linux-master/mm/ksm.c

38 #include <linux/ksm.h>
50 #include <trace/events/ksm.h>
75  * The stable tree holds pointers to all the merged pages (ksm pages), sorted
123  * struct ksm_mm_slot - ksm information per mm that is being scanned
150  * @node: rb node of this ksm page in the stable tree
154  * @hlist: hlist head of rmap_items using this ksm page
155  * @kpfn: page frame number of this ksm page (perhaps temporarily on wrong nid)
640 	/* return 1 if the page is an normal ksm page or KSM-placed zero page */
657  * We use break_ksm to break COW on a ksm page by triggering unsharing,
658  * such that the ksm page will get replaced by an exclusive anonymous page.
660  * We take great care only to touch a ksm page, in a VM_MERGEABLE vma,
662  * Could a ksm page appear anywhere else?  Actually yes, in a VM_PFNMAP
704 	 * even ksmd can fail in this way - though it's usually breaking ksm
901  * is still its ksm page, despite having held no reference to it.
907  * You would expect the stable_node to hold a reference to the ksm page.
911  * "keyhole reference": access to the ksm page from the stable node peeps
1060  * that - an rmap_item is assigned to the stable tree after inserting ksm
1130 		 * since that allows for an unmapped ksm page to be recognized
1362  * replace_page - replace page in vma by new ksm page
1365  * @kpage:    the ksm page we replace page by
1481 	if (page == kpage)			/* ksm page forked */
1519 			 * ptes: make sure that the ksm page would be swapped.
1536  * but no new kernel page is allocated: kpage must already be a ksm page.
1574  * pages into one ksm page, NULL otherwise.
1576  * Note that this function upgrades page to ksm page: if one of the pages
1577  * is already a ksm page, try_to_merge_with_ksm_page should be used.
1591 		 * If that fails, we have a ksm page with only one pte
1828 		/* ksm page forked */
2061  * stable_tree_insert - insert stable tree node pointing to new ksm page
2212 		 * Don't substitute a ksm page for a forked page.
2256  * the same ksm page.
2440 			 * to a ksm page left outside the stable tree,
2495  * Calculate skip age for the ksm page age. The age determines how often
2743  * ksm_do_scan  - the ksm scanner main worker function.
2860  * ksm_enable_merge_any - Add mm to mm ksm list and enable merging on all
3021 	 * Beware: ksm may already have noticed it exiting and freed the slot.
3173  * Collect processes when the error hit an ksm page.
3903 	.name = "ksm",
3923 		pr_err("ksm: creating kthread failed\n");
3931 		pr_err("ksm: register sysfs failed\n");