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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-21 08:19:28 +00:00
![Guenter Roeck](/assets/img/avatar_default.png)
Current upstream kernel hangs with mips and powerpc targets in uniprocessor mode if SECCOMP is configured. Bisect points to commitdbd952127d
("seccomp: introduce writer locking"). Turns out that code such as BUG_ON(!spin_is_locked(&list_lock)); can not be used in uniprocessor mode because spin_is_locked() always returns false in this configuration, and that assert_spin_locked() exists for that very purpose and must be used instead. Fixes:dbd952127d
("seccomp: introduce writer locking") Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Kees Cook <keescook@chromium.org>
1991 lines
48 KiB
C
1991 lines
48 KiB
C
/*
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* linux/kernel/fork.c
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*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*/
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/*
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* 'fork.c' contains the help-routines for the 'fork' system call
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* (see also entry.S and others).
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* Fork is rather simple, once you get the hang of it, but the memory
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* management can be a bitch. See 'mm/memory.c': 'copy_page_range()'
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*/
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/unistd.h>
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#include <linux/module.h>
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#include <linux/vmalloc.h>
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#include <linux/completion.h>
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#include <linux/personality.h>
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#include <linux/mempolicy.h>
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#include <linux/sem.h>
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#include <linux/file.h>
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#include <linux/fdtable.h>
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#include <linux/iocontext.h>
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#include <linux/key.h>
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#include <linux/binfmts.h>
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#include <linux/mman.h>
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#include <linux/mmu_notifier.h>
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#include <linux/fs.h>
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#include <linux/mm.h>
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#include <linux/vmacache.h>
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#include <linux/nsproxy.h>
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#include <linux/capability.h>
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#include <linux/cpu.h>
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#include <linux/cgroup.h>
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#include <linux/security.h>
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#include <linux/hugetlb.h>
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#include <linux/seccomp.h>
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#include <linux/swap.h>
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#include <linux/syscalls.h>
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#include <linux/jiffies.h>
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#include <linux/futex.h>
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#include <linux/compat.h>
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#include <linux/kthread.h>
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#include <linux/task_io_accounting_ops.h>
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#include <linux/rcupdate.h>
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#include <linux/ptrace.h>
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#include <linux/mount.h>
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#include <linux/audit.h>
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#include <linux/memcontrol.h>
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#include <linux/ftrace.h>
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#include <linux/proc_fs.h>
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#include <linux/profile.h>
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#include <linux/rmap.h>
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#include <linux/ksm.h>
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#include <linux/acct.h>
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#include <linux/tsacct_kern.h>
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#include <linux/cn_proc.h>
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#include <linux/freezer.h>
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#include <linux/delayacct.h>
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#include <linux/taskstats_kern.h>
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#include <linux/random.h>
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#include <linux/tty.h>
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#include <linux/blkdev.h>
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#include <linux/fs_struct.h>
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#include <linux/magic.h>
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#include <linux/perf_event.h>
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#include <linux/posix-timers.h>
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#include <linux/user-return-notifier.h>
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#include <linux/oom.h>
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#include <linux/khugepaged.h>
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#include <linux/signalfd.h>
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#include <linux/uprobes.h>
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#include <linux/aio.h>
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#include <linux/compiler.h>
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#include <asm/pgtable.h>
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#include <asm/pgalloc.h>
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#include <asm/uaccess.h>
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#include <asm/mmu_context.h>
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#include <asm/cacheflush.h>
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#include <asm/tlbflush.h>
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#include <trace/events/sched.h>
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#define CREATE_TRACE_POINTS
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#include <trace/events/task.h>
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/*
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* Protected counters by write_lock_irq(&tasklist_lock)
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*/
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unsigned long total_forks; /* Handle normal Linux uptimes. */
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int nr_threads; /* The idle threads do not count.. */
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int max_threads; /* tunable limit on nr_threads */
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DEFINE_PER_CPU(unsigned long, process_counts) = 0;
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__cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
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#ifdef CONFIG_PROVE_RCU
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int lockdep_tasklist_lock_is_held(void)
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{
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return lockdep_is_held(&tasklist_lock);
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}
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EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held);
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#endif /* #ifdef CONFIG_PROVE_RCU */
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int nr_processes(void)
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{
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int cpu;
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int total = 0;
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for_each_possible_cpu(cpu)
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total += per_cpu(process_counts, cpu);
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return total;
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}
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void __weak arch_release_task_struct(struct task_struct *tsk)
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{
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}
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#ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
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static struct kmem_cache *task_struct_cachep;
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static inline struct task_struct *alloc_task_struct_node(int node)
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{
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return kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node);
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}
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static inline void free_task_struct(struct task_struct *tsk)
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{
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kmem_cache_free(task_struct_cachep, tsk);
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}
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#endif
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void __weak arch_release_thread_info(struct thread_info *ti)
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{
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}
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#ifndef CONFIG_ARCH_THREAD_INFO_ALLOCATOR
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/*
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* Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
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* kmemcache based allocator.
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*/
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# if THREAD_SIZE >= PAGE_SIZE
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static struct thread_info *alloc_thread_info_node(struct task_struct *tsk,
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int node)
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{
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struct page *page = alloc_kmem_pages_node(node, THREADINFO_GFP,
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THREAD_SIZE_ORDER);
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return page ? page_address(page) : NULL;
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}
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static inline void free_thread_info(struct thread_info *ti)
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{
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free_kmem_pages((unsigned long)ti, THREAD_SIZE_ORDER);
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}
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# else
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static struct kmem_cache *thread_info_cache;
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static struct thread_info *alloc_thread_info_node(struct task_struct *tsk,
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int node)
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{
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return kmem_cache_alloc_node(thread_info_cache, THREADINFO_GFP, node);
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}
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static void free_thread_info(struct thread_info *ti)
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{
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kmem_cache_free(thread_info_cache, ti);
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}
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void thread_info_cache_init(void)
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{
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thread_info_cache = kmem_cache_create("thread_info", THREAD_SIZE,
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THREAD_SIZE, 0, NULL);
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BUG_ON(thread_info_cache == NULL);
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}
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# endif
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#endif
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/* SLAB cache for signal_struct structures (tsk->signal) */
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static struct kmem_cache *signal_cachep;
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/* SLAB cache for sighand_struct structures (tsk->sighand) */
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struct kmem_cache *sighand_cachep;
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/* SLAB cache for files_struct structures (tsk->files) */
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struct kmem_cache *files_cachep;
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/* SLAB cache for fs_struct structures (tsk->fs) */
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struct kmem_cache *fs_cachep;
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/* SLAB cache for vm_area_struct structures */
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struct kmem_cache *vm_area_cachep;
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/* SLAB cache for mm_struct structures (tsk->mm) */
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static struct kmem_cache *mm_cachep;
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static void account_kernel_stack(struct thread_info *ti, int account)
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{
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struct zone *zone = page_zone(virt_to_page(ti));
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mod_zone_page_state(zone, NR_KERNEL_STACK, account);
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}
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void free_task(struct task_struct *tsk)
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{
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account_kernel_stack(tsk->stack, -1);
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arch_release_thread_info(tsk->stack);
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free_thread_info(tsk->stack);
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rt_mutex_debug_task_free(tsk);
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ftrace_graph_exit_task(tsk);
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put_seccomp_filter(tsk);
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arch_release_task_struct(tsk);
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free_task_struct(tsk);
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}
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EXPORT_SYMBOL(free_task);
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static inline void free_signal_struct(struct signal_struct *sig)
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{
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taskstats_tgid_free(sig);
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sched_autogroup_exit(sig);
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kmem_cache_free(signal_cachep, sig);
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}
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static inline void put_signal_struct(struct signal_struct *sig)
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{
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if (atomic_dec_and_test(&sig->sigcnt))
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free_signal_struct(sig);
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}
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void __put_task_struct(struct task_struct *tsk)
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{
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WARN_ON(!tsk->exit_state);
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WARN_ON(atomic_read(&tsk->usage));
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WARN_ON(tsk == current);
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task_numa_free(tsk);
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security_task_free(tsk);
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exit_creds(tsk);
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delayacct_tsk_free(tsk);
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put_signal_struct(tsk->signal);
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if (!profile_handoff_task(tsk))
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free_task(tsk);
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}
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EXPORT_SYMBOL_GPL(__put_task_struct);
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void __init __weak arch_task_cache_init(void) { }
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void __init fork_init(unsigned long mempages)
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{
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#ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
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#ifndef ARCH_MIN_TASKALIGN
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#define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
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#endif
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/* create a slab on which task_structs can be allocated */
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task_struct_cachep =
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kmem_cache_create("task_struct", sizeof(struct task_struct),
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ARCH_MIN_TASKALIGN, SLAB_PANIC | SLAB_NOTRACK, NULL);
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#endif
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/* do the arch specific task caches init */
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arch_task_cache_init();
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/*
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* The default maximum number of threads is set to a safe
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* value: the thread structures can take up at most half
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* of memory.
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*/
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max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE);
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/*
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* we need to allow at least 20 threads to boot a system
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*/
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if (max_threads < 20)
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max_threads = 20;
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init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
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init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
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init_task.signal->rlim[RLIMIT_SIGPENDING] =
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init_task.signal->rlim[RLIMIT_NPROC];
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}
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int __weak arch_dup_task_struct(struct task_struct *dst,
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struct task_struct *src)
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{
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*dst = *src;
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return 0;
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}
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static struct task_struct *dup_task_struct(struct task_struct *orig)
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{
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struct task_struct *tsk;
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struct thread_info *ti;
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unsigned long *stackend;
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int node = tsk_fork_get_node(orig);
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int err;
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tsk = alloc_task_struct_node(node);
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if (!tsk)
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return NULL;
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ti = alloc_thread_info_node(tsk, node);
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if (!ti)
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goto free_tsk;
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err = arch_dup_task_struct(tsk, orig);
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if (err)
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goto free_ti;
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tsk->stack = ti;
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#ifdef CONFIG_SECCOMP
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/*
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* We must handle setting up seccomp filters once we're under
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* the sighand lock in case orig has changed between now and
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* then. Until then, filter must be NULL to avoid messing up
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* the usage counts on the error path calling free_task.
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*/
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tsk->seccomp.filter = NULL;
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#endif
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setup_thread_stack(tsk, orig);
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clear_user_return_notifier(tsk);
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clear_tsk_need_resched(tsk);
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stackend = end_of_stack(tsk);
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*stackend = STACK_END_MAGIC; /* for overflow detection */
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#ifdef CONFIG_CC_STACKPROTECTOR
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tsk->stack_canary = get_random_int();
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#endif
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/*
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* One for us, one for whoever does the "release_task()" (usually
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* parent)
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*/
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atomic_set(&tsk->usage, 2);
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#ifdef CONFIG_BLK_DEV_IO_TRACE
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tsk->btrace_seq = 0;
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#endif
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tsk->splice_pipe = NULL;
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tsk->task_frag.page = NULL;
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account_kernel_stack(ti, 1);
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return tsk;
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free_ti:
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free_thread_info(ti);
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free_tsk:
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free_task_struct(tsk);
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return NULL;
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}
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#ifdef CONFIG_MMU
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static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
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{
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struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
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struct rb_node **rb_link, *rb_parent;
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int retval;
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unsigned long charge;
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uprobe_start_dup_mmap();
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down_write(&oldmm->mmap_sem);
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flush_cache_dup_mm(oldmm);
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uprobe_dup_mmap(oldmm, mm);
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/*
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* Not linked in yet - no deadlock potential:
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*/
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down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
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mm->total_vm = oldmm->total_vm;
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mm->shared_vm = oldmm->shared_vm;
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mm->exec_vm = oldmm->exec_vm;
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mm->stack_vm = oldmm->stack_vm;
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rb_link = &mm->mm_rb.rb_node;
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rb_parent = NULL;
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pprev = &mm->mmap;
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retval = ksm_fork(mm, oldmm);
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if (retval)
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goto out;
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retval = khugepaged_fork(mm, oldmm);
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if (retval)
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goto out;
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prev = NULL;
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for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
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struct file *file;
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if (mpnt->vm_flags & VM_DONTCOPY) {
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vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
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-vma_pages(mpnt));
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continue;
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}
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charge = 0;
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if (mpnt->vm_flags & VM_ACCOUNT) {
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unsigned long len = vma_pages(mpnt);
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if (security_vm_enough_memory_mm(oldmm, len)) /* sic */
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goto fail_nomem;
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charge = len;
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}
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tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
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if (!tmp)
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goto fail_nomem;
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*tmp = *mpnt;
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INIT_LIST_HEAD(&tmp->anon_vma_chain);
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retval = vma_dup_policy(mpnt, tmp);
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if (retval)
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goto fail_nomem_policy;
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tmp->vm_mm = mm;
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if (anon_vma_fork(tmp, mpnt))
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goto fail_nomem_anon_vma_fork;
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tmp->vm_flags &= ~VM_LOCKED;
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tmp->vm_next = tmp->vm_prev = NULL;
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file = tmp->vm_file;
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if (file) {
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struct inode *inode = file_inode(file);
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struct address_space *mapping = file->f_mapping;
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get_file(file);
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if (tmp->vm_flags & VM_DENYWRITE)
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atomic_dec(&inode->i_writecount);
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mutex_lock(&mapping->i_mmap_mutex);
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if (tmp->vm_flags & VM_SHARED)
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atomic_inc(&mapping->i_mmap_writable);
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flush_dcache_mmap_lock(mapping);
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/* insert tmp into the share list, just after mpnt */
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if (unlikely(tmp->vm_flags & VM_NONLINEAR))
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vma_nonlinear_insert(tmp,
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&mapping->i_mmap_nonlinear);
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else
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vma_interval_tree_insert_after(tmp, mpnt,
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&mapping->i_mmap);
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flush_dcache_mmap_unlock(mapping);
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mutex_unlock(&mapping->i_mmap_mutex);
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}
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/*
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* Clear hugetlb-related page reserves for children. This only
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* affects MAP_PRIVATE mappings. Faults generated by the child
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* are not guaranteed to succeed, even if read-only
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*/
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if (is_vm_hugetlb_page(tmp))
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reset_vma_resv_huge_pages(tmp);
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/*
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* Link in the new vma and copy the page table entries.
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*/
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*pprev = tmp;
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pprev = &tmp->vm_next;
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tmp->vm_prev = prev;
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prev = tmp;
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__vma_link_rb(mm, tmp, rb_link, rb_parent);
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rb_link = &tmp->vm_rb.rb_right;
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rb_parent = &tmp->vm_rb;
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mm->map_count++;
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retval = copy_page_range(mm, oldmm, mpnt);
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if (tmp->vm_ops && tmp->vm_ops->open)
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tmp->vm_ops->open(tmp);
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if (retval)
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goto out;
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}
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/* a new mm has just been created */
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arch_dup_mmap(oldmm, mm);
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retval = 0;
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out:
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up_write(&mm->mmap_sem);
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flush_tlb_mm(oldmm);
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up_write(&oldmm->mmap_sem);
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uprobe_end_dup_mmap();
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return retval;
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fail_nomem_anon_vma_fork:
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mpol_put(vma_policy(tmp));
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fail_nomem_policy:
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kmem_cache_free(vm_area_cachep, tmp);
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fail_nomem:
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retval = -ENOMEM;
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vm_unacct_memory(charge);
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goto out;
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}
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static inline int mm_alloc_pgd(struct mm_struct *mm)
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{
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mm->pgd = pgd_alloc(mm);
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if (unlikely(!mm->pgd))
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return -ENOMEM;
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return 0;
|
|
}
|
|
|
|
static inline void mm_free_pgd(struct mm_struct *mm)
|
|
{
|
|
pgd_free(mm, mm->pgd);
|
|
}
|
|
#else
|
|
#define dup_mmap(mm, oldmm) (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)
|
|
{
|
|
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 void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
|
|
{
|
|
#ifdef CONFIG_MEMCG
|
|
mm->owner = p;
|
|
#endif
|
|
}
|
|
|
|
static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p)
|
|
{
|
|
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;
|
|
atomic_long_set(&mm->nr_ptes, 0);
|
|
mm->map_count = 0;
|
|
mm->locked_vm = 0;
|
|
mm->pinned_vm = 0;
|
|
memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
|
|
spin_lock_init(&mm->page_table_lock);
|
|
mm_init_cpumask(mm);
|
|
mm_init_aio(mm);
|
|
mm_init_owner(mm, p);
|
|
mmu_notifier_mm_init(mm);
|
|
clear_tlb_flush_pending(mm);
|
|
#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
|
|
mm->pmd_huge_pte = NULL;
|
|
#endif
|
|
|
|
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;
|
|
|
|
return mm;
|
|
|
|
fail_nocontext:
|
|
mm_free_pgd(mm);
|
|
fail_nopgd:
|
|
free_mm(mm);
|
|
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 defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
|
|
VM_BUG_ON(mm->pmd_huge_pte);
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* 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);
|
|
}
|
|
|
|
/*
|
|
* 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);
|
|
mmu_notifier_mm_destroy(mm);
|
|
check_mm(mm);
|
|
free_mm(mm);
|
|
}
|
|
EXPORT_SYMBOL_GPL(__mmdrop);
|
|
|
|
/*
|
|
* 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)) {
|
|
uprobe_clear_state(mm);
|
|
exit_aio(mm);
|
|
ksm_exit(mm);
|
|
khugepaged_exit(mm); /* must run before exit_mmap */
|
|
exit_mmap(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);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(mmput);
|
|
|
|
void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
|
|
{
|
|
if (new_exe_file)
|
|
get_file(new_exe_file);
|
|
if (mm->exe_file)
|
|
fput(mm->exe_file);
|
|
mm->exe_file = new_exe_file;
|
|
}
|
|
|
|
struct file *get_mm_exe_file(struct mm_struct *mm)
|
|
{
|
|
struct file *exe_file;
|
|
|
|
/* We need mmap_sem to protect against races with removal of exe_file */
|
|
down_read(&mm->mmap_sem);
|
|
exe_file = mm->exe_file;
|
|
if (exe_file)
|
|
get_file(exe_file);
|
|
up_read(&mm->mmap_sem);
|
|
return exe_file;
|
|
}
|
|
|
|
static void dup_mm_exe_file(struct mm_struct *oldmm, struct mm_struct *newmm)
|
|
{
|
|
/* It's safe to write the exe_file pointer without exe_file_lock because
|
|
* this is called during fork when the task is not yet in /proc */
|
|
newmm->exe_file = get_mm_exe_file(oldmm);
|
|
}
|
|
|
|
/**
|
|
* 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
|
|
atomic_inc(&mm->mm_users);
|
|
}
|
|
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();
|
|
killed = wait_for_completion_killable(vfork);
|
|
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)
|
|
{
|
|
/* Get rid of any futexes when releasing the mm */
|
|
#ifdef CONFIG_FUTEX
|
|
if (unlikely(tsk->robust_list)) {
|
|
exit_robust_list(tsk);
|
|
tsk->robust_list = NULL;
|
|
}
|
|
#ifdef CONFIG_COMPAT
|
|
if (unlikely(tsk->compat_robust_list)) {
|
|
compat_exit_robust_list(tsk);
|
|
tsk->compat_robust_list = NULL;
|
|
}
|
|
#endif
|
|
if (unlikely(!list_empty(&tsk->pi_state_list)))
|
|
exit_pi_state_list(tsk);
|
|
#endif
|
|
|
|
uprobe_free_utask(tsk);
|
|
|
|
/* Get rid of any cached register state */
|
|
deactivate_mm(tsk, mm);
|
|
|
|
/*
|
|
* If we're exiting normally, clear a user-space tid field if
|
|
* requested. We leave this alone when dying by signal, to leave
|
|
* the value intact in a core dump, and to save the unnecessary
|
|
* trouble, say, a killed vfork parent shouldn't touch this mm.
|
|
* Userland only wants this done for a sys_exit.
|
|
*/
|
|
if (tsk->clear_child_tid) {
|
|
if (!(tsk->flags & PF_SIGNALED) &&
|
|
atomic_read(&mm->mm_users) > 1) {
|
|
/*
|
|
* We don't check the error code - if userspace has
|
|
* not set up a proper pointer then tough luck.
|
|
*/
|
|
put_user(0, tsk->clear_child_tid);
|
|
sys_futex(tsk->clear_child_tid, FUTEX_WAKE,
|
|
1, NULL, NULL, 0);
|
|
}
|
|
tsk->clear_child_tid = NULL;
|
|
}
|
|
|
|
/*
|
|
* All done, finally we can wake up parent and return this mm to him.
|
|
* Also kthread_stop() uses this completion for synchronization.
|
|
*/
|
|
if (tsk->vfork_done)
|
|
complete_vfork_done(tsk);
|
|
}
|
|
|
|
/*
|
|
* Allocate a new mm structure and copy contents from the
|
|
* mm structure of the passed in task structure.
|
|
*/
|
|
static struct mm_struct *dup_mm(struct task_struct *tsk)
|
|
{
|
|
struct mm_struct *mm, *oldmm = current->mm;
|
|
int err;
|
|
|
|
mm = allocate_mm();
|
|
if (!mm)
|
|
goto fail_nomem;
|
|
|
|
memcpy(mm, oldmm, sizeof(*mm));
|
|
|
|
if (!mm_init(mm, tsk))
|
|
goto fail_nomem;
|
|
|
|
dup_mm_exe_file(oldmm, mm);
|
|
|
|
err = dup_mmap(mm, oldmm);
|
|
if (err)
|
|
goto free_pt;
|
|
|
|
mm->hiwater_rss = get_mm_rss(mm);
|
|
mm->hiwater_vm = mm->total_vm;
|
|
|
|
if (mm->binfmt && !try_module_get(mm->binfmt->module))
|
|
goto free_pt;
|
|
|
|
return mm;
|
|
|
|
free_pt:
|
|
/* don't put binfmt in mmput, we haven't got module yet */
|
|
mm->binfmt = NULL;
|
|
mmput(mm);
|
|
|
|
fail_nomem:
|
|
return NULL;
|
|
}
|
|
|
|
static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)
|
|
{
|
|
struct mm_struct *mm, *oldmm;
|
|
int retval;
|
|
|
|
tsk->min_flt = tsk->maj_flt = 0;
|
|
tsk->nvcsw = tsk->nivcsw = 0;
|
|
#ifdef CONFIG_DETECT_HUNG_TASK
|
|
tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw;
|
|
#endif
|
|
|
|
tsk->mm = NULL;
|
|
tsk->active_mm = NULL;
|
|
|
|
/*
|
|
* Are we cloning a kernel thread?
|
|
*
|
|
* We need to steal a active VM for that..
|
|
*/
|
|
oldmm = current->mm;
|
|
if (!oldmm)
|
|
return 0;
|
|
|
|
/* initialize the new vmacache entries */
|
|
vmacache_flush(tsk);
|
|
|
|
if (clone_flags & CLONE_VM) {
|
|
atomic_inc(&oldmm->mm_users);
|
|
mm = oldmm;
|
|
goto good_mm;
|
|
}
|
|
|
|
retval = -ENOMEM;
|
|
mm = dup_mm(tsk);
|
|
if (!mm)
|
|
goto fail_nomem;
|
|
|
|
good_mm:
|
|
tsk->mm = mm;
|
|
tsk->active_mm = mm;
|
|
return 0;
|
|
|
|
fail_nomem:
|
|
return retval;
|
|
}
|
|
|
|
static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
|
|
{
|
|
struct fs_struct *fs = current->fs;
|
|
if (clone_flags & CLONE_FS) {
|
|
/* tsk->fs is already what we want */
|
|
spin_lock(&fs->lock);
|
|
if (fs->in_exec) {
|
|
spin_unlock(&fs->lock);
|
|
return -EAGAIN;
|
|
}
|
|
fs->users++;
|
|
spin_unlock(&fs->lock);
|
|
return 0;
|
|
}
|
|
tsk->fs = copy_fs_struct(fs);
|
|
if (!tsk->fs)
|
|
return -ENOMEM;
|
|
return 0;
|
|
}
|
|
|
|
static int copy_files(unsigned long clone_flags, struct task_struct *tsk)
|
|
{
|
|
struct files_struct *oldf, *newf;
|
|
int error = 0;
|
|
|
|
/*
|
|
* A background process may not have any files ...
|
|
*/
|
|
oldf = current->files;
|
|
if (!oldf)
|
|
goto out;
|
|
|
|
if (clone_flags & CLONE_FILES) {
|
|
atomic_inc(&oldf->count);
|
|
goto out;
|
|
}
|
|
|
|
newf = dup_fd(oldf, &error);
|
|
if (!newf)
|
|
goto out;
|
|
|
|
tsk->files = newf;
|
|
error = 0;
|
|
out:
|
|
return error;
|
|
}
|
|
|
|
static int copy_io(unsigned long clone_flags, struct task_struct *tsk)
|
|
{
|
|
#ifdef CONFIG_BLOCK
|
|
struct io_context *ioc = current->io_context;
|
|
struct io_context *new_ioc;
|
|
|
|
if (!ioc)
|
|
return 0;
|
|
/*
|
|
* Share io context with parent, if CLONE_IO is set
|
|
*/
|
|
if (clone_flags & CLONE_IO) {
|
|
ioc_task_link(ioc);
|
|
tsk->io_context = ioc;
|
|
} else if (ioprio_valid(ioc->ioprio)) {
|
|
new_ioc = get_task_io_context(tsk, GFP_KERNEL, NUMA_NO_NODE);
|
|
if (unlikely(!new_ioc))
|
|
return -ENOMEM;
|
|
|
|
new_ioc->ioprio = ioc->ioprio;
|
|
put_io_context(new_ioc);
|
|
}
|
|
#endif
|
|
return 0;
|
|
}
|
|
|
|
static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
|
|
{
|
|
struct sighand_struct *sig;
|
|
|
|
if (clone_flags & CLONE_SIGHAND) {
|
|
atomic_inc(¤t->sighand->count);
|
|
return 0;
|
|
}
|
|
sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
|
|
rcu_assign_pointer(tsk->sighand, sig);
|
|
if (!sig)
|
|
return -ENOMEM;
|
|
atomic_set(&sig->count, 1);
|
|
memcpy(sig->action, current->sighand->action, sizeof(sig->action));
|
|
return 0;
|
|
}
|
|
|
|
void __cleanup_sighand(struct sighand_struct *sighand)
|
|
{
|
|
if (atomic_dec_and_test(&sighand->count)) {
|
|
signalfd_cleanup(sighand);
|
|
kmem_cache_free(sighand_cachep, sighand);
|
|
}
|
|
}
|
|
|
|
|
|
/*
|
|
* Initialize POSIX timer handling for a thread group.
|
|
*/
|
|
static void posix_cpu_timers_init_group(struct signal_struct *sig)
|
|
{
|
|
unsigned long cpu_limit;
|
|
|
|
/* Thread group counters. */
|
|
thread_group_cputime_init(sig);
|
|
|
|
cpu_limit = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
|
|
if (cpu_limit != RLIM_INFINITY) {
|
|
sig->cputime_expires.prof_exp = secs_to_cputime(cpu_limit);
|
|
sig->cputimer.running = 1;
|
|
}
|
|
|
|
/* The timer lists. */
|
|
INIT_LIST_HEAD(&sig->cpu_timers[0]);
|
|
INIT_LIST_HEAD(&sig->cpu_timers[1]);
|
|
INIT_LIST_HEAD(&sig->cpu_timers[2]);
|
|
}
|
|
|
|
static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
|
|
{
|
|
struct signal_struct *sig;
|
|
|
|
if (clone_flags & CLONE_THREAD)
|
|
return 0;
|
|
|
|
sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL);
|
|
tsk->signal = sig;
|
|
if (!sig)
|
|
return -ENOMEM;
|
|
|
|
sig->nr_threads = 1;
|
|
atomic_set(&sig->live, 1);
|
|
atomic_set(&sig->sigcnt, 1);
|
|
|
|
/* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */
|
|
sig->thread_head = (struct list_head)LIST_HEAD_INIT(tsk->thread_node);
|
|
tsk->thread_node = (struct list_head)LIST_HEAD_INIT(sig->thread_head);
|
|
|
|
init_waitqueue_head(&sig->wait_chldexit);
|
|
sig->curr_target = tsk;
|
|
init_sigpending(&sig->shared_pending);
|
|
INIT_LIST_HEAD(&sig->posix_timers);
|
|
|
|
hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
|
|
sig->real_timer.function = it_real_fn;
|
|
|
|
task_lock(current->group_leader);
|
|
memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
|
|
task_unlock(current->group_leader);
|
|
|
|
posix_cpu_timers_init_group(sig);
|
|
|
|
tty_audit_fork(sig);
|
|
sched_autogroup_fork(sig);
|
|
|
|
#ifdef CONFIG_CGROUPS
|
|
init_rwsem(&sig->group_rwsem);
|
|
#endif
|
|
|
|
sig->oom_score_adj = current->signal->oom_score_adj;
|
|
sig->oom_score_adj_min = current->signal->oom_score_adj_min;
|
|
|
|
sig->has_child_subreaper = current->signal->has_child_subreaper ||
|
|
current->signal->is_child_subreaper;
|
|
|
|
mutex_init(&sig->cred_guard_mutex);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void copy_seccomp(struct task_struct *p)
|
|
{
|
|
#ifdef CONFIG_SECCOMP
|
|
/*
|
|
* Must be called with sighand->lock held, which is common to
|
|
* all threads in the group. Holding cred_guard_mutex is not
|
|
* needed because this new task is not yet running and cannot
|
|
* be racing exec.
|
|
*/
|
|
assert_spin_locked(¤t->sighand->siglock);
|
|
|
|
/* Ref-count the new filter user, and assign it. */
|
|
get_seccomp_filter(current);
|
|
p->seccomp = current->seccomp;
|
|
|
|
/*
|
|
* Explicitly enable no_new_privs here in case it got set
|
|
* between the task_struct being duplicated and holding the
|
|
* sighand lock. The seccomp state and nnp must be in sync.
|
|
*/
|
|
if (task_no_new_privs(current))
|
|
task_set_no_new_privs(p);
|
|
|
|
/*
|
|
* If the parent gained a seccomp mode after copying thread
|
|
* flags and between before we held the sighand lock, we have
|
|
* to manually enable the seccomp thread flag here.
|
|
*/
|
|
if (p->seccomp.mode != SECCOMP_MODE_DISABLED)
|
|
set_tsk_thread_flag(p, TIF_SECCOMP);
|
|
#endif
|
|
}
|
|
|
|
SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr)
|
|
{
|
|
current->clear_child_tid = tidptr;
|
|
|
|
return task_pid_vnr(current);
|
|
}
|
|
|
|
static void rt_mutex_init_task(struct task_struct *p)
|
|
{
|
|
raw_spin_lock_init(&p->pi_lock);
|
|
#ifdef CONFIG_RT_MUTEXES
|
|
p->pi_waiters = RB_ROOT;
|
|
p->pi_waiters_leftmost = NULL;
|
|
p->pi_blocked_on = NULL;
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* Initialize POSIX timer handling for a single task.
|
|
*/
|
|
static void posix_cpu_timers_init(struct task_struct *tsk)
|
|
{
|
|
tsk->cputime_expires.prof_exp = 0;
|
|
tsk->cputime_expires.virt_exp = 0;
|
|
tsk->cputime_expires.sched_exp = 0;
|
|
INIT_LIST_HEAD(&tsk->cpu_timers[0]);
|
|
INIT_LIST_HEAD(&tsk->cpu_timers[1]);
|
|
INIT_LIST_HEAD(&tsk->cpu_timers[2]);
|
|
}
|
|
|
|
static inline void
|
|
init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid)
|
|
{
|
|
task->pids[type].pid = pid;
|
|
}
|
|
|
|
/*
|
|
* This creates a new process as a copy of the old one,
|
|
* but does not actually start it yet.
|
|
*
|
|
* It copies the registers, and all the appropriate
|
|
* parts of the process environment (as per the clone
|
|
* flags). The actual kick-off is left to the caller.
|
|
*/
|
|
static struct task_struct *copy_process(unsigned long clone_flags,
|
|
unsigned long stack_start,
|
|
unsigned long stack_size,
|
|
int __user *child_tidptr,
|
|
struct pid *pid,
|
|
int trace)
|
|
{
|
|
int retval;
|
|
struct task_struct *p;
|
|
|
|
if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
if ((clone_flags & (CLONE_NEWUSER|CLONE_FS)) == (CLONE_NEWUSER|CLONE_FS))
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
/*
|
|
* Thread groups must share signals as well, and detached threads
|
|
* can only be started up within the thread group.
|
|
*/
|
|
if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
/*
|
|
* Shared signal handlers imply shared VM. By way of the above,
|
|
* thread groups also imply shared VM. Blocking this case allows
|
|
* for various simplifications in other code.
|
|
*/
|
|
if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
/*
|
|
* Siblings of global init remain as zombies on exit since they are
|
|
* not reaped by their parent (swapper). To solve this and to avoid
|
|
* multi-rooted process trees, prevent global and container-inits
|
|
* from creating siblings.
|
|
*/
|
|
if ((clone_flags & CLONE_PARENT) &&
|
|
current->signal->flags & SIGNAL_UNKILLABLE)
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
/*
|
|
* If the new process will be in a different pid or user namespace
|
|
* do not allow it to share a thread group or signal handlers or
|
|
* parent with the forking task.
|
|
*/
|
|
if (clone_flags & CLONE_SIGHAND) {
|
|
if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) ||
|
|
(task_active_pid_ns(current) !=
|
|
current->nsproxy->pid_ns_for_children))
|
|
return ERR_PTR(-EINVAL);
|
|
}
|
|
|
|
retval = security_task_create(clone_flags);
|
|
if (retval)
|
|
goto fork_out;
|
|
|
|
retval = -ENOMEM;
|
|
p = dup_task_struct(current);
|
|
if (!p)
|
|
goto fork_out;
|
|
|
|
ftrace_graph_init_task(p);
|
|
|
|
rt_mutex_init_task(p);
|
|
|
|
#ifdef CONFIG_PROVE_LOCKING
|
|
DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled);
|
|
DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
|
|
#endif
|
|
retval = -EAGAIN;
|
|
if (atomic_read(&p->real_cred->user->processes) >=
|
|
task_rlimit(p, RLIMIT_NPROC)) {
|
|
if (p->real_cred->user != INIT_USER &&
|
|
!capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN))
|
|
goto bad_fork_free;
|
|
}
|
|
current->flags &= ~PF_NPROC_EXCEEDED;
|
|
|
|
retval = copy_creds(p, clone_flags);
|
|
if (retval < 0)
|
|
goto bad_fork_free;
|
|
|
|
/*
|
|
* If multiple threads are within copy_process(), then this check
|
|
* triggers too late. This doesn't hurt, the check is only there
|
|
* to stop root fork bombs.
|
|
*/
|
|
retval = -EAGAIN;
|
|
if (nr_threads >= max_threads)
|
|
goto bad_fork_cleanup_count;
|
|
|
|
if (!try_module_get(task_thread_info(p)->exec_domain->module))
|
|
goto bad_fork_cleanup_count;
|
|
|
|
delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
|
|
p->flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER);
|
|
p->flags |= PF_FORKNOEXEC;
|
|
INIT_LIST_HEAD(&p->children);
|
|
INIT_LIST_HEAD(&p->sibling);
|
|
rcu_copy_process(p);
|
|
p->vfork_done = NULL;
|
|
spin_lock_init(&p->alloc_lock);
|
|
|
|
init_sigpending(&p->pending);
|
|
|
|
p->utime = p->stime = p->gtime = 0;
|
|
p->utimescaled = p->stimescaled = 0;
|
|
#ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
|
|
p->prev_cputime.utime = p->prev_cputime.stime = 0;
|
|
#endif
|
|
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
|
|
seqlock_init(&p->vtime_seqlock);
|
|
p->vtime_snap = 0;
|
|
p->vtime_snap_whence = VTIME_SLEEPING;
|
|
#endif
|
|
|
|
#if defined(SPLIT_RSS_COUNTING)
|
|
memset(&p->rss_stat, 0, sizeof(p->rss_stat));
|
|
#endif
|
|
|
|
p->default_timer_slack_ns = current->timer_slack_ns;
|
|
|
|
task_io_accounting_init(&p->ioac);
|
|
acct_clear_integrals(p);
|
|
|
|
posix_cpu_timers_init(p);
|
|
|
|
p->start_time = ktime_get_ns();
|
|
p->real_start_time = ktime_get_boot_ns();
|
|
p->io_context = NULL;
|
|
p->audit_context = NULL;
|
|
if (clone_flags & CLONE_THREAD)
|
|
threadgroup_change_begin(current);
|
|
cgroup_fork(p);
|
|
#ifdef CONFIG_NUMA
|
|
p->mempolicy = mpol_dup(p->mempolicy);
|
|
if (IS_ERR(p->mempolicy)) {
|
|
retval = PTR_ERR(p->mempolicy);
|
|
p->mempolicy = NULL;
|
|
goto bad_fork_cleanup_threadgroup_lock;
|
|
}
|
|
#endif
|
|
#ifdef CONFIG_CPUSETS
|
|
p->cpuset_mem_spread_rotor = NUMA_NO_NODE;
|
|
p->cpuset_slab_spread_rotor = NUMA_NO_NODE;
|
|
seqcount_init(&p->mems_allowed_seq);
|
|
#endif
|
|
#ifdef CONFIG_TRACE_IRQFLAGS
|
|
p->irq_events = 0;
|
|
p->hardirqs_enabled = 0;
|
|
p->hardirq_enable_ip = 0;
|
|
p->hardirq_enable_event = 0;
|
|
p->hardirq_disable_ip = _THIS_IP_;
|
|
p->hardirq_disable_event = 0;
|
|
p->softirqs_enabled = 1;
|
|
p->softirq_enable_ip = _THIS_IP_;
|
|
p->softirq_enable_event = 0;
|
|
p->softirq_disable_ip = 0;
|
|
p->softirq_disable_event = 0;
|
|
p->hardirq_context = 0;
|
|
p->softirq_context = 0;
|
|
#endif
|
|
#ifdef CONFIG_LOCKDEP
|
|
p->lockdep_depth = 0; /* no locks held yet */
|
|
p->curr_chain_key = 0;
|
|
p->lockdep_recursion = 0;
|
|
#endif
|
|
|
|
#ifdef CONFIG_DEBUG_MUTEXES
|
|
p->blocked_on = NULL; /* not blocked yet */
|
|
#endif
|
|
#ifdef CONFIG_BCACHE
|
|
p->sequential_io = 0;
|
|
p->sequential_io_avg = 0;
|
|
#endif
|
|
|
|
/* Perform scheduler related setup. Assign this task to a CPU. */
|
|
retval = sched_fork(clone_flags, p);
|
|
if (retval)
|
|
goto bad_fork_cleanup_policy;
|
|
|
|
retval = perf_event_init_task(p);
|
|
if (retval)
|
|
goto bad_fork_cleanup_policy;
|
|
retval = audit_alloc(p);
|
|
if (retval)
|
|
goto bad_fork_cleanup_policy;
|
|
/* copy all the process information */
|
|
shm_init_task(p);
|
|
retval = copy_semundo(clone_flags, p);
|
|
if (retval)
|
|
goto bad_fork_cleanup_audit;
|
|
retval = copy_files(clone_flags, p);
|
|
if (retval)
|
|
goto bad_fork_cleanup_semundo;
|
|
retval = copy_fs(clone_flags, p);
|
|
if (retval)
|
|
goto bad_fork_cleanup_files;
|
|
retval = copy_sighand(clone_flags, p);
|
|
if (retval)
|
|
goto bad_fork_cleanup_fs;
|
|
retval = copy_signal(clone_flags, p);
|
|
if (retval)
|
|
goto bad_fork_cleanup_sighand;
|
|
retval = copy_mm(clone_flags, p);
|
|
if (retval)
|
|
goto bad_fork_cleanup_signal;
|
|
retval = copy_namespaces(clone_flags, p);
|
|
if (retval)
|
|
goto bad_fork_cleanup_mm;
|
|
retval = copy_io(clone_flags, p);
|
|
if (retval)
|
|
goto bad_fork_cleanup_namespaces;
|
|
retval = copy_thread(clone_flags, stack_start, stack_size, p);
|
|
if (retval)
|
|
goto bad_fork_cleanup_io;
|
|
|
|
if (pid != &init_struct_pid) {
|
|
retval = -ENOMEM;
|
|
pid = alloc_pid(p->nsproxy->pid_ns_for_children);
|
|
if (!pid)
|
|
goto bad_fork_cleanup_io;
|
|
}
|
|
|
|
p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
|
|
/*
|
|
* Clear TID on mm_release()?
|
|
*/
|
|
p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr : NULL;
|
|
#ifdef CONFIG_BLOCK
|
|
p->plug = NULL;
|
|
#endif
|
|
#ifdef CONFIG_FUTEX
|
|
p->robust_list = NULL;
|
|
#ifdef CONFIG_COMPAT
|
|
p->compat_robust_list = NULL;
|
|
#endif
|
|
INIT_LIST_HEAD(&p->pi_state_list);
|
|
p->pi_state_cache = NULL;
|
|
#endif
|
|
/*
|
|
* sigaltstack should be cleared when sharing the same VM
|
|
*/
|
|
if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
|
|
p->sas_ss_sp = p->sas_ss_size = 0;
|
|
|
|
/*
|
|
* Syscall tracing and stepping should be turned off in the
|
|
* child regardless of CLONE_PTRACE.
|
|
*/
|
|
user_disable_single_step(p);
|
|
clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
|
|
#ifdef TIF_SYSCALL_EMU
|
|
clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
|
|
#endif
|
|
clear_all_latency_tracing(p);
|
|
|
|
/* ok, now we should be set up.. */
|
|
p->pid = pid_nr(pid);
|
|
if (clone_flags & CLONE_THREAD) {
|
|
p->exit_signal = -1;
|
|
p->group_leader = current->group_leader;
|
|
p->tgid = current->tgid;
|
|
} else {
|
|
if (clone_flags & CLONE_PARENT)
|
|
p->exit_signal = current->group_leader->exit_signal;
|
|
else
|
|
p->exit_signal = (clone_flags & CSIGNAL);
|
|
p->group_leader = p;
|
|
p->tgid = p->pid;
|
|
}
|
|
|
|
p->nr_dirtied = 0;
|
|
p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10);
|
|
p->dirty_paused_when = 0;
|
|
|
|
p->pdeath_signal = 0;
|
|
INIT_LIST_HEAD(&p->thread_group);
|
|
p->task_works = NULL;
|
|
|
|
/*
|
|
* Make it visible to the rest of the system, but dont wake it up yet.
|
|
* Need tasklist lock for parent etc handling!
|
|
*/
|
|
write_lock_irq(&tasklist_lock);
|
|
|
|
/* CLONE_PARENT re-uses the old parent */
|
|
if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
|
|
p->real_parent = current->real_parent;
|
|
p->parent_exec_id = current->parent_exec_id;
|
|
} else {
|
|
p->real_parent = current;
|
|
p->parent_exec_id = current->self_exec_id;
|
|
}
|
|
|
|
spin_lock(¤t->sighand->siglock);
|
|
|
|
/*
|
|
* Copy seccomp details explicitly here, in case they were changed
|
|
* before holding sighand lock.
|
|
*/
|
|
copy_seccomp(p);
|
|
|
|
/*
|
|
* Process group and session signals need to be delivered to just the
|
|
* parent before the fork or both the parent and the child after the
|
|
* fork. Restart if a signal comes in before we add the new process to
|
|
* it's process group.
|
|
* A fatal signal pending means that current will exit, so the new
|
|
* thread can't slip out of an OOM kill (or normal SIGKILL).
|
|
*/
|
|
recalc_sigpending();
|
|
if (signal_pending(current)) {
|
|
spin_unlock(¤t->sighand->siglock);
|
|
write_unlock_irq(&tasklist_lock);
|
|
retval = -ERESTARTNOINTR;
|
|
goto bad_fork_free_pid;
|
|
}
|
|
|
|
if (likely(p->pid)) {
|
|
ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace);
|
|
|
|
init_task_pid(p, PIDTYPE_PID, pid);
|
|
if (thread_group_leader(p)) {
|
|
init_task_pid(p, PIDTYPE_PGID, task_pgrp(current));
|
|
init_task_pid(p, PIDTYPE_SID, task_session(current));
|
|
|
|
if (is_child_reaper(pid)) {
|
|
ns_of_pid(pid)->child_reaper = p;
|
|
p->signal->flags |= SIGNAL_UNKILLABLE;
|
|
}
|
|
|
|
p->signal->leader_pid = pid;
|
|
p->signal->tty = tty_kref_get(current->signal->tty);
|
|
list_add_tail(&p->sibling, &p->real_parent->children);
|
|
list_add_tail_rcu(&p->tasks, &init_task.tasks);
|
|
attach_pid(p, PIDTYPE_PGID);
|
|
attach_pid(p, PIDTYPE_SID);
|
|
__this_cpu_inc(process_counts);
|
|
} else {
|
|
current->signal->nr_threads++;
|
|
atomic_inc(¤t->signal->live);
|
|
atomic_inc(¤t->signal->sigcnt);
|
|
list_add_tail_rcu(&p->thread_group,
|
|
&p->group_leader->thread_group);
|
|
list_add_tail_rcu(&p->thread_node,
|
|
&p->signal->thread_head);
|
|
}
|
|
attach_pid(p, PIDTYPE_PID);
|
|
nr_threads++;
|
|
}
|
|
|
|
total_forks++;
|
|
spin_unlock(¤t->sighand->siglock);
|
|
syscall_tracepoint_update(p);
|
|
write_unlock_irq(&tasklist_lock);
|
|
|
|
proc_fork_connector(p);
|
|
cgroup_post_fork(p);
|
|
if (clone_flags & CLONE_THREAD)
|
|
threadgroup_change_end(current);
|
|
perf_event_fork(p);
|
|
|
|
trace_task_newtask(p, clone_flags);
|
|
uprobe_copy_process(p, clone_flags);
|
|
|
|
return p;
|
|
|
|
bad_fork_free_pid:
|
|
if (pid != &init_struct_pid)
|
|
free_pid(pid);
|
|
bad_fork_cleanup_io:
|
|
if (p->io_context)
|
|
exit_io_context(p);
|
|
bad_fork_cleanup_namespaces:
|
|
exit_task_namespaces(p);
|
|
bad_fork_cleanup_mm:
|
|
if (p->mm)
|
|
mmput(p->mm);
|
|
bad_fork_cleanup_signal:
|
|
if (!(clone_flags & CLONE_THREAD))
|
|
free_signal_struct(p->signal);
|
|
bad_fork_cleanup_sighand:
|
|
__cleanup_sighand(p->sighand);
|
|
bad_fork_cleanup_fs:
|
|
exit_fs(p); /* blocking */
|
|
bad_fork_cleanup_files:
|
|
exit_files(p); /* blocking */
|
|
bad_fork_cleanup_semundo:
|
|
exit_sem(p);
|
|
bad_fork_cleanup_audit:
|
|
audit_free(p);
|
|
bad_fork_cleanup_policy:
|
|
perf_event_free_task(p);
|
|
#ifdef CONFIG_NUMA
|
|
mpol_put(p->mempolicy);
|
|
bad_fork_cleanup_threadgroup_lock:
|
|
#endif
|
|
if (clone_flags & CLONE_THREAD)
|
|
threadgroup_change_end(current);
|
|
delayacct_tsk_free(p);
|
|
module_put(task_thread_info(p)->exec_domain->module);
|
|
bad_fork_cleanup_count:
|
|
atomic_dec(&p->cred->user->processes);
|
|
exit_creds(p);
|
|
bad_fork_free:
|
|
free_task(p);
|
|
fork_out:
|
|
return ERR_PTR(retval);
|
|
}
|
|
|
|
static inline void init_idle_pids(struct pid_link *links)
|
|
{
|
|
enum pid_type type;
|
|
|
|
for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) {
|
|
INIT_HLIST_NODE(&links[type].node); /* not really needed */
|
|
links[type].pid = &init_struct_pid;
|
|
}
|
|
}
|
|
|
|
struct task_struct *fork_idle(int cpu)
|
|
{
|
|
struct task_struct *task;
|
|
task = copy_process(CLONE_VM, 0, 0, NULL, &init_struct_pid, 0);
|
|
if (!IS_ERR(task)) {
|
|
init_idle_pids(task->pids);
|
|
init_idle(task, cpu);
|
|
}
|
|
|
|
return task;
|
|
}
|
|
|
|
/*
|
|
* Ok, this is the main fork-routine.
|
|
*
|
|
* It copies the process, and if successful kick-starts
|
|
* it and waits for it to finish using the VM if required.
|
|
*/
|
|
long do_fork(unsigned long clone_flags,
|
|
unsigned long stack_start,
|
|
unsigned long stack_size,
|
|
int __user *parent_tidptr,
|
|
int __user *child_tidptr)
|
|
{
|
|
struct task_struct *p;
|
|
int trace = 0;
|
|
long nr;
|
|
|
|
/*
|
|
* Determine whether and which event to report to ptracer. When
|
|
* called from kernel_thread or CLONE_UNTRACED is explicitly
|
|
* requested, no event is reported; otherwise, report if the event
|
|
* for the type of forking is enabled.
|
|
*/
|
|
if (!(clone_flags & CLONE_UNTRACED)) {
|
|
if (clone_flags & CLONE_VFORK)
|
|
trace = PTRACE_EVENT_VFORK;
|
|
else if ((clone_flags & CSIGNAL) != SIGCHLD)
|
|
trace = PTRACE_EVENT_CLONE;
|
|
else
|
|
trace = PTRACE_EVENT_FORK;
|
|
|
|
if (likely(!ptrace_event_enabled(current, trace)))
|
|
trace = 0;
|
|
}
|
|
|
|
p = copy_process(clone_flags, stack_start, stack_size,
|
|
child_tidptr, NULL, trace);
|
|
/*
|
|
* Do this prior waking up the new thread - the thread pointer
|
|
* might get invalid after that point, if the thread exits quickly.
|
|
*/
|
|
if (!IS_ERR(p)) {
|
|
struct completion vfork;
|
|
struct pid *pid;
|
|
|
|
trace_sched_process_fork(current, p);
|
|
|
|
pid = get_task_pid(p, PIDTYPE_PID);
|
|
nr = pid_vnr(pid);
|
|
|
|
if (clone_flags & CLONE_PARENT_SETTID)
|
|
put_user(nr, parent_tidptr);
|
|
|
|
if (clone_flags & CLONE_VFORK) {
|
|
p->vfork_done = &vfork;
|
|
init_completion(&vfork);
|
|
get_task_struct(p);
|
|
}
|
|
|
|
wake_up_new_task(p);
|
|
|
|
/* forking complete and child started to run, tell ptracer */
|
|
if (unlikely(trace))
|
|
ptrace_event_pid(trace, pid);
|
|
|
|
if (clone_flags & CLONE_VFORK) {
|
|
if (!wait_for_vfork_done(p, &vfork))
|
|
ptrace_event_pid(PTRACE_EVENT_VFORK_DONE, pid);
|
|
}
|
|
|
|
put_pid(pid);
|
|
} else {
|
|
nr = PTR_ERR(p);
|
|
}
|
|
return nr;
|
|
}
|
|
|
|
/*
|
|
* Create a kernel thread.
|
|
*/
|
|
pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
|
|
{
|
|
return do_fork(flags|CLONE_VM|CLONE_UNTRACED, (unsigned long)fn,
|
|
(unsigned long)arg, NULL, NULL);
|
|
}
|
|
|
|
#ifdef __ARCH_WANT_SYS_FORK
|
|
SYSCALL_DEFINE0(fork)
|
|
{
|
|
#ifdef CONFIG_MMU
|
|
return do_fork(SIGCHLD, 0, 0, NULL, NULL);
|
|
#else
|
|
/* can not support in nommu mode */
|
|
return -EINVAL;
|
|
#endif
|
|
}
|
|
#endif
|
|
|
|
#ifdef __ARCH_WANT_SYS_VFORK
|
|
SYSCALL_DEFINE0(vfork)
|
|
{
|
|
return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, 0,
|
|
0, NULL, NULL);
|
|
}
|
|
#endif
|
|
|
|
#ifdef __ARCH_WANT_SYS_CLONE
|
|
#ifdef CONFIG_CLONE_BACKWARDS
|
|
SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
|
|
int __user *, parent_tidptr,
|
|
int, tls_val,
|
|
int __user *, child_tidptr)
|
|
#elif defined(CONFIG_CLONE_BACKWARDS2)
|
|
SYSCALL_DEFINE5(clone, unsigned long, newsp, unsigned long, clone_flags,
|
|
int __user *, parent_tidptr,
|
|
int __user *, child_tidptr,
|
|
int, tls_val)
|
|
#elif defined(CONFIG_CLONE_BACKWARDS3)
|
|
SYSCALL_DEFINE6(clone, unsigned long, clone_flags, unsigned long, newsp,
|
|
int, stack_size,
|
|
int __user *, parent_tidptr,
|
|
int __user *, child_tidptr,
|
|
int, tls_val)
|
|
#else
|
|
SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
|
|
int __user *, parent_tidptr,
|
|
int __user *, child_tidptr,
|
|
int, tls_val)
|
|
#endif
|
|
{
|
|
return do_fork(clone_flags, newsp, 0, parent_tidptr, child_tidptr);
|
|
}
|
|
#endif
|
|
|
|
#ifndef ARCH_MIN_MMSTRUCT_ALIGN
|
|
#define ARCH_MIN_MMSTRUCT_ALIGN 0
|
|
#endif
|
|
|
|
static void sighand_ctor(void *data)
|
|
{
|
|
struct sighand_struct *sighand = data;
|
|
|
|
spin_lock_init(&sighand->siglock);
|
|
init_waitqueue_head(&sighand->signalfd_wqh);
|
|
}
|
|
|
|
void __init proc_caches_init(void)
|
|
{
|
|
sighand_cachep = kmem_cache_create("sighand_cache",
|
|
sizeof(struct sighand_struct), 0,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU|
|
|
SLAB_NOTRACK, sighand_ctor);
|
|
signal_cachep = kmem_cache_create("signal_cache",
|
|
sizeof(struct signal_struct), 0,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
|
|
files_cachep = kmem_cache_create("files_cache",
|
|
sizeof(struct files_struct), 0,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
|
|
fs_cachep = kmem_cache_create("fs_cache",
|
|
sizeof(struct fs_struct), 0,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
|
|
/*
|
|
* FIXME! The "sizeof(struct mm_struct)" currently includes the
|
|
* whole struct cpumask for the OFFSTACK case. We could change
|
|
* this to *only* allocate as much of it as required by the
|
|
* maximum number of CPU's we can ever have. The cpumask_allocation
|
|
* is at the end of the structure, exactly for that reason.
|
|
*/
|
|
mm_cachep = kmem_cache_create("mm_struct",
|
|
sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
|
|
vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC);
|
|
mmap_init();
|
|
nsproxy_cache_init();
|
|
}
|
|
|
|
/*
|
|
* Check constraints on flags passed to the unshare system call.
|
|
*/
|
|
static int check_unshare_flags(unsigned long unshare_flags)
|
|
{
|
|
if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
|
|
CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
|
|
CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET|
|
|
CLONE_NEWUSER|CLONE_NEWPID))
|
|
return -EINVAL;
|
|
/*
|
|
* Not implemented, but pretend it works if there is nothing to
|
|
* unshare. Note that unsharing CLONE_THREAD or CLONE_SIGHAND
|
|
* needs to unshare vm.
|
|
*/
|
|
if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) {
|
|
/* FIXME: get_task_mm() increments ->mm_users */
|
|
if (atomic_read(¤t->mm->mm_users) > 1)
|
|
return -EINVAL;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Unshare the filesystem structure if it is being shared
|
|
*/
|
|
static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
|
|
{
|
|
struct fs_struct *fs = current->fs;
|
|
|
|
if (!(unshare_flags & CLONE_FS) || !fs)
|
|
return 0;
|
|
|
|
/* don't need lock here; in the worst case we'll do useless copy */
|
|
if (fs->users == 1)
|
|
return 0;
|
|
|
|
*new_fsp = copy_fs_struct(fs);
|
|
if (!*new_fsp)
|
|
return -ENOMEM;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Unshare file descriptor table if it is being shared
|
|
*/
|
|
static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp)
|
|
{
|
|
struct files_struct *fd = current->files;
|
|
int error = 0;
|
|
|
|
if ((unshare_flags & CLONE_FILES) &&
|
|
(fd && atomic_read(&fd->count) > 1)) {
|
|
*new_fdp = dup_fd(fd, &error);
|
|
if (!*new_fdp)
|
|
return error;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* unshare allows a process to 'unshare' part of the process
|
|
* context which was originally shared using clone. copy_*
|
|
* functions used by do_fork() cannot be used here directly
|
|
* because they modify an inactive task_struct that is being
|
|
* constructed. Here we are modifying the current, active,
|
|
* task_struct.
|
|
*/
|
|
SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
|
|
{
|
|
struct fs_struct *fs, *new_fs = NULL;
|
|
struct files_struct *fd, *new_fd = NULL;
|
|
struct cred *new_cred = NULL;
|
|
struct nsproxy *new_nsproxy = NULL;
|
|
int do_sysvsem = 0;
|
|
int err;
|
|
|
|
/*
|
|
* If unsharing a user namespace must also unshare the thread.
|
|
*/
|
|
if (unshare_flags & CLONE_NEWUSER)
|
|
unshare_flags |= CLONE_THREAD | CLONE_FS;
|
|
/*
|
|
* If unsharing a thread from a thread group, must also unshare vm.
|
|
*/
|
|
if (unshare_flags & CLONE_THREAD)
|
|
unshare_flags |= CLONE_VM;
|
|
/*
|
|
* If unsharing vm, must also unshare signal handlers.
|
|
*/
|
|
if (unshare_flags & CLONE_VM)
|
|
unshare_flags |= CLONE_SIGHAND;
|
|
/*
|
|
* If unsharing namespace, must also unshare filesystem information.
|
|
*/
|
|
if (unshare_flags & CLONE_NEWNS)
|
|
unshare_flags |= CLONE_FS;
|
|
|
|
err = check_unshare_flags(unshare_flags);
|
|
if (err)
|
|
goto bad_unshare_out;
|
|
/*
|
|
* CLONE_NEWIPC must also detach from the undolist: after switching
|
|
* to a new ipc namespace, the semaphore arrays from the old
|
|
* namespace are unreachable.
|
|
*/
|
|
if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
|
|
do_sysvsem = 1;
|
|
err = unshare_fs(unshare_flags, &new_fs);
|
|
if (err)
|
|
goto bad_unshare_out;
|
|
err = unshare_fd(unshare_flags, &new_fd);
|
|
if (err)
|
|
goto bad_unshare_cleanup_fs;
|
|
err = unshare_userns(unshare_flags, &new_cred);
|
|
if (err)
|
|
goto bad_unshare_cleanup_fd;
|
|
err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy,
|
|
new_cred, new_fs);
|
|
if (err)
|
|
goto bad_unshare_cleanup_cred;
|
|
|
|
if (new_fs || new_fd || do_sysvsem || new_cred || new_nsproxy) {
|
|
if (do_sysvsem) {
|
|
/*
|
|
* CLONE_SYSVSEM is equivalent to sys_exit().
|
|
*/
|
|
exit_sem(current);
|
|
}
|
|
if (unshare_flags & CLONE_NEWIPC) {
|
|
/* Orphan segments in old ns (see sem above). */
|
|
exit_shm(current);
|
|
shm_init_task(current);
|
|
}
|
|
|
|
if (new_nsproxy)
|
|
switch_task_namespaces(current, new_nsproxy);
|
|
|
|
task_lock(current);
|
|
|
|
if (new_fs) {
|
|
fs = current->fs;
|
|
spin_lock(&fs->lock);
|
|
current->fs = new_fs;
|
|
if (--fs->users)
|
|
new_fs = NULL;
|
|
else
|
|
new_fs = fs;
|
|
spin_unlock(&fs->lock);
|
|
}
|
|
|
|
if (new_fd) {
|
|
fd = current->files;
|
|
current->files = new_fd;
|
|
new_fd = fd;
|
|
}
|
|
|
|
task_unlock(current);
|
|
|
|
if (new_cred) {
|
|
/* Install the new user namespace */
|
|
commit_creds(new_cred);
|
|
new_cred = NULL;
|
|
}
|
|
}
|
|
|
|
bad_unshare_cleanup_cred:
|
|
if (new_cred)
|
|
put_cred(new_cred);
|
|
bad_unshare_cleanup_fd:
|
|
if (new_fd)
|
|
put_files_struct(new_fd);
|
|
|
|
bad_unshare_cleanup_fs:
|
|
if (new_fs)
|
|
free_fs_struct(new_fs);
|
|
|
|
bad_unshare_out:
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* Helper to unshare the files of the current task.
|
|
* We don't want to expose copy_files internals to
|
|
* the exec layer of the kernel.
|
|
*/
|
|
|
|
int unshare_files(struct files_struct **displaced)
|
|
{
|
|
struct task_struct *task = current;
|
|
struct files_struct *copy = NULL;
|
|
int error;
|
|
|
|
error = unshare_fd(CLONE_FILES, ©);
|
|
if (error || !copy) {
|
|
*displaced = NULL;
|
|
return error;
|
|
}
|
|
*displaced = task->files;
|
|
task_lock(task);
|
|
task->files = copy;
|
|
task_unlock(task);
|
|
return 0;
|
|
}
|