mm/page_isolation.c - third_party/kernel - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * linux/mm/page_isolation.c
  */

 #include <linux/mm.h>
 #include <linux/page-isolation.h>
 #include <linux/pageblock-flags.h>
 #include <linux/memory.h>
 #include <linux/hugetlb.h>
 #include <linux/page_owner.h>
 #include <linux/migrate.h>
 #include "internal.h"

 #define CREATE_TRACE_POINTS
 #include <trace/events/page_isolation.h>

 static int set_migratetype_isolate(struct page *page, int migratetype, int isol_flags)
 {
 	struct zone *zone = page_zone(page);
 	struct page *unmovable;
 	unsigned long flags;

 	spin_lock_irqsave(&zone->lock, flags);

 	/*
 	 * We assume the caller intended to SET migrate type to isolate.
 	 * If it is already set, then someone else must have raced and
 	 * set it before us.
 	 */
 	if (is_migrate_isolate_page(page)) {
 		spin_unlock_irqrestore(&zone->lock, flags);
 		return -EBUSY;
 	}

 	/*
 	 * FIXME: Now, memory hotplug doesn't call shrink_slab() by itself.
 	 * We just check MOVABLE pages.
 	 */
 	unmovable = has_unmovable_pages(zone, page, migratetype, isol_flags);
 	if (!unmovable) {
 		unsigned long nr_pages;
 		int mt = get_pageblock_migratetype(page);

 		set_pageblock_migratetype(page, MIGRATE_ISOLATE);
 		zone->nr_isolate_pageblock++;
 		nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE,
 									NULL);

 		__mod_zone_freepage_state(zone, -nr_pages, mt);
 		spin_unlock_irqrestore(&zone->lock, flags);
 		return 0;
 	}

 	spin_unlock_irqrestore(&zone->lock, flags);
 	if (isol_flags & REPORT_FAILURE) {
 		/*
 		 * printk() with zone->lock held will likely trigger a
 		 * lockdep splat, so defer it here.
 		 */
 		dump_page(unmovable, "unmovable page");
 	}

 	return -EBUSY;
 }

 static void unset_migratetype_isolate(struct page *page, unsigned migratetype)
 {
 	struct zone *zone;
 	unsigned long flags, nr_pages;
 	bool isolated_page = false;
 	unsigned int order;
 	unsigned long pfn, buddy_pfn;
 	struct page *buddy;

 	zone = page_zone(page);
 	spin_lock_irqsave(&zone->lock, flags);
 	if (!is_migrate_isolate_page(page))
 		goto out;

 	/*
 	 * Because freepage with more than pageblock_order on isolated
 	 * pageblock is restricted to merge due to freepage counting problem,
 	 * it is possible that there is free buddy page.
 	 * move_freepages_block() doesn't care of merge so we need other
 	 * approach in order to merge them. Isolation and free will make
 	 * these pages to be merged.
 	 */
 	if (PageBuddy(page)) {
 		order = buddy_order(page);
 		if (order >= pageblock_order && order < MAX_ORDER - 1) {
 			pfn = page_to_pfn(page);
 			buddy_pfn = __find_buddy_pfn(pfn, order);
 			buddy = page + (buddy_pfn - pfn);

 			if (!is_migrate_isolate_page(buddy)) {
 				__isolate_free_page(page, order);
 				isolated_page = true;
 			}
 		}
 	}

 	/*
 	 * If we isolate freepage with more than pageblock_order, there
 	 * should be no freepage in the range, so we could avoid costly
 	 * pageblock scanning for freepage moving.
 	 *
 	 * We didn't actually touch any of the isolated pages, so place them
 	 * to the tail of the freelist. This is an optimization for memory
 	 * onlining - just onlined memory won't immediately be considered for
 	 * allocation.
 	 */
 	if (!isolated_page) {
 		nr_pages = move_freepages_block(zone, page, migratetype, NULL);
 		__mod_zone_freepage_state(zone, nr_pages, migratetype);
 	}
 	set_pageblock_migratetype(page, migratetype);
 	if (isolated_page)
 		__putback_isolated_page(page, order, migratetype);
 	zone->nr_isolate_pageblock--;
 out:
 	spin_unlock_irqrestore(&zone->lock, flags);
 }

 static inline struct page *
 __first_valid_page(unsigned long pfn, unsigned long nr_pages)
 {
 	int i;

 	for (i = 0; i < nr_pages; i++) {
 		struct page *page;

 		page = pfn_to_online_page(pfn + i);
 		if (!page)
 			continue;
 		return page;
 	}
 	return NULL;
 }

 /**
  * start_isolate_page_range() - make page-allocation-type of range of pages to
  * be MIGRATE_ISOLATE.
  * @start_pfn:		The lower PFN of the range to be isolated.
  * @end_pfn:		The upper PFN of the range to be isolated.
  *			start_pfn/end_pfn must be aligned to pageblock_order.
  * @migratetype:	Migrate type to set in error recovery.
  * @flags:		The following flags are allowed (they can be combined in
  *			a bit mask)
  *			MEMORY_OFFLINE - isolate to offline (!allocate) memory
  *					 e.g., skip over PageHWPoison() pages
  *					 and PageOffline() pages.
  *			REPORT_FAILURE - report details about the failure to
  *			isolate the range
  *
  * Making page-allocation-type to be MIGRATE_ISOLATE means free pages in
  * the range will never be allocated. Any free pages and pages freed in the
  * future will not be allocated again. If specified range includes migrate types
  * other than MOVABLE or CMA, this will fail with -EBUSY. For isolating all
  * pages in the range finally, the caller have to free all pages in the range.
  * test_page_isolated() can be used for test it.
  *
  * There is no high level synchronization mechanism that prevents two threads
  * from trying to isolate overlapping ranges. If this happens, one thread
  * will notice pageblocks in the overlapping range already set to isolate.
  * This happens in set_migratetype_isolate, and set_migratetype_isolate
  * returns an error. We then clean up by restoring the migration type on
  * pageblocks we may have modified and return -EBUSY to caller. This
  * prevents two threads from simultaneously working on overlapping ranges.
  *
  * Please note that there is no strong synchronization with the page allocator
  * either. Pages might be freed while their page blocks are marked ISOLATED.
  * A call to drain_all_pages() after isolation can flush most of them. However
  * in some cases pages might still end up on pcp lists and that would allow
  * for their allocation even when they are in fact isolated already. Depending
  * on how strong of a guarantee the caller needs, zone_pcp_disable/enable()
  * might be used to flush and disable pcplist before isolation and enable after
  * unisolation.
  *
  * Return: 0 on success and -EBUSY if any part of range cannot be isolated.
  */
 int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
 			     unsigned migratetype, int flags)
 {
 	unsigned long pfn;
 	unsigned long undo_pfn;
 	struct page *page;

 	BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages));
 	BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages));

 	for (pfn = start_pfn;
 	     pfn < end_pfn;
 	     pfn += pageblock_nr_pages) {
 		page = __first_valid_page(pfn, pageblock_nr_pages);
 		if (page) {
 			if (set_migratetype_isolate(page, migratetype, flags)) {
 				undo_pfn = pfn;
 				goto undo;
 			}
 		}
 	}
 	return 0;
 undo:
 	for (pfn = start_pfn;
 	     pfn < undo_pfn;
 	     pfn += pageblock_nr_pages) {
 		struct page *page = pfn_to_online_page(pfn);
 		if (!page)
 			continue;
 		unset_migratetype_isolate(page, migratetype);
 	}

 	return -EBUSY;
 }

 /*
  * Make isolated pages available again.
  */
 void undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
 			    unsigned migratetype)
 {
 	unsigned long pfn;
 	struct page *page;

 	BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages));
 	BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages));

 	for (pfn = start_pfn;
 	     pfn < end_pfn;
 	     pfn += pageblock_nr_pages) {
 		page = __first_valid_page(pfn, pageblock_nr_pages);
 		if (!page || !is_migrate_isolate_page(page))
 			continue;
 		unset_migratetype_isolate(page, migratetype);
 	}
 }
 /*
  * Test all pages in the range is free(means isolated) or not.
  * all pages in [start_pfn...end_pfn) must be in the same zone.
  * zone->lock must be held before call this.
  *
  * Returns the last tested pfn.
  */
 static unsigned long
 __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn,
 				  int flags)
 {
 	struct page *page;

 	while (pfn < end_pfn) {
 		page = pfn_to_page(pfn);
 		if (PageBuddy(page))
 			/*
 			 * If the page is on a free list, it has to be on
 			 * the correct MIGRATE_ISOLATE freelist. There is no
 			 * simple way to verify that as VM_BUG_ON(), though.
 			 */
 			pfn += 1 << buddy_order(page);
 		else if ((flags & MEMORY_OFFLINE) && PageHWPoison(page))
 			/* A HWPoisoned page cannot be also PageBuddy */
 			pfn++;
 		else if ((flags & MEMORY_OFFLINE) && PageOffline(page) &&
 			 !page_count(page))
 			/*
 			 * The responsible driver agreed to skip PageOffline()
 			 * pages when offlining memory by dropping its
 			 * reference in MEM_GOING_OFFLINE.
 			 */
 			pfn++;
 		else
 			break;
 	}

 	return pfn;
 }

 /* Caller should ensure that requested range is in a single zone */
 int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn,
 			int isol_flags)
 {
 	unsigned long pfn, flags;
 	struct page *page;
 	struct zone *zone;
 	int ret;

 	/*
 	 * Note: pageblock_nr_pages != MAX_ORDER. Then, chunks of free pages
 	 * are not aligned to pageblock_nr_pages.
 	 * Then we just check migratetype first.
 	 */
 	for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
 		page = __first_valid_page(pfn, pageblock_nr_pages);
 		if (page && !is_migrate_isolate_page(page))
 			break;
 	}
 	page = __first_valid_page(start_pfn, end_pfn - start_pfn);
 	if ((pfn < end_pfn) || !page) {
 		ret = -EBUSY;
 		goto out;
 	}

 	/* Check all pages are free or marked as ISOLATED */
 	zone = page_zone(page);
 	spin_lock_irqsave(&zone->lock, flags);
 	pfn = __test_page_isolated_in_pageblock(start_pfn, end_pfn, isol_flags);
 	spin_unlock_irqrestore(&zone->lock, flags);

 	ret = pfn < end_pfn ? -EBUSY : 0;

 out:
 	trace_test_pages_isolated(start_pfn, end_pfn, pfn);

 	return ret;
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* linux/mm/page_isolation.c
	*/

	#include <linux/mm.h>
	#include <linux/page-isolation.h>
	#include <linux/pageblock-flags.h>
	#include <linux/memory.h>
	#include <linux/hugetlb.h>
	#include <linux/page_owner.h>
	#include <linux/migrate.h>
	#include "internal.h"

	#define CREATE_TRACE_POINTS
	#include <trace/events/page_isolation.h>

	static int set_migratetype_isolate(struct page *page, int migratetype, int isol_flags)
	{
	struct zone *zone = page_zone(page);
	struct page *unmovable;
	unsigned long flags;

	spin_lock_irqsave(&zone->lock, flags);

	/*
	* We assume the caller intended to SET migrate type to isolate.
	* If it is already set, then someone else must have raced and
	* set it before us.
	*/
	if (is_migrate_isolate_page(page)) {
	spin_unlock_irqrestore(&zone->lock, flags);
	return -EBUSY;
	}

	/*
	* FIXME: Now, memory hotplug doesn't call shrink_slab() by itself.
	* We just check MOVABLE pages.
	*/
	unmovable = has_unmovable_pages(zone, page, migratetype, isol_flags);
	if (!unmovable) {
	unsigned long nr_pages;
	int mt = get_pageblock_migratetype(page);

	set_pageblock_migratetype(page, MIGRATE_ISOLATE);
	zone->nr_isolate_pageblock++;
	nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE,
	NULL);

	__mod_zone_freepage_state(zone, -nr_pages, mt);
	spin_unlock_irqrestore(&zone->lock, flags);
	return 0;
	}

	spin_unlock_irqrestore(&zone->lock, flags);
	if (isol_flags & REPORT_FAILURE) {
	/*
	* printk() with zone->lock held will likely trigger a
	* lockdep splat, so defer it here.
	*/
	dump_page(unmovable, "unmovable page");
	}

	return -EBUSY;
	}

	static void unset_migratetype_isolate(struct page *page, unsigned migratetype)
	{
	struct zone *zone;
	unsigned long flags, nr_pages;
	bool isolated_page = false;
	unsigned int order;
	unsigned long pfn, buddy_pfn;
	struct page *buddy;

	zone = page_zone(page);
	spin_lock_irqsave(&zone->lock, flags);
	if (!is_migrate_isolate_page(page))
	goto out;

	/*
	* Because freepage with more than pageblock_order on isolated
	* pageblock is restricted to merge due to freepage counting problem,
	* it is possible that there is free buddy page.
	* move_freepages_block() doesn't care of merge so we need other
	* approach in order to merge them. Isolation and free will make
	* these pages to be merged.
	*/
	if (PageBuddy(page)) {
	order = buddy_order(page);
	if (order >= pageblock_order && order < MAX_ORDER - 1) {
	pfn = page_to_pfn(page);
	buddy_pfn = __find_buddy_pfn(pfn, order);
	buddy = page + (buddy_pfn - pfn);

	if (!is_migrate_isolate_page(buddy)) {
	__isolate_free_page(page, order);
	isolated_page = true;
	}
	}
	}

	/*
	* If we isolate freepage with more than pageblock_order, there
	* should be no freepage in the range, so we could avoid costly
	* pageblock scanning for freepage moving.
	*
	* We didn't actually touch any of the isolated pages, so place them
	* to the tail of the freelist. This is an optimization for memory
	* onlining - just onlined memory won't immediately be considered for
	* allocation.
	*/
	if (!isolated_page) {
	nr_pages = move_freepages_block(zone, page, migratetype, NULL);
	__mod_zone_freepage_state(zone, nr_pages, migratetype);
	}
	set_pageblock_migratetype(page, migratetype);
	if (isolated_page)
	__putback_isolated_page(page, order, migratetype);
	zone->nr_isolate_pageblock--;
	out:
	spin_unlock_irqrestore(&zone->lock, flags);
	}

	static inline struct page *
	__first_valid_page(unsigned long pfn, unsigned long nr_pages)
	{
	int i;

	for (i = 0; i < nr_pages; i++) {
	struct page *page;

	page = pfn_to_online_page(pfn + i);
	if (!page)
	continue;
	return page;
	}
	return NULL;
	}

	/**
	* start_isolate_page_range() - make page-allocation-type of range of pages to
	* be MIGRATE_ISOLATE.
	* @start_pfn: The lower PFN of the range to be isolated.
	* @end_pfn: The upper PFN of the range to be isolated.
	* start_pfn/end_pfn must be aligned to pageblock_order.
	* @migratetype: Migrate type to set in error recovery.
	* @flags: The following flags are allowed (they can be combined in
	* a bit mask)
	* MEMORY_OFFLINE - isolate to offline (!allocate) memory
	* e.g., skip over PageHWPoison() pages
	* and PageOffline() pages.
	* REPORT_FAILURE - report details about the failure to
	* isolate the range
	*
	* Making page-allocation-type to be MIGRATE_ISOLATE means free pages in
	* the range will never be allocated. Any free pages and pages freed in the
	* future will not be allocated again. If specified range includes migrate types
	* other than MOVABLE or CMA, this will fail with -EBUSY. For isolating all
	* pages in the range finally, the caller have to free all pages in the range.
	* test_page_isolated() can be used for test it.
	*
	* There is no high level synchronization mechanism that prevents two threads
	* from trying to isolate overlapping ranges. If this happens, one thread
	* will notice pageblocks in the overlapping range already set to isolate.
	* This happens in set_migratetype_isolate, and set_migratetype_isolate
	* returns an error. We then clean up by restoring the migration type on
	* pageblocks we may have modified and return -EBUSY to caller. This
	* prevents two threads from simultaneously working on overlapping ranges.
	*
	* Please note that there is no strong synchronization with the page allocator
	* either. Pages might be freed while their page blocks are marked ISOLATED.
	* A call to drain_all_pages() after isolation can flush most of them. However
	* in some cases pages might still end up on pcp lists and that would allow
	* for their allocation even when they are in fact isolated already. Depending
	* on how strong of a guarantee the caller needs, zone_pcp_disable/enable()
	* might be used to flush and disable pcplist before isolation and enable after
	* unisolation.
	*
	* Return: 0 on success and -EBUSY if any part of range cannot be isolated.
	*/
	int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
	unsigned migratetype, int flags)
	{
	unsigned long pfn;
	unsigned long undo_pfn;
	struct page *page;

	BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages));
	BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages));

	for (pfn = start_pfn;
	pfn < end_pfn;
	pfn += pageblock_nr_pages) {
	page = __first_valid_page(pfn, pageblock_nr_pages);
	if (page) {
	if (set_migratetype_isolate(page, migratetype, flags)) {
	undo_pfn = pfn;
	goto undo;
	}
	}
	}
	return 0;
	undo:
	for (pfn = start_pfn;
	pfn < undo_pfn;
	pfn += pageblock_nr_pages) {
	struct page *page = pfn_to_online_page(pfn);
	if (!page)
	continue;
	unset_migratetype_isolate(page, migratetype);
	}

	return -EBUSY;
	}

	/*
	* Make isolated pages available again.
	*/
	void undo_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
	unsigned migratetype)
	{
	unsigned long pfn;
	struct page *page;

	BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages));
	BUG_ON(!IS_ALIGNED(end_pfn, pageblock_nr_pages));

	for (pfn = start_pfn;
	pfn < end_pfn;
	pfn += pageblock_nr_pages) {
	page = __first_valid_page(pfn, pageblock_nr_pages);
	if (!page \|\| !is_migrate_isolate_page(page))
	continue;
	unset_migratetype_isolate(page, migratetype);
	}
	}
	/*
	* Test all pages in the range is free(means isolated) or not.
	* all pages in [start_pfn...end_pfn) must be in the same zone.
	* zone->lock must be held before call this.
	*
	* Returns the last tested pfn.
	*/
	static unsigned long
	__test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn,
	int flags)
	{
	struct page *page;

	while (pfn < end_pfn) {
	page = pfn_to_page(pfn);
	if (PageBuddy(page))
	/*
	* If the page is on a free list, it has to be on
	* the correct MIGRATE_ISOLATE freelist. There is no
	* simple way to verify that as VM_BUG_ON(), though.
	*/
	pfn += 1 << buddy_order(page);
	else if ((flags & MEMORY_OFFLINE) && PageHWPoison(page))
	/* A HWPoisoned page cannot be also PageBuddy */
	pfn++;
	else if ((flags & MEMORY_OFFLINE) && PageOffline(page) &&
	!page_count(page))
	/*
	* The responsible driver agreed to skip PageOffline()
	* pages when offlining memory by dropping its
	* reference in MEM_GOING_OFFLINE.
	*/
	pfn++;
	else
	break;
	}

	return pfn;
	}

	/* Caller should ensure that requested range is in a single zone */
	int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn,
	int isol_flags)
	{
	unsigned long pfn, flags;
	struct page *page;
	struct zone *zone;
	int ret;

	/*
	* Note: pageblock_nr_pages != MAX_ORDER. Then, chunks of free pages
	* are not aligned to pageblock_nr_pages.
	* Then we just check migratetype first.
	*/
	for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
	page = __first_valid_page(pfn, pageblock_nr_pages);
	if (page && !is_migrate_isolate_page(page))
	break;
	}
	page = __first_valid_page(start_pfn, end_pfn - start_pfn);
	if ((pfn < end_pfn) \|\| !page) {
	ret = -EBUSY;
	goto out;
	}

	/* Check all pages are free or marked as ISOLATED */
	zone = page_zone(page);
	spin_lock_irqsave(&zone->lock, flags);
	pfn = __test_page_isolated_in_pageblock(start_pfn, end_pfn, isol_flags);
	spin_unlock_irqrestore(&zone->lock, flags);

	ret = pfn < end_pfn ? -EBUSY : 0;

	out:
	trace_test_pages_isolated(start_pfn, end_pfn, pfn);

	return ret;
	}