change system file

hc

2024-10-09 244b2c5ca8b14627e4a17755e5922221e121c771

 kernel/mm/rmap.c
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..
@@ -91,7 +91,8 @@
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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->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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@@ -199,6 +200,7 @@
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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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@@ -208,8 +210,7 @@
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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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+		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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@@ -294,19 +295,19 @@
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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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+		 * 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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-		 * 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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+		 * 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 != src->anon_vma && anon_vma->degree < 2)
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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->degree++;
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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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@@ -356,6 +357,7 @@
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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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@@ -376,7 +378,7 @@
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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->parent->num_children++;
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 	anon_vma_unlock_write(anon_vma);
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 	return 0;
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@@ -408,7 +410,7 @@
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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.rb_root)) {
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-			anon_vma->parent->degree--;
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+			anon_vma->parent->num_children--;
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 			continue;
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 		}
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@@ -416,7 +418,8 @@
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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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+		vma->anon_vma->num_active_vmas--;
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+
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 	unlock_anon_vma_root(root);
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 	/*
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@@ -427,7 +430,8 @@
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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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-		VM_WARN_ON(anon_vma->degree);
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+		VM_WARN_ON(anon_vma->num_children);
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+		VM_WARN_ON(anon_vma->num_active_vmas);
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 		put_anon_vma(anon_vma);
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 		list_del(&avc->same_vma);
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@@ -911,6 +915,7 @@
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 	return rwc.contended ? -1 : pra.referenced;
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 }
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+EXPORT_SYMBOL_GPL(page_referenced);
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 static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma,
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 			    unsigned long address, void *arg)