
|
|
* returned with PG_mlocked cleared if no other vmas have it mlocked.
|
|
*/
|
|
|
|
void try_to_munlock(struct page *page)
|
|
{
|
|
struct rmap_walk_control rwc = {
|
|
.rmap_one = try_to_unmap_one,
|
|
.arg = (void *)TTU_MUNLOCK,
|
|
.done = page_not_mapped,
|
|
.anon_lock = page_lock_anon_vma_read,
|
|
|
|
};
|
|
|
|
VM_BUG_ON_PAGE(!PageLocked(page) || PageLRU(page), page);
|
|
VM_BUG_ON_PAGE(PageCompound(page) && PageDoubleMap(page), page);
|
|
|
|
rmap_walk(page, &rwc);
|
|
}
|
|
|
|
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 page *page,
|
|
struct rmap_walk_control *rwc)
|
|
{
|
|
struct anon_vma *anon_vma;
|
|
|
|
if (rwc->anon_lock)
|
|
return rwc->anon_lock(page);
|
|
|
|
/*
|
|
* Note: remove_migration_ptes() cannot use page_lock_anon_vma_read()
|
|
* because that depends on page_mapped(); but not all its usages
|
|
* are holding mmap_sem. Users without mmap_sem are required to
|
|
* take a reference count to prevent the anon_vma disappearing
|
|
*/
|
|
anon_vma = page_anon_vma(page);
|
|
if (!anon_vma)
|
|
return NULL;
|
|
|
|
anon_vma_lock_read(anon_vma);
|
|
return anon_vma;
|
|
}
|
|
|
|
/*
|
|
* rmap_walk_anon - do something to anonymous page using the object-based
|
|
* rmap method
|
|
* @page: the page to be handled
|
|
* @rwc: control variable according to each walk type
|
|
*
|
|
* Find all the mappings of a page using the mapping pointer and the vma chains
|
|
* contained in the anon_vma struct it points to.
|
|
*
|
|
* When called from try_to_munlock(), the mmap_sem of the mm containing the vma
|
|
* where the page was found will be held for write. So, we won't recheck
|
|
* vm_flags for that VMA. That should be OK, because that vma shouldn't be
|
|
* LOCKED.
|
|
*/
|
|
static void rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc,
|
|
bool locked)
|
|
{
|
|
struct anon_vma *anon_vma;
|
|
pgoff_t pgoff_start, pgoff_end;
|
|
struct anon_vma_chain *avc;
|
|
|
|
if (locked) {
|
|
anon_vma = page_anon_vma(page);
|
|
/* anon_vma disappear under us? */
|
|
VM_BUG_ON_PAGE(!anon_vma, page);
|
|
} else {
|
|
anon_vma = rmap_walk_anon_lock(page, rwc);
|
|
}
|
|
if (!anon_vma)
|
|
return;
|
|
|
|
pgoff_start = page_to_pgoff(page);
|
|
pgoff_end = pgoff_start + hpage_nr_pages(page) - 1;
|
|
anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root,
|
|
pgoff_start, pgoff_end) {
|
|
struct vm_area_struct *vma = avc->vma;
|
|
unsigned long address = vma_address(page, vma);
|
|
|
|
cond_resched();
|
|
|
|
if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
|
|
continue;
|
|
|
|
if (!rwc->rmap_one(page, vma, address, rwc->arg))
|
|
break;
|
|
if (rwc->done && rwc->done(page))
|
|
break;
|
|
}
|
|
|
|
if (!locked)
|
|
anon_vma_unlock_read(anon_vma);
|
|
}
|
|
|
|
/*
|
|
* rmap_walk_file - do something to file page using the object-based rmap method
|
|
* @page: the page to be handled
|
|
* @rwc: control variable according to each walk type
|
|
*
|
|
* Find all the mappings of a page using the mapping pointer and the vma chains
|
|
* contained in the address_space struct it points to.
|
|
*
|
|
* When called from try_to_munlock(), the mmap_sem of the mm containing the vma
|
|
* where the page was found will be held for write. So, we won't recheck
|
|
* vm_flags for that VMA. That should be OK, because that vma shouldn't be
|
|
* LOCKED.
|
|
*/
|
|
static void rmap_walk_file(struct page *page, struct rmap_walk_control *rwc,
|
|
bool locked)
|
|
{
|
|
struct address_space *mapping = page_mapping(page);
|
|
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_PAGE(!PageLocked(page), page);
|
|
|
|
if (!mapping)
|
|
return;
|
|
|
|
pgoff_start = page_to_pgoff(page);
|
|
pgoff_end = pgoff_start + hpage_nr_pages(page) - 1;
|
|
if (!locked)
|
|
i_mmap_lock_read(mapping);
|
|
vma_interval_tree_foreach(vma, &mapping->i_mmap,
|
|
pgoff_start, pgoff_end) {
|
|
unsigned long address = vma_address(page, vma);
|
|
|
|
cond_resched();
|
|
|
|
if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
|
|
continue;
|
|
|
|
if (!rwc->rmap_one(page, vma, address, rwc->arg))
|
|
goto done;
|
|
if (rwc->done && rwc->done(page))
|
|
goto done;
|
|
}
|
|
|
|
done:
|
|
if (!locked)
|
|
i_mmap_unlock_read(mapping);
|
|
}
|
|
|
|
void rmap_walk(struct page *page, struct rmap_walk_control *rwc)
|
|
{
|
|
if (unlikely(PageKsm(page)))
|
|
rmap_walk_ksm(page, rwc);
|
|
else if (PageAnon(page))
|
|
rmap_walk_anon(page, rwc, false);
|
|
else
|
|
rmap_walk_file(page, rwc, false);
|
|
}
|
|
|
|
/* Like rmap_walk, but caller holds relevant rmap lock */
|
|
void rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc)
|
|
{
|
|
/* no ksm support for now */
|
|
VM_BUG_ON_PAGE(PageKsm(page), page);
|
|
if (PageAnon(page))
|
|
rmap_walk_anon(page, rwc, true);
|
|
else
|
|
rmap_walk_file(page, rwc, true);
|
|
}
|
|
|
|
#ifdef CONFIG_HUGETLB_PAGE
|
|
/*
|
|
* The following three 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.
|
|
*/
|
|
static void __hugepage_set_anon_rmap(struct page *page,
|
|
struct vm_area_struct *vma, unsigned long address, int exclusive)
|
|
{
|
|
struct anon_vma *anon_vma = vma->anon_vma;
|
|
|
|
BUG_ON(!anon_vma);
|
|
|
|
if (PageAnon(page))
|
|
return;
|
|
if (!exclusive)
|
|
anon_vma = anon_vma->root;
|
|
|
|
anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
|
|
page->mapping = (struct address_space *) anon_vma;
|
|
page->index = linear_page_index(vma, address);
|
|
}
|
|
|
|
void hugepage_add_anon_rmap(struct page *page,
|
|
struct vm_area_struct *vma, unsigned long address)
|
|
{
|
|
struct anon_vma *anon_vma = vma->anon_vma;
|
|
int first;
|
|
|
|
BUG_ON(!PageLocked(page));
|
|
BUG_ON(!anon_vma);
|
|
/* address might be in next vma when migration races vma_adjust */
|
|
first = atomic_inc_and_test(compound_mapcount_ptr(page));
|
|
if (first)
|
|
__hugepage_set_anon_rmap(page, vma, address, 0);
|
|
}
|
|
|
|
void hugepage_add_new_anon_rmap(struct page *page,
|
|
struct vm_area_struct *vma, unsigned long address)
|
|
{
|
|
BUG_ON(address < vma->vm_start || address >= vma->vm_end);
|
|
atomic_set(compound_mapcount_ptr(page), 0);
|
|
__hugepage_set_anon_rmap(page, vma, address, 1);
|
|
}
|
|
#endif /* CONFIG_HUGETLB_PAGE */
|