Merge tag 'mm-stable-2024-03-13-20-04' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:

 - Sumanth Korikkar has taught s390 to allocate hotplug-time page frames
   from hotplugged memory rather than only from main memory. Series
   "implement "memmap on memory" feature on s390".

 - More folio conversions from Matthew Wilcox in the series

	"Convert memcontrol charge moving to use folios"
	"mm: convert mm counter to take a folio"

 - Chengming Zhou has optimized zswap's rbtree locking, providing
   significant reductions in system time and modest but measurable
   reductions in overall runtimes. The series is "mm/zswap: optimize the
   scalability of zswap rb-tree".

 - Chengming Zhou has also provided the series "mm/zswap: optimize zswap
   lru list" which provides measurable runtime benefits in some
   swap-intensive situations.

 - And Chengming Zhou further optimizes zswap in the series "mm/zswap:
   optimize for dynamic zswap_pools". Measured improvements are modest.

 - zswap cleanups and simplifications from Yosry Ahmed in the series
   "mm: zswap: simplify zswap_swapoff()".

 - In the series "Add DAX ABI for memmap_on_memory", Vishal Verma has
   contributed several DAX cleanups as well as adding a sysfs tunable to
   control the memmap_on_memory setting when the dax device is
   hotplugged as system memory.

 - Johannes Weiner has added the large series "mm: zswap: cleanups",
   which does that.

 - More DAMON work from SeongJae Park in the series

	"mm/damon: make DAMON debugfs interface deprecation unignorable"
	"selftests/damon: add more tests for core functionalities and corner cases"
	"Docs/mm/damon: misc readability improvements"
	"mm/damon: let DAMOS feeds and tame/auto-tune itself"

 - In the series "mm/mempolicy: weighted interleave mempolicy and sysfs
   extension" Rakie Kim has developed a new mempolicy interleaving
   policy wherein we allocate memory across nodes in a weighted fashion
   rather than uniformly. This is beneficial in heterogeneous memory
   environments appearing with CXL.

 - Christophe Leroy has contributed some cleanup and consolidation work
   against the ARM pagetable dumping code in the series "mm: ptdump:
   Refactor CONFIG_DEBUG_WX and check_wx_pages debugfs attribute".

 - Luis Chamberlain has added some additional xarray selftesting in the
   series "test_xarray: advanced API multi-index tests".

 - Muhammad Usama Anjum has reworked the selftest code to make its
   human-readable output conform to the TAP ("Test Anything Protocol")
   format. Amongst other things, this opens up the use of third-party
   tools to parse and process out selftesting results.

 - Ryan Roberts has added fork()-time PTE batching of THP ptes in the
   series "mm/memory: optimize fork() with PTE-mapped THP". Mainly
   targeted at arm64, this significantly speeds up fork() when the
   process has a large number of pte-mapped folios.

 - David Hildenbrand also gets in on the THP pte batching game in his
   series "mm/memory: optimize unmap/zap with PTE-mapped THP". It
   implements batching during munmap() and other pte teardown
   situations. The microbenchmark improvements are nice.

 - And in the series "Transparent Contiguous PTEs for User Mappings"
   Ryan Roberts further utilizes arm's pte's contiguous bit ("contpte
   mappings"). Kernel build times on arm64 improved nicely. Ryan's
   series "Address some contpte nits" provides some followup work.

 - In the series "mm/hugetlb: Restore the reservation" Breno Leitao has
   fixed an obscure hugetlb race which was causing unnecessary page
   faults. He has also added a reproducer under the selftest code.

 - In the series "selftests/mm: Output cleanups for the compaction
   test", Mark Brown did what the title claims.

 - Kinsey Ho has added the series "mm/mglru: code cleanup and
   refactoring".

 - Even more zswap material from Nhat Pham. The series "fix and extend
   zswap kselftests" does as claimed.

 - In the series "Introduce cpu_dcache_is_aliasing() to fix DAX
   regression" Mathieu Desnoyers has cleaned up and fixed rather a mess
   in our handling of DAX on archiecctures which have virtually aliasing
   data caches. The arm architecture is the main beneficiary.

 - Lokesh Gidra's series "per-vma locks in userfaultfd" provides
   dramatic improvements in worst-case mmap_lock hold times during
   certain userfaultfd operations.

 - Some page_owner enhancements and maintenance work from Oscar Salvador
   in his series

	"page_owner: print stacks and their outstanding allocations"
	"page_owner: Fixup and cleanup"

 - Uladzislau Rezki has contributed some vmalloc scalability
   improvements in his series "Mitigate a vmap lock contention". It
   realizes a 12x improvement for a certain microbenchmark.

 - Some kexec/crash cleanup work from Baoquan He in the series "Split
   crash out from kexec and clean up related config items".

 - Some zsmalloc maintenance work from Chengming Zhou in the series

	"mm/zsmalloc: fix and optimize objects/page migration"
	"mm/zsmalloc: some cleanup for get/set_zspage_mapping()"

 - Zi Yan has taught the MM to perform compaction on folios larger than
   order=0. This a step along the path to implementaton of the merging
   of large anonymous folios. The series is named "Enable >0 order folio
   memory compaction".

 - Christoph Hellwig has done quite a lot of cleanup work in the
   pagecache writeback code in his series "convert write_cache_pages()
   to an iterator".

 - Some modest hugetlb cleanups and speedups in Vishal Moola's series
   "Handle hugetlb faults under the VMA lock".

 - Zi Yan has changed the page splitting code so we can split huge pages
   into sizes other than order-0 to better utilize large folios. The
   series is named "Split a folio to any lower order folios".

 - David Hildenbrand has contributed the series "mm: remove
   total_mapcount()", a cleanup.

 - Matthew Wilcox has sought to improve the performance of bulk memory
   freeing in his series "Rearrange batched folio freeing".

 - Gang Li's series "hugetlb: parallelize hugetlb page init on boot"
   provides large improvements in bootup times on large machines which
   are configured to use large numbers of hugetlb pages.

 - Matthew Wilcox's series "PageFlags cleanups" does that.

 - Qi Zheng's series "minor fixes and supplement for ptdesc" does that
   also. S390 is affected.

 - Cleanups to our pagemap utility functions from Peter Xu in his series
   "mm/treewide: Replace pXd_large() with pXd_leaf()".

 - Nico Pache has fixed a few things with our hugepage selftests in his
   series "selftests/mm: Improve Hugepage Test Handling in MM
   Selftests".

 - Also, of course, many singleton patches to many things. Please see
   the individual changelogs for details.

* tag 'mm-stable-2024-03-13-20-04' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (435 commits)
  mm/zswap: remove the memcpy if acomp is not sleepable
  crypto: introduce: acomp_is_async to expose if comp drivers might sleep
  memtest: use {READ,WRITE}_ONCE in memory scanning
  mm: prohibit the last subpage from reusing the entire large folio
  mm: recover pud_leaf() definitions in nopmd case
  selftests/mm: skip the hugetlb-madvise tests on unmet hugepage requirements
  selftests/mm: skip uffd hugetlb tests with insufficient hugepages
  selftests/mm: dont fail testsuite due to a lack of hugepages
  mm/huge_memory: skip invalid debugfs new_order input for folio split
  mm/huge_memory: check new folio order when split a folio
  mm, vmscan: retry kswapd's priority loop with cache_trim_mode off on failure
  mm: add an explicit smp_wmb() to UFFDIO_CONTINUE
  mm: fix list corruption in put_pages_list
  mm: remove folio from deferred split list before uncharging it
  filemap: avoid unnecessary major faults in filemap_fault()
  mm,page_owner: drop unnecessary check
  mm,page_owner: check for null stack_record before bumping its refcount
  mm: swap: fix race between free_swap_and_cache() and swapoff()
  mm/treewide: align up pXd_leaf() retval across archs
  mm/treewide: drop pXd_large()
  ...

1 files changed, 206 insertions, 4 deletions

diff --git a/mm/page_owner.c b/mm/page_owner.c
index 5634e5d890f8..e7139952ffd9 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -36,6 +36,15 @@ struct page_owner {
 	pid_t free_tgid;
 };
 
+struct stack {
+	struct stack_record *stack_record;
+	struct stack *next;
+};
+static struct stack dummy_stack;
+static struct stack failure_stack;
+static struct stack *stack_list;
+static DEFINE_SPINLOCK(stack_list_lock);
+
 static bool page_owner_enabled __initdata;
 DEFINE_STATIC_KEY_FALSE(page_owner_inited);
 
@@ -95,6 +104,15 @@ static __init void init_page_owner(void)
 	register_early_stack();
 	static_branch_enable(&page_owner_inited);
 	init_early_allocated_pages();
+	/* Initialize dummy and failure stacks and link them to stack_list */
+	dummy_stack.stack_record = __stack_depot_get_stack_record(dummy_handle);
+	failure_stack.stack_record = __stack_depot_get_stack_record(failure_handle);
+	if (dummy_stack.stack_record)
+		refcount_set(&dummy_stack.stack_record->count, 1);
+	if (failure_stack.stack_record)
+		refcount_set(&failure_stack.stack_record->count, 1);
+	dummy_stack.next = &failure_stack;
+	stack_list = &dummy_stack;
 }
 
 struct page_ext_operations page_owner_ops = {
@@ -135,11 +153,74 @@ static noinline depot_stack_handle_t save_stack(gfp_t flags)
 	return handle;
 }
 
+static void add_stack_record_to_list(struct stack_record *stack_record,
+				     gfp_t gfp_mask)
+{
+	unsigned long flags;
+	struct stack *stack;
+
+	/* Filter gfp_mask the same way stackdepot does, for consistency */
+	gfp_mask &= ~GFP_ZONEMASK;
+	gfp_mask &= (GFP_ATOMIC | GFP_KERNEL);
+	gfp_mask |= __GFP_NOWARN;
+
+	stack = kmalloc(sizeof(*stack), gfp_mask);
+	if (!stack)
+		return;
+
+	stack->stack_record = stack_record;
+	stack->next = NULL;
+
+	spin_lock_irqsave(&stack_list_lock, flags);
+	stack->next = stack_list;
+	/*
+	 * This pairs with smp_load_acquire() from function
+	 * stack_start(). This guarantees that stack_start()
+	 * will see an updated stack_list before starting to
+	 * traverse the list.
+	 */
+	smp_store_release(&stack_list, stack);
+	spin_unlock_irqrestore(&stack_list_lock, flags);
+}
+
+static void inc_stack_record_count(depot_stack_handle_t handle, gfp_t gfp_mask)
+{
+	struct stack_record *stack_record = __stack_depot_get_stack_record(handle);
+
+	if (!stack_record)
+		return;
+
+	/*
+	 * New stack_record's that do not use STACK_DEPOT_FLAG_GET start
+	 * with REFCOUNT_SATURATED to catch spurious increments of their
+	 * refcount.
+	 * Since we do not use STACK_DEPOT_FLAG_GET API, let us
+	 * set a refcount of 1 ourselves.
+	 */
+	if (refcount_read(&stack_record->count) == REFCOUNT_SATURATED) {
+		int old = REFCOUNT_SATURATED;
+
+		if (atomic_try_cmpxchg_relaxed(&stack_record->count.refs, &old, 1))
+			/* Add the new stack_record to our list */
+			add_stack_record_to_list(stack_record, gfp_mask);
+	}
+	refcount_inc(&stack_record->count);
+}
+
+static void dec_stack_record_count(depot_stack_handle_t handle)
+{
+	struct stack_record *stack_record = __stack_depot_get_stack_record(handle);
+
+	if (stack_record)
+		refcount_dec(&stack_record->count);
+}
+
 void __reset_page_owner(struct page *page, unsigned short order)
 {
 	int i;
 	struct page_ext *page_ext;
 	depot_stack_handle_t handle;
+	depot_stack_handle_t alloc_handle;
 	struct page_owner *page_owner;
 	u64 free_ts_nsec = local_clock();
 
@@ -147,17 +228,29 @@ void __reset_page_owner(struct page *page, unsigned short order)
 	if (unlikely(!page_ext))
 		return;
 
+	page_owner = get_page_owner(page_ext);
+	alloc_handle = page_owner->handle;
+
 	handle = save_stack(GFP_NOWAIT | __GFP_NOWARN);
 	for (i = 0; i < (1 << order); i++) {
 		__clear_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags);
-		page_owner = get_page_owner(page_ext);
 		page_owner->free_handle = handle;
 		page_owner->free_ts_nsec = free_ts_nsec;
 		page_owner->free_pid = current->pid;
 		page_owner->free_tgid = current->tgid;
 		page_ext = page_ext_next(page_ext);
+		page_owner = get_page_owner(page_ext);
 	}
 	page_ext_put(page_ext);
+	if (alloc_handle != early_handle)
+		/*
+		 * early_handle is being set as a handle for all those
+		 * early allocated pages. See init_pages_in_zone().
+		 * Since their refcount is not being incremented because
+		 * the machinery is not ready yet, we cannot decrement
+		 * their refcount either.
+		 */
+		dec_stack_record_count(alloc_handle);
 }
 
 static inline void __set_page_owner_handle(struct page_ext *page_ext,
@@ -199,6 +292,7 @@ noinline void __set_page_owner(struct page *page, unsigned short order,
 		return;
 	__set_page_owner_handle(page_ext, handle, order, gfp_mask);
 	page_ext_put(page_ext);
+	inc_stack_record_count(handle, gfp_mask);
 }
 
 void __set_page_owner_migrate_reason(struct page *page, int reason)
@@ -214,7 +308,7 @@ void __set_page_owner_migrate_reason(struct page *page, int reason)
 	page_ext_put(page_ext);
 }
 
-void __split_page_owner(struct page *page, unsigned int nr)
+void __split_page_owner(struct page *page, int old_order, int new_order)
 {
 	int i;
 	struct page_ext *page_ext = page_ext_get(page);
@@ -223,9 +317,9 @@ void __split_page_owner(struct page *page, unsigned int nr)
 	if (unlikely(!page_ext))
 		return;
 
-	for (i = 0; i < nr; i++) {
+	for (i = 0; i < (1 << old_order); i++) {
 		page_owner = get_page_owner(page_ext);
-		page_owner->order = 0;
+		page_owner->order = new_order;
 		page_ext = page_ext_next(page_ext);
 	}
 	page_ext_put(page_ext);
@@ -719,8 +813,111 @@ static const struct file_operations proc_page_owner_operations = {
 	.llseek		= lseek_page_owner,
 };
 
+static void *stack_start(struct seq_file *m, loff_t *ppos)
+{
+	struct stack *stack;
+
+	if (*ppos == -1UL)
+		return NULL;
+
+	if (!*ppos) {
+		/*
+		 * This pairs with smp_store_release() from function
+		 * add_stack_record_to_list(), so we get a consistent
+		 * value of stack_list.
+		 */
+		stack = smp_load_acquire(&stack_list);
+	} else {
+		stack = m->private;
+		stack = stack->next;
+	}
+
+	m->private = stack;
+
+	return stack;
+}
+
+static void *stack_next(struct seq_file *m, void *v, loff_t *ppos)
+{
+	struct stack *stack = v;
+
+	stack = stack->next;
+	*ppos = stack ? *ppos + 1 : -1UL;
+	m->private = stack;
+
+	return stack;
+}
+
+static unsigned long page_owner_stack_threshold;
+
+static int stack_print(struct seq_file *m, void *v)
+{
+	int i, stack_count;
+	struct stack *stack = v;
+	unsigned long *entries;
+	unsigned long nr_entries;
+	struct stack_record *stack_record = stack->stack_record;
+
+	if (!stack->stack_record)
+		return 0;
+
+	nr_entries = stack_record->size;
+	entries = stack_record->entries;
+	stack_count = refcount_read(&stack_record->count) - 1;
+
+	if (stack_count < 1 || stack_count < page_owner_stack_threshold)
+		return 0;
+
+	for (i = 0; i < nr_entries; i++)
+		seq_printf(m, " %pS\n", (void *)entries[i]);
+	seq_printf(m, "stack_count: %d\n\n", stack_count);
+
+	return 0;
+}
+
+static void stack_stop(struct seq_file *m, void *v)
+{
+}
+
+static const struct seq_operations page_owner_stack_op = {
+	.start	= stack_start,
+	.next	= stack_next,
+	.stop	= stack_stop,
+	.show	= stack_print
+};
+
+static int page_owner_stack_open(struct inode *inode, struct file *file)
+{
+	return seq_open_private(file, &page_owner_stack_op, 0);
+}
+
+static const struct file_operations page_owner_stack_operations = {
+	.open		= page_owner_stack_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release,
+};
+
+static int page_owner_threshold_get(void *data, u64 *val)
+{
+	*val = READ_ONCE(page_owner_stack_threshold);
+	return 0;
+}
+
+static int page_owner_threshold_set(void *data, u64 val)
+{
+	WRITE_ONCE(page_owner_stack_threshold, val);
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(proc_page_owner_threshold, &page_owner_threshold_get,
+			&page_owner_threshold_set, "%llu");
+
+
 static int __init pageowner_init(void)
 {
+	struct dentry *dir;
+
 	if (!static_branch_unlikely(&page_owner_inited)) {
 		pr_info("page_owner is disabled\n");
 		return 0;
@@ -728,6 +925,11 @@ static int __init pageowner_init(void)
 
 	debugfs_create_file("page_owner", 0400, NULL, NULL,
 			    &proc_page_owner_operations);
+	dir = debugfs_create_dir("page_owner_stacks", NULL);
+	debugfs_create_file("show_stacks", 0400, dir, NULL,
+			    &page_owner_stack_operations);
+	debugfs_create_file("count_threshold", 0600, dir, NULL,
+			    &proc_page_owner_threshold);
 
 	return 0;
 }