auxvec.h « asm-xtensa « include - litmus-rt.git - The LITMUS^RT kernel.

index : litmus-rt.git

The LITMUS^RT kernel.

Bjoern Brandenburg

about summary refs log blame commit diff stats

path: root/include/asm-xtensa/auxvec.h

blob: 257dec75c5af129a50b2bf52303b3b895c99765a (plain) (tree)

36d57ac4a818

#ifndef __XTENSA_AUXVEC_H
#define __XTENSA_AUXVEC_H

#endif

t.cgi/litmus-rt-budgetable-locks.git/.git/commit/kernel/fork.c?h=update_litmus_2019&id=037741a6d4ab2e4b0580dae97aca963d8a8dc68f'>037741a6d4ab

819077398514

2c4704756cab

819077398514

819077398514

73b9ebfe126a

6883f81aac6f

819077398514

819077398514

909ea9646809

80628ca06c5d

60d4de3ff7f7

924de3b8c941

80628ca06c5d

0c740d0afc3b

73b9ebfe126a

819077398514

28
29

30
31
32

39
40
41

45
46

62
63
64

68
69

97
98
99

105
106

107
108
109

121
122
123

127
128
129

163
164

165
166

167
168

202
203

207
208
209

211
212
213

214
215
216

218
219

223
224

234
235

244
245

246
247

248
249

257
258

262
263
264

265
266

276
277

278
279

280
281

294
295

300
301

305
306

309
310
311

313
314

315
316

319
320

322
323

325
326

328
329

331
332

340
341

388
389

391
392

424
425
426

462
463

533
534

674
675

676
677

678
679

703
704

719
720
721

726
727

742
743
744

749
750

751
752

755
756

758
759

760
761
762

764
765

797
798

800
801

802
803

804
805
806

814
815
816

822
823

825
826

843
844

849
850

852
853
854

855
856

859
860
861

862
863

891
892

900
901

917
918

928
929
930

936
937

938
939

954
955

961
962
963

987
988

990
991
992

999
1000

1012
1013
1014

1023
1024

1047
1048

1054
1055

1082
1083

1118
1119

1129
1130

1131
1132
1133

1134
1135

1151
1152

1178
1179
1180

1195
1196

1256
1257

1273
1274

1277
1278

1282
1283

1285
1286

1287
1288

1289
1290

1291
1292
1293

1295
1296
1297

1307
1308

1319
1320

1331
1332

1335
1336

1344
1345

1353
1354
1355

1356
1357
1358

1359
1360

1366
1367

1375
1376

1392
1393
1394

1403
1404
1405

1411
1412

1413
1414

1423
1424
1425

1427
1428

1463
1464
1465

1467
1468
1469

1474
1475

1477
1478

1479
1480

1489
1490
1491

1494
1495
1496

1498
1499

1505
1506
1507

1514
1515

1518
1519

1526
1527

1532
1533

1539
1540
1541

1544
1545

1580
1581

1588
1589

1590
1591
1592

1627
1628
1629

1631
1632

1640
1641
1642

1649
1650

1656
1657
1658

1669
1670
1671

1676
1677

1738
1739

1772
1773

1785
1786
1787

1788
1789
1790

1835
1836

1857
1858
1859

1867
1868
1869

1872
1873

1874
1875

1877
1878
1879

1883
1884

1885
1886

1889
1890
1891

1899
1900
1901

1905
1906

1908
1909

1911
1912

1917
1918

1920
1921
1922

1923
1924

1925
1926
1927

1929
1930

1936
1937

1945
1946
1947

1951
1952
1953

1971
1972
1973

1978
1979
1980

1987
1988
1989

1992
1993

1994
1995

2002
2003
2004

2005
2006

2008
2009

2011
2012

2014
2015

2017
2018

2020
2021

2023
2024

2026
2027

2031
2032

2035
2036

2039
2040

2067
2068
2069

2075
2076

2079
2080
2081

2083
2084

2085
2086

2090
2091
2092

2096
2097

2106
2107
2108

2110
2111

2128
2129

2139
2140

2141
2142
2143

2144
2145

2149
2150

2152
2153

2155
2156

2158
2159

2165
2166

2169
2170
2171

2179
2180
2181

2190
2191
2192

2195
2196

2209
2210

2212
2213
2214

2217
2218

2219
2220

2235
2236

2239
2240

2242
2243

2245
2246

2252
2253
2254

2255
2256

2258
2259

2263
2264

2278
2279

2280
2281

2299
2300
2301

2303
2304

2310
2311

2312
2313
2314

2328
2329
2330

2345
2346

2347
2348

2358
2359

2381
2382

2395
2396
2397

2399
2400
2401

2403
2404

2406
2407

2427
2428

2437
2438
2439

2441
2442
2443

2468
2469

2509
2510

2616
2617
2618

2656
2657
2658

2661
2662

2663
2664

2665
2666

2667
2668

2671
2672

2685
2686
2687

2689
2690

2694
2695

2696
2697

2707
2708

2728
2729

2762
2763

2791
2792

2793
2794

2822
2823

2825
2826

2852
2853

2854
2855

2863
2864

2878
2879

2880
2881

2882
2883
2884

2889
2890

2893
2894
2895

// SPDX-License-Identifier: GPL-2.0-only
/*
 *  linux/kernel/fork.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

/*
 *  'fork.c' contains the help-routines for the 'fork' system call
 * (see also entry.S and others).
 * Fork is rather simple, once you get the hang of it, but the memory
 * management can be a bitch. See 'mm/memory.c': 'copy_page_range()'
 */

#include <linux/anon_inodes.h>
#include <linux/slab.h>
#include <linux/sched/autogroup.h>
#include <linux/sched/mm.h>
#include <linux/sched/coredump.h>
#include <linux/sched/user.h>
#include <linux/sched/numa_balancing.h>
#include <linux/sched/stat.h>
#include <linux/sched/task.h>
#include <linux/sched/task_stack.h>
#include <linux/sched/cputime.h>
#include <linux/seq_file.h>
#include <linux/rtmutex.h>
#include <linux/init.h>
#include <linux/unistd.h>
#include <linux/module.h>
#include <linux/vmalloc.h>
#include <linux/completion.h>
#include <linux/personality.h>
#include <linux/mempolicy.h>
#include <linux/sem.h>
#include <linux/file.h>
#include <linux/fdtable.h>
#include <linux/iocontext.h>
#include <linux/key.h>
#include <linux/binfmts.h>
#include <linux/mman.h>
#include <linux/mmu_notifier.h>
#include <linux/hmm.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/vmacache.h>
#include <linux/nsproxy.h>
#include <linux/capability.h>
#include <linux/cpu.h>
#include <linux/cgroup.h>
#include <linux/security.h>
#include <linux/hugetlb.h>
#include <linux/seccomp.h>
#include <linux/swap.h>
#include <linux/syscalls.h>
#include <linux/jiffies.h>
#include <linux/futex.h>
#include <linux/compat.h>
#include <linux/kthread.h>
#include <linux/task_io_accounting_ops.h>
#include <linux/rcupdate.h>
#include <linux/ptrace.h>
#include <linux/mount.h>
#include <linux/audit.h>
#include <linux/memcontrol.h>
#include <linux/ftrace.h>
#include <linux/proc_fs.h>
#include <linux/profile.h>
#include <linux/rmap.h>
#include <linux/ksm.h>
#include <linux/acct.h>
#include <linux/userfaultfd_k.h>
#include <linux/tsacct_kern.h>
#include <linux/cn_proc.h>
#include <linux/freezer.h>
#include <linux/delayacct.h>
#include <linux/taskstats_kern.h>
#include <linux/random.h>
#include <linux/tty.h>
#include <linux/blkdev.h>
#include <linux/fs_struct.h>
#include <linux/magic.h>
#include <linux/perf_event.h>
#include <linux/posix-timers.h>
#include <linux/user-return-notifier.h>
#include <linux/oom.h>
#include <linux/khugepaged.h>
#include <linux/signalfd.h>
#include <linux/uprobes.h>
#include <linux/aio.h>
#include <linux/compiler.h>
#include <linux/sysctl.h>
#include <linux/kcov.h>
#include <linux/livepatch.h>
#include <linux/thread_info.h>
#include <linux/stackleak.h>

#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <linux/uaccess.h>
#include <asm/mmu_context.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>

#include <trace/events/sched.h>

#define CREATE_TRACE_POINTS
#include <trace/events/task.h>

/*
 * Minimum number of threads to boot the kernel
 */
#define MIN_THREADS 20

/*
 * Maximum number of threads
 */
#define MAX_THREADS FUTEX_TID_MASK

/*
 * Protected counters by write_lock_irq(&tasklist_lock)
 */
unsigned long total_forks;	/* Handle normal Linux uptimes. */
int nr_threads;			/* The idle threads do not count.. */

static int max_threads;		/* tunable limit on nr_threads */

DEFINE_PER_CPU(unsigned long, process_counts) = 0;

__cacheline_aligned DEFINE_RWLOCK(tasklist_lock);  /* outer */

#ifdef CONFIG_PROVE_RCU
int lockdep_tasklist_lock_is_held(void)
{
	return lockdep_is_held(&tasklist_lock);
}
EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held);
#endif /* #ifdef CONFIG_PROVE_RCU */

int nr_processes(void)
{
	int cpu;
	int total = 0;

	for_each_possible_cpu(cpu)
		total += per_cpu(process_counts, cpu);

	return total;
}

void __weak arch_release_task_struct(struct task_struct *tsk)
{
}

#ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
static struct kmem_cache *task_struct_cachep;

static inline struct task_struct *alloc_task_struct_node(int node)
{
	return kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node);
}

static inline void free_task_struct(struct task_struct *tsk)
{
	kmem_cache_free(task_struct_cachep, tsk);
}
#endif

#ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR

/*
 * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
 * kmemcache based allocator.
 */
# if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)

#ifdef CONFIG_VMAP_STACK
/*
 * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
 * flush.  Try to minimize the number of calls by caching stacks.
 */
#define NR_CACHED_STACKS 2
static DEFINE_PER_CPU(struct vm_struct *, cached_stacks[NR_CACHED_STACKS]);

static int free_vm_stack_cache(unsigned int cpu)
{
	struct vm_struct **cached_vm_stacks = per_cpu_ptr(cached_stacks, cpu);
	int i;

	for (i = 0; i < NR_CACHED_STACKS; i++) {
		struct vm_struct *vm_stack = cached_vm_stacks[i];

		if (!vm_stack)
			continue;

		vfree(vm_stack->addr);
		cached_vm_stacks[i] = NULL;
	}

	return 0;
}
#endif

static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
{
#ifdef CONFIG_VMAP_STACK
	void *stack;
	int i;

	for (i = 0; i < NR_CACHED_STACKS; i++) {
		struct vm_struct *s;

		s = this_cpu_xchg(cached_stacks[i], NULL);

		if (!s)
			continue;

		/* Clear stale pointers from reused stack. */
		memset(s->addr, 0, THREAD_SIZE);

		tsk->stack_vm_area = s;
		tsk->stack = s->addr;
		return s->addr;
	}

	/*
	 * Allocated stacks are cached and later reused by new threads,
	 * so memcg accounting is performed manually on assigning/releasing
	 * stacks to tasks. Drop __GFP_ACCOUNT.
	 */
	stack = __vmalloc_node_range(THREAD_SIZE, THREAD_ALIGN,
				     VMALLOC_START, VMALLOC_END,
				     THREADINFO_GFP & ~__GFP_ACCOUNT,
				     PAGE_KERNEL,
				     0, node, __builtin_return_address(0));

	/*
	 * We can't call find_vm_area() in interrupt context, and
	 * free_thread_stack() can be called in interrupt context,
	 * so cache the vm_struct.
	 */
	if (stack) {
		tsk->stack_vm_area = find_vm_area(stack);
		tsk->stack = stack;
	}
	return stack;
#else
	struct page *page = alloc_pages_node(node, THREADINFO_GFP,
					     THREAD_SIZE_ORDER);

	if (likely(page)) {
		tsk->stack = page_address(page);
		return tsk->stack;
	}
	return NULL;
#endif
}

static inline void free_thread_stack(struct task_struct *tsk)
{
#ifdef CONFIG_VMAP_STACK
	struct vm_struct *vm = task_stack_vm_area(tsk);

	if (vm) {
		int i;

		for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
			mod_memcg_page_state(vm->pages[i],
					     MEMCG_KERNEL_STACK_KB,
					     -(int)(PAGE_SIZE / 1024));

			memcg_kmem_uncharge(vm->pages[i], 0);
		}

		for (i = 0; i < NR_CACHED_STACKS; i++) {
			if (this_cpu_cmpxchg(cached_stacks[i],
					NULL, tsk->stack_vm_area) != NULL)
				continue;

			return;
		}

		vfree_atomic(tsk->stack);
		return;
	}
#endif

	__free_pages(virt_to_page(tsk->stack), THREAD_SIZE_ORDER);
}
# else
static struct kmem_cache *thread_stack_cache;

static unsigned long *alloc_thread_stack_node(struct task_struct *tsk,
						  int node)
{
	unsigned long *stack;
	stack = kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node);
	tsk->stack = stack;
	return stack;
}

static void free_thread_stack(struct task_struct *tsk)
{
	kmem_cache_free(thread_stack_cache, tsk->stack);
}

void thread_stack_cache_init(void)
{
	thread_stack_cache = kmem_cache_create_usercopy("thread_stack",
					THREAD_SIZE, THREAD_SIZE, 0, 0,
					THREAD_SIZE, NULL);
	BUG_ON(thread_stack_cache == NULL);
}
# endif
#endif

/* SLAB cache for signal_struct structures (tsk->signal) */
static struct kmem_cache *signal_cachep;

/* SLAB cache for sighand_struct structures (tsk->sighand) */
struct kmem_cache *sighand_cachep;

/* SLAB cache for files_struct structures (tsk->files) */
struct kmem_cache *files_cachep;

/* SLAB cache for fs_struct structures (tsk->fs) */
struct kmem_cache *fs_cachep;

/* SLAB cache for vm_area_struct structures */
static struct kmem_cache *vm_area_cachep;

/* SLAB cache for mm_struct structures (tsk->mm) */
static struct kmem_cache *mm_cachep;

struct vm_area_struct *vm_area_alloc(struct mm_struct *mm)
{
	struct vm_area_struct *vma;

	vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
	if (vma)
		vma_init(vma, mm);
	return vma;
}

struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig)
{
	struct vm_area_struct *new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);

	if (new) {
		*new = *orig;
		INIT_LIST_HEAD(&new->anon_vma_chain);
	}
	return new;
}

void vm_area_free(struct vm_area_struct *vma)
{
	kmem_cache_free(vm_area_cachep, vma);
}

static void account_kernel_stack(struct task_struct *tsk, int account)
{
	void *stack = task_stack_page(tsk);
	struct vm_struct *vm = task_stack_vm_area(tsk);

	BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK) && PAGE_SIZE % 1024 != 0);

	if (vm) {
		int i;

		BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);

		for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
			mod_zone_page_state(page_zone(vm->pages[i]),
					    NR_KERNEL_STACK_KB,
					    PAGE_SIZE / 1024 * account);
		}
	} else {
		/*
		 * All stack pages are in the same zone and belong to the
		 * same memcg.
		 */
		struct page *first_page = virt_to_page(stack);

		mod_zone_page_state(page_zone(first_page), NR_KERNEL_STACK_KB,
				    THREAD_SIZE / 1024 * account);

		mod_memcg_page_state(first_page, MEMCG_KERNEL_STACK_KB,
				     account * (THREAD_SIZE / 1024));
	}
}

static int memcg_charge_kernel_stack(struct task_struct *tsk)
{
#ifdef CONFIG_VMAP_STACK
	struct vm_struct *vm = task_stack_vm_area(tsk);
	int ret;

	if (vm) {
		int i;

		for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
			/*
			 * If memcg_kmem_charge() fails, page->mem_cgroup
			 * pointer is NULL, and both memcg_kmem_uncharge()
			 * and mod_memcg_page_state() in free_thread_stack()
			 * will ignore this page. So it's safe.
			 */
			ret = memcg_kmem_charge(vm->pages[i], GFP_KERNEL, 0);
			if (ret)
				return ret;

			mod_memcg_page_state(vm->pages[i],
					     MEMCG_KERNEL_STACK_KB,
					     PAGE_SIZE / 1024);
		}
	}
#endif
	return 0;
}

static void release_task_stack(struct task_struct *tsk)
{
	if (WARN_ON(tsk->state != TASK_DEAD))
		return;  /* Better to leak the stack than to free prematurely */

	account_kernel_stack(tsk, -1);
	free_thread_stack(tsk);
	tsk->stack = NULL;
#ifdef CONFIG_VMAP_STACK
	tsk->stack_vm_area = NULL;
#endif
}

#ifdef CONFIG_THREAD_INFO_IN_TASK
void put_task_stack(struct task_struct *tsk)
{
	if (refcount_dec_and_test(&tsk->stack_refcount))
		release_task_stack(tsk);
}
#endif

void free_task(struct task_struct *tsk)
{
#ifndef CONFIG_THREAD_INFO_IN_TASK
	/*
	 * The task is finally done with both the stack and thread_info,
	 * so free both.
	 */
	release_task_stack(tsk);
#else
	/*
	 * If the task had a separate stack allocation, it should be gone
	 * by now.
	 */
	WARN_ON_ONCE(refcount_read(&tsk->stack_refcount) != 0);
#endif
	rt_mutex_debug_task_free(tsk);
	ftrace_graph_exit_task(tsk);
	put_seccomp_filter(tsk);
	arch_release_task_struct(tsk);
	if (tsk->flags & PF_KTHREAD)
		free_kthread_struct(tsk);
	free_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;
		/*
		 * Don't duplicate many vmas if we've been oom-killed (for
		 * example)
		 */
		if (fatal_signal_pending(current)) {
			retval = -EINTR;
			goto out;
		}
		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 = vm_area_dup(mpnt);
		if (!tmp)
			goto fail_nomem;
		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:
	vm_area_free(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.
 */
void __mmdrop(struct mm_struct *mm)
{
	BUG_ON(mm == &init_mm);
	WARN_ON_ONCE(mm == current->mm);
	WARN_ON_ONCE(mm == current->active_mm);
	mm_free_pgd(mm);
	destroy_context(mm);
	mmu_notifier_mm_destroy(mm);
	check_mm(mm);
	put_user_ns(mm->user_ns);
	free_mm(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);
	sched_autogroup_exit(sig);
	/*
	 * __mmdrop is not safe to call from softirq context on x86 due to
	 * pgd_dtor so postpone it to the async context
	 */
	if (sig->oom_mm)
		mmdrop_async(sig->oom_mm);
	kmem_cache_free(signal_cachep, sig);
}

static inline void put_signal_struct(struct signal_struct *sig)
{
	if (refcount_dec_and_test(&sig->sigcnt))
		free_signal_struct(sig);
}

void __put_task_struct(struct task_struct *tsk)
{
	WARN_ON(!tsk->exit_state);
	WARN_ON(refcount_read(&tsk->usage));
	WARN_ON(tsk == current);

	cgroup_free(tsk);
	task_numa_free(tsk);
	security_task_free(tsk);
	exit_creds(tsk);
	delayacct_tsk_free(tsk);
	put_signal_struct(tsk->signal);

	if (!profile_handoff_task(tsk))
		free_task(tsk);
}
EXPORT_SYMBOL_GPL(__put_task_struct);

void __init __weak arch_task_cache_init(void) { }

/*
 * set_max_threads
 */
static void set_max_threads(unsigned int max_threads_suggested)
{
	u64 threads;
	unsigned long nr_pages = totalram_pages();

	/*
	 * The number of threads shall be limited such that the thread
	 * structures may only consume a small part of the available memory.
	 */
	if (fls64(nr_pages) + fls64(PAGE_SIZE) > 64)
		threads = MAX_THREADS;
	else
		threads = div64_u64((u64) nr_pages * (u64) PAGE_SIZE,
				    (u64) THREAD_SIZE * 8UL);

	if (threads > max_threads_suggested)
		threads = max_threads_suggested;

	max_threads = clamp_t(u64, threads, MIN_THREADS, MAX_THREADS);
}

#ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
/* Initialized by the architecture: */
int arch_task_struct_size __read_mostly;
#endif

static void task_struct_whitelist(unsigned long *offset, unsigned long *size)
{
	/* Fetch thread_struct whitelist for the architecture. */
	arch_thread_struct_whitelist(offset, size);

	/*
	 * Handle zero-sized whitelist or empty thread_struct, otherwise
	 * adjust offset to position of thread_struct in task_struct.
	 */
	if (unlikely(*size == 0))
		*offset = 0;
	else
		*offset += offsetof(struct task_struct, thread);
}

void __init fork_init(void)
{
	int i;
#ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
#ifndef ARCH_MIN_TASKALIGN
#define ARCH_MIN_TASKALIGN	0
#endif
	int align = max_t(int, L1_CACHE_BYTES, ARCH_MIN_TASKALIGN);
	unsigned long useroffset, usersize;

	/* create a slab on which task_structs can be allocated */
	task_struct_whitelist(&useroffset, &usersize);
	task_struct_cachep = kmem_cache_create_usercopy("task_struct",
			arch_task_struct_size, align,
			SLAB_PANIC|SLAB_ACCOUNT,
			useroffset, usersize, NULL);
#endif

	/* do the arch specific task caches init */
	arch_task_cache_init();

	set_max_threads(MAX_THREADS);

	init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
	init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
	init_task.signal->rlim[RLIMIT_SIGPENDING] =
		init_task.signal->rlim[RLIMIT_NPROC];

	for (i = 0; i < UCOUNT_COUNTS; i++) {
		init_user_ns.ucount_max[i] = max_threads/2;
	}

#ifdef CONFIG_VMAP_STACK
	cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "fork:vm_stack_cache",
			  NULL, free_vm_stack_cache);
#endif

	lockdep_init_task(&init_task);
	uprobes_init();
}

int __weak arch_dup_task_struct(struct task_struct *dst,
					       struct task_struct *src)
{
	*dst = *src;
	return 0;
}

void set_task_stack_end_magic(struct task_struct *tsk)
{
	unsigned long *stackend;

	stackend = end_of_stack(tsk);
	*stackend = STACK_END_MAGIC;	/* for overflow detection */
}

static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
{
	struct task_struct *tsk;
	unsigned long *stack;
	struct vm_struct *stack_vm_area __maybe_unused;
	int err;

	if (node == NUMA_NO_NODE)
		node = tsk_fork_get_node(orig);
	tsk = alloc_task_struct_node(node);
	if (!tsk)
		return NULL;

	stack = alloc_thread_stack_node(tsk, node);
	if (!stack)
		goto free_tsk;

	if (memcg_charge_kernel_stack(tsk))
		goto free_stack;

	stack_vm_area = task_stack_vm_area(tsk);

	err = arch_dup_task_struct(tsk, orig);

	/*
	 * arch_dup_task_struct() clobbers the stack-related fields.  Make
	 * sure they're properly initialized before using any stack-related
	 * functions again.
	 */
	tsk->stack = stack;
#ifdef CONFIG_VMAP_STACK
	tsk->stack_vm_area = stack_vm_area;
#endif
#ifdef CONFIG_THREAD_INFO_IN_TASK
	refcount_set(&tsk->stack_refcount, 1);
#endif

	if (err)
		goto free_stack;

#ifdef CONFIG_SECCOMP
	/*
	 * We must handle setting up seccomp filters once we're under
	 * the sighand lock in case orig has changed between now and
	 * then. Until then, filter must be NULL to avoid messing up
	 * the usage counts on the error path calling free_task.
	 */
	tsk->seccomp.filter = NULL;
#endif

	setup_thread_stack(tsk, orig);
	clear_user_return_notifier(tsk);
	clear_tsk_need_resched(tsk);
	set_task_stack_end_magic(tsk);

#ifdef CONFIG_STACKPROTECTOR
	tsk->stack_canary = get_random_canary();
#endif
	if (orig->cpus_ptr == &orig->cpus_mask)
		tsk->cpus_ptr = &tsk->cpus_mask;

	/*
	 * One for us, one for whoever does the "release_task()" (usually
	 * parent)
	 */
	refcount_set(&tsk->usage, 2);
#ifdef CONFIG_BLK_DEV_IO_TRACE
	tsk->btrace_seq = 0;
#endif
	tsk->splice_pipe = NULL;
	tsk->task_frag.page = NULL;
	tsk->wake_q.next = NULL;

	account_kernel_stack(tsk, 1);

	kcov_task_init(tsk);

#ifdef CONFIG_FAULT_INJECTION
	tsk->fail_nth = 0;
#endif

#ifdef CONFIG_BLK_CGROUP
	tsk->throttle_queue = NULL;
	tsk->use_memdelay = 0;
#endif

#ifdef CONFIG_MEMCG
	tsk->active_memcg = NULL;
#endif
	return tsk;

free_stack:
	free_thread_stack(tsk);
free_tsk:
	free_task_struct(tsk);
	return NULL;
}

__cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);

static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT;

static int __init coredump_filter_setup(char *s)
{
	default_dump_filter =
		(simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) &
		MMF_DUMP_FILTER_MASK;
	return 1;
}

__setup("coredump_filter=", coredump_filter_setup);

#include <linux/init_task.h>

static void mm_init_aio(struct mm_struct *mm)
{
#ifdef CONFIG_AIO
	spin_lock_init(&mm->ioctx_lock);
	mm->ioctx_table = NULL;
#endif
}

static __always_inline void mm_clear_owner(struct mm_struct *mm,
					   struct task_struct *p)
{
#ifdef CONFIG_MEMCG
	if (mm->owner == p)
		WRITE_ONCE(mm->owner, NULL);
#endif
}

static void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
{
#ifdef CONFIG_MEMCG
	mm->owner = p;
#endif
}

static void mm_init_uprobes_state(struct mm_struct *mm)
{
#ifdef CONFIG_UPROBES
	mm->uprobes_state.xol_area = NULL;
#endif
}

static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
	struct user_namespace *user_ns)
{
	mm->mmap = NULL;
	mm->mm_rb = RB_ROOT;
	mm->vmacache_seqnum = 0;
	atomic_set(&mm->mm_users, 1);
	atomic_set(&mm->mm_count, 1);
	init_rwsem(&mm->mmap_sem);
	INIT_LIST_HEAD(&mm->mmlist);
	mm->core_state = NULL;
	mm_pgtables_bytes_init(mm);
	mm->map_count = 0;
	mm->locked_vm = 0;
	atomic64_set(&mm->pinned_vm, 0);
	memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
	spin_lock_init(&mm->page_table_lock);
	spin_lock_init(&mm->arg_lock);
	mm_init_cpumask(mm);
	mm_init_aio(mm);
	mm_init_owner(mm, p);
	RCU_INIT_POINTER(mm->exe_file, NULL);
	mmu_notifier_mm_init(mm);
	hmm_mm_init(mm);
	init_tlb_flush_pending(mm);
#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
	mm->pmd_huge_pte = NULL;
#endif
	mm_init_uprobes_state(mm);

	if (current->mm) {
		mm->flags = current->mm->flags & MMF_INIT_MASK;
		mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK;
	} else {
		mm->flags = default_dump_filter;
		mm->def_flags = 0;
	}

	if (mm_alloc_pgd(mm))
		goto fail_nopgd;

	if (init_new_context(p, mm))
		goto fail_nocontext;

	mm->user_ns = get_user_ns(user_ns);
	return mm;

fail_nocontext:
	mm_free_pgd(mm);
fail_nopgd:
	free_mm(mm);
	return NULL;
}

/*
 * Allocate and initialize an mm_struct.
 */
struct mm_struct *mm_alloc(void)
{
	struct mm_struct *mm;

	mm = allocate_mm();
	if (!mm)
		return NULL;

	memset(mm, 0, sizeof(*mm));
	return mm_init(mm, current, current_user_ns());
}

static inline void __mmput(struct mm_struct *mm)
{
	VM_BUG_ON(atomic_read(&mm->mm_users));

	uprobe_clear_state(mm);
	exit_aio(mm);
	ksm_exit(mm);
	khugepaged_exit(mm); /* must run before exit_mmap */
	exit_mmap(mm);
	mm_put_huge_zero_page(mm);
	set_mm_exe_file(mm, NULL);
	if (!list_empty(&mm->mmlist)) {
		spin_lock(&mmlist_lock);
		list_del(&mm->mmlist);
		spin_unlock(&mmlist_lock);
	}
	if (mm->binfmt)
		module_put(mm->binfmt->module);
	mmdrop(mm);
}

/*
 * Decrement the use count and release all resources for an mm.
 */
void mmput(struct mm_struct *mm)
{
	might_sleep();

	if (atomic_dec_and_test(&mm->mm_users))
		__mmput(mm);
}
EXPORT_SYMBOL_GPL(mmput);

#ifdef CONFIG_MMU
static void mmput_async_fn(struct work_struct *work)
{
	struct mm_struct *mm = container_of(work, struct mm_struct,
					    async_put_work);

	__mmput(mm);
}

void mmput_async(struct mm_struct *mm)
{
	if (atomic_dec_and_test(&mm->mm_users)) {
		INIT_WORK(&mm->async_put_work, mmput_async_fn);
		schedule_work(&mm->async_put_work);
	}
}
#endif

/**
 * set_mm_exe_file - change a reference to the mm's executable file
 *
 * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
 *
 * Main users are mmput() and sys_execve(). Callers prevent concurrent
 * invocations: in mmput() nobody alive left, in execve task is single
 * threaded. sys_prctl(PR_SET_MM_MAP/EXE_FILE) also needs to set the
 * mm->exe_file, but does so without using set_mm_exe_file() in order
 * to do avoid the need for any locks.
 */
void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
{
	struct file *old_exe_file;

	/*
	 * It is safe to dereference the exe_file without RCU as
	 * this function is only called if nobody else can access
	 * this mm -- see comment above for justification.
	 */
	old_exe_file = rcu_dereference_raw(mm->exe_file);

	if (new_exe_file)
		get_file(new_exe_file);
	rcu_assign_pointer(mm->exe_file, new_exe_file);
	if (old_exe_file)
		fput(old_exe_file);
}

/**
 * get_mm_exe_file - acquire a reference to the mm's executable file
 *
 * Returns %NULL if mm has no associated executable file.
 * User must release file via fput().
 */
struct file *get_mm_exe_file(struct mm_struct *mm)
{
	struct file *exe_file;

	rcu_read_lock();
	exe_file = rcu_dereference(mm->exe_file);
	if (exe_file && !get_file_rcu(exe_file))
		exe_file = NULL;
	rcu_read_unlock();
	return exe_file;
}
EXPORT_SYMBOL(get_mm_exe_file);

/**
 * get_task_exe_file - acquire a reference to the task's executable file
 *
 * Returns %NULL if task's mm (if any) has no associated executable file or
 * this is a kernel thread with borrowed mm (see the comment above get_task_mm).
 * User must release file via fput().
 */
struct file *get_task_exe_file(struct task_struct *task)
{
	struct file *exe_file = NULL;
	struct mm_struct *mm;

	task_lock(task);
	mm = task->mm;
	if (mm) {
		if (!(task->flags & PF_KTHREAD))
			exe_file = get_mm_exe_file(mm);
	}
	task_unlock(task);
	return exe_file;
}
EXPORT_SYMBOL(get_task_exe_file);

/**
 * get_task_mm - acquire a reference to the task's mm
 *
 * Returns %NULL if the task has no mm.  Checks PF_KTHREAD (meaning
 * this kernel workthread has transiently adopted a user mm with use_mm,
 * to do its AIO) is not set and if so returns a reference to it, after
 * bumping up the use count.  User must release the mm via mmput()
 * after use.  Typically used by /proc and ptrace.
 */
struct mm_struct *get_task_mm(struct task_struct *task)
{
	struct mm_struct *mm;

	task_lock(task);
	mm = task->mm;
	if (mm) {
		if (task->flags & PF_KTHREAD)
			mm = NULL;
		else
			mmget(mm);
	}
	task_unlock(task);
	return mm;
}
EXPORT_SYMBOL_GPL(get_task_mm);

struct mm_struct *mm_access(struct task_struct *task, unsigned int mode)
{
	struct mm_struct *mm;
	int err;

	err =  mutex_lock_killable(&task->signal->cred_guard_mutex);
	if (err)
		return ERR_PTR(err);

	mm = get_task_mm(task);
	if (mm && mm != current->mm &&
			!ptrace_may_access(task, mode)) {
		mmput(mm);
		mm = ERR_PTR(-EACCES);
	}
	mutex_unlock(&task->signal->cred_guard_mutex);

	return mm;
}

static void complete_vfork_done(struct task_struct *tsk)
{
	struct completion *vfork;

	task_lock(tsk);
	vfork = tsk->vfork_done;
	if (likely(vfork)) {
		tsk->vfork_done = NULL;
		complete(vfork);
	}
	task_unlock(tsk);
}

static int wait_for_vfork_done(struct task_struct *child,
				struct completion *vfork)
{
	int killed;

	freezer_do_not_count();
	cgroup_enter_frozen();
	killed = wait_for_completion_killable(vfork);
	cgroup_leave_frozen(false);
	freezer_count();

	if (killed) {
		task_lock(child);
		child->vfork_done = NULL;
		task_unlock(child);
	}

	put_task_struct(child);
	return killed;
}

/* Please note the differences between mmput and mm_release.
 * mmput is called whenever we stop holding onto a mm_struct,
 * error success whatever.
 *
 * mm_release is called after a mm_struct has been removed
 * from the current process.
 *
 * This difference is important for error handling, when we
 * only half set up a mm_struct for a new process and need to restore
 * the old one.  Because we mmput the new mm_struct before
 * restoring the old one. . .
 * Eric Biederman 10 January 1998
 */
void mm_release(struct task_struct *tsk, struct mm_struct *mm)
{