include/linux/sched/mm.h: uninline mmdrop_async(), etc

mmdrop_async() is only used in fork.c.  Move that and its support
functions into fork.c, uninline it all.

Quite a lot of code gets moved around to avoid forward declarations.

Cc: Ingo Molnar <mingo@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/sched/mm.h

@@ -11,7 +11,7 @@
 /*
  * Routines for handling mm_structs
  */
-extern struct mm_struct * mm_alloc(void);
+extern struct mm_struct *mm_alloc(void);
 
 /**
  * mmgrab() - Pin a &struct mm_struct.
@@ -35,27 +35,7 @@ static inline void mmgrab(struct mm_struct *mm)
 	atomic_inc(&mm->mm_count);
 }
 
-/* mmdrop drops the mm and the page tables */
-extern void __mmdrop(struct mm_struct *);
-static inline void mmdrop(struct mm_struct *mm)
-{
-	if (unlikely(atomic_dec_and_test(&mm->mm_count)))
-		__mmdrop(mm);
-}
-
-static inline void mmdrop_async_fn(struct work_struct *work)
-{
-	struct mm_struct *mm = container_of(work, struct mm_struct, async_put_work);
-	__mmdrop(mm);
-}
-
-static inline void mmdrop_async(struct mm_struct *mm)
-{
-	if (unlikely(atomic_dec_and_test(&mm->mm_count))) {
-		INIT_WORK(&mm->async_put_work, mmdrop_async_fn);
-		schedule_work(&mm->async_put_work);
-	}
-}
+extern void mmdrop(struct mm_struct *mm);
 
 /**
  * mmget() - Pin the address space associated with a &struct mm_struct.

kernel/fork.c

@@ -77,6 +77,7 @@
 #include <linux/blkdev.h>
 #include <linux/fs_struct.h>
 #include <linux/magic.h>
+#include <linux/sched/mm.h>
 #include <linux/perf_event.h>
 #include <linux/posix-timers.h>
 #include <linux/user-return-notifier.h>
@@ -390,6 +391,241 @@ void free_task(struct task_struct *tsk)
 }
 EXPORT_SYMBOL(free_task);
 
+#ifdef CONFIG_MMU
+static __latent_entropy int dup_mmap(struct mm_struct *mm,
+					struct mm_struct *oldmm)
+{
+	struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
+	struct rb_node **rb_link, *rb_parent;
+	int retval;
+	unsigned long charge;
+	LIST_HEAD(uf);
+
+	uprobe_start_dup_mmap();
+	if (down_write_killable(&oldmm->mmap_sem)) {
+		retval = -EINTR;
+		goto fail_uprobe_end;
+	}
+	flush_cache_dup_mm(oldmm);
+	uprobe_dup_mmap(oldmm, mm);
+	/*
+	 * Not linked in yet - no deadlock potential:
+	 */
+	down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
+
+	/* No ordering required: file already has been exposed. */
+	RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm));
+
+	mm->total_vm = oldmm->total_vm;
+	mm->data_vm = oldmm->data_vm;
+	mm->exec_vm = oldmm->exec_vm;
+	mm->stack_vm = oldmm->stack_vm;
+
+	rb_link = &mm->mm_rb.rb_node;
+	rb_parent = NULL;
+	pprev = &mm->mmap;
+	retval = ksm_fork(mm, oldmm);
+	if (retval)
+		goto out;
+	retval = khugepaged_fork(mm, oldmm);
+	if (retval)
+		goto out;
+
+	prev = NULL;
+	for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
+		struct file *file;
+
+		if (mpnt->vm_flags & VM_DONTCOPY) {
+			vm_stat_account(mm, mpnt->vm_flags, -vma_pages(mpnt));
+			continue;
+		}
+		charge = 0;
+		if (mpnt->vm_flags & VM_ACCOUNT) {
+			unsigned long len = vma_pages(mpnt);
+
+			if (security_vm_enough_memory_mm(oldmm, len)) /* sic */
+				goto fail_nomem;
+			charge = len;
+		}
+		tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
+		if (!tmp)
+			goto fail_nomem;
+		*tmp = *mpnt;
+		INIT_LIST_HEAD(&tmp->anon_vma_chain);
+		retval = vma_dup_policy(mpnt, tmp);
+		if (retval)
+			goto fail_nomem_policy;
+		tmp->vm_mm = mm;
+		retval = dup_userfaultfd(tmp, &uf);
+		if (retval)
+			goto fail_nomem_anon_vma_fork;
+		if (tmp->vm_flags & VM_WIPEONFORK) {
+			/* VM_WIPEONFORK gets a clean slate in the child. */
+			tmp->anon_vma = NULL;
+			if (anon_vma_prepare(tmp))
+				goto fail_nomem_anon_vma_fork;
+		} else if (anon_vma_fork(tmp, mpnt))
+			goto fail_nomem_anon_vma_fork;
+		tmp->vm_flags &= ~(VM_LOCKED | VM_LOCKONFAULT);
+		tmp->vm_next = tmp->vm_prev = NULL;
+		file = tmp->vm_file;
+		if (file) {
+			struct inode *inode = file_inode(file);
+			struct address_space *mapping = file->f_mapping;
+
+			get_file(file);
+			if (tmp->vm_flags & VM_DENYWRITE)
+				atomic_dec(&inode->i_writecount);
+			i_mmap_lock_write(mapping);
+			if (tmp->vm_flags & VM_SHARED)
+				atomic_inc(&mapping->i_mmap_writable);
+			flush_dcache_mmap_lock(mapping);
+			/* insert tmp into the share list, just after mpnt */
+			vma_interval_tree_insert_after(tmp, mpnt,
+					&mapping->i_mmap);
+			flush_dcache_mmap_unlock(mapping);
+			i_mmap_unlock_write(mapping);
+		}
+
+		/*
+		 * Clear hugetlb-related page reserves for children. This only
+		 * affects MAP_PRIVATE mappings. Faults generated by the child
+		 * are not guaranteed to succeed, even if read-only
+		 */
+		if (is_vm_hugetlb_page(tmp))
+			reset_vma_resv_huge_pages(tmp);
+
+		/*
+		 * Link in the new vma and copy the page table entries.
+		 */
+		*pprev = tmp;
+		pprev = &tmp->vm_next;
+		tmp->vm_prev = prev;
+		prev = tmp;
+
+		__vma_link_rb(mm, tmp, rb_link, rb_parent);
+		rb_link = &tmp->vm_rb.rb_right;
+		rb_parent = &tmp->vm_rb;
+
+		mm->map_count++;
+		if (!(tmp->vm_flags & VM_WIPEONFORK))
+			retval = copy_page_range(mm, oldmm, mpnt);
+
+		if (tmp->vm_ops && tmp->vm_ops->open)
+			tmp->vm_ops->open(tmp);
+
+		if (retval)
+			goto out;
+	}
+	/* a new mm has just been created */
+	arch_dup_mmap(oldmm, mm);
+	retval = 0;
+out:
+	up_write(&mm->mmap_sem);
+	flush_tlb_mm(oldmm);
+	up_write(&oldmm->mmap_sem);
+	dup_userfaultfd_complete(&uf);
+fail_uprobe_end:
+	uprobe_end_dup_mmap();
+	return retval;
+fail_nomem_anon_vma_fork:
+	mpol_put(vma_policy(tmp));
+fail_nomem_policy:
+	kmem_cache_free(vm_area_cachep, tmp);
+fail_nomem:
+	retval = -ENOMEM;
+	vm_unacct_memory(charge);
+	goto out;
+}
+
+static inline int mm_alloc_pgd(struct mm_struct *mm)
+{
+	mm->pgd = pgd_alloc(mm);
+	if (unlikely(!mm->pgd))
+		return -ENOMEM;
+	return 0;
+}
+
+static inline void mm_free_pgd(struct mm_struct *mm)
+{
+	pgd_free(mm, mm->pgd);
+}
+#else
+static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
+{
+	down_write(&oldmm->mmap_sem);
+	RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm));
+	up_write(&oldmm->mmap_sem);
+	return 0;
+}
+#define mm_alloc_pgd(mm)	(0)
+#define mm_free_pgd(mm)
+#endif /* CONFIG_MMU */
+
+static void check_mm(struct mm_struct *mm)
+{
+	int i;
+
+	for (i = 0; i < NR_MM_COUNTERS; i++) {
+		long x = atomic_long_read(&mm->rss_stat.count[i]);
+
+		if (unlikely(x))
+			printk(KERN_ALERT "BUG: Bad rss-counter state "
+					  "mm:%p idx:%d val:%ld\n", mm, i, x);
+	}
+
+	if (mm_pgtables_bytes(mm))
+		pr_alert("BUG: non-zero pgtables_bytes on freeing mm: %ld\n",
+				mm_pgtables_bytes(mm));
+
+#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
+	VM_BUG_ON_MM(mm->pmd_huge_pte, mm);
+#endif
+}
+
+#define allocate_mm()	(kmem_cache_alloc(mm_cachep, GFP_KERNEL))
+#define free_mm(mm)	(kmem_cache_free(mm_cachep, (mm)))
+
+/*
+ * Called when the last reference to the mm
+ * is dropped: either by a lazy thread or by
+ * mmput. Free the page directory and the mm.
+ */
+static void __mmdrop(struct mm_struct *mm)
+{
+	BUG_ON(mm == &init_mm);
+	mm_free_pgd(mm);
+	destroy_context(mm);
+	hmm_mm_destroy(mm);
+	mmu_notifier_mm_destroy(mm);
+	check_mm(mm);
+	put_user_ns(mm->user_ns);
+	free_mm(mm);
+}
+
+void mmdrop(struct mm_struct *mm)
+{
+	if (unlikely(atomic_dec_and_test(&mm->mm_count)))
+		__mmdrop(mm);
+}
+EXPORT_SYMBOL_GPL(mmdrop);
+
+static void mmdrop_async_fn(struct work_struct *work)
+{
+	struct mm_struct *mm;
+
+	mm = container_of(work, struct mm_struct, async_put_work);
+	__mmdrop(mm);
+}
+
+static void mmdrop_async(struct mm_struct *mm)
+{
+	if (unlikely(atomic_dec_and_test(&mm->mm_count))) {
+		INIT_WORK(&mm->async_put_work, mmdrop_async_fn);
+		schedule_work(&mm->async_put_work);
+	}
+}
+
 static inline void free_signal_struct(struct signal_struct *sig)
 {
 	taskstats_tgid_free(sig);
@@ -594,181 +830,8 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
 	return NULL;
 }
 
-#ifdef CONFIG_MMU
-static __latent_entropy int dup_mmap(struct mm_struct *mm,
-					struct mm_struct *oldmm)
-{
-	struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
-	struct rb_node **rb_link, *rb_parent;
-	int retval;
-	unsigned long charge;
-	LIST_HEAD(uf);
-
-	uprobe_start_dup_mmap();
-	if (down_write_killable(&oldmm->mmap_sem)) {
-		retval = -EINTR;
-		goto fail_uprobe_end;
-	}
-	flush_cache_dup_mm(oldmm);
-	uprobe_dup_mmap(oldmm, mm);
-	/*
-	 * Not linked in yet - no deadlock potential:
-	 */
-	down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
-
-	/* No ordering required: file already has been exposed. */
-	RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm));
-
-	mm->total_vm = oldmm->total_vm;
-	mm->data_vm = oldmm->data_vm;
-	mm->exec_vm = oldmm->exec_vm;
-	mm->stack_vm = oldmm->stack_vm;
-
-	rb_link = &mm->mm_rb.rb_node;
-	rb_parent = NULL;
-	pprev = &mm->mmap;
-	retval = ksm_fork(mm, oldmm);
-	if (retval)
-		goto out;
-	retval = khugepaged_fork(mm, oldmm);
-	if (retval)
-		goto out;
-
-	prev = NULL;
-	for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
-		struct file *file;
-
-		if (mpnt->vm_flags & VM_DONTCOPY) {
-			vm_stat_account(mm, mpnt->vm_flags, -vma_pages(mpnt));
-			continue;
-		}
-		charge = 0;
-		if (mpnt->vm_flags & VM_ACCOUNT) {
-			unsigned long len = vma_pages(mpnt);
-
-			if (security_vm_enough_memory_mm(oldmm, len)) /* sic */
-				goto fail_nomem;
-			charge = len;
-		}
-		tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
-		if (!tmp)
-			goto fail_nomem;
-		*tmp = *mpnt;
-		INIT_LIST_HEAD(&tmp->anon_vma_chain);
-		retval = vma_dup_policy(mpnt, tmp);
-		if (retval)
-			goto fail_nomem_policy;
-		tmp->vm_mm = mm;
-		retval = dup_userfaultfd(tmp, &uf);
-		if (retval)
-			goto fail_nomem_anon_vma_fork;
-		if (tmp->vm_flags & VM_WIPEONFORK) {
-			/* VM_WIPEONFORK gets a clean slate in the child. */
-			tmp->anon_vma = NULL;
-			if (anon_vma_prepare(tmp))
-				goto fail_nomem_anon_vma_fork;
-		} else if (anon_vma_fork(tmp, mpnt))
-			goto fail_nomem_anon_vma_fork;
-		tmp->vm_flags &= ~(VM_LOCKED | VM_LOCKONFAULT);
-		tmp->vm_next = tmp->vm_prev = NULL;
-		file = tmp->vm_file;
-		if (file) {
-			struct inode *inode = file_inode(file);
-			struct address_space *mapping = file->f_mapping;
-
-			get_file(file);
-			if (tmp->vm_flags & VM_DENYWRITE)
-				atomic_dec(&inode->i_writecount);
-			i_mmap_lock_write(mapping);
-			if (tmp->vm_flags & VM_SHARED)
-				atomic_inc(&mapping->i_mmap_writable);
-			flush_dcache_mmap_lock(mapping);
-			/* insert tmp into the share list, just after mpnt */
-			vma_interval_tree_insert_after(tmp, mpnt,
-					&mapping->i_mmap);
-			flush_dcache_mmap_unlock(mapping);
-			i_mmap_unlock_write(mapping);
-		}
-
-		/*
-		 * Clear hugetlb-related page reserves for children. This only
-		 * affects MAP_PRIVATE mappings. Faults generated by the child
-		 * are not guaranteed to succeed, even if read-only
-		 */
-		if (is_vm_hugetlb_page(tmp))
-			reset_vma_resv_huge_pages(tmp);
-
-		/*
-		 * Link in the new vma and copy the page table entries.
-		 */
-		*pprev = tmp;
-		pprev = &tmp->vm_next;
-		tmp->vm_prev = prev;
-		prev = tmp;
-
-		__vma_link_rb(mm, tmp, rb_link, rb_parent);
-		rb_link = &tmp->vm_rb.rb_right;
-		rb_parent = &tmp->vm_rb;
-
-		mm->map_count++;
-		if (!(tmp->vm_flags & VM_WIPEONFORK))
-			retval = copy_page_range(mm, oldmm, mpnt);
-
-		if (tmp->vm_ops && tmp->vm_ops->open)
-			tmp->vm_ops->open(tmp);
-
-		if (retval)
-			goto out;
-	}
-	/* a new mm has just been created */
-	retval = arch_dup_mmap(oldmm, mm);
-out:
-	up_write(&mm->mmap_sem);
-	flush_tlb_mm(oldmm);
-	up_write(&oldmm->mmap_sem);
-	dup_userfaultfd_complete(&uf);
-fail_uprobe_end:
-	uprobe_end_dup_mmap();
-	return retval;
-fail_nomem_anon_vma_fork:
-	mpol_put(vma_policy(tmp));
-fail_nomem_policy:
-	kmem_cache_free(vm_area_cachep, tmp);
-fail_nomem:
-	retval = -ENOMEM;
-	vm_unacct_memory(charge);
-	goto out;
-}
-
-static inline int mm_alloc_pgd(struct mm_struct *mm)
-{
-	mm->pgd = pgd_alloc(mm);
-	if (unlikely(!mm->pgd))
-		return -ENOMEM;
-	return 0;
-}
-
-static inline void mm_free_pgd(struct mm_struct *mm)
-{
-	pgd_free(mm, mm->pgd);
-}
-#else
-static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
-{
-	down_write(&oldmm->mmap_sem);
-	RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm));
-	up_write(&oldmm->mmap_sem);
-	return 0;
-}
-#define mm_alloc_pgd(mm)	(0)
-#define mm_free_pgd(mm)
-#endif /* CONFIG_MMU */
-
 __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
 
-#define allocate_mm()	(kmem_cache_alloc(mm_cachep, GFP_KERNEL))
-#define free_mm(mm)	(kmem_cache_free(mm_cachep, (mm)))
-
 static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT;
 
 static int __init coredump_filter_setup(char *s)
@@ -858,27 +921,6 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
 	return NULL;
 }
 
-static void check_mm(struct mm_struct *mm)
-{
-	int i;
-
-	for (i = 0; i < NR_MM_COUNTERS; i++) {
-		long x = atomic_long_read(&mm->rss_stat.count[i]);
-
-		if (unlikely(x))
-			printk(KERN_ALERT "BUG: Bad rss-counter state "
-					  "mm:%p idx:%d val:%ld\n", mm, i, x);
-	}
-
-	if (mm_pgtables_bytes(mm))
-		pr_alert("BUG: non-zero pgtables_bytes on freeing mm: %ld\n",
-				mm_pgtables_bytes(mm));
-
-#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
-	VM_BUG_ON_MM(mm->pmd_huge_pte, mm);
-#endif
-}
-
 /*
  * Allocate and initialize an mm_struct.
  */
@@ -894,24 +936,6 @@ struct mm_struct *mm_alloc(void)
 	return mm_init(mm, current, current_user_ns());
 }
 
-/*
- * Called when the last reference to the mm
- * is dropped: either by a lazy thread or by
- * mmput. Free the page directory and the mm.
- */
-void __mmdrop(struct mm_struct *mm)
-{
-	BUG_ON(mm == &init_mm);
-	mm_free_pgd(mm);
-	destroy_context(mm);
-	hmm_mm_destroy(mm);
-	mmu_notifier_mm_destroy(mm);
-	check_mm(mm);
-	put_user_ns(mm->user_ns);
-	free_mm(mm);
-}
-EXPORT_SYMBOL_GPL(__mmdrop);
-
 static inline void __mmput(struct mm_struct *mm)
 {
 	VM_BUG_ON(atomic_read(&mm->mm_users));