Q: Given the following code slice:
```
1 static inline void free_the_page(struct page *page, unsigned int order)
2 {
3 	if (pcp_allowed_order(order))		/* Via pcp? */
4 		free_unref_page(page, order);
5 	else
6 		__free_pages_ok(page, order, FPI_NONE);
7 }
8 static __always_inline bool free_pages_prepare(struct page *page,
9 			unsigned int order, fpi_t fpi_flags)
10 {
11 	int bad = 0;
12 	bool skip_kasan_poison = should_skip_kasan_poison(page, fpi_flags);
13 	bool init = want_init_on_free();
14 
15 	VM_BUG_ON_PAGE(PageTail(page), page);
16 
17 	trace_mm_page_free(page, order);
18 	kmsan_free_page(page, order);
19 
20 	if (unlikely(PageHWPoison(page)) && !order) {
21 		/*
22 		 * Do not let hwpoison pages hit pcplists/buddy
23 		 * Untie memcg state and reset page's owner
24 		 */
25 		if (memcg_kmem_online() && PageMemcgKmem(page))
26 			__memcg_kmem_uncharge_page(page, order);
27 		reset_page_owner(page, order);
28 		page_table_check_free(page, order);
29 		return false;
30 	}
31 
32 	/*
33 	 * Check tail pages before head page information is cleared to
34 	 * avoid checking PageCompound for order-0 pages.
35 	 */
36 	if (unlikely(order)) {
37 		bool compound = PageCompound(page);
38 		int i;
39 
40 		VM_BUG_ON_PAGE(compound && compound_order(page) != order, page);
41 
42 		if (compound)
43 			page[1].flags &= ~PAGE_FLAGS_SECOND;
44 		for (i = 1; i < (1 << order); i++) {
45 			if (compound)
46 				bad += free_tail_page_prepare(page, page + i);
47 			if (is_check_pages_enabled()) {
48 				if (free_page_is_bad(page + i)) {
49 					bad++;
50 					continue;
51 				}
52 			}
53 			(page + i)->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
54 		}
55 	}
56 	if (PageMappingFlags(page))
57 		page->mapping = NULL;
58 	if (memcg_kmem_online() && PageMemcgKmem(page))
59 		__memcg_kmem_uncharge_page(page, order);
60 	if (is_check_pages_enabled()) {
61 		if (free_page_is_bad(page))
62 			bad++;
63 		if (bad)
64 			return false;
65 	}
66 
67 	page_cpupid_reset_last(page);
68 	page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
69 	reset_page_owner(page, order);
70 	page_table_check_free(page, order);
71 
72 	if (!PageHighMem(page)) {
73 		debug_check_no_locks_freed(page_address(page),
74 					   PAGE_SIZE << order);
75 		debug_check_no_obj_freed(page_address(page),
76 					   PAGE_SIZE << order);
77 	}
78 
79 	kernel_poison_pages(page, 1 << order);
80 
81 	/*
82 	 * As memory initialization might be integrated into KASAN,
83 	 * KASAN poisoning and memory initialization code must be
84 	 * kept together to avoid discrepancies in behavior.
85 	 *
86 	 * With hardware tag-based KASAN, memory tags must be set before the
87 	 * page becomes unavailable via debug_pagealloc or arch_free_page.
88 	 */
89 	if (!skip_kasan_poison) {
90 		kasan_poison_pages(page, order, init);
91 
92 		/* Memory is already initialized if KASAN did it internally. */
93 		if (kasan_has_integrated_init())
94 			init = false;
95 	}
96 	if (init)
97 		kernel_init_pages(page, 1 << order);
98 
99 	/*
100 	 * arch_free_page() can make the page's contents inaccessible.  s390
101 	 * does this.  So nothing which can access the page's contents should
102 	 * happen after this.
103 	 */
104 	arch_free_page(page, order);
105 
106 	debug_pagealloc_unmap_pages(page, 1 << order);
107 
108 	return true;
109 }
110 void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info)
111 {
112 	mutex_lock(&ring_info->ring_buffer_mutex);
113 	vunmap(ring_info->ring_buffer);
114 	ring_info->ring_buffer = NULL;
115 	mutex_unlock(&ring_info->ring_buffer_mutex);
116 
117 	kfree(ring_info->pkt_buffer);
118 	ring_info->pkt_buffer = NULL;
119 	ring_info->pkt_buffer_size = 0;
120 }
121 static inline int page_ref_dec_and_test(struct page *page)
122 {
123 	int ret = atomic_dec_and_test(&page->_refcount);
124 
125 	if (page_ref_tracepoint_active(page_ref_mod_and_test))
126 		__page_ref_mod_and_test(page, -1, ret);
127 	return ret;
128 }
129 void __sched mutex_lock(struct mutex *lock)
130 {
131 	might_sleep();
132 
133 	if (!__mutex_trylock_fast(lock))
134 		__mutex_lock_slowpath(lock);
135 }
136 static inline bool has_isolate_pageblock(struct zone *zone)
137 {
138 	return zone->nr_isolate_pageblock;
139 }
140 static void free_pcppages_bulk(struct zone *zone, int count,
141 					struct per_cpu_pages *pcp,
142 					int pindex)
143 {
144 	unsigned long flags;
145 	unsigned int order;
146 	bool isolated_pageblocks;
147 	struct page *page;
148 
149 	/*
150 	 * Ensure proper count is passed which otherwise would stuck in the
151 	 * below while (list_empty(list)) loop.
152 	 */
153 	count = min(pcp->count, count);
154 
155 	/* Ensure requested pindex is drained first. */
156 	pindex = pindex - 1;
157 
158 	spin_lock_irqsave(&zone->lock, flags);
159 	isolated_pageblocks = has_isolate_pageblock(zone);
160 
161 	while (count > 0) {
162 		struct list_head *list;
163 		int nr_pages;
164 
165 		/* Remove pages from lists in a round-robin fashion. */
166 		do {
167 			if (++pindex > NR_PCP_LISTS - 1)
168 				pindex = 0;
169 			list = &pcp->lists[pindex];
170 		} while (list_empty(list));
171 
172 		order = pindex_to_order(pindex);
173 		nr_pages = 1 << order;
174 		do {
175 			int mt;
176 
177 			page = list_last_entry(list, struct page, pcp_list);
178 			mt = get_pcppage_migratetype(page);
179 
180 			/* must delete to avoid corrupting pcp list */
181 			list_del(&page->pcp_list);
182 			count -= nr_pages;
183 			pcp->count -= nr_pages;
184 
185 			/* MIGRATE_ISOLATE page should not go to pcplists */
186 			VM_BUG_ON_PAGE(is_migrate_isolate(mt), page);
187 			/* Pageblock could have been isolated meanwhile */
188 			if (unlikely(isolated_pageblocks))
189 				mt = get_pageblock_migratetype(page);
190 
191 			__free_one_page(page, page_to_pfn(page), zone, order, mt, FPI_NONE);
192 			trace_mm_page_pcpu_drain(page, order, mt);
193 		} while (count > 0 && !list_empty(list));
194 	}
195 
196 	spin_unlock_irqrestore(&zone->lock, flags);
197 }
198 static bool free_unref_page_prepare(struct page *page, unsigned long pfn,
199 							unsigned int order)
200 {
201 	int migratetype;
202 
203 	if (!free_pages_prepare(page, order, FPI_NONE))
204 		return false;
205 
206 	migratetype = get_pfnblock_migratetype(page, pfn);
207 	set_pcppage_migratetype(page, migratetype);
208 	return true;
209 }
210 static __always_inline int page_is_fake_head(struct page *page)
211 {
212 	return page_fixed_fake_head(page) != page;
213 }
214 void __sched mutex_unlock(struct mutex *lock)
215 {
216 	mutex_release(&lock->dep_map, _RET_IP_);
217 	__rt_mutex_unlock(&lock->rtmutex);
218 }
219 static int nr_pcp_free(struct per_cpu_pages *pcp, int high, bool free_high)
220 {
221 	int min_nr_free, max_nr_free;
222 	int batch = READ_ONCE(pcp->batch);
223 
224 	/* Free everything if batch freeing high-order pages. */
225 	if (unlikely(free_high))
226 		return pcp->count;
227 
228 	/* Check for PCP disabled or boot pageset */
229 	if (unlikely(high < batch))
230 		return 1;
231 
232 	/* Leave at least pcp->batch pages on the list */
233 	min_nr_free = batch;
234 	max_nr_free = high - batch;
235 
236 	/*
237 	 * Double the number of pages freed each time there is subsequent
238 	 * freeing of pages without any allocation.
239 	 */
240 	batch <<= pcp->free_factor;
241 	if (batch < max_nr_free)
242 		pcp->free_factor++;
243 	batch = clamp(batch, min_nr_free, max_nr_free);
244 
245 	return batch;
246 }
247 static inline void set_pcppage_migratetype(struct page *page, int migratetype)
248 {
249 	page->index = migratetype;
250 }
251 static __always_inline int PageHead(struct page *page)
252 {
253 	PF_POISONED_CHECK(page);
254 	return test_bit(PG_head, &page->flags) && !page_is_fake_head(page);
255 }
256 static __always_inline int get_pfnblock_migratetype(const struct page *page,
257 					unsigned long pfn)
258 {
259 	return get_pfnblock_flags_mask(page, pfn, MIGRATETYPE_MASK);
260 }
261 void vunmap(const void *addr)
262 {
263 	BUG();
264 }
265 static void __free_pages_ok(struct page *page, unsigned int order,
266 			    fpi_t fpi_flags)
267 {
268 	unsigned long flags;
269 	int migratetype;
270 	unsigned long pfn = page_to_pfn(page);
271 	struct zone *zone = page_zone(page);
272 
273 	if (!free_pages_prepare(page, order, fpi_flags))
274 		return;
275 
276 	/*
277 	 * Calling get_pfnblock_migratetype() without spin_lock_irqsave() here
278 	 * is used to avoid calling get_pfnblock_migratetype() under the lock.
279 	 * This will reduce the lock holding time.
280 	 */
281 	migratetype = get_pfnblock_migratetype(page, pfn);
282 
283 	spin_lock_irqsave(&zone->lock, flags);
284 	if (unlikely(has_isolate_pageblock(zone) ||
285 		is_migrate_isolate(migratetype))) {
286 		migratetype = get_pfnblock_migratetype(page, pfn);
287 	}
288 	__free_one_page(page, pfn, zone, order, migratetype, fpi_flags);
289 	spin_unlock_irqrestore(&zone->lock, flags);
290 
291 	__count_vm_events(PGFREE, 1 << order);
292 }
293 static inline enum zone_type page_zonenum(const struct page *page)
294 {
295 	ASSERT_EXCLUSIVE_BITS(page->flags, ZONES_MASK << ZONES_PGSHIFT);
296 	return (page->flags >> ZONES_PGSHIFT) & ZONES_MASK;
297 }
298 static __always_inline void __rt_mutex_unlock(struct rt_mutex_base *lock)
299 {
300 	if (likely(rt_mutex_cmpxchg_release(lock, current, NULL)))
301 		return;
302 
303 	rt_mutex_slowunlock(lock);
304 }
305 static inline int page_ref_count(const struct page *page)
306 {
307 	return atomic_read(&page->_refcount);
308 }
309 static void free_unref_page_commit(struct zone *zone, struct per_cpu_pages *pcp,
310 				   struct page *page, int migratetype,
311 				   unsigned int order)
312 {
313 	int high;
314 	int pindex;
315 	bool free_high;
316 
317 	__count_vm_events(PGFREE, 1 << order);
318 	pindex = order_to_pindex(migratetype, order);
319 	list_add(&page->pcp_list, &pcp->lists[pindex]);
320 	pcp->count += 1 << order;
321 
322 	/*
323 	 * As high-order pages other than THP's stored on PCP can contribute
324 	 * to fragmentation, limit the number stored when PCP is heavily
325 	 * freeing without allocation. The remainder after bulk freeing
326 	 * stops will be drained from vmstat refresh context.
327 	 */
328 	free_high = (pcp->free_factor && order && order <= PAGE_ALLOC_COSTLY_ORDER);
329 
330 	high = nr_pcp_high(pcp, zone, free_high);
331 	if (pcp->count >= high) {
332 		free_pcppages_bulk(zone, nr_pcp_free(pcp, high, free_high), pcp, pindex);
333 	}
334 }
335 static int nr_pcp_high(struct per_cpu_pages *pcp, struct zone *zone,
336 		       bool free_high)
337 {
338 	int high = READ_ONCE(pcp->high);
339 
340 	if (unlikely(!high || free_high))
341 		return 0;
342 
343 	if (!test_bit(ZONE_RECLAIM_ACTIVE, &zone->flags))
344 		return high;
345 
346 	/*
347 	 * If reclaim is active, limit the number of pages that can be
348 	 * stored on pcp lists
349 	 */
350 	return min(READ_ONCE(pcp->batch) << 2, high);
351 }
352 static inline void __free_one_page(struct page *page,
353 		unsigned long pfn,
354 		struct zone *zone, unsigned int order,
355 		int migratetype, fpi_t fpi_flags)
356 {
357 	struct capture_control *capc = task_capc(zone);
358 	unsigned long buddy_pfn = 0;
359 	unsigned long combined_pfn;
360 	struct page *buddy;
361 	bool to_tail;
362 
363 	VM_BUG_ON(!zone_is_initialized(zone));
364 	VM_BUG_ON_PAGE(page->flags & PAGE_FLAGS_CHECK_AT_PREP, page);
365 
366 	VM_BUG_ON(migratetype == -1);
367 	if (likely(!is_migrate_isolate(migratetype)))
368 		__mod_zone_freepage_state(zone, 1 << order, migratetype);
369 
370 	VM_BUG_ON_PAGE(pfn & ((1 << order) - 1), page);
371 	VM_BUG_ON_PAGE(bad_range(zone, page), page);
372 
373 	while (order < MAX_ORDER) {
374 		if (compaction_capture(capc, page, order, migratetype)) {
375 			__mod_zone_freepage_state(zone, -(1 << order),
376 								migratetype);
377 			return;
378 		}
379 
380 		buddy = find_buddy_page_pfn(page, pfn, order, &buddy_pfn);
381 		if (!buddy)
382 			goto done_merging;
383 
384 		if (unlikely(order >= pageblock_order)) {
385 			/*
386 			 * We want to prevent merge between freepages on pageblock
387 			 * without fallbacks and normal pageblock. Without this,
388 			 * pageblock isolation could cause incorrect freepage or CMA
389 			 * accounting or HIGHATOMIC accounting.
390 			 */
391 			int buddy_mt = get_pfnblock_migratetype(buddy, buddy_pfn);
392 
393 			if (migratetype != buddy_mt
394 					&& (!migratetype_is_mergeable(migratetype) ||
395 						!migratetype_is_mergeable(buddy_mt)))
396 				goto done_merging;
397 		}
398 
399 		/*
400 		 * Our buddy is free or it is CONFIG_DEBUG_PAGEALLOC guard page,
401 		 * merge with it and move up one order.
402 		 */
403 		if (page_is_guard(buddy))
404 			clear_page_guard(zone, buddy, order, migratetype);
405 		else
406 			del_page_from_free_list(buddy, zone, order);
407 		combined_pfn = buddy_pfn & pfn;
408 		page = page + (combined_pfn - pfn);
409 		pfn = combined_pfn;
410 		order++;
411 	}
412 
413 done_merging:
414 	set_buddy_order(page, order);
415 
416 	if (fpi_flags & FPI_TO_TAIL)
417 		to_tail = true;
418 	else if (is_shuffle_order(order))
419 		to_tail = shuffle_pick_tail();
420 	else
421 		to_tail = buddy_merge_likely(pfn, buddy_pfn, page, order);
422 
423 	if (to_tail)
424 		add_to_free_list_tail(page, zone, order, migratetype);
425 	else
426 		add_to_free_list(page, zone, order, migratetype);
427 
428 	/* Notify page reporting subsystem of freed page */
429 	if (!(fpi_flags & FPI_SKIP_REPORT_NOTIFY))
430 		page_reporting_notify_free(order);
431 }
432 int page_to_nid(const struct page *page)
433 {
434 	return section_to_node_table[page_to_section(page)];
435 }
436 void free_unref_page(struct page *page, unsigned int order)
437 {
438 	unsigned long __maybe_unused UP_flags;
439 	struct per_cpu_pages *pcp;
440 	struct zone *zone;
441 	unsigned long pfn = page_to_pfn(page);
442 	int migratetype, pcpmigratetype;
443 
444 	if (!free_unref_page_prepare(page, pfn, order))
445 		return;
446 
447 	/*
448 	 * We only track unmovable, reclaimable and movable on pcp lists.
449 	 * Place ISOLATE pages on the isolated list because they are being
450 	 * offlined but treat HIGHATOMIC and CMA as movable pages so we can
451 	 * get those areas back if necessary. Otherwise, we may have to free
452 	 * excessively into the page allocator
453 	 */
454 	migratetype = pcpmigratetype = get_pcppage_migratetype(page);
455 	if (unlikely(migratetype >= MIGRATE_PCPTYPES)) {
456 		if (unlikely(is_migrate_isolate(migratetype))) {
457 			free_one_page(page_zone(page), page, pfn, order, migratetype, FPI_NONE);
458 			return;
459 		}
460 		pcpmigratetype = MIGRATE_MOVABLE;
461 	}
462 
463 	zone = page_zone(page);
464 	pcp_trylock_prepare(UP_flags);
465 	pcp = pcp_spin_trylock(zone->per_cpu_pageset);
466 	if (pcp) {
467 		free_unref_page_commit(zone, pcp, page, pcpmigratetype, order);
468 		pcp_spin_unlock(pcp);
469 	} else {
470 		free_one_page(zone, page, pfn, order, migratetype, FPI_NONE);
471 	}
472 	pcp_trylock_finish(UP_flags);
473 }
474 static inline void kfree(void *p)
475 {
476 	if (p >= __kfree_ignore_start && p < __kfree_ignore_end)
477 		return;
478 	free(p);
479 }
480 void __free_pages(struct page *page, unsigned int order)
481 {
482 	/* get PageHead before we drop reference */
483 	int head = PageHead(page);
484 
485 	if (put_page_testzero(page))
486 		free_the_page(page, order);
487 	else if (!head)
488 		while (order-- > 0)
489 			free_the_page(page + (1 << order), order);
490 }
491 static inline int put_page_testzero(struct page *page)
492 {
493 	VM_BUG_ON_PAGE(page_ref_count(page) == 0, page);
494 	return page_ref_dec_and_test(page);
495 }
496 static inline void spin_unlock_irqrestore(spinlock_t *lock, unsigned long f)
497 {
498 	spin_unlock(lock);
499 }
500 static noinline void __sched
501 __mutex_lock_slowpath(struct mutex *lock)
502 {
503 	__mutex_lock(lock, TASK_UNINTERRUPTIBLE, 0, NULL, _RET_IP_);
504 }
505 out:		/* free if the candidate is valid */
506 		if (!IS_ERR(candidate))
507 			erofs_put_metabuf(target);
508 		return de;
509 	}
510 	return candidate;
511 }
512 static inline void spin_lock_irqsave(spinlock_t *lock, unsigned long f)
513 {
514 	spin_lock(lock);
515 }
516 static inline struct zone *page_zone(const struct page *page)
517 {
518 	return &NODE_DATA(page_to_nid(page))->node_zones[page_zonenum(page)];
519 }
520 static inline void free_the_page(struct page *page, unsigned int order)
521 {
522 	if (pcp_allowed_order(order))		/* Via pcp? */
523 		free_unref_page(page, order);
524 	else
525 		__free_pages_ok(page, order, FPI_NONE);
526 }
527 void vmbus_free_ring(struct vmbus_channel *channel)
528 {
529         hv_ringbuffer_cleanup(&channel->outbound);
530         hv_ringbuffer_cleanup(&channel->inbound);
531 
532         if (channel->ringbuffer_page) {
533                 __free_pages(channel->ringbuffer_page,
534                              get_order(channel->ringbuffer_pagecount
535                                        << PAGE_SHIFT));
536                 channel->ringbuffer_page = NULL;
537         }
538 }
539 static void free_one_page(struct zone *zone,
540 				struct page *page, unsigned long pfn,
541 				unsigned int order,
542 				int migratetype, fpi_t fpi_flags)
543 {
544 	unsigned long flags;
545 
546 	spin_lock_irqsave(&zone->lock, flags);
547 	if (unlikely(has_isolate_pageblock(zone) ||
548 		is_migrate_isolate(migratetype))) {
549 		migratetype = get_pfnblock_migratetype(page, pfn);
550 	}
551 	__free_one_page(page, pfn, zone, order, migratetype, fpi_flags);
552 	spin_unlock_irqrestore(&zone->lock, flags);
553 }
554 static inline bool is_migrate_isolate(int migratetype)
555 {
556 	return migratetype == MIGRATE_ISOLATE;
557 }
558 static inline int get_pcppage_migratetype(struct page *page)
559 {
560 	return page->index;
561 }
562 static __inline__ int
563 get_order (unsigned long size)
564 {
565 	long double d = size - 1;
566 	long order;
567 
568 	order = ia64_getf_exp(d);
569 	order = order - PAGE_SHIFT - 0xffff + 1;
570 	if (order < 0)
571 		order = 0;
572 	return order;
573 }
574 static __always_inline bool __mutex_trylock_fast(struct mutex *lock)
575 {
576 	unsigned long curr = (unsigned long)current;
577 	unsigned long zero = 0UL;
578 
579 	if (atomic_long_try_cmpxchg_acquire(&lock->owner, &zero, curr))
580 		return true;
581 
582 	return false;
583 }
584 static inline void list_add(struct list_head *new, struct list_head *head)
585 {
586 	__list_add(new, head, head->next);
587 }
588 static inline void __count_vm_events(enum vm_event_item item, long delta)
589 {
590 	raw_cpu_add(vm_event_states.event[item], delta);
591 }
```
which has a vulnerability among CWE-457,CWE-476 and among lines:
```
4 		free_unref_page(page, order);
6 		__free_pages_ok(page, order, FPI_NONE);
15 	VM_BUG_ON_PAGE(PageTail(page), page);
16 
```
Please generate five possible patches for the vulnerability.