Merge tag 'mm-hotfixes-stable-2024-03-27-11-25' of...

Merge tag 'mm-hotfixes-stable-2024-03-27-11-25' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull misc fixes from Andrew Morton:
 "Various hotfixes. About half are cc:stable and the remainder address
  post-6.8 issues or aren't considered suitable for backporting.

  zswap figures prominently in the post-6.8 issues - folloup against the
  large amount of changes we have just made to that code.

  Apart from that, all over the map"

* tag 'mm-hotfixes-stable-2024-03-27-11-25' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (21 commits)
  crash: use macro to add crashk_res into iomem early for specific arch
  mm: zswap: fix data loss on SWP_SYNCHRONOUS_IO devices
  selftests/mm: fix ARM related issue with fork after pthread_create
  hexagon: vmlinux.lds.S: handle attributes section
  userfaultfd: fix deadlock warning when locking src and dst VMAs
  tmpfs: fix race on handling dquot rbtree
  selftests/mm: sigbus-wp test requires UFFD_FEATURE_WP_HUGETLBFS_SHMEM
  mm: zswap: fix writeback shinker GFP_NOIO/GFP_NOFS recursion
  ARM: prctl: reject PR_SET_MDWE on pre-ARMv6
  prctl: generalize PR_SET_MDWE support check to be per-arch
  MAINTAINERS: remove incorrect M: tag for dm-devel@lists.linux.dev
  mm: zswap: fix kernel BUG in sg_init_one
  selftests: mm: restore settings from only parent process
  tools/Makefile: remove cgroup target
  mm: cachestat: fix two shmem bugs
  mm: increase folio batch size
  mm,page_owner: fix recursion
  mailmap: update entry for Leonard Crestez
  init: open /initrd.image with O_LARGEFILE
  selftests/mm: Fix build with _FORTIFY_SOURCE
  ...

.mailmap

@@ -340,7 +340,8 @@ Lee Jones <lee@kernel.org> <joneslee@google.com>
 Lee Jones <lee@kernel.org> <lee.jones@canonical.com>
 Lee Jones <lee@kernel.org> <lee.jones@linaro.org>
 Lee Jones <lee@kernel.org> <lee@ubuntu.com>
-Leonard Crestez <leonard.crestez@nxp.com> Leonard Crestez <cdleonard@gmail.com>
+Leonard Crestez <cdleonard@gmail.com> <leonard.crestez@nxp.com>
+Leonard Crestez <cdleonard@gmail.com> <leonard.crestez@intel.com>
 Leonardo Bras <leobras.c@gmail.com> <leonardo@linux.ibm.com>
 Leonard Göhrs <l.goehrs@pengutronix.de>
 Leonid I Ananiev <leonid.i.ananiev@intel.com>

MAINTAINERS

@@ -6173,7 +6173,6 @@ F:	include/uapi/linux/dm-*.h
 
 DEVICE-MAPPER VDO TARGET
 M:	Matthew Sakai <msakai@redhat.com>
-M:	dm-devel@lists.linux.dev
 L:	dm-devel@lists.linux.dev
 S:	Maintained
 F:	Documentation/admin-guide/device-mapper/vdo*.rst

arch/arm/include/asm/mman.h

+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_MMAN_H__
+#define __ASM_MMAN_H__
+
+#include <asm/system_info.h>
+#include <uapi/asm/mman.h>
+
+static inline bool arch_memory_deny_write_exec_supported(void)
+{
+	return cpu_architecture() >= CPU_ARCH_ARMv6;
+}
+#define arch_memory_deny_write_exec_supported arch_memory_deny_write_exec_supported
+
+#endif /* __ASM_MMAN_H__ */

arch/hexagon/kernel/vmlinux.lds.S

@@ -63,6 +63,7 @@ SECTIONS
 	STABS_DEBUG
 	DWARF_DEBUG
 	ELF_DETAILS
+	.hexagon.attributes 0 : { *(.hexagon.attributes) }
 
 	DISCARDS
 }

arch/parisc/include/asm/mman.h

+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_MMAN_H__
+#define __ASM_MMAN_H__
+
+#include <uapi/asm/mman.h>
+
+/* PARISC cannot allow mdwe as it needs writable stacks */
+static inline bool arch_memory_deny_write_exec_supported(void)
+{
+	return false;
+}
+#define arch_memory_deny_write_exec_supported arch_memory_deny_write_exec_supported
+
+#endif /* __ASM_MMAN_H__ */

arch/x86/include/asm/crash_reserve.h

@@ -39,4 +39,6 @@ static inline unsigned long crash_low_size_default(void)
 #endif
 }
 
+#define HAVE_ARCH_ADD_CRASH_RES_TO_IOMEM_EARLY
+
 #endif /* _X86_CRASH_RESERVE_H */

include/linux/mman.h

@@ -162,6 +162,14 @@ calc_vm_flag_bits(unsigned long flags)
 
 unsigned long vm_commit_limit(void);
 
+#ifndef arch_memory_deny_write_exec_supported
+static inline bool arch_memory_deny_write_exec_supported(void)
+{
+	return true;
+}
+#define arch_memory_deny_write_exec_supported arch_memory_deny_write_exec_supported
+#endif
+
 /*
  * Denies creating a writable executable mapping or gaining executable permissions.
  *

include/linux/pagevec.h

@@ -11,8 +11,8 @@
 
 #include <linux/types.h>
 
-/* 15 pointers + header align the folio_batch structure to a power of two */
-#define PAGEVEC_SIZE	15
+/* 31 pointers + header align the folio_batch structure to a power of two */
+#define PAGEVEC_SIZE	31
 
 struct folio;
 

init/initramfs.c

@@ -682,7 +682,7 @@ static void __init populate_initrd_image(char *err)
 
 	printk(KERN_INFO "rootfs image is not initramfs (%s); looks like an initrd\n",
 			err);
-	file = filp_open("/initrd.image", O_WRONLY | O_CREAT, 0700);
+	file = filp_open("/initrd.image", O_WRONLY|O_CREAT|O_LARGEFILE, 0700);
 	if (IS_ERR(file))
 		return;
 

kernel/crash_reserve.c

@@ -366,7 +366,9 @@ static int __init reserve_crashkernel_low(unsigned long long low_size)
 
 	crashk_low_res.start = low_base;
 	crashk_low_res.end   = low_base + low_size - 1;
+#ifdef HAVE_ARCH_ADD_CRASH_RES_TO_IOMEM_EARLY
 	insert_resource(&iomem_resource, &crashk_low_res);
+#endif
 #endif
 	return 0;
 }
@@ -448,8 +450,12 @@ void __init reserve_crashkernel_generic(char *cmdline,
 
 	crashk_res.start = crash_base;
 	crashk_res.end = crash_base + crash_size - 1;
+#ifdef HAVE_ARCH_ADD_CRASH_RES_TO_IOMEM_EARLY
+	insert_resource(&iomem_resource, &crashk_res);
+#endif
 }
 
+#ifndef HAVE_ARCH_ADD_CRASH_RES_TO_IOMEM_EARLY
 static __init int insert_crashkernel_resources(void)
 {
 	if (crashk_res.start < crashk_res.end)
@@ -462,3 +468,4 @@ static __init int insert_crashkernel_resources(void)
 }
 early_initcall(insert_crashkernel_resources);
 #endif
+#endif

kernel/sys.c

@@ -2408,8 +2408,11 @@ static inline int prctl_set_mdwe(unsigned long bits, unsigned long arg3,
 	if (bits & PR_MDWE_NO_INHERIT && !(bits & PR_MDWE_REFUSE_EXEC_GAIN))
 		return -EINVAL;
 
-	/* PARISC cannot allow mdwe as it needs writable stacks */
-	if (IS_ENABLED(CONFIG_PARISC))
+	/*
+	 * EOPNOTSUPP might be more appropriate here in principle, but
+	 * existing userspace depends on EINVAL specifically.
+	 */
+	if (!arch_memory_deny_write_exec_supported())
 		return -EINVAL;
 
 	current_bits = get_current_mdwe();

mm/filemap.c

@@ -4197,7 +4197,23 @@ static void filemap_cachestat(struct address_space *mapping,
 				/* shmem file - in swap cache */
 				swp_entry_t swp = radix_to_swp_entry(folio);
 
+				/* swapin error results in poisoned entry */
+				if (non_swap_entry(swp))
+					goto resched;
+
+				/*
+				 * Getting a swap entry from the shmem
+				 * inode means we beat
+				 * shmem_unuse(). rcu_read_lock()
+				 * ensures swapoff waits for us before
+				 * freeing the swapper space. However,
+				 * we can race with swapping and
+				 * invalidation, so there might not be
+				 * a shadow in the swapcache (yet).
+				 */
 				shadow = get_shadow_from_swap_cache(swp);
+				if (!shadow)
+					goto resched;
 			}
 #endif
 			if (workingset_test_recent(shadow, true, &workingset))

mm/memory.c

@@ -1536,7 +1536,9 @@ static inline int zap_present_ptes(struct mmu_gather *tlb,
 		ptep_get_and_clear_full(mm, addr, pte, tlb->fullmm);
 		arch_check_zapped_pte(vma, ptent);
 		tlb_remove_tlb_entry(tlb, pte, addr);
-		VM_WARN_ON_ONCE(userfaultfd_wp(vma));
+		if (userfaultfd_pte_wp(vma, ptent))
+			zap_install_uffd_wp_if_needed(vma, addr, pte, 1,
+						      details, ptent);
 		ksm_might_unmap_zero_page(mm, ptent);
 		return 1;
 	}

mm/page_owner.c

@@ -54,6 +54,22 @@ static depot_stack_handle_t early_handle;
 
 static void init_early_allocated_pages(void);
 
+static inline void set_current_in_page_owner(void)
+{
+	/*
+	 * Avoid recursion.
+	 *
+	 * We might need to allocate more memory from page_owner code, so make
+	 * sure to signal it in order to avoid recursion.
+	 */
+	current->in_page_owner = 1;
+}
+
+static inline void unset_current_in_page_owner(void)
+{
+	current->in_page_owner = 0;
+}
+
 static int __init early_page_owner_param(char *buf)
 {
 	int ret = kstrtobool(buf, &page_owner_enabled);
@@ -133,23 +149,16 @@ static noinline depot_stack_handle_t save_stack(gfp_t flags)
 	depot_stack_handle_t handle;
 	unsigned int nr_entries;
 
-	/*
-	 * Avoid recursion.
-	 *
-	 * Sometimes page metadata allocation tracking requires more
-	 * memory to be allocated:
-	 * - when new stack trace is saved to stack depot
-	 */
 	if (current->in_page_owner)
 		return dummy_handle;
-	current->in_page_owner = 1;
 
+	set_current_in_page_owner();
 	nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 2);
 	handle = stack_depot_save(entries, nr_entries, flags);
 	if (!handle)
 		handle = failure_handle;
+	unset_current_in_page_owner();
 
-	current->in_page_owner = 0;
 	return handle;
 }
 
@@ -164,9 +173,13 @@ static void add_stack_record_to_list(struct stack_record *stack_record,
 	gfp_mask &= (GFP_ATOMIC | GFP_KERNEL);
 	gfp_mask |= __GFP_NOWARN;
 
+	set_current_in_page_owner();
 	stack = kmalloc(sizeof(*stack), gfp_mask);
-	if (!stack)
+	if (!stack) {
+		unset_current_in_page_owner();
 		return;
+	}
+	unset_current_in_page_owner();
 
 	stack->stack_record = stack_record;
 	stack->next = NULL;

mm/shmem_quota.c

@@ -116,7 +116,7 @@ static int shmem_free_file_info(struct super_block *sb, int type)
 static int shmem_get_next_id(struct super_block *sb, struct kqid *qid)
 {
 	struct mem_dqinfo *info = sb_dqinfo(sb, qid->type);
-	struct rb_node *node = ((struct rb_root *)info->dqi_priv)->rb_node;
+	struct rb_node *node;
 	qid_t id = from_kqid(&init_user_ns, *qid);
 	struct quota_info *dqopt = sb_dqopt(sb);
 	struct quota_id *entry = NULL;
@@ -126,6 +126,7 @@ static int shmem_get_next_id(struct super_block *sb, struct kqid *qid)
 		return -ESRCH;
 
 	down_read(&dqopt->dqio_sem);
+	node = ((struct rb_root *)info->dqi_priv)->rb_node;
 	while (node) {
 		entry = rb_entry(node, struct quota_id, node);
 
@@ -165,7 +166,7 @@ static int shmem_get_next_id(struct super_block *sb, struct kqid *qid)
 static int shmem_acquire_dquot(struct dquot *dquot)
 {
 	struct mem_dqinfo *info = sb_dqinfo(dquot->dq_sb, dquot->dq_id.type);
-	struct rb_node **n = &((struct rb_root *)info->dqi_priv)->rb_node;
+	struct rb_node **n;
 	struct shmem_sb_info *sbinfo = dquot->dq_sb->s_fs_info;
 	struct rb_node *parent = NULL, *new_node = NULL;
 	struct quota_id *new_entry, *entry;
@@ -176,6 +177,8 @@ static int shmem_acquire_dquot(struct dquot *dquot)
 	mutex_lock(&dquot->dq_lock);
 
 	down_write(&dqopt->dqio_sem);
+	n = &((struct rb_root *)info->dqi_priv)->rb_node;
+
 	while (*n) {
 		parent = *n;
 		entry = rb_entry(parent, struct quota_id, node);
@@ -264,7 +267,7 @@ static bool shmem_is_empty_dquot(struct dquot *dquot)
 static int shmem_release_dquot(struct dquot *dquot)
 {
 	struct mem_dqinfo *info = sb_dqinfo(dquot->dq_sb, dquot->dq_id.type);
-	struct rb_node *node = ((struct rb_root *)info->dqi_priv)->rb_node;
+	struct rb_node *node;
 	qid_t id = from_kqid(&init_user_ns, dquot->dq_id);
 	struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);
 	struct quota_id *entry = NULL;
@@ -275,6 +278,7 @@ static int shmem_release_dquot(struct dquot *dquot)
 		goto out_dqlock;
 
 	down_write(&dqopt->dqio_sem);
+	node = ((struct rb_root *)info->dqi_priv)->rb_node;
 	while (node) {
 		entry = rb_entry(node, struct quota_id, node);
 

mm/userfaultfd.c

@@ -1444,7 +1444,8 @@ static int uffd_move_lock(struct mm_struct *mm,
 		 */
 		down_read(&(*dst_vmap)->vm_lock->lock);
 		if (*dst_vmap != *src_vmap)
-			down_read(&(*src_vmap)->vm_lock->lock);
+			down_read_nested(&(*src_vmap)->vm_lock->lock,
+					 SINGLE_DEPTH_NESTING);
 	}
 	mmap_read_unlock(mm);
 	return err;

mm/zswap.c

@@ -1080,7 +1080,17 @@ static void zswap_decompress(struct zswap_entry *entry, struct page *page)
 	mutex_lock(&acomp_ctx->mutex);
 
 	src = zpool_map_handle(zpool, entry->handle, ZPOOL_MM_RO);
-	if (acomp_ctx->is_sleepable && !zpool_can_sleep_mapped(zpool)) {
+	/*
+	 * If zpool_map_handle is atomic, we cannot reliably utilize its mapped buffer
+	 * to do crypto_acomp_decompress() which might sleep. In such cases, we must
+	 * resort to copying the buffer to a temporary one.
+	 * Meanwhile, zpool_map_handle() might return a non-linearly mapped buffer,
+	 * such as a kmap address of high memory or even ever a vmap address.
+	 * However, sg_init_one is only equipped to handle linearly mapped low memory.
+	 * In such cases, we also must copy the buffer to a temporary and lowmem one.
+	 */
+	if ((acomp_ctx->is_sleepable && !zpool_can_sleep_mapped(zpool)) ||
+	    !virt_addr_valid(src)) {
 		memcpy(acomp_ctx->buffer, src, entry->length);
 		src = acomp_ctx->buffer;
 		zpool_unmap_handle(zpool, entry->handle);
@@ -1094,7 +1104,7 @@ static void zswap_decompress(struct zswap_entry *entry, struct page *page)
 	BUG_ON(acomp_ctx->req->dlen != PAGE_SIZE);
 	mutex_unlock(&acomp_ctx->mutex);
 
-	if (!acomp_ctx->is_sleepable || zpool_can_sleep_mapped(zpool))
+	if (src != acomp_ctx->buffer)
 		zpool_unmap_handle(zpool, entry->handle);
 }
 
@@ -1313,6 +1323,14 @@ static unsigned long zswap_shrinker_count(struct shrinker *shrinker,
 	if (!zswap_shrinker_enabled || !mem_cgroup_zswap_writeback_enabled(memcg))
 		return 0;
 
+	/*
+	 * The shrinker resumes swap writeback, which will enter block
+	 * and may enter fs. XXX: Harmonize with vmscan.c __GFP_FS
+	 * rules (may_enter_fs()), which apply on a per-folio basis.
+	 */
+	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;
@@ -1618,6 +1636,7 @@ bool zswap_load(struct folio *folio)
 	swp_entry_t swp = folio->swap;
 	pgoff_t offset = swp_offset(swp);
 	struct page *page = &folio->page;
+	bool swapcache = folio_test_swapcache(folio);
 	struct zswap_tree *tree = swap_zswap_tree(swp);
 	struct zswap_entry *entry;
 	u8 *dst;
@@ -1630,7 +1649,20 @@ bool zswap_load(struct folio *folio)
 		spin_unlock(&tree->lock);
 		return false;
 	}
-	zswap_rb_erase(&tree->rbroot, entry);
+	/*
+	 * When reading into the swapcache, invalidate our entry. The
+	 * swapcache can be the authoritative owner of the page and
+	 * its mappings, and the pressure that results from having two
+	 * in-memory copies outweighs any benefits of caching the
+	 * compression work.
+	 *
+	 * (Most swapins go through the swapcache. The notable
+	 * exception is the singleton fault on SWP_SYNCHRONOUS_IO
+	 * files, which reads into a private page and may free it if
+	 * the fault fails. We remain the primary owner of the entry.)
+	 */
+	if (swapcache)
+		zswap_rb_erase(&tree->rbroot, entry);
 	spin_unlock(&tree->lock);
 
 	if (entry->length)
@@ -1645,9 +1677,10 @@ bool zswap_load(struct folio *folio)
 	if (entry->objcg)
 		count_objcg_event(entry->objcg, ZSWPIN);
 
-	zswap_entry_free(entry);
-
-	folio_mark_dirty(folio);
+	if (swapcache) {
+		zswap_entry_free(entry);
+		folio_mark_dirty(folio);
+	}
 
 	return true;
 }

tools/Makefile

@@ -11,7 +11,6 @@ help:
 	@echo ''
 	@echo '  acpi                   - ACPI tools'
 	@echo '  bpf                    - misc BPF tools'
-	@echo '  cgroup                 - cgroup tools'
 	@echo '  counter                - counter tools'
 	@echo '  cpupower               - a tool for all things x86 CPU power'
 	@echo '  debugging              - tools for debugging'
@@ -69,7 +68,7 @@ acpi: FORCE
 cpupower: FORCE
 	$(call descend,power/$@)
 
-cgroup counter firewire hv guest bootconfig spi usb virtio mm bpf iio gpio objtool leds wmi pci firmware debugging tracing: FORCE
+counter firewire hv guest bootconfig spi usb virtio mm bpf iio gpio objtool leds wmi pci firmware debugging tracing: FORCE
 	$(call descend,$@)
 
 bpf/%: FORCE
@@ -116,7 +115,7 @@ freefall: FORCE
 kvm_stat: FORCE
 	$(call descend,kvm/$@)
 
-all: acpi cgroup counter cpupower gpio hv firewire \
+all: acpi counter cpupower gpio hv firewire \
 		perf selftests bootconfig spi turbostat usb \
 		virtio mm bpf x86_energy_perf_policy \
 		tmon freefall iio objtool kvm_stat wmi \
@@ -128,7 +127,7 @@ acpi_install:
 cpupower_install:
 	$(call descend,power/$(@:_install=),install)
 
-cgroup_install counter_install firewire_install gpio_install hv_install iio_install perf_install bootconfig_install spi_install usb_install virtio_install mm_install bpf_install objtool_install wmi_install pci_install debugging_install tracing_install:
+counter_install firewire_install gpio_install hv_install iio_install perf_install bootconfig_install spi_install usb_install virtio_install mm_install bpf_install objtool_install wmi_install pci_install debugging_install tracing_install:
 	$(call descend,$(@:_install=),install)
 
 selftests_install:
@@ -155,7 +154,7 @@ freefall_install:
 kvm_stat_install:
 	$(call descend,kvm/$(@:_install=),install)
 
-install: acpi_install cgroup_install counter_install cpupower_install gpio_install \
+install: acpi_install counter_install cpupower_install gpio_install \
 		hv_install firewire_install iio_install \
 		perf_install selftests_install turbostat_install usb_install \
 		virtio_install mm_install bpf_install x86_energy_perf_policy_install \
@@ -169,7 +168,7 @@ acpi_clean:
 cpupower_clean:
 	$(call descend,power/cpupower,clean)
 
-cgroup_clean counter_clean hv_clean firewire_clean bootconfig_clean spi_clean usb_clean virtio_clean mm_clean wmi_clean bpf_clean iio_clean gpio_clean objtool_clean leds_clean pci_clean firmware_clean debugging_clean tracing_clean:
+counter_clean hv_clean firewire_clean bootconfig_clean spi_clean usb_clean virtio_clean mm_clean wmi_clean bpf_clean iio_clean gpio_clean objtool_clean leds_clean pci_clean firmware_clean debugging_clean tracing_clean:
 	$(call descend,$(@:_clean=),clean)
 
 libapi_clean:
@@ -209,7 +208,7 @@ freefall_clean:
 build_clean:
 	$(call descend,build,clean)
 
-clean: acpi_clean cgroup_clean counter_clean cpupower_clean hv_clean firewire_clean \
+clean: acpi_clean counter_clean cpupower_clean hv_clean firewire_clean \
 		perf_clean selftests_clean turbostat_clean bootconfig_clean spi_clean usb_clean virtio_clean \
 		mm_clean bpf_clean iio_clean x86_energy_perf_policy_clean tmon_clean \
 		freefall_clean build_clean libbpf_clean libsubcmd_clean \

tools/testing/selftests/mm/gup_test.c

@@ -203,7 +203,7 @@ int main(int argc, char **argv)
 	ksft_print_header();
 	ksft_set_plan(nthreads);
 
-	filed = open(file, O_RDWR|O_CREAT);
+	filed = open(file, O_RDWR|O_CREAT, 0664);
 	if (filed < 0)
 		ksft_exit_fail_msg("Unable to open %s: %s\n", file, strerror(errno));
 

tools/testing/selftests/mm/protection_keys.c

@@ -1745,9 +1745,12 @@ void pkey_setup_shadow(void)
 	shadow_pkey_reg = __read_pkey_reg();
 }
 
+pid_t parent_pid;
+
 void restore_settings_atexit(void)
 {
-	cat_into_file(buf, "/proc/sys/vm/nr_hugepages");
+	if (parent_pid == getpid())
+		cat_into_file(buf, "/proc/sys/vm/nr_hugepages");
 }
 
 void save_settings(void)
@@ -1773,6 +1776,7 @@ void save_settings(void)
 		exit(__LINE__);
 	}
 
+	parent_pid = getpid();
 	atexit(restore_settings_atexit);
 	close(fd);
 }

tools/testing/selftests/mm/soft-dirty.c

@@ -137,7 +137,7 @@ static void test_mprotect(int pagemap_fd, int pagesize, bool anon)
 		if (!map)
 			ksft_exit_fail_msg("anon mmap failed\n");
 	} else {
-		test_fd = open(fname, O_RDWR | O_CREAT);
+		test_fd = open(fname, O_RDWR | O_CREAT, 0664);
 		if (test_fd < 0) {
 			ksft_test_result_skip("Test %s open() file failed\n", __func__);
 			return;

tools/testing/selftests/mm/split_huge_page_test.c

@@ -223,7 +223,7 @@ void split_file_backed_thp(void)
 		ksft_exit_fail_msg("Fail to create file-backed THP split testing file\n");
 	}
 
-	fd = open(testfile, O_CREAT|O_WRONLY);
+	fd = open(testfile, O_CREAT|O_WRONLY, 0664);
 	if (fd == -1) {
 		ksft_perror("Cannot open testing file");
 		goto cleanup;

tools/testing/selftests/mm/uffd-common.c

@@ -18,6 +18,7 @@ bool test_uffdio_wp = true;
 unsigned long long *count_verify;
 uffd_test_ops_t *uffd_test_ops;
 uffd_test_case_ops_t *uffd_test_case_ops;
+atomic_bool ready_for_fork;
 
 static int uffd_mem_fd_create(off_t mem_size, bool hugetlb)
 {
@@ -518,6 +519,8 @@ void *uffd_poll_thread(void *arg)
 	pollfd[1].fd = pipefd[cpu*2];
 	pollfd[1].events = POLLIN;
 
+	ready_for_fork = true;
+
 	for (;;) {
 		ret = poll(pollfd, 2, -1);
 		if (ret <= 0) {

tools/testing/selftests/mm/uffd-common.h

@@ -32,6 +32,7 @@
 #include <inttypes.h>
 #include <stdint.h>
 #include <sys/random.h>
+#include <stdatomic.h>
 
 #include "../kselftest.h"
 #include "vm_util.h"
@@ -103,6 +104,7 @@ extern bool map_shared;
 extern bool test_uffdio_wp;
 extern unsigned long long *count_verify;
 extern volatile bool test_uffdio_copy_eexist;
+extern atomic_bool ready_for_fork;
 
 extern uffd_test_ops_t anon_uffd_test_ops;
 extern uffd_test_ops_t shmem_uffd_test_ops;

tools/testing/selftests/mm/uffd-unit-tests.c

@@ -775,6 +775,8 @@ static void uffd_sigbus_test_common(bool wp)
 	char c;
 	struct uffd_args args = { 0 };
 
+	ready_for_fork = false;
+
 	fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK);
 
 	if (uffd_register(uffd, area_dst, nr_pages * page_size,
@@ -790,6 +792,9 @@ static void uffd_sigbus_test_common(bool wp)
 	if (pthread_create(&uffd_mon, NULL, uffd_poll_thread, &args))
 		err("uffd_poll_thread create");
 
+	while (!ready_for_fork)
+		; /* Wait for the poll_thread to start executing before forking */
+
 	pid = fork();
 	if (pid < 0)
 		err("fork");
@@ -829,6 +834,8 @@ static void uffd_events_test_common(bool wp)
 	char c;
 	struct uffd_args args = { 0 };
 
+	ready_for_fork = false;
+
 	fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK);
 	if (uffd_register(uffd, area_dst, nr_pages * page_size,
 			  true, wp, false))
@@ -838,6 +845,9 @@ static void uffd_events_test_common(bool wp)
 	if (pthread_create(&uffd_mon, NULL, uffd_poll_thread, &args))
 		err("uffd_poll_thread create");
 
+	while (!ready_for_fork)
+		; /* Wait for the poll_thread to start executing before forking */
+
 	pid = fork();
 	if (pid < 0)
 		err("fork");
@@ -1427,7 +1437,8 @@ uffd_test_case_t uffd_tests[] = {
 		.uffd_fn = uffd_sigbus_wp_test,
 		.mem_targets = MEM_ALL,
 		.uffd_feature_required = UFFD_FEATURE_SIGBUS |
-		UFFD_FEATURE_EVENT_FORK | UFFD_FEATURE_PAGEFAULT_FLAG_WP,
+		UFFD_FEATURE_EVENT_FORK | UFFD_FEATURE_PAGEFAULT_FLAG_WP |
+		UFFD_FEATURE_WP_HUGETLBFS_SHMEM,
 	},
 	{
 		.name = "events",