FAILED: patch "[PATCH] mm: turn folio_test_hugetlb into a PageType" failed to apply to 6.6-stable tree

PATCH New [email protected] 2 participants 2 messages Apr 29, 2024

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Stable branch Memory management MM core Tracing +1 more subsystems

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2024-04-29 11:25 UTC #0 lore raw

The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x d99e3140a4d33e26066183ff727d8f02f56bec64
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2024042908-squint-barometer-51de@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:

d99e3140a4d3 ("mm: turn folio_test_hugetlb into a PageType")
29cfe7556bfd ("mm: constify more page/folio tests")
443cbaf9e2fd ("crash: split vmcoreinfo exporting code out from crash_core.c")
85fcde402db1 ("kexec: split crashkernel reservation code out from crash_core.c")
55c49fee57af ("mm/vmalloc: remove vmap_area_list")
d093602919ad ("mm: vmalloc: remove global vmap_area_root rb-tree")
7fa8cee00316 ("mm: vmalloc: move vmap_init_free_space() down in vmalloc.c")
4a693ce65b18 ("kdump: defer the insertion of crashkernel resources")
9f2a63523582 ("Merge tag 'mm-nonmm-stable-2024-01-09-10-33' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From d99e3140a4d33e26066183ff727d8f02f56bec64 Mon Sep 17 00:00:00 2001
From: "Matthew Wilcox (Oracle)" <[email protected]>
Date: Thu, 21 Mar 2024 14:24:43 +0000
Subject: [PATCH] mm: turn folio_test_hugetlb into a PageType

The current folio_test_hugetlb() can be fooled by a concurrent folio split into returning true for a folio which has never belonged to hugetlbfs. This can't happen if the caller holds a refcount on it, but we have a few places (memory-failure, compaction, procfs) which do not and should not take a speculative reference.

Since hugetlb pages do not use individual page mapcounts (they are always fully mapped and use the entire_mapcount field to record the number of mappings), the PageType field is available now that page_mapcount() ignores the value in this field.

In compaction and with CONFIG_DEBUG_VM enabled, the current implementation can result in an oops, as reported by Luis. This happens since 9c5ccf2db04b ("mm: remove HUGETLB_PAGE_DTOR") effectively added some VM_BUG_ON() checks in the PageHuge() testing path.

[[email protected]: update vmcoreinfo]

Link https://lkml.kernel.org/r/[email protected] open here

Fixes 9c5ccf2db04b ("mm: remove HUGETLB_PAGE_DTOR")

Signed-off-by Matthew Wilcox (Oracle) <[email protected]>

Reviewed-by David Hildenbrand <[email protected]>

Acked-by Vlastimil Babka <[email protected]>

Reported-by Luis Chamberlain <[email protected]>

Closes https://bugzilla.kernel.org/show_bug.cgi?id=218227

Cc Miaohe Lin <[email protected]>

Cc Muchun Song <[email protected]>

Cc Oscar Salvador <[email protected]>

Cc <[email protected]>

Signed-off-by Andrew Morton <[email protected]>

include/linux/page-flags.h +33 ~~-37~~

index 35a0087d0910..4bf1c25fd1dc 100644
@@ -190,7 +190,6 @@ enum pageflags {
 
 	/* At least one page in this folio has the hwpoison flag set */
 	PG_has_hwpoisoned = PG_error,
-	PG_hugetlb = PG_active,
 	PG_large_rmappable = PG_workingset, /* anon or file-backed */
 };

@@ -876,29 +875,6 @@ TESTPAGEFLAG_FALSE(LargeRmappable, large_rmappable)
 
 #define PG_head_mask ((1UL << PG_head))
 
-#ifdef CONFIG_HUGETLB_PAGE
-int PageHuge(const struct page *page);
-SETPAGEFLAG(HugeTLB, hugetlb, PF_SECOND)
-CLEARPAGEFLAG(HugeTLB, hugetlb, PF_SECOND)
-
-/**
- * folio_test_hugetlb - Determine if the folio belongs to hugetlbfs
- * @folio: The folio to test.
- *
- * Context: Any context.  Caller should have a reference on the folio to
- * prevent it from being turned into a tail page.
- * Return: True for hugetlbfs folios, false for anon folios or folios
- * belonging to other filesystems.
- */
-static inline bool folio_test_hugetlb(const struct folio *folio)
-{
-	return folio_test_large(folio) &&
-		test_bit(PG_hugetlb, const_folio_flags(folio, 1));
-}
-#else
-TESTPAGEFLAG_FALSE(Huge, hugetlb)
-#endif
-
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 /*
  * PageHuge() only returns true for hugetlbfs pages, but not for

@@ -954,18 +930,6 @@ PAGEFLAG_FALSE(HasHWPoisoned, has_hwpoisoned)
 	TESTSCFLAG_FALSE(HasHWPoisoned, has_hwpoisoned)
 #endif
 
-/*
- * Check if a page is currently marked HWPoisoned. Note that this check is
- * best effort only and inherently racy: there is no way to synchronize with
- * failing hardware.
- */
-static inline bool is_page_hwpoison(struct page *page)
-{
-	if (PageHWPoison(page))
-		return true;
-	return PageHuge(page) && PageHWPoison(compound_head(page));
-}
-
 /*
  * For pages that are never mapped to userspace (and aren't PageSlab),
  * page_type may be used.  Because it is initialised to -1, we invert the

@@ -982,6 +946,7 @@ static inline bool is_page_hwpoison(struct page *page)
 #define PG_offline	0x00000100
 #define PG_table	0x00000200
 #define PG_guard	0x00000400
+#define PG_hugetlb	0x00000800
 
 #define PageType(page, flag)						\
 	((page->page_type & (PAGE_TYPE_BASE | flag)) == PAGE_TYPE_BASE)

@@ -1076,6 +1041,37 @@ PAGE_TYPE_OPS(Table, table, pgtable)
  */
 PAGE_TYPE_OPS(Guard, guard, guard)
 
+#ifdef CONFIG_HUGETLB_PAGE
+FOLIO_TYPE_OPS(hugetlb, hugetlb)
+#else
+FOLIO_TEST_FLAG_FALSE(hugetlb)
+#endif
+
+/**
+ * PageHuge - Determine if the page belongs to hugetlbfs
+ * @page: The page to test.
+ *
+ * Context: Any context.
+ * Return: True for hugetlbfs pages, false for anon pages or pages
+ * belonging to other filesystems.
+ */
+static inline bool PageHuge(const struct page *page)
+{
+	return folio_test_hugetlb(page_folio(page));
+}
+
+/*
+ * Check if a page is currently marked HWPoisoned. Note that this check is
+ * best effort only and inherently racy: there is no way to synchronize with
+ * failing hardware.
+ */
+static inline bool is_page_hwpoison(struct page *page)
+{
+	if (PageHWPoison(page))
+		return true;
+	return PageHuge(page) && PageHWPoison(compound_head(page));
+}
+
 extern bool is_free_buddy_page(struct page *page);
 
 PAGEFLAG(Isolated, isolated, PF_ANY);

@@ -1142,7 +1138,7 @@ static __always_inline void __ClearPageAnonExclusive(struct page *page)
  */
 #define PAGE_FLAGS_SECOND						\
 	(0xffUL /* order */		| 1UL << PG_has_hwpoisoned |	\
-	 1UL << PG_hugetlb		| 1UL << PG_large_rmappable)
+	 1UL << PG_large_rmappable)
 
 #define PAGE_FLAGS_PRIVATE				\
 	(1UL << PG_private | 1UL << PG_private_2)

include/trace/events/mmflags.h +1 -0

index d801409b33cf..d55e53ac91bd 100644
@@ -135,6 +135,7 @@ IF_HAVE_PG_ARCH_X(arch_3)
 #define DEF_PAGETYPE_NAME(_name) { PG_##_name, __stringify(_name) }
 
 #define __def_pagetype_names						\
+	DEF_PAGETYPE_NAME(hugetlb),					\
 	DEF_PAGETYPE_NAME(offline),					\
 	DEF_PAGETYPE_NAME(guard),					\
 	DEF_PAGETYPE_NAME(table),					\

kernel/vmcore_info.c +2 -3

index f95516cd45bb..23c125c2e243 100644
@@ -205,11 +205,10 @@ static int __init crash_save_vmcoreinfo_init(void)
 	VMCOREINFO_NUMBER(PG_head_mask);
 #define PAGE_BUDDY_MAPCOUNT_VALUE	(~PG_buddy)
 	VMCOREINFO_NUMBER(PAGE_BUDDY_MAPCOUNT_VALUE);
-#ifdef CONFIG_HUGETLB_PAGE
-	VMCOREINFO_NUMBER(PG_hugetlb);
+#define PAGE_HUGETLB_MAPCOUNT_VALUE	(~PG_hugetlb)
+	VMCOREINFO_NUMBER(PAGE_HUGETLB_MAPCOUNT_VALUE);
 #define PAGE_OFFLINE_MAPCOUNT_VALUE	(~PG_offline)
 	VMCOREINFO_NUMBER(PAGE_OFFLINE_MAPCOUNT_VALUE);
-#endif
 
 #ifdef CONFIG_KALLSYMS
 	VMCOREINFO_SYMBOL(kallsyms_names);

mm/hugetlb.c +3 ~~-19~~

index 53e0ab5c0845..4553241f0fb2 100644
@@ -1624,7 +1624,7 @@ static inline void __clear_hugetlb_destructor(struct hstate *h,
 {
 	lockdep_assert_held(&hugetlb_lock);
 
-	folio_clear_hugetlb(folio);
+	__folio_clear_hugetlb(folio);
 }
 
 /*

@@ -1711,7 +1711,7 @@ static void add_hugetlb_folio(struct hstate *h, struct folio *folio,
 		h->surplus_huge_pages_node[nid]++;
 	}
 
-	folio_set_hugetlb(folio);
+	__folio_set_hugetlb(folio);
 	folio_change_private(folio, NULL);
 	/*
 	 * We have to set hugetlb_vmemmap_optimized again as above

@@ -2049,7 +2049,7 @@ static void __prep_account_new_huge_page(struct hstate *h, int nid)
 
 static void init_new_hugetlb_folio(struct hstate *h, struct folio *folio)
 {
-	folio_set_hugetlb(folio);
+	__folio_set_hugetlb(folio);
 	INIT_LIST_HEAD(&folio->lru);
 	hugetlb_set_folio_subpool(folio, NULL);
 	set_hugetlb_cgroup(folio, NULL);

@@ -2159,22 +2159,6 @@ static bool prep_compound_gigantic_folio_for_demote(struct folio *folio,
 	return __prep_compound_gigantic_folio(folio, order, true);
 }
 
-/*
- * PageHuge() only returns true for hugetlbfs pages, but not for normal or
- * transparent huge pages.  See the PageTransHuge() documentation for more
- * details.
- */
-int PageHuge(const struct page *page)
-{
-	const struct folio *folio;
-
-	if (!PageCompound(page))
-		return 0;
-	folio = page_folio(page);
-	return folio_test_hugetlb(folio);
-}
-EXPORT_SYMBOL_GPL(PageHuge);
-
 /*
  * Find and lock address space (mapping) in write mode.
  *

Matthew Wilcox (Oracle)

2024-04-29 13:31 UTC #1 lore raw

PATCH 1/1 mm: turn folio_test_hugetlb into a PageType