mm/rmap: factor lock function out of rmap_walk_anon()
When we traverse anon_vma, we need to take a read-side anon_lock. But there is subtle difference in the situation so that we can't use same method to take a lock in each cases. Therefore, we need to make rmap_walk_anon() taking difference lock function. This patch is the first step, factoring lock function for anon_lock out of rmap_walk_anon(). It will be used in case of removing migration entry and in default of rmap_walk_anon(). Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Hillf Danton <dhillf@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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1 changed files with 20 additions and 8 deletions
28
mm/rmap.c
28
mm/rmap.c
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@ -1684,6 +1684,24 @@ void __put_anon_vma(struct anon_vma *anon_vma)
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}
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#ifdef CONFIG_MIGRATION
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static struct anon_vma *rmap_walk_anon_lock(struct page *page)
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{
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struct anon_vma *anon_vma;
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/*
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* Note: remove_migration_ptes() cannot use page_lock_anon_vma_read()
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* because that depends on page_mapped(); but not all its usages
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* are holding mmap_sem. Users without mmap_sem are required to
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* take a reference count to prevent the anon_vma disappearing
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*/
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anon_vma = page_anon_vma(page);
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if (!anon_vma)
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return NULL;
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anon_vma_lock_read(anon_vma);
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return anon_vma;
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}
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/*
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* rmap_walk() and its helpers rmap_walk_anon() and rmap_walk_file():
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* Called by migrate.c to remove migration ptes, but might be used more later.
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@ -1696,16 +1714,10 @@ static int rmap_walk_anon(struct page *page, int (*rmap_one)(struct page *,
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struct anon_vma_chain *avc;
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int ret = SWAP_AGAIN;
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/*
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* Note: remove_migration_ptes() cannot use page_lock_anon_vma_read()
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* because that depends on page_mapped(); but not all its usages
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* are holding mmap_sem. Users without mmap_sem are required to
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* take a reference count to prevent the anon_vma disappearing
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*/
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anon_vma = page_anon_vma(page);
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anon_vma = rmap_walk_anon_lock(page);
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if (!anon_vma)
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return ret;
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anon_vma_lock_read(anon_vma);
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anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
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struct vm_area_struct *vma = avc->vma;
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unsigned long address = vma_address(page, vma);
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