X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=mm%2Fksm.c;h=5575f8628fef5306611055092e47ed9f472f4027;hb=fcffb947668073fd9c47da33f8e72add7f62163d;hp=722e3f2a8dc5b56f768287096e6787c57b6f2469;hpb=9ba6929480088a85c1ff60a4b1f1c9fc80dbd2b7;p=safe%2Fjmp%2Flinux-2.6

diff --git a/mm/ksm.c b/mm/ksm.c
index 722e3f2..5575f86 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -30,9 +30,9 @@
 #include <linux/slab.h>
 #include <linux/rbtree.h>
 #include <linux/mmu_notifier.h>
+#include <linux/swap.h>
 #include <linux/ksm.h>
 
-#include <asm/tlb.h>
 #include <asm/tlbflush.h>
 
 /*
@@ -166,15 +166,15 @@ static unsigned long ksm_rmap_items;
 static unsigned long ksm_max_kernel_pages;
 
 /* Number of pages ksmd should scan in one batch */
-static unsigned int ksm_thread_pages_to_scan;
+static unsigned int ksm_thread_pages_to_scan = 100;
 
 /* Milliseconds ksmd should sleep between batches */
-static unsigned int ksm_thread_sleep_millisecs;
+static unsigned int ksm_thread_sleep_millisecs = 20;
 
 #define KSM_RUN_STOP	0
 #define KSM_RUN_MERGE	1
 #define KSM_RUN_UNMERGE	2
-static unsigned int ksm_run;
+static unsigned int ksm_run = KSM_RUN_STOP;
 
 static DECLARE_WAIT_QUEUE_HEAD(ksm_thread_wait);
 static DEFINE_MUTEX(ksm_thread_mutex);
@@ -285,6 +285,19 @@ static inline int in_stable_tree(struct rmap_item *rmap_item)
 }
 
 /*
+ * ksmd, and unmerge_and_remove_all_rmap_items(), must not touch an mm's
+ * page tables after it has passed through ksm_exit() - which, if necessary,
+ * takes mmap_sem briefly to serialize against them.  ksm_exit() does not set
+ * a special flag: they can just back out as soon as mm_users goes to zero.
+ * ksm_test_exit() is used throughout to make this test for exit: in some
+ * places for correctness, in some places just to avoid unnecessary work.
+ */
+static inline bool ksm_test_exit(struct mm_struct *mm)
+{
+	return atomic_read(&mm->mm_users) == 0;
+}
+
+/*
  * We use break_ksm to break COW on a ksm page: it's a stripped down
  *
  *	if (get_user_pages(current, mm, addr, 1, 1, 1, &page, NULL) == 1)
@@ -506,6 +519,10 @@ static int unmerge_ksm_pages(struct vm_area_struct *vma,
 	return err;
 }
 
+#ifdef CONFIG_SYSFS
+/*
+ * Only called through the sysfs control interface:
+ */
 static int unmerge_and_remove_all_rmap_items(void)
 {
 	struct mm_slot *mm_slot;
@@ -563,6 +580,7 @@ error:
 	spin_unlock(&ksm_mmlist_lock);
 	return err;
 }
+#endif /* CONFIG_SYSFS */
 
 static u32 calc_checksum(struct page *page)
 {
@@ -994,6 +1012,7 @@ static struct rmap_item *unstable_tree_search_insert(struct page *page,
 		struct rmap_item *tree_rmap_item;
 		int ret;
 
+		cond_resched();
 		tree_rmap_item = rb_entry(*new, struct rmap_item, node);
 		page2[0] = get_mergeable_page(tree_rmap_item);
 		if (!page2[0])
@@ -1416,8 +1435,7 @@ int __ksm_enter(struct mm_struct *mm)
 	return 0;
 }
 
-void __ksm_exit(struct mm_struct *mm,
-		struct mmu_gather **tlbp, unsigned long end)
+void __ksm_exit(struct mm_struct *mm)
 {
 	struct mm_slot *mm_slot;
 	int easy_to_free = 0;
@@ -1450,13 +1468,16 @@ void __ksm_exit(struct mm_struct *mm,
 		clear_bit(MMF_VM_MERGEABLE, &mm->flags);
 		mmdrop(mm);
 	} else if (mm_slot) {
-		tlb_finish_mmu(*tlbp, 0, end);
 		down_write(&mm->mmap_sem);
 		up_write(&mm->mmap_sem);
-		*tlbp = tlb_gather_mmu(mm, 1);
 	}
 }
 
+#ifdef CONFIG_SYSFS
+/*
+ * This all compiles without CONFIG_SYSFS, but is a waste of space.
+ */
+
 #define KSM_ATTR_RO(_name) \
 	static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
 #define KSM_ATTR(_name) \
@@ -1538,7 +1559,9 @@ static ssize_t run_store(struct kobject *kobj, struct kobj_attribute *attr,
 	if (ksm_run != flags) {
 		ksm_run = flags;
 		if (flags & KSM_RUN_UNMERGE) {
+			current->flags |= PF_OOM_ORIGIN;
 			err = unmerge_and_remove_all_rmap_items();
+			current->flags &= ~PF_OOM_ORIGIN;
 			if (err) {
 				ksm_run = KSM_RUN_STOP;
 				count = err;
@@ -1639,12 +1662,15 @@ static struct attribute_group ksm_attr_group = {
 	.attrs = ksm_attrs,
 	.name = "ksm",
 };
+#endif /* CONFIG_SYSFS */
 
 static int __init ksm_init(void)
 {
 	struct task_struct *ksm_thread;
 	int err;
 
+	ksm_max_kernel_pages = totalram_pages / 4;
+
 	err = ksm_slab_init();
 	if (err)
 		goto out;
@@ -1660,16 +1686,20 @@ static int __init ksm_init(void)
 		goto out_free2;
 	}
 
+#ifdef CONFIG_SYSFS
 	err = sysfs_create_group(mm_kobj, &ksm_attr_group);
 	if (err) {
 		printk(KERN_ERR "ksm: register sysfs failed\n");
-		goto out_free3;
+		kthread_stop(ksm_thread);
+		goto out_free2;
 	}
+#else
+	ksm_run = KSM_RUN_MERGE;	/* no way for user to start it */
+
+#endif /* CONFIG_SYSFS */
 
 	return 0;
 
-out_free3:
-	kthread_stop(ksm_thread);
 out_free2:
 	mm_slots_hash_free();
 out_free1: