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![Linus Torvalds](/assets/img/avatar_default.png)
Like vm_area_dup(), it initializes the anon_vma_chain head, and the basic mm pointer. The rest of the fields end up being different for different users, although the plan is to also initialize the 'vm_ops' field to a dummy entry. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2560 lines
61 KiB
C
2560 lines
61 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/sched/autogroup.h>
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#include <linux/sched/mm.h>
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#include <linux/sched/coredump.h>
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#include <linux/sched/user.h>
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#include <linux/sched/numa_balancing.h>
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#include <linux/sched/stat.h>
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#include <linux/sched/task.h>
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#include <linux/sched/task_stack.h>
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#include <linux/sched/cputime.h>
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#include <linux/rtmutex.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/hmm.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/userfaultfd_k.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/sched/mm.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 <linux/sysctl.h>
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#include <linux/kcov.h>
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#include <linux/livepatch.h>
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#include <linux/thread_info.h>
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#include <asm/pgtable.h>
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#include <asm/pgalloc.h>
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#include <linux/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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* Minimum number of threads to boot the kernel
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*/
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#define MIN_THREADS 20
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/*
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* Maximum number of threads
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*/
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#define MAX_THREADS FUTEX_TID_MASK
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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_stack(unsigned long *stack)
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{
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}
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#ifndef CONFIG_ARCH_THREAD_STACK_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 || defined(CONFIG_VMAP_STACK)
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#ifdef CONFIG_VMAP_STACK
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/*
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* vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
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* flush. Try to minimize the number of calls by caching stacks.
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*/
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#define NR_CACHED_STACKS 2
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static DEFINE_PER_CPU(struct vm_struct *, cached_stacks[NR_CACHED_STACKS]);
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static int free_vm_stack_cache(unsigned int cpu)
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{
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struct vm_struct **cached_vm_stacks = per_cpu_ptr(cached_stacks, cpu);
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int i;
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for (i = 0; i < NR_CACHED_STACKS; i++) {
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struct vm_struct *vm_stack = cached_vm_stacks[i];
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if (!vm_stack)
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continue;
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vfree(vm_stack->addr);
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cached_vm_stacks[i] = NULL;
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}
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return 0;
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}
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#endif
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static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
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{
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#ifdef CONFIG_VMAP_STACK
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void *stack;
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int i;
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for (i = 0; i < NR_CACHED_STACKS; i++) {
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struct vm_struct *s;
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s = this_cpu_xchg(cached_stacks[i], NULL);
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if (!s)
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continue;
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/* Clear stale pointers from reused stack. */
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memset(s->addr, 0, THREAD_SIZE);
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tsk->stack_vm_area = s;
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return s->addr;
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}
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stack = __vmalloc_node_range(THREAD_SIZE, THREAD_ALIGN,
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VMALLOC_START, VMALLOC_END,
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THREADINFO_GFP,
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PAGE_KERNEL,
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0, node, __builtin_return_address(0));
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/*
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* We can't call find_vm_area() in interrupt context, and
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* free_thread_stack() can be called in interrupt context,
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* so cache the vm_struct.
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*/
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if (stack)
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tsk->stack_vm_area = find_vm_area(stack);
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return stack;
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#else
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struct page *page = alloc_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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#endif
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}
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static inline void free_thread_stack(struct task_struct *tsk)
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{
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#ifdef CONFIG_VMAP_STACK
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if (task_stack_vm_area(tsk)) {
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int i;
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for (i = 0; i < NR_CACHED_STACKS; i++) {
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if (this_cpu_cmpxchg(cached_stacks[i],
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NULL, tsk->stack_vm_area) != NULL)
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continue;
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return;
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}
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vfree_atomic(tsk->stack);
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return;
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}
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#endif
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__free_pages(virt_to_page(tsk->stack), THREAD_SIZE_ORDER);
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}
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# else
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static struct kmem_cache *thread_stack_cache;
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static unsigned long *alloc_thread_stack_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_stack_cache, THREADINFO_GFP, node);
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}
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static void free_thread_stack(struct task_struct *tsk)
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{
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kmem_cache_free(thread_stack_cache, tsk->stack);
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}
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void thread_stack_cache_init(void)
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{
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thread_stack_cache = kmem_cache_create_usercopy("thread_stack",
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THREAD_SIZE, THREAD_SIZE, 0, 0,
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THREAD_SIZE, NULL);
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BUG_ON(thread_stack_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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static 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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struct vm_area_struct *vm_area_alloc(struct mm_struct *mm)
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{
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struct vm_area_struct *vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
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if (vma) {
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vma->vm_mm = mm;
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INIT_LIST_HEAD(&vma->anon_vma_chain);
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}
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return vma;
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}
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struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig)
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{
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struct vm_area_struct *new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
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if (new) {
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*new = *orig;
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INIT_LIST_HEAD(&new->anon_vma_chain);
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}
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return new;
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}
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void vm_area_free(struct vm_area_struct *vma)
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{
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kmem_cache_free(vm_area_cachep, vma);
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}
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static void account_kernel_stack(struct task_struct *tsk, int account)
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{
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void *stack = task_stack_page(tsk);
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struct vm_struct *vm = task_stack_vm_area(tsk);
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BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK) && PAGE_SIZE % 1024 != 0);
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if (vm) {
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int i;
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BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
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for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
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mod_zone_page_state(page_zone(vm->pages[i]),
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NR_KERNEL_STACK_KB,
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PAGE_SIZE / 1024 * account);
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}
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/* All stack pages belong to the same memcg. */
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mod_memcg_page_state(vm->pages[0], MEMCG_KERNEL_STACK_KB,
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account * (THREAD_SIZE / 1024));
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} else {
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/*
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* All stack pages are in the same zone and belong to the
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* same memcg.
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*/
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struct page *first_page = virt_to_page(stack);
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mod_zone_page_state(page_zone(first_page), NR_KERNEL_STACK_KB,
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THREAD_SIZE / 1024 * account);
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mod_memcg_page_state(first_page, MEMCG_KERNEL_STACK_KB,
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account * (THREAD_SIZE / 1024));
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}
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}
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static void release_task_stack(struct task_struct *tsk)
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{
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if (WARN_ON(tsk->state != TASK_DEAD))
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return; /* Better to leak the stack than to free prematurely */
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account_kernel_stack(tsk, -1);
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arch_release_thread_stack(tsk->stack);
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free_thread_stack(tsk);
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tsk->stack = NULL;
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#ifdef CONFIG_VMAP_STACK
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tsk->stack_vm_area = NULL;
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#endif
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}
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#ifdef CONFIG_THREAD_INFO_IN_TASK
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void put_task_stack(struct task_struct *tsk)
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{
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if (atomic_dec_and_test(&tsk->stack_refcount))
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release_task_stack(tsk);
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}
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#endif
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void free_task(struct task_struct *tsk)
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{
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#ifndef CONFIG_THREAD_INFO_IN_TASK
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/*
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* The task is finally done with both the stack and thread_info,
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* so free both.
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*/
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release_task_stack(tsk);
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#else
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/*
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* If the task had a separate stack allocation, it should be gone
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* by now.
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*/
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WARN_ON_ONCE(atomic_read(&tsk->stack_refcount) != 0);
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#endif
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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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if (tsk->flags & PF_KTHREAD)
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free_kthread_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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|
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#ifdef CONFIG_MMU
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static __latent_entropy int dup_mmap(struct mm_struct *mm,
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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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LIST_HEAD(uf);
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|
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uprobe_start_dup_mmap();
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if (down_write_killable(&oldmm->mmap_sem)) {
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retval = -EINTR;
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goto fail_uprobe_end;
|
|
}
|
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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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|
|
/* No ordering required: file already has been exposed. */
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RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm));
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|
|
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mm->total_vm = oldmm->total_vm;
|
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mm->data_vm = oldmm->data_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);
|
|
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, -vma_pages(mpnt));
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continue;
|
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}
|
|
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);
|
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|
|
if (security_vm_enough_memory_mm(oldmm, len)) /* sic */
|
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goto fail_nomem;
|
|
charge = len;
|
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}
|
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tmp = vm_area_dup(mpnt);
|
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if (!tmp)
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goto fail_nomem;
|
|
retval = vma_dup_policy(mpnt, tmp);
|
|
if (retval)
|
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goto fail_nomem_policy;
|
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tmp->vm_mm = mm;
|
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retval = dup_userfaultfd(tmp, &uf);
|
|
if (retval)
|
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goto fail_nomem_anon_vma_fork;
|
|
if (tmp->vm_flags & VM_WIPEONFORK) {
|
|
/* VM_WIPEONFORK gets a clean slate in the child. */
|
|
tmp->anon_vma = NULL;
|
|
if (anon_vma_prepare(tmp))
|
|
goto fail_nomem_anon_vma_fork;
|
|
} else if (anon_vma_fork(tmp, mpnt))
|
|
goto fail_nomem_anon_vma_fork;
|
|
tmp->vm_flags &= ~(VM_LOCKED | VM_LOCKONFAULT);
|
|
tmp->vm_next = tmp->vm_prev = NULL;
|
|
file = tmp->vm_file;
|
|
if (file) {
|
|
struct inode *inode = file_inode(file);
|
|
struct address_space *mapping = file->f_mapping;
|
|
|
|
get_file(file);
|
|
if (tmp->vm_flags & VM_DENYWRITE)
|
|
atomic_dec(&inode->i_writecount);
|
|
i_mmap_lock_write(mapping);
|
|
if (tmp->vm_flags & VM_SHARED)
|
|
atomic_inc(&mapping->i_mmap_writable);
|
|
flush_dcache_mmap_lock(mapping);
|
|
/* insert tmp into the share list, just after mpnt */
|
|
vma_interval_tree_insert_after(tmp, mpnt,
|
|
&mapping->i_mmap);
|
|
flush_dcache_mmap_unlock(mapping);
|
|
i_mmap_unlock_write(mapping);
|
|
}
|
|
|
|
/*
|
|
* Clear hugetlb-related page reserves for children. This only
|
|
* affects MAP_PRIVATE mappings. Faults generated by the child
|
|
* are not guaranteed to succeed, even if read-only
|
|
*/
|
|
if (is_vm_hugetlb_page(tmp))
|
|
reset_vma_resv_huge_pages(tmp);
|
|
|
|
/*
|
|
* Link in the new vma and copy the page table entries.
|
|
*/
|
|
*pprev = tmp;
|
|
pprev = &tmp->vm_next;
|
|
tmp->vm_prev = prev;
|
|
prev = tmp;
|
|
|
|
__vma_link_rb(mm, tmp, rb_link, rb_parent);
|
|
rb_link = &tmp->vm_rb.rb_right;
|
|
rb_parent = &tmp->vm_rb;
|
|
|
|
mm->map_count++;
|
|
if (!(tmp->vm_flags & VM_WIPEONFORK))
|
|
retval = copy_page_range(mm, oldmm, mpnt);
|
|
|
|
if (tmp->vm_ops && tmp->vm_ops->open)
|
|
tmp->vm_ops->open(tmp);
|
|
|
|
if (retval)
|
|
goto out;
|
|
}
|
|
/* a new mm has just been created */
|
|
arch_dup_mmap(oldmm, mm);
|
|
retval = 0;
|
|
out:
|
|
up_write(&mm->mmap_sem);
|
|
flush_tlb_mm(oldmm);
|
|
up_write(&oldmm->mmap_sem);
|
|
dup_userfaultfd_complete(&uf);
|
|
fail_uprobe_end:
|
|
uprobe_end_dup_mmap();
|
|
return retval;
|
|
fail_nomem_anon_vma_fork:
|
|
mpol_put(vma_policy(tmp));
|
|
fail_nomem_policy:
|
|
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);
|
|
hmm_mm_destroy(mm);
|
|
mmu_notifier_mm_destroy(mm);
|
|
check_mm(mm);
|
|
put_user_ns(mm->user_ns);
|
|
free_mm(mm);
|
|
}
|
|
EXPORT_SYMBOL_GPL(__mmdrop);
|
|
|
|
static 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 (atomic_dec_and_test(&sig->sigcnt))
|
|
free_signal_struct(sig);
|
|
}
|
|
|
|
void __put_task_struct(struct task_struct *tsk)
|
|
{
|
|
WARN_ON(!tsk->exit_state);
|
|
WARN_ON(atomic_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;
|
|
|
|
/*
|
|
* The number of threads shall be limited such that the thread
|
|
* structures may only consume a small part of the available memory.
|
|
*/
|
|
if (fls64(totalram_pages) + fls64(PAGE_SIZE) > 64)
|
|
threads = MAX_THREADS;
|
|
else
|
|
threads = div64_u64((u64) totalram_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);
|
|
}
|
|
|
|
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;
|
|
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;
|
|
|
|
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
|
|
atomic_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
|
|
|
|
/*
|
|
* One for us, one for whoever does the "release_task()" (usually
|
|
* parent)
|
|
*/
|
|
atomic_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
|
|
|
|
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 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;
|
|
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();
|
|
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);
|
|
|
|
/*
|
|
* Signal userspace if we're not exiting with a core dump
|
|
* because we want to leave the value intact for debugging
|
|
* purposes.
|
|
*/
|
|
if (tsk->clear_child_tid) {
|
|
if (!(tsk->signal->flags & SIGNAL_GROUP_COREDUMP) &&
|
|
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);
|
|
do_futex(tsk->clear_child_tid, FUTEX_WAKE,
|
|
1, NULL, NULL, 0, 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, mm->user_ns))
|
|
goto fail_nomem;
|
|
|
|
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) {
|
|
mmget(oldmm);
|
|
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);
|
|
/*
|
|
* sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it
|
|
* without an RCU grace period, see __lock_task_sighand().
|
|
*/
|
|
kmem_cache_free(sighand_cachep, sighand);
|
|
}
|
|
}
|
|
|
|
#ifdef CONFIG_POSIX_TIMERS
|
|
/*
|
|
* Initialize POSIX timer handling for a thread group.
|
|
*/
|
|
static void posix_cpu_timers_init_group(struct signal_struct *sig)
|
|
{
|
|
unsigned long cpu_limit;
|
|
|
|
cpu_limit = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
|
|
if (cpu_limit != RLIM_INFINITY) {
|
|
sig->cputime_expires.prof_exp = cpu_limit * NSEC_PER_SEC;
|
|
sig->cputimer.running = true;
|
|
}
|
|
|
|
/* The timer lists. */
|
|
INIT_LIST_HEAD(&sig->cpu_timers[0]);
|
|
INIT_LIST_HEAD(&sig->cpu_timers[1]);
|
|
INIT_LIST_HEAD(&sig->cpu_timers[2]);
|
|
}
|
|
#else
|
|
static inline void posix_cpu_timers_init_group(struct signal_struct *sig) { }
|
|
#endif
|
|
|
|
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);
|
|
seqlock_init(&sig->stats_lock);
|
|
prev_cputime_init(&sig->prev_cputime);
|
|
|
|
#ifdef CONFIG_POSIX_TIMERS
|
|
INIT_LIST_HEAD(&sig->posix_timers);
|
|
hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
|
|
sig->real_timer.function = it_real_fn;
|
|
#endif
|
|
|
|
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);
|
|
|
|
sig->oom_score_adj = current->signal->oom_score_adj;
|
|
sig->oom_score_adj_min = current->signal->oom_score_adj_min;
|
|
|
|
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_CACHED;
|
|
p->pi_top_task = NULL;
|
|
p->pi_blocked_on = NULL;
|
|
#endif
|
|
}
|
|
|
|
#ifdef CONFIG_POSIX_TIMERS
|
|
/*
|
|
* 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]);
|
|
}
|
|
#else
|
|
static inline void posix_cpu_timers_init(struct task_struct *tsk) { }
|
|
#endif
|
|
|
|
static inline void
|
|
init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid)
|
|
{
|
|
task->pids[type].pid = pid;
|
|
}
|
|
|
|
static inline void rcu_copy_process(struct task_struct *p)
|
|
{
|
|
#ifdef CONFIG_PREEMPT_RCU
|
|
p->rcu_read_lock_nesting = 0;
|
|
p->rcu_read_unlock_special.s = 0;
|
|
p->rcu_blocked_node = NULL;
|
|
INIT_LIST_HEAD(&p->rcu_node_entry);
|
|
#endif /* #ifdef CONFIG_PREEMPT_RCU */
|
|
#ifdef CONFIG_TASKS_RCU
|
|
p->rcu_tasks_holdout = false;
|
|
INIT_LIST_HEAD(&p->rcu_tasks_holdout_list);
|
|
p->rcu_tasks_idle_cpu = -1;
|
|
#endif /* #ifdef CONFIG_TASKS_RCU */
|
|
}
|
|
|
|
/*
|
|
* 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 __latent_entropy 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,
|
|
unsigned long tls,
|
|
int node)
|
|
{
|
|
int retval;
|
|
struct task_struct *p;
|
|
|
|
/*
|
|
* Don't allow sharing the root directory with processes in a different
|
|
* namespace
|
|
*/
|
|
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 with the forking task.
|
|
*/
|
|
if (clone_flags & CLONE_THREAD) {
|
|
if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) ||
|
|
(task_active_pid_ns(current) !=
|
|
current->nsproxy->pid_ns_for_children))
|
|
return ERR_PTR(-EINVAL);
|
|
}
|
|
|
|
retval = -ENOMEM;
|
|
p = dup_task_struct(current, node);
|
|
if (!p)
|
|
goto fork_out;
|
|
|
|
/*
|
|
* This _must_ happen before we call free_task(), i.e. before we jump
|
|
* to any of the bad_fork_* labels. This is to avoid freeing
|
|
* p->set_child_tid which is (ab)used as a kthread's data pointer for
|
|
* kernel threads (PF_KTHREAD).
|
|
*/
|
|
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;
|
|
|
|
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;
|
|
|
|
delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
|
|
p->flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER | PF_IDLE);
|
|
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;
|
|
#ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
|
|
p->utimescaled = p->stimescaled = 0;
|
|
#endif
|
|
prev_cputime_init(&p->prev_cputime);
|
|
|
|
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
|
|
seqcount_init(&p->vtime.seqcount);
|
|
p->vtime.starttime = 0;
|
|
p->vtime.state = VTIME_INACTIVE;
|
|
#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;
|
|
audit_set_context(p, NULL);
|
|
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
|
|
|
|
p->pagefault_disabled = 0;
|
|
|
|
#ifdef CONFIG_LOCKDEP
|
|
p->lockdep_depth = 0; /* no locks held yet */
|
|
p->curr_chain_key = 0;
|
|
p->lockdep_recursion = 0;
|
|
lockdep_init_task(p);
|
|
#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_perf;
|
|
/* copy all the process information */
|
|
shm_init_task(p);
|
|
retval = security_task_alloc(p, clone_flags);
|
|
if (retval)
|
|
goto bad_fork_cleanup_audit;
|
|
retval = copy_semundo(clone_flags, p);
|
|
if (retval)
|
|
goto bad_fork_cleanup_security;
|
|
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_tls(clone_flags, stack_start, stack_size, p, tls);
|
|
if (retval)
|
|
goto bad_fork_cleanup_io;
|
|
|
|
if (pid != &init_struct_pid) {
|
|
pid = alloc_pid(p->nsproxy->pid_ns_for_children);
|
|
if (IS_ERR(pid)) {
|
|
retval = PTR_ERR(pid);
|
|
goto bad_fork_cleanup_thread;
|
|
}
|
|
}
|
|
|
|
#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)
|
|
sas_ss_reset(p);
|
|
|
|
/*
|
|
* 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;
|
|
|
|
cgroup_threadgroup_change_begin(current);
|
|
/*
|
|
* Ensure that the cgroup subsystem policies allow the new process to be
|
|
* forked. It should be noted the the new process's css_set can be changed
|
|
* between here and cgroup_post_fork() if an organisation operation is in
|
|
* progress.
|
|
*/
|
|
retval = cgroup_can_fork(p);
|
|
if (retval)
|
|
goto bad_fork_free_pid;
|
|
|
|
/*
|
|
* 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;
|
|
}
|
|
|
|
klp_copy_process(p);
|
|
|
|
spin_lock(¤t->sighand->siglock);
|
|
|
|
/*
|
|
* Copy seccomp details explicitly here, in case they were changed
|
|
* before holding sighand lock.
|
|
*/
|
|
copy_seccomp(p);
|
|
|
|
rseq_fork(p, clone_flags);
|
|
|
|
/*
|
|
* 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)) {
|
|
retval = -ERESTARTNOINTR;
|
|
goto bad_fork_cancel_cgroup;
|
|
}
|
|
if (unlikely(!(ns_of_pid(pid)->pid_allocated & PIDNS_ADDING))) {
|
|
retval = -ENOMEM;
|
|
goto bad_fork_cancel_cgroup;
|
|
}
|
|
|
|
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);
|
|
/*
|
|
* Inherit has_child_subreaper flag under the same
|
|
* tasklist_lock with adding child to the process tree
|
|
* for propagate_has_child_subreaper optimization.
|
|
*/
|
|
p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper ||
|
|
p->real_parent->signal->is_child_subreaper;
|
|
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);
|
|
cgroup_threadgroup_change_end(current);
|
|
perf_event_fork(p);
|
|
|
|
trace_task_newtask(p, clone_flags);
|
|
uprobe_copy_process(p, clone_flags);
|
|
|
|
return p;
|
|
|
|
bad_fork_cancel_cgroup:
|
|
spin_unlock(¤t->sighand->siglock);
|
|
write_unlock_irq(&tasklist_lock);
|
|
cgroup_cancel_fork(p);
|
|
bad_fork_free_pid:
|
|
cgroup_threadgroup_change_end(current);
|
|
if (pid != &init_struct_pid)
|
|
free_pid(pid);
|
|
bad_fork_cleanup_thread:
|
|
exit_thread(p);
|
|
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_security:
|
|
security_task_free(p);
|
|
bad_fork_cleanup_audit:
|
|
audit_free(p);
|
|
bad_fork_cleanup_perf:
|
|
perf_event_free_task(p);
|
|
bad_fork_cleanup_policy:
|
|
lockdep_free_task(p);
|
|
#ifdef CONFIG_NUMA
|
|
mpol_put(p->mempolicy);
|
|
bad_fork_cleanup_threadgroup_lock:
|
|
#endif
|
|
delayacct_tsk_free(p);
|
|
bad_fork_cleanup_count:
|
|
atomic_dec(&p->cred->user->processes);
|
|
exit_creds(p);
|
|
bad_fork_free:
|
|
p->state = TASK_DEAD;
|
|
put_task_stack(p);
|
|
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, 0,
|
|
cpu_to_node(cpu));
|
|
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,
|
|
unsigned long tls)
|
|
{
|
|
struct completion vfork;
|
|
struct pid *pid;
|
|
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, tls, NUMA_NO_NODE);
|
|
add_latent_entropy();
|
|
|
|
if (IS_ERR(p))
|
|
return PTR_ERR(p);
|
|
|
|
/*
|
|
* Do this prior waking up the new thread - the thread pointer
|
|
* might get invalid after that point, if the thread exits quickly.
|
|
*/
|
|
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);
|
|
return nr;
|
|
}
|
|
|
|
#ifndef CONFIG_HAVE_COPY_THREAD_TLS
|
|
/* For compatibility with architectures that call do_fork directly rather than
|
|
* using the syscall entry points below. */
|
|
long do_fork(unsigned long clone_flags,
|
|
unsigned long stack_start,
|
|
unsigned long stack_size,
|
|
int __user *parent_tidptr,
|
|
int __user *child_tidptr)
|
|
{
|
|
return _do_fork(clone_flags, stack_start, stack_size,
|
|
parent_tidptr, child_tidptr, 0);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* 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, 0);
|
|
}
|
|
|
|
#ifdef __ARCH_WANT_SYS_FORK
|
|
SYSCALL_DEFINE0(fork)
|
|
{
|
|
#ifdef CONFIG_MMU
|
|
return _do_fork(SIGCHLD, 0, 0, NULL, NULL, 0);
|
|
#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, 0);
|
|
}
|
|
#endif
|
|
|
|
#ifdef __ARCH_WANT_SYS_CLONE
|
|
#ifdef CONFIG_CLONE_BACKWARDS
|
|
SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
|
|
int __user *, parent_tidptr,
|
|
unsigned long, tls,
|
|
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,
|
|
unsigned long, tls)
|
|
#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,
|
|
unsigned long, tls)
|
|
#else
|
|
SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
|
|
int __user *, parent_tidptr,
|
|
int __user *, child_tidptr,
|
|
unsigned long, tls)
|
|
#endif
|
|
{
|
|
return _do_fork(clone_flags, newsp, 0, parent_tidptr, child_tidptr, tls);
|
|
}
|
|
#endif
|
|
|
|
void walk_process_tree(struct task_struct *top, proc_visitor visitor, void *data)
|
|
{
|
|
struct task_struct *leader, *parent, *child;
|
|
int res;
|
|
|
|
read_lock(&tasklist_lock);
|
|
leader = top = top->group_leader;
|
|
down:
|
|
for_each_thread(leader, parent) {
|
|
list_for_each_entry(child, &parent->children, sibling) {
|
|
res = visitor(child, data);
|
|
if (res) {
|
|
if (res < 0)
|
|
goto out;
|
|
leader = child;
|
|
goto down;
|
|
}
|
|
up:
|
|
;
|
|
}
|
|
}
|
|
|
|
if (leader != top) {
|
|
child = leader;
|
|
parent = child->real_parent;
|
|
leader = parent->group_leader;
|
|
goto up;
|
|
}
|
|
out:
|
|
read_unlock(&tasklist_lock);
|
|
}
|
|
|
|
#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_TYPESAFE_BY_RCU|
|
|
SLAB_ACCOUNT, sighand_ctor);
|
|
signal_cachep = kmem_cache_create("signal_cache",
|
|
sizeof(struct signal_struct), 0,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
|
|
NULL);
|
|
files_cachep = kmem_cache_create("files_cache",
|
|
sizeof(struct files_struct), 0,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
|
|
NULL);
|
|
fs_cachep = kmem_cache_create("fs_cache",
|
|
sizeof(struct fs_struct), 0,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
|
|
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_usercopy("mm_struct",
|
|
sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN,
|
|
SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
|
|
offsetof(struct mm_struct, saved_auxv),
|
|
sizeof_field(struct mm_struct, saved_auxv),
|
|
NULL);
|
|
vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC|SLAB_ACCOUNT);
|
|
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|CLONE_NEWCGROUP))
|
|
return -EINVAL;
|
|
/*
|
|
* Not implemented, but pretend it works if there is nothing
|
|
* to unshare. Note that unsharing the address space or the
|
|
* signal handlers also need to unshare the signal queues (aka
|
|
* CLONE_THREAD).
|
|
*/
|
|
if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) {
|
|
if (!thread_group_empty(current))
|
|
return -EINVAL;
|
|
}
|
|
if (unshare_flags & (CLONE_SIGHAND | CLONE_VM)) {
|
|
if (atomic_read(¤t->sighand->count) > 1)
|
|
return -EINVAL;
|
|
}
|
|
if (unshare_flags & CLONE_VM) {
|
|
if (!current_is_single_threaded())
|
|
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.
|
|
*/
|
|
int ksys_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 group
|
|
* and unshare the filesystem root and working directories.
|
|
*/
|
|
if (unshare_flags & CLONE_NEWUSER)
|
|
unshare_flags |= CLONE_THREAD | CLONE_FS;
|
|
/*
|
|
* If unsharing vm, must also unshare signal handlers.
|
|
*/
|
|
if (unshare_flags & CLONE_VM)
|
|
unshare_flags |= CLONE_SIGHAND;
|
|
/*
|
|
* If unsharing a signal handlers, must also unshare the signal queues.
|
|
*/
|
|
if (unshare_flags & CLONE_SIGHAND)
|
|
unshare_flags |= CLONE_THREAD;
|
|
/*
|
|
* 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;
|
|
}
|
|
}
|
|
|
|
perf_event_namespaces(current);
|
|
|
|
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;
|
|
}
|
|
|
|
SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
|
|
{
|
|
return ksys_unshare(unshare_flags);
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
}
|
|
|
|
int sysctl_max_threads(struct ctl_table *table, int write,
|
|
void __user *buffer, size_t *lenp, loff_t *ppos)
|
|
{
|
|
struct ctl_table t;
|
|
int ret;
|
|
int threads = max_threads;
|
|
int min = MIN_THREADS;
|
|
int max = MAX_THREADS;
|
|
|
|
t = *table;
|
|
t.data = &threads;
|
|
t.extra1 = &min;
|
|
t.extra2 = &max;
|
|
|
|
ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
|
|
if (ret || !write)
|
|
return ret;
|
|
|
|
set_max_threads(threads);
|
|
|
|
return 0;
|
|
}
|