Merge tag 'mm-hotfixes-stable-2024-04-26-13-30' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull misc fixes from Andrew Morton:
 "11 hotfixes. 8 are cc:stable and the remaining 3 (nice ratio!) address
  post-6.8 issues or aren't considered suitable for backporting.

  All except one of these are for MM. I see no particular theme - it's
  singletons all over"

* tag 'mm-hotfixes-stable-2024-04-26-13-30' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
  mm/hugetlb: fix DEBUG_LOCKS_WARN_ON(1) when dissolve_free_hugetlb_folio()
  selftests: mm: protection_keys: save/restore nr_hugepages value from launch script
  stackdepot: respect __GFP_NOLOCKDEP allocation flag
  hugetlb: check for anon_vma prior to folio allocation
  mm: zswap: fix shrinker NULL crash with cgroup_disable=memory
  mm: turn folio_test_hugetlb into a PageType
  mm: support page_mapcount() on page_has_type() pages
  mm: create FOLIO_FLAG_FALSE and FOLIO_TYPE_OPS macros
  mm/hugetlb: fix missing hugetlb_lock for resv uncharge
  selftests: mm: fix unused and uninitialized variable warning
  selftests/harness: remove use of LINE_MAX

13 files changed, 137 insertions, 152 deletions

diff --git a/fs/proc/page.c b/fs/proc/page.c
index 195b077c0fac..9223856c934b 100644
--- a/fs/proc/page.c
+++ b/fs/proc/page.c
@@ -67,7 +67,7 @@ static ssize_t kpagecount_read(struct file *file, char __user *buf,
 		 */
 		ppage = pfn_to_online_page(pfn);
 
-		if (!ppage || PageSlab(ppage) || page_has_type(ppage))
+		if (!ppage)
 			pcount = 0;
 		else
 			pcount = page_mapcount(ppage);
@@ -124,11 +124,8 @@ u64 stable_page_flags(struct page *page)
 
 	/*
 	 * pseudo flags for the well known (anonymous) memory mapped pages
-	 *
-	 * Note that page->_mapcount is overloaded in SLAB, so the
-	 * simple test in page_mapped() is not enough.
 	 */
-	if (!PageSlab(page) && page_mapped(page))
+	if (page_mapped(page))
 		u |= 1 << KPF_MMAP;
 	if (PageAnon(page))
 		u |= 1 << KPF_ANON;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 7b0ee64225de..b6bdaa18b9e9 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1223,14 +1223,16 @@ static inline void page_mapcount_reset(struct page *page)
  * a large folio, it includes the number of times this page is mapped
  * as part of that folio.
  *
- * The result is undefined for pages which cannot be mapped into userspace.
- * For example SLAB or special types of pages. See function page_has_type().
- * They use this field in struct page differently.
+ * Will report 0 for pages which cannot be mapped into userspace, eg
+ * slab, page tables and similar.
  */
 static inline int page_mapcount(struct page *page)
 {
 	int mapcount = atomic_read(&page->_mapcount) + 1;
 
+	/* Handle page_has_type() pages */
+	if (mapcount < 0)
+		mapcount = 0;
 	if (unlikely(PageCompound(page)))
 		mapcount += folio_entire_mapcount(page_folio(page));
 
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 652d77805e99..4bf1c25fd1dc 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -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 */
 };
 
@@ -458,30 +457,51 @@ static __always_inline int TestClearPage##uname(struct page *page)	\
 	TESTSETFLAG(uname, lname, policy)				\
 	TESTCLEARFLAG(uname, lname, policy)
 
+#define FOLIO_TEST_FLAG_FALSE(name)					\
+static inline bool folio_test_##name(const struct folio *folio)		\
+{ return false; }
+#define FOLIO_SET_FLAG_NOOP(name)					\
+static inline void folio_set_##name(struct folio *folio) { }
+#define FOLIO_CLEAR_FLAG_NOOP(name)					\
+static inline void folio_clear_##name(struct folio *folio) { }
+#define __FOLIO_SET_FLAG_NOOP(name)					\
+static inline void __folio_set_##name(struct folio *folio) { }
+#define __FOLIO_CLEAR_FLAG_NOOP(name)					\
+static inline void __folio_clear_##name(struct folio *folio) { }
+#define FOLIO_TEST_SET_FLAG_FALSE(name)					\
+static inline bool folio_test_set_##name(struct folio *folio)		\
+{ return false; }
+#define FOLIO_TEST_CLEAR_FLAG_FALSE(name)				\
+static inline bool folio_test_clear_##name(struct folio *folio)		\
+{ return false; }
+
+#define FOLIO_FLAG_FALSE(name)						\
+FOLIO_TEST_FLAG_FALSE(name)						\
+FOLIO_SET_FLAG_NOOP(name)						\
+FOLIO_CLEAR_FLAG_NOOP(name)
+
 #define TESTPAGEFLAG_FALSE(uname, lname)				\
-static inline bool folio_test_##lname(const struct folio *folio) { return false; } \
+FOLIO_TEST_FLAG_FALSE(lname)						\
 static inline int Page##uname(const struct page *page) { return 0; }
 
 #define SETPAGEFLAG_NOOP(uname, lname)					\
-static inline void folio_set_##lname(struct folio *folio) { }		\
+FOLIO_SET_FLAG_NOOP(lname)						\
 static inline void SetPage##uname(struct page *page) {  }
 
 #define CLEARPAGEFLAG_NOOP(uname, lname)				\
-static inline void folio_clear_##lname(struct folio *folio) { }		\
+FOLIO_CLEAR_FLAG_NOOP(lname)						\
 static inline void ClearPage##uname(struct page *page) {  }
 
 #define __CLEARPAGEFLAG_NOOP(uname, lname)				\
-static inline void __folio_clear_##lname(struct folio *folio) { }	\
+__FOLIO_CLEAR_FLAG_NOOP(lname)						\
 static inline void __ClearPage##uname(struct page *page) {  }
 
 #define TESTSETFLAG_FALSE(uname, lname)					\
-static inline bool folio_test_set_##lname(struct folio *folio)		\
-{ return 0; }								\
+FOLIO_TEST_SET_FLAG_FALSE(lname)					\
 static inline int TestSetPage##uname(struct page *page) { return 0; }
 
 #define TESTCLEARFLAG_FALSE(uname, lname)				\
-static inline bool folio_test_clear_##lname(struct folio *folio)	\
-{ return 0; }								\
+FOLIO_TEST_CLEAR_FLAG_FALSE(lname)					\
 static inline int TestClearPage##uname(struct page *page) { return 0; }
 
 #define PAGEFLAG_FALSE(uname, lname) TESTPAGEFLAG_FALSE(uname, lname)	\
@@ -855,29 +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
@@ -934,33 +931,22 @@ PAGEFLAG_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
  * sense of the bit, so __SetPageFoo *clears* the bit used for PageFoo, and
  * __ClearPageFoo *sets* the bit used for PageFoo.  We reserve a few high and
- * low bits so that an underflow or overflow of page_mapcount() won't be
+ * low bits so that an underflow or overflow of _mapcount won't be
  * mistaken for a page type value.
  */
 
 #define PAGE_TYPE_BASE	0xf0000000
-/* Reserve		0x0000007f to catch underflows of page_mapcount */
+/* Reserve		0x0000007f to catch underflows of _mapcount */
 #define PAGE_MAPCOUNT_RESERVE	-128
 #define PG_buddy	0x00000080
 #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)
@@ -977,35 +963,38 @@ static inline int page_has_type(const struct page *page)
 	return page_type_has_type(page->page_type);
 }
 
+#define FOLIO_TYPE_OPS(lname, fname)					\
+static __always_inline bool folio_test_##fname(const struct folio *folio)\
+{									\
+	return folio_test_type(folio, PG_##lname);			\
+}									\
+static __always_inline void __folio_set_##fname(struct folio *folio)	\
+{									\
+	VM_BUG_ON_FOLIO(!folio_test_type(folio, 0), folio);		\
+	folio->page.page_type &= ~PG_##lname;				\
+}									\
+static __always_inline void __folio_clear_##fname(struct folio *folio)	\
+{									\
+	VM_BUG_ON_FOLIO(!folio_test_##fname(folio), folio);		\
+	folio->page.page_type |= PG_##lname;				\
+}
+
 #define PAGE_TYPE_OPS(uname, lname, fname)				\
+FOLIO_TYPE_OPS(lname, fname)						\
 static __always_inline int Page##uname(const struct page *page)		\
 {									\
 	return PageType(page, PG_##lname);				\
 }									\
-static __always_inline int folio_test_##fname(const struct folio *folio)\
-{									\
-	return folio_test_type(folio, PG_##lname);			\
-}									\
 static __always_inline void __SetPage##uname(struct page *page)		\
 {									\
 	VM_BUG_ON_PAGE(!PageType(page, 0), page);			\
 	page->page_type &= ~PG_##lname;					\
 }									\
-static __always_inline void __folio_set_##fname(struct folio *folio)	\
-{									\
-	VM_BUG_ON_FOLIO(!folio_test_type(folio, 0), folio);		\
-	folio->page.page_type &= ~PG_##lname;				\
-}									\
 static __always_inline void __ClearPage##uname(struct page *page)	\
 {									\
 	VM_BUG_ON_PAGE(!Page##uname(page), page);			\
 	page->page_type |= PG_##lname;					\
-}									\
-static __always_inline void __folio_clear_##fname(struct folio *folio)	\
-{									\
-	VM_BUG_ON_FOLIO(!folio_test_##fname(folio), folio);		\
-	folio->page.page_type |= PG_##lname;				\
-}									\
+}
 
 /*
  * PageBuddy() indicates that the page is free and in the buddy system
@@ -1052,6 +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);
@@ -1118,7 +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)
diff --git a/include/trace/events/mmflags.h b/include/trace/events/mmflags.h
index d801409b33cf..d55e53ac91bd 100644
--- a/include/trace/events/mmflags.h
+++ b/include/trace/events/mmflags.h
@@ -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),					\
diff --git a/kernel/vmcore_info.c b/kernel/vmcore_info.c
index f95516cd45bb..23c125c2e243 100644
--- a/kernel/vmcore_info.c
+++ b/kernel/vmcore_info.c
@@ -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);
diff --git a/lib/stackdepot.c b/lib/stackdepot.c
index 68c97387aa54..cd8f23455285 100644
--- a/lib/stackdepot.c
+++ b/lib/stackdepot.c
@@ -627,10 +627,10 @@ depot_stack_handle_t stack_depot_save_flags(unsigned long *entries,
 		/*
 		 * Zero out zone modifiers, as we don't have specific zone
 		 * requirements. Keep the flags related to allocation in atomic
-		 * contexts and I/O.
+		 * contexts, I/O, nolockdep.
 		 */
 		alloc_flags &= ~GFP_ZONEMASK;
-		alloc_flags &= (GFP_ATOMIC | GFP_KERNEL);
+		alloc_flags &= (GFP_ATOMIC | GFP_KERNEL | __GFP_NOLOCKDEP);
 		alloc_flags |= __GFP_NOWARN;
 		page = alloc_pages(alloc_flags, DEPOT_POOL_ORDER);
 		if (page)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 31d00eee028f..ce7be5c24442 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -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
@@ -1781,7 +1781,7 @@ static void __update_and_free_hugetlb_folio(struct hstate *h,
 	 * If vmemmap pages were allocated above, then we need to clear the
 	 * hugetlb destructor under the hugetlb lock.
 	 */
-	if (clear_dtor) {
+	if (folio_test_hugetlb(folio)) {
 		spin_lock_irq(&hugetlb_lock);
 		__clear_hugetlb_destructor(h, folio);
 		spin_unlock_irq(&hugetlb_lock);
@@ -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);
@@ -2160,22 +2160,6 @@ static bool prep_compound_gigantic_folio_for_demote(struct folio *folio,
 }
 
 /*
- * 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.
  *
  * Upon entry, the page is locked which means that page_mapping() is
@@ -3268,9 +3252,12 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma,
 
 		rsv_adjust = hugepage_subpool_put_pages(spool, 1);
 		hugetlb_acct_memory(h, -rsv_adjust);
-		if (deferred_reserve)
+		if (deferred_reserve) {
+			spin_lock_irq(&hugetlb_lock);
 			hugetlb_cgroup_uncharge_folio_rsvd(hstate_index(h),
 					pages_per_huge_page(h), folio);
+			spin_unlock_irq(&hugetlb_lock);
+		}
 	}
 
 	if (!memcg_charge_ret)
@@ -6274,6 +6261,12 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
 							VM_UFFD_MISSING);
 		}
 
+		if (!(vma->vm_flags & VM_MAYSHARE)) {
+			ret = vmf_anon_prepare(vmf);
+			if (unlikely(ret))
+				goto out;
+		}
+
 		folio = alloc_hugetlb_folio(vma, haddr, 0);
 		if (IS_ERR(folio)) {
 			/*
@@ -6310,15 +6303,12 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
 				 */
 				restore_reserve_on_error(h, vma, haddr, folio);
 				folio_put(folio);
+				ret = VM_FAULT_SIGBUS;
 				goto out;
 			}
 			new_pagecache_folio = true;
 		} else {
 			folio_lock(folio);
-
-			ret = vmf_anon_prepare(vmf);
-			if (unlikely(ret))
-				goto backout_unlocked;
 			anon_rmap = 1;
 		}
 	} else {
diff --git a/mm/zswap.c b/mm/zswap.c
index caed028945b0..6f8850c44b61 100644
--- a/mm/zswap.c
+++ b/mm/zswap.c
@@ -1331,15 +1331,22 @@ static unsigned long zswap_shrinker_count(struct shrinker *shrinker,
 	if (!gfp_has_io_fs(sc->gfp_mask))
 		return 0;
 
-#ifdef CONFIG_MEMCG_KMEM
-	mem_cgroup_flush_stats(memcg);
-	nr_backing = memcg_page_state(memcg, MEMCG_ZSWAP_B) >> PAGE_SHIFT;
-	nr_stored = memcg_page_state(memcg, MEMCG_ZSWAPPED);
-#else
-	/* use pool stats instead of memcg stats */
-	nr_backing = zswap_pool_total_size >> PAGE_SHIFT;
-	nr_stored = atomic_read(&zswap_nr_stored);
-#endif
+	/*
+	 * For memcg, use the cgroup-wide ZSWAP stats since we don't
+	 * have them per-node and thus per-lruvec. Careful if memcg is
+	 * runtime-disabled: we can get sc->memcg == NULL, which is ok
+	 * for the lruvec, but not for memcg_page_state().
+	 *
+	 * Without memcg, use the zswap pool-wide metrics.
+	 */
+	if (!mem_cgroup_disabled()) {
+		mem_cgroup_flush_stats(memcg);
+		nr_backing = memcg_page_state(memcg, MEMCG_ZSWAP_B) >> PAGE_SHIFT;
+		nr_stored = memcg_page_state(memcg, MEMCG_ZSWAPPED);
+	} else {
+		nr_backing = zswap_pool_total_size >> PAGE_SHIFT;
+		nr_stored = atomic_read(&zswap_nr_stored);
+	}
 
 	if (!nr_stored)
 		return 0;
diff --git a/tools/testing/selftests/kselftest_harness.h b/tools/testing/selftests/kselftest_harness.h
index ba3ddeda24bf..d98702b6955d 100644
--- a/tools/testing/selftests/kselftest_harness.h
+++ b/tools/testing/selftests/kselftest_harness.h
@@ -56,7 +56,6 @@
 #include <asm/types.h>
 #include <ctype.h>
 #include <errno.h>
-#include <limits.h>
 #include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
@@ -1159,7 +1158,7 @@ void __run_test(struct __fixture_metadata *f,
 		struct __test_metadata *t)
 {
 	struct __test_xfail *xfail;
-	char test_name[LINE_MAX];
+	char *test_name;
 	const char *diagnostic;
 
 	/* reset test struct */
@@ -1167,8 +1166,12 @@ void __run_test(struct __fixture_metadata *f,
 	t->trigger = 0;
 	memset(t->results->reason, 0, sizeof(t->results->reason));
 
-	snprintf(test_name, sizeof(test_name), "%s%s%s.%s",
-		 f->name, variant->name[0] ? "." : "", variant->name, t->name);
+	if (asprintf(&test_name, "%s%s%s.%s", f->name,
+		variant->name[0] ? "." : "", variant->name, t->name) == -1) {
+		ksft_print_msg("ERROR ALLOCATING MEMORY\n");
+		t->exit_code = KSFT_FAIL;
+		_exit(t->exit_code);
+	}
 
 	ksft_print_msg(" RUN           %s ...\n", test_name);
 
@@ -1206,6 +1209,7 @@ void __run_test(struct __fixture_metadata *f,
 
 	ksft_test_result_code(t->exit_code, test_name,
 			      diagnostic ? "%s" : NULL, diagnostic);
+	free(test_name);
 }
 
 static int test_harness_run(int argc, char **argv)
diff --git a/tools/testing/selftests/mm/mdwe_test.c b/tools/testing/selftests/mm/mdwe_test.c
index 200bedcdc32e..1e01d3ddc11c 100644
--- a/tools/testing/selftests/mm/mdwe_test.c
+++ b/tools/testing/selftests/mm/mdwe_test.c
@@ -7,6 +7,7 @@
 #include <linux/mman.h>
 #include <linux/prctl.h>
 
+#define _GNU_SOURCE
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/auxv.h>
diff --git a/tools/testing/selftests/mm/protection_keys.c b/tools/testing/selftests/mm/protection_keys.c
index 374a308174d2..48dc151f8fca 100644
--- a/tools/testing/selftests/mm/protection_keys.c
+++ b/tools/testing/selftests/mm/protection_keys.c
@@ -54,7 +54,6 @@ int test_nr;
 u64 shadow_pkey_reg;
 int dprint_in_signal;
 char dprint_in_signal_buffer[DPRINT_IN_SIGNAL_BUF_SIZE];
-char buf[256];
 
 void cat_into_file(char *str, char *file)
 {
@@ -1745,42 +1744,6 @@ void pkey_setup_shadow(void)
 	shadow_pkey_reg = __read_pkey_reg();
 }
 
-pid_t parent_pid;
-
-void restore_settings_atexit(void)
-{
-	if (parent_pid == getpid())
-		cat_into_file(buf, "/proc/sys/vm/nr_hugepages");
-}
-
-void save_settings(void)
-{
-	int fd;
-	int err;
-
-	if (geteuid())
-		return;
-
-	fd = open("/proc/sys/vm/nr_hugepages", O_RDONLY);
-	if (fd < 0) {
-		fprintf(stderr, "error opening\n");
-		perror("error: ");
-		exit(__LINE__);
-	}
-
-	/* -1 to guarantee leaving the trailing \0 */
-	err = read(fd, buf, sizeof(buf)-1);
-	if (err < 0) {
-		fprintf(stderr, "error reading\n");
-		perror("error: ");
-		exit(__LINE__);
-	}
-
-	parent_pid = getpid();
-	atexit(restore_settings_atexit);
-	close(fd);
-}
-
 int main(void)
 {
 	int nr_iterations = 22;
@@ -1788,7 +1751,6 @@ int main(void)
 
 	srand((unsigned int)time(NULL));
 
-	save_settings();
 	setup_handlers();
 
 	printf("has pkeys: %d\n", pkeys_supported);
diff --git a/tools/testing/selftests/mm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh
index c2c542fe7b17..4bdb3a0c7a60 100755
--- a/tools/testing/selftests/mm/run_vmtests.sh
+++ b/tools/testing/selftests/mm/run_vmtests.sh
@@ -385,6 +385,7 @@ CATEGORY="ksm_numa" run_test ./ksm_tests -N -m 0
 CATEGORY="ksm" run_test ./ksm_functional_tests
 
 # protection_keys tests
+nr_hugepgs=$(cat /proc/sys/vm/nr_hugepages)
 if [ -x ./protection_keys_32 ]
 then
 	CATEGORY="pkey" run_test ./protection_keys_32
@@ -394,6 +395,7 @@ if [ -x ./protection_keys_64 ]
 then
 	CATEGORY="pkey" run_test ./protection_keys_64
 fi
+echo "$nr_hugepgs" > /proc/sys/vm/nr_hugepages
 
 if [ -x ./soft-dirty ]
 then
diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
index 6c988bd2f335..d3c7f5fb3e7b 100644
--- a/tools/testing/selftests/mm/split_huge_page_test.c
+++ b/tools/testing/selftests/mm/split_huge_page_test.c
@@ -300,7 +300,7 @@ int create_pagecache_thp_and_fd(const char *testfile, size_t fd_size, int *fd,
 		char **addr)
 {
 	size_t i;
-	int dummy;
+	int __attribute__((unused)) dummy = 0;
 
 	srand(time(NULL));