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2023-12-08 01573e231f18eb2d99162747186f59511f56b64d 
 kernel/include/linux/page-flags.h
....@@ -17,8 +17,37 @@
1717 /*
1818  * Various page->flags bits:
1919  *
20
- * PG_reserved is set for special pages, which can never be swapped out. Some
21
- * of them might not even exist...
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+ * PG_reserved is set for special pages. The "struct page" of such a page
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+ * should in general not be touched (e.g. set dirty) except by its owner.
22
+ * Pages marked as PG_reserved include:
23
+ * - Pages part of the kernel image (including vDSO) and similar (e.g. BIOS,
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+ *   initrd, HW tables)
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+ * - Pages reserved or allocated early during boot (before the page allocator
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+ *   was initialized). This includes (depending on the architecture) the
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+ *   initial vmemmap, initial page tables, crashkernel, elfcorehdr, and much
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+ *   much more. Once (if ever) freed, PG_reserved is cleared and they will
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+ *   be given to the page allocator.
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+ * - Pages falling into physical memory gaps - not IORESOURCE_SYSRAM. Trying
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+ *   to read/write these pages might end badly. Don't touch!
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+ * - The zero page(s)
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+ * - Pages not added to the page allocator when onlining a section because
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+ *   they were excluded via the online_page_callback() or because they are
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+ *   PG_hwpoison.
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+ * - Pages allocated in the context of kexec/kdump (loaded kernel image,
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+ *   control pages, vmcoreinfo)
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+ * - MMIO/DMA pages. Some architectures don't allow to ioremap pages that are
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+ *   not marked PG_reserved (as they might be in use by somebody else who does
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+ *   not respect the caching strategy).
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+ * - Pages part of an offline section (struct pages of offline sections should
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+ *   not be trusted as they will be initialized when first onlined).
43
+ * - MCA pages on ia64
44
+ * - Pages holding CPU notes for POWER Firmware Assisted Dump
45
+ * - Device memory (e.g. PMEM, DAX, HMM)
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+ * Some PG_reserved pages will be excluded from the hibernation image.
47
+ * PG_reserved does in general not hinder anybody from dumping or swapping
48
+ * and is no longer required for remap_pfn_range(). ioremap might require it.
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+ * Consequently, PG_reserved for a page mapped into user space can indicate
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+ * the zero page, the vDSO, MMIO pages or device memory.
2251  *
2352  * The PG_private bitflag is set on pagecache pages if they contain filesystem
2453  * specific data (which is normally at page->private). It can be used by
....@@ -33,6 +62,11 @@
3362  *
3463  * page_waitqueue(page) is a wait queue of all tasks waiting for the page
3564  * to become unlocked.
65
+ *
66
+ * PG_swapbacked is set when a page uses swap as a backing storage.  This are
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+ * usually PageAnon or shmem pages but please note that even anonymous pages
68
+ * might lose their PG_swapbacked flag when they simply can be dropped (e.g. as
69
+ * a result of MADV_FREE).
3670  *
3771  * PG_uptodate tells whether the page's contents is valid.  When a read
3872  * completes, the page becomes uptodate, unless a disk I/O error happened.
....@@ -98,9 +132,15 @@
98132 #ifdef CONFIG_MEMORY_FAILURE
99133 	PG_hwpoison,		/* hardware poisoned page. Don't touch */
100134 #endif
101
-#if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
135
+#if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
102136 	PG_young,
103137 	PG_idle,
138
+#endif
139
+#ifdef CONFIG_64BIT
140
+	PG_arch_2,
141
+#endif
142
+#ifdef CONFIG_KASAN_HW_TAGS
143
+	PG_skip_kasan_poison,
104144 #endif
105145 	__NR_PAGEFLAGS,
106146 
....@@ -123,15 +163,20 @@
123163 	PG_savepinned = PG_dirty,
124164 	/* Has a grant mapping of another (foreign) domain's page. */
125165 	PG_foreign = PG_owner_priv_1,
166
+	/* Remapped by swiotlb-xen. */
167
+	PG_xen_remapped = PG_owner_priv_1,
126168 
127169 	/* SLOB */
128170 	PG_slob_free = PG_private,
129171 
130172 	/* Compound pages. Stored in first tail page's flags */
131
-	PG_double_map = PG_private_2,
173
+	PG_double_map = PG_workingset,
132174 
133175 	/* non-lru isolated movable page */
134176 	PG_isolated = PG_reclaim,
177
+
178
+	/* Only valid for buddy pages. Used to track pages that are reported */
179
+	PG_reported = PG_uptodate,
135180 };
136181 
137182 #ifndef __GENERATING_BOUNDS_H
....@@ -163,6 +208,14 @@
163208 	return page->flags == PAGE_POISON_PATTERN;
164209 }
165210 
211
+#ifdef CONFIG_DEBUG_VM
212
+void page_init_poison(struct page *page, size_t size);
213
+#else
214
+static inline void page_init_poison(struct page *page, size_t size)
215
+{
216
+}
217
+#endif
218
+
166219 /*
167220  * Page flags policies wrt compound pages
168221  *
....@@ -185,6 +238,9 @@
185238  *
186239  * PF_NO_COMPOUND:
187240  *     the page flag is not relevant for compound pages.
241
+ *
242
+ * PF_SECOND:
243
+ *     the page flag is stored in the first tail page.
188244  */
189245 #define PF_POISONED_CHECK(page) ({					\
190246 		VM_BUG_ON_PGFLAGS(PagePoisoned(page), page);		\
....@@ -200,6 +256,9 @@
200256 #define PF_NO_COMPOUND(page, enforce) ({				\
201257 		VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page);	\
202258 		PF_POISONED_CHECK(page); })
259
+#define PF_SECOND(page, enforce) ({					\
260
+		VM_BUG_ON_PGFLAGS(!PageHead(page), page);		\
261
+		PF_POISONED_CHECK(&page[1]); })
203262 
204263 /*
205264  * Macros to create function definitions for page flags
....@@ -292,9 +351,12 @@
292351 	TESTSCFLAG(Pinned, pinned, PF_NO_COMPOUND)
293352 PAGEFLAG(SavePinned, savepinned, PF_NO_COMPOUND);
294353 PAGEFLAG(Foreign, foreign, PF_NO_COMPOUND);
354
+PAGEFLAG(XenRemapped, xen_remapped, PF_NO_COMPOUND)
355
+	TESTCLEARFLAG(XenRemapped, xen_remapped, PF_NO_COMPOUND)
295356 
296357 PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
297358 	__CLEARPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
359
+	__SETPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
298360 PAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
299361 	__CLEARPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
300362 	__SETPAGEFLAG(SwapBacked, swapbacked, PF_NO_TAIL)
....@@ -372,22 +434,32 @@
372434 PAGEFLAG(HWPoison, hwpoison, PF_ANY)
373435 TESTSCFLAG(HWPoison, hwpoison, PF_ANY)
374436 #define __PG_HWPOISON (1UL << PG_hwpoison)
375
-extern bool set_hwpoison_free_buddy_page(struct page *page);
437
+extern bool take_page_off_buddy(struct page *page);
376438 #else
377439 PAGEFLAG_FALSE(HWPoison)
378
-static inline bool set_hwpoison_free_buddy_page(struct page *page)
379
-{
380
-	return 0;
381
-}
382440 #define __PG_HWPOISON 0
383441 #endif
384442 
385
-#if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
443
+#if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
386444 TESTPAGEFLAG(Young, young, PF_ANY)
387445 SETPAGEFLAG(Young, young, PF_ANY)
388446 TESTCLEARFLAG(Young, young, PF_ANY)
389447 PAGEFLAG(Idle, idle, PF_ANY)
390448 #endif
449
+
450
+#ifdef CONFIG_KASAN_HW_TAGS
451
+PAGEFLAG(SkipKASanPoison, skip_kasan_poison, PF_HEAD)
452
+#else
453
+PAGEFLAG_FALSE(SkipKASanPoison)
454
+#endif
455
+
456
+/*
457
+ * PageReported() is used to track reported free pages within the Buddy
458
+ * allocator. We can use the non-atomic version of the test and set
459
+ * operations as both should be shielded with the zone lock to prevent
460
+ * any possible races on the setting or clearing of the bit.
461
+ */
462
+__PAGEFLAG(Reported, reported, PF_NO_COMPOUND)
391463 
392464 /*
393465  * On an anonymous page mapped into a user virtual memory area,
....@@ -627,42 +699,15 @@
627699  *
628700  * See also __split_huge_pmd_locked() and page_remove_anon_compound_rmap().
629701  */
630
-static inline int PageDoubleMap(struct page *page)
631
-{
632
-	return PageHead(page) && test_bit(PG_double_map, &page[1].flags);
633
-}
634
-
635
-static inline void SetPageDoubleMap(struct page *page)
636
-{
637
-	VM_BUG_ON_PAGE(!PageHead(page), page);
638
-	set_bit(PG_double_map, &page[1].flags);
639
-}
640
-
641
-static inline void ClearPageDoubleMap(struct page *page)
642
-{
643
-	VM_BUG_ON_PAGE(!PageHead(page), page);
644
-	clear_bit(PG_double_map, &page[1].flags);
645
-}
646
-static inline int TestSetPageDoubleMap(struct page *page)
647
-{
648
-	VM_BUG_ON_PAGE(!PageHead(page), page);
649
-	return test_and_set_bit(PG_double_map, &page[1].flags);
650
-}
651
-
652
-static inline int TestClearPageDoubleMap(struct page *page)
653
-{
654
-	VM_BUG_ON_PAGE(!PageHead(page), page);
655
-	return test_and_clear_bit(PG_double_map, &page[1].flags);
656
-}
657
-
702
+PAGEFLAG(DoubleMap, double_map, PF_SECOND)
703
+	TESTSCFLAG(DoubleMap, double_map, PF_SECOND)
658704 #else
659705 TESTPAGEFLAG_FALSE(TransHuge)
660706 TESTPAGEFLAG_FALSE(TransCompound)
661707 TESTPAGEFLAG_FALSE(TransCompoundMap)
662708 TESTPAGEFLAG_FALSE(TransTail)
663709 PAGEFLAG_FALSE(DoubleMap)
664
-	TESTSETFLAG_FALSE(DoubleMap)
665
-	TESTCLEARFLAG_FALSE(DoubleMap)
710
+	TESTSCFLAG_FALSE(DoubleMap)
666711 #endif
667712 
668713 /*
....@@ -676,13 +721,20 @@
676721 
677722 #define PAGE_TYPE_BASE	0xf0000000
678723 /* Reserve		0x0000007f to catch underflows of page_mapcount */
724
+#define PAGE_MAPCOUNT_RESERVE	-128
679725 #define PG_buddy	0x00000080
680
-#define PG_balloon	0x00000100
726
+#define PG_offline	0x00000100
681727 #define PG_kmemcg	0x00000200
682728 #define PG_table	0x00000400
729
+#define PG_guard	0x00000800
683730 
684731 #define PageType(page, flag)						\
685732 	((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)
733
+
734
+static inline int page_has_type(struct page *page)
735
+{
736
+	return (int)page->page_type < PAGE_MAPCOUNT_RESERVE;
737
+}
686738 
687739 #define PAGE_TYPE_OPS(uname, lname)					\
688740 static __always_inline int Page##uname(struct page *page)		\
....@@ -707,10 +759,23 @@
707759 PAGE_TYPE_OPS(Buddy, buddy)
708760 
709761 /*
710
- * PageBalloon() is true for pages that are on the balloon page list
711
- * (see mm/balloon_compaction.c).
762
+ * PageOffline() indicates that the page is logically offline although the
763
+ * containing section is online. (e.g. inflated in a balloon driver or
764
+ * not onlined when onlining the section).
765
+ * The content of these pages is effectively stale. Such pages should not
766
+ * be touched (read/write/dump/save) except by their owner.
767
+ *
768
+ * If a driver wants to allow to offline unmovable PageOffline() pages without
769
+ * putting them back to the buddy, it can do so via the memory notifier by
770
+ * decrementing the reference count in MEM_GOING_OFFLINE and incrementing the
771
+ * reference count in MEM_CANCEL_OFFLINE. When offlining, the PageOffline()
772
+ * pages (now with a reference count of zero) are treated like free pages,
773
+ * allowing the containing memory block to get offlined. A driver that
774
+ * relies on this feature is aware that re-onlining the memory block will
775
+ * require to re-set the pages PageOffline() and not giving them to the
776
+ * buddy via online_page_callback_t.
712777  */
713
-PAGE_TYPE_OPS(Balloon, balloon)
778
+PAGE_TYPE_OPS(Offline, offline)
714779 
715780 /*
716781  * If kmemcg is enabled, the buddy allocator will set PageKmemcg() on
....@@ -723,9 +788,14 @@
723788  */
724789 PAGE_TYPE_OPS(Table, table)
725790 
791
+/*
792
+ * Marks guardpages used with debug_pagealloc.
793
+ */
794
+PAGE_TYPE_OPS(Guard, guard)
795
+
726796 extern bool is_free_buddy_page(struct page *page);
727797 
728
-__PAGEFLAG(Isolated, isolated, PF_ANY);
798
+PAGEFLAG(Isolated, isolated, PF_ANY);
729799 
730800 /*
731801  * If network-based swap is enabled, sl*b must keep track of whether pages
....@@ -802,6 +872,7 @@
802872 #undef PF_ONLY_HEAD
803873 #undef PF_NO_TAIL
804874 #undef PF_NO_COMPOUND
875
+#undef PF_SECOND
805876 #endif /* !__GENERATING_BOUNDS_H */
806877 
807878 #endif	/* PAGE_FLAGS_H */