Root/init/main.c

1/*
2 * linux/init/main.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 *
6 * GK 2/5/95 - Changed to support mounting root fs via NFS
7 * Added initrd & change_root: Werner Almesberger & Hans Lermen, Feb '96
8 * Moan early if gcc is old, avoiding bogus kernels - Paul Gortmaker, May '96
9 * Simplified starting of init: Michael A. Griffith <grif@acm.org>
10 */
11
12#define DEBUG /* Enable initcall_debug */
13
14#include <linux/types.h>
15#include <linux/module.h>
16#include <linux/proc_fs.h>
17#include <linux/kernel.h>
18#include <linux/syscalls.h>
19#include <linux/stackprotector.h>
20#include <linux/string.h>
21#include <linux/ctype.h>
22#include <linux/delay.h>
23#include <linux/ioport.h>
24#include <linux/init.h>
25#include <linux/initrd.h>
26#include <linux/bootmem.h>
27#include <linux/acpi.h>
28#include <linux/tty.h>
29#include <linux/percpu.h>
30#include <linux/kmod.h>
31#include <linux/vmalloc.h>
32#include <linux/kernel_stat.h>
33#include <linux/start_kernel.h>
34#include <linux/security.h>
35#include <linux/smp.h>
36#include <linux/profile.h>
37#include <linux/rcupdate.h>
38#include <linux/moduleparam.h>
39#include <linux/kallsyms.h>
40#include <linux/writeback.h>
41#include <linux/cpu.h>
42#include <linux/cpuset.h>
43#include <linux/cgroup.h>
44#include <linux/efi.h>
45#include <linux/tick.h>
46#include <linux/interrupt.h>
47#include <linux/taskstats_kern.h>
48#include <linux/delayacct.h>
49#include <linux/unistd.h>
50#include <linux/rmap.h>
51#include <linux/mempolicy.h>
52#include <linux/key.h>
53#include <linux/buffer_head.h>
54#include <linux/page_cgroup.h>
55#include <linux/debug_locks.h>
56#include <linux/debugobjects.h>
57#include <linux/lockdep.h>
58#include <linux/kmemleak.h>
59#include <linux/pid_namespace.h>
60#include <linux/device.h>
61#include <linux/kthread.h>
62#include <linux/sched.h>
63#include <linux/signal.h>
64#include <linux/idr.h>
65#include <linux/kgdb.h>
66#include <linux/ftrace.h>
67#include <linux/async.h>
68#include <linux/kmemcheck.h>
69#include <linux/sfi.h>
70#include <linux/shmem_fs.h>
71#include <linux/slab.h>
72#include <linux/perf_event.h>
73#include <linux/file.h>
74#include <linux/ptrace.h>
75#include <linux/blkdev.h>
76#include <linux/elevator.h>
77#include <linux/sched_clock.h>
78#include <linux/context_tracking.h>
79#include <linux/random.h>
80
81#include <asm/io.h>
82#include <asm/bugs.h>
83#include <asm/setup.h>
84#include <asm/sections.h>
85#include <asm/cacheflush.h>
86
87#ifdef CONFIG_X86_LOCAL_APIC
88#include <asm/smp.h>
89#endif
90
91static int kernel_init(void *);
92
93extern void init_IRQ(void);
94extern void fork_init(unsigned long);
95extern void mca_init(void);
96extern void sbus_init(void);
97extern void radix_tree_init(void);
98#ifndef CONFIG_DEBUG_RODATA
99static inline void mark_rodata_ro(void) { }
100#endif
101
102#ifdef CONFIG_TC
103extern void tc_init(void);
104#endif
105
106/*
107 * Debug helper: via this flag we know that we are in 'early bootup code'
108 * where only the boot processor is running with IRQ disabled. This means
109 * two things - IRQ must not be enabled before the flag is cleared and some
110 * operations which are not allowed with IRQ disabled are allowed while the
111 * flag is set.
112 */
113bool early_boot_irqs_disabled __read_mostly;
114
115enum system_states system_state __read_mostly;
116EXPORT_SYMBOL(system_state);
117
118/*
119 * Boot command-line arguments
120 */
121#define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
122#define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT
123
124extern void time_init(void);
125/* Default late time init is NULL. archs can override this later. */
126void (*__initdata late_time_init)(void);
127extern void softirq_init(void);
128
129/* Untouched command line saved by arch-specific code. */
130char __initdata boot_command_line[COMMAND_LINE_SIZE];
131/* Untouched saved command line (eg. for /proc) */
132char *saved_command_line;
133/* Command line for parameter parsing */
134static char *static_command_line;
135
136static char *execute_command;
137static char *ramdisk_execute_command;
138
139/*
140 * If set, this is an indication to the drivers that reset the underlying
141 * device before going ahead with the initialization otherwise driver might
142 * rely on the BIOS and skip the reset operation.
143 *
144 * This is useful if kernel is booting in an unreliable environment.
145 * For ex. kdump situaiton where previous kernel has crashed, BIOS has been
146 * skipped and devices will be in unknown state.
147 */
148unsigned int reset_devices;
149EXPORT_SYMBOL(reset_devices);
150
151static int __init set_reset_devices(char *str)
152{
153    reset_devices = 1;
154    return 1;
155}
156
157__setup("reset_devices", set_reset_devices);
158
159static const char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
160const char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
161static const char *panic_later, *panic_param;
162
163extern const struct obs_kernel_param __setup_start[], __setup_end[];
164
165static int __init obsolete_checksetup(char *line)
166{
167    const struct obs_kernel_param *p;
168    int had_early_param = 0;
169
170    p = __setup_start;
171    do {
172        int n = strlen(p->str);
173        if (parameqn(line, p->str, n)) {
174            if (p->early) {
175                /* Already done in parse_early_param?
176                 * (Needs exact match on param part).
177                 * Keep iterating, as we can have early
178                 * params and __setups of same names 8( */
179                if (line[n] == '\0' || line[n] == '=')
180                    had_early_param = 1;
181            } else if (!p->setup_func) {
182                pr_warn("Parameter %s is obsolete, ignored\n",
183                    p->str);
184                return 1;
185            } else if (p->setup_func(line + n))
186                return 1;
187        }
188        p++;
189    } while (p < __setup_end);
190
191    return had_early_param;
192}
193
194/*
195 * This should be approx 2 Bo*oMips to start (note initial shift), and will
196 * still work even if initially too large, it will just take slightly longer
197 */
198unsigned long loops_per_jiffy = (1<<12);
199
200EXPORT_SYMBOL(loops_per_jiffy);
201
202static int __init debug_kernel(char *str)
203{
204    console_loglevel = 10;
205    return 0;
206}
207
208static int __init quiet_kernel(char *str)
209{
210    console_loglevel = 4;
211    return 0;
212}
213
214early_param("debug", debug_kernel);
215early_param("quiet", quiet_kernel);
216
217static int __init loglevel(char *str)
218{
219    int newlevel;
220
221    /*
222     * Only update loglevel value when a correct setting was passed,
223     * to prevent blind crashes (when loglevel being set to 0) that
224     * are quite hard to debug
225     */
226    if (get_option(&str, &newlevel)) {
227        console_loglevel = newlevel;
228        return 0;
229    }
230
231    return -EINVAL;
232}
233
234early_param("loglevel", loglevel);
235
236/* Change NUL term back to "=", to make "param" the whole string. */
237static int __init repair_env_string(char *param, char *val, const char *unused)
238{
239    if (val) {
240        /* param=val or param="val"? */
241        if (val == param+strlen(param)+1)
242            val[-1] = '=';
243        else if (val == param+strlen(param)+2) {
244            val[-2] = '=';
245            memmove(val-1, val, strlen(val)+1);
246            val--;
247        } else
248            BUG();
249    }
250    return 0;
251}
252
253/*
254 * Unknown boot options get handed to init, unless they look like
255 * unused parameters (modprobe will find them in /proc/cmdline).
256 */
257static int __init unknown_bootoption(char *param, char *val, const char *unused)
258{
259    repair_env_string(param, val, unused);
260
261    /* Handle obsolete-style parameters */
262    if (obsolete_checksetup(param))
263        return 0;
264
265    /* Unused module parameter. */
266    if (strchr(param, '.') && (!val || strchr(param, '.') < val))
267        return 0;
268
269    if (panic_later)
270        return 0;
271
272    if (val) {
273        /* Environment option */
274        unsigned int i;
275        for (i = 0; envp_init[i]; i++) {
276            if (i == MAX_INIT_ENVS) {
277                panic_later = "Too many boot env vars at `%s'";
278                panic_param = param;
279            }
280            if (!strncmp(param, envp_init[i], val - param))
281                break;
282        }
283        envp_init[i] = param;
284    } else {
285        /* Command line option */
286        unsigned int i;
287        for (i = 0; argv_init[i]; i++) {
288            if (i == MAX_INIT_ARGS) {
289                panic_later = "Too many boot init vars at `%s'";
290                panic_param = param;
291            }
292        }
293        argv_init[i] = param;
294    }
295    return 0;
296}
297
298static int __init init_setup(char *str)
299{
300    unsigned int i;
301
302    execute_command = str;
303    /*
304     * In case LILO is going to boot us with default command line,
305     * it prepends "auto" before the whole cmdline which makes
306     * the shell think it should execute a script with such name.
307     * So we ignore all arguments entered _before_ init=... [MJ]
308     */
309    for (i = 1; i < MAX_INIT_ARGS; i++)
310        argv_init[i] = NULL;
311    return 1;
312}
313__setup("init=", init_setup);
314
315static int __init rdinit_setup(char *str)
316{
317    unsigned int i;
318
319    ramdisk_execute_command = str;
320    /* See "auto" comment in init_setup */
321    for (i = 1; i < MAX_INIT_ARGS; i++)
322        argv_init[i] = NULL;
323    return 1;
324}
325__setup("rdinit=", rdinit_setup);
326
327#ifndef CONFIG_SMP
328static const unsigned int setup_max_cpus = NR_CPUS;
329#ifdef CONFIG_X86_LOCAL_APIC
330static void __init smp_init(void)
331{
332    APIC_init_uniprocessor();
333}
334#else
335#define smp_init() do { } while (0)
336#endif
337
338static inline void setup_nr_cpu_ids(void) { }
339static inline void smp_prepare_cpus(unsigned int maxcpus) { }
340#endif
341
342/*
343 * We need to store the untouched command line for future reference.
344 * We also need to store the touched command line since the parameter
345 * parsing is performed in place, and we should allow a component to
346 * store reference of name/value for future reference.
347 */
348static void __init setup_command_line(char *command_line)
349{
350    saved_command_line = alloc_bootmem(strlen (boot_command_line)+1);
351    static_command_line = alloc_bootmem(strlen (command_line)+1);
352    strcpy (saved_command_line, boot_command_line);
353    strcpy (static_command_line, command_line);
354}
355
356/*
357 * We need to finalize in a non-__init function or else race conditions
358 * between the root thread and the init thread may cause start_kernel to
359 * be reaped by free_initmem before the root thread has proceeded to
360 * cpu_idle.
361 *
362 * gcc-3.4 accidentally inlines this function, so use noinline.
363 */
364
365static __initdata DECLARE_COMPLETION(kthreadd_done);
366
367static noinline void __init_refok rest_init(void)
368{
369    int pid;
370
371    rcu_scheduler_starting();
372    /*
373     * We need to spawn init first so that it obtains pid 1, however
374     * the init task will end up wanting to create kthreads, which, if
375     * we schedule it before we create kthreadd, will OOPS.
376     */
377    kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
378    numa_default_policy();
379    pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
380    rcu_read_lock();
381    kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
382    rcu_read_unlock();
383    complete(&kthreadd_done);
384
385    /*
386     * The boot idle thread must execute schedule()
387     * at least once to get things moving:
388     */
389    init_idle_bootup_task(current);
390    schedule_preempt_disabled();
391    /* Call into cpu_idle with preempt disabled */
392    cpu_startup_entry(CPUHP_ONLINE);
393}
394
395/* Check for early params. */
396static int __init do_early_param(char *param, char *val, const char *unused)
397{
398    const struct obs_kernel_param *p;
399
400    for (p = __setup_start; p < __setup_end; p++) {
401        if ((p->early && parameq(param, p->str)) ||
402            (strcmp(param, "console") == 0 &&
403             strcmp(p->str, "earlycon") == 0)
404        ) {
405            if (p->setup_func(val) != 0)
406                pr_warn("Malformed early option '%s'\n", param);
407        }
408    }
409    /* We accept everything at this stage. */
410    return 0;
411}
412
413void __init parse_early_options(char *cmdline)
414{
415    parse_args("early options", cmdline, NULL, 0, 0, 0, do_early_param);
416}
417
418/* Arch code calls this early on, or if not, just before other parsing. */
419void __init parse_early_param(void)
420{
421    static __initdata int done = 0;
422    static __initdata char tmp_cmdline[COMMAND_LINE_SIZE];
423
424    if (done)
425        return;
426
427    /* All fall through to do_early_param. */
428    strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
429    parse_early_options(tmp_cmdline);
430    done = 1;
431}
432
433/*
434 * Activate the first processor.
435 */
436
437static void __init boot_cpu_init(void)
438{
439    int cpu = smp_processor_id();
440    /* Mark the boot cpu "present", "online" etc for SMP and UP case */
441    set_cpu_online(cpu, true);
442    set_cpu_active(cpu, true);
443    set_cpu_present(cpu, true);
444    set_cpu_possible(cpu, true);
445}
446
447void __init __weak smp_setup_processor_id(void)
448{
449}
450
451# if THREAD_SIZE >= PAGE_SIZE
452void __init __weak thread_info_cache_init(void)
453{
454}
455#endif
456
457/*
458 * Set up kernel memory allocators
459 */
460static void __init mm_init(void)
461{
462    /*
463     * page_cgroup requires contiguous pages,
464     * bigger than MAX_ORDER unless SPARSEMEM.
465     */
466    page_cgroup_init_flatmem();
467    mem_init();
468    kmem_cache_init();
469    percpu_init_late();
470    pgtable_cache_init();
471    vmalloc_init();
472}
473
474asmlinkage void __init start_kernel(void)
475{
476    char * command_line;
477    extern const struct kernel_param __start___param[], __stop___param[];
478
479    /*
480     * Need to run as early as possible, to initialize the
481     * lockdep hash:
482     */
483    lockdep_init();
484    smp_setup_processor_id();
485    debug_objects_early_init();
486
487    /*
488     * Set up the the initial canary ASAP:
489     */
490    boot_init_stack_canary();
491
492    cgroup_init_early();
493
494    local_irq_disable();
495    early_boot_irqs_disabled = true;
496
497/*
498 * Interrupts are still disabled. Do necessary setups, then
499 * enable them
500 */
501    boot_cpu_init();
502    page_address_init();
503    pr_notice("%s", linux_banner);
504    setup_arch(&command_line);
505    mm_init_owner(&init_mm, &init_task);
506    mm_init_cpumask(&init_mm);
507    setup_command_line(command_line);
508    setup_nr_cpu_ids();
509    setup_per_cpu_areas();
510    smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
511
512    build_all_zonelists(NULL, NULL);
513    page_alloc_init();
514
515    pr_notice("Kernel command line: %s\n", boot_command_line);
516    parse_early_param();
517    parse_args("Booting kernel", static_command_line, __start___param,
518           __stop___param - __start___param,
519           -1, -1, &unknown_bootoption);
520
521    jump_label_init();
522
523    /*
524     * These use large bootmem allocations and must precede
525     * kmem_cache_init()
526     */
527    setup_log_buf(0);
528    pidhash_init();
529    vfs_caches_init_early();
530    sort_main_extable();
531    trap_init();
532    mm_init();
533
534    /*
535     * Set up the scheduler prior starting any interrupts (such as the
536     * timer interrupt). Full topology setup happens at smp_init()
537     * time - but meanwhile we still have a functioning scheduler.
538     */
539    sched_init();
540    /*
541     * Disable preemption - early bootup scheduling is extremely
542     * fragile until we cpu_idle() for the first time.
543     */
544    preempt_disable();
545    if (WARN(!irqs_disabled(), "Interrupts were enabled *very* early, fixing it\n"))
546        local_irq_disable();
547    idr_init_cache();
548    rcu_init();
549    tick_nohz_init();
550    context_tracking_init();
551    radix_tree_init();
552    /* init some links before init_ISA_irqs() */
553    early_irq_init();
554    init_IRQ();
555    tick_init();
556    init_timers();
557    hrtimers_init();
558    softirq_init();
559    timekeeping_init();
560    time_init();
561    sched_clock_postinit();
562    perf_event_init();
563    profile_init();
564    call_function_init();
565    WARN(!irqs_disabled(), "Interrupts were enabled early\n");
566    early_boot_irqs_disabled = false;
567    local_irq_enable();
568
569    kmem_cache_init_late();
570
571    /*
572     * HACK ALERT! This is early. We're enabling the console before
573     * we've done PCI setups etc, and console_init() must be aware of
574     * this. But we do want output early, in case something goes wrong.
575     */
576    console_init();
577    if (panic_later)
578        panic(panic_later, panic_param);
579
580    lockdep_info();
581
582    /*
583     * Need to run this when irqs are enabled, because it wants
584     * to self-test [hard/soft]-irqs on/off lock inversion bugs
585     * too:
586     */
587    locking_selftest();
588
589#ifdef CONFIG_BLK_DEV_INITRD
590    if (initrd_start && !initrd_below_start_ok &&
591        page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
592        pr_crit("initrd overwritten (0x%08lx < 0x%08lx) - disabling it.\n",
593            page_to_pfn(virt_to_page((void *)initrd_start)),
594            min_low_pfn);
595        initrd_start = 0;
596    }
597#endif
598    page_cgroup_init();
599    debug_objects_mem_init();
600    kmemleak_init();
601    setup_per_cpu_pageset();
602    numa_policy_init();
603    if (late_time_init)
604        late_time_init();
605    sched_clock_init();
606    calibrate_delay();
607    pidmap_init();
608    anon_vma_init();
609#ifdef CONFIG_X86
610    if (efi_enabled(EFI_RUNTIME_SERVICES))
611        efi_enter_virtual_mode();
612#endif
613    thread_info_cache_init();
614    cred_init();
615    fork_init(totalram_pages);
616    proc_caches_init();
617    buffer_init();
618    key_init();
619    security_init();
620    dbg_late_init();
621    vfs_caches_init(totalram_pages);
622    signals_init();
623    /* rootfs populating might need page-writeback */
624    page_writeback_init();
625#ifdef CONFIG_PROC_FS
626    proc_root_init();
627#endif
628    cgroup_init();
629    cpuset_init();
630    taskstats_init_early();
631    delayacct_init();
632
633    check_bugs();
634
635    acpi_early_init(); /* before LAPIC and SMP init */
636    sfi_init_late();
637
638    if (efi_enabled(EFI_RUNTIME_SERVICES)) {
639        efi_late_init();
640        efi_free_boot_services();
641    }
642
643    ftrace_init();
644
645    /* Do the rest non-__init'ed, we're now alive */
646    rest_init();
647}
648
649/* Call all constructor functions linked into the kernel. */
650static void __init do_ctors(void)
651{
652#ifdef CONFIG_CONSTRUCTORS
653    ctor_fn_t *fn = (ctor_fn_t *) __ctors_start;
654
655    for (; fn < (ctor_fn_t *) __ctors_end; fn++)
656        (*fn)();
657#endif
658}
659
660bool initcall_debug;
661core_param(initcall_debug, initcall_debug, bool, 0644);
662
663static int __init_or_module do_one_initcall_debug(initcall_t fn)
664{
665    ktime_t calltime, delta, rettime;
666    unsigned long long duration;
667    int ret;
668
669    pr_debug("calling %pF @ %i\n", fn, task_pid_nr(current));
670    calltime = ktime_get();
671    ret = fn();
672    rettime = ktime_get();
673    delta = ktime_sub(rettime, calltime);
674    duration = (unsigned long long) ktime_to_ns(delta) >> 10;
675    pr_debug("initcall %pF returned %d after %lld usecs\n",
676         fn, ret, duration);
677
678    return ret;
679}
680
681int __init_or_module do_one_initcall(initcall_t fn)
682{
683    int count = preempt_count();
684    int ret;
685    char msgbuf[64];
686
687    if (initcall_debug)
688        ret = do_one_initcall_debug(fn);
689    else
690        ret = fn();
691
692    msgbuf[0] = 0;
693
694    if (preempt_count() != count) {
695        sprintf(msgbuf, "preemption imbalance ");
696        preempt_count() = count;
697    }
698    if (irqs_disabled()) {
699        strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
700        local_irq_enable();
701    }
702    WARN(msgbuf[0], "initcall %pF returned with %s\n", fn, msgbuf);
703
704    return ret;
705}
706
707
708extern initcall_t __initcall_start[];
709extern initcall_t __initcall0_start[];
710extern initcall_t __initcall1_start[];
711extern initcall_t __initcall2_start[];
712extern initcall_t __initcall3_start[];
713extern initcall_t __initcall4_start[];
714extern initcall_t __initcall5_start[];
715extern initcall_t __initcall6_start[];
716extern initcall_t __initcall7_start[];
717extern initcall_t __initcall_end[];
718
719static initcall_t *initcall_levels[] __initdata = {
720    __initcall0_start,
721    __initcall1_start,
722    __initcall2_start,
723    __initcall3_start,
724    __initcall4_start,
725    __initcall5_start,
726    __initcall6_start,
727    __initcall7_start,
728    __initcall_end,
729};
730
731/* Keep these in sync with initcalls in include/linux/init.h */
732static char *initcall_level_names[] __initdata = {
733    "early",
734    "core",
735    "postcore",
736    "arch",
737    "subsys",
738    "fs",
739    "device",
740    "late",
741};
742
743static void __init do_initcall_level(int level)
744{
745    extern const struct kernel_param __start___param[], __stop___param[];
746    initcall_t *fn;
747
748    strcpy(static_command_line, saved_command_line);
749    parse_args(initcall_level_names[level],
750           static_command_line, __start___param,
751           __stop___param - __start___param,
752           level, level,
753           &repair_env_string);
754
755    for (fn = initcall_levels[level]; fn < initcall_levels[level+1]; fn++)
756        do_one_initcall(*fn);
757}
758
759static void __init do_initcalls(void)
760{
761    int level;
762
763    for (level = 0; level < ARRAY_SIZE(initcall_levels) - 1; level++)
764        do_initcall_level(level);
765}
766
767/*
768 * Ok, the machine is now initialized. None of the devices
769 * have been touched yet, but the CPU subsystem is up and
770 * running, and memory and process management works.
771 *
772 * Now we can finally start doing some real work..
773 */
774static void __init do_basic_setup(void)
775{
776    cpuset_init_smp();
777    usermodehelper_init();
778    shmem_init();
779    driver_init();
780    init_irq_proc();
781    do_ctors();
782    usermodehelper_enable();
783    do_initcalls();
784    random_int_secret_init();
785}
786
787static void __init do_pre_smp_initcalls(void)
788{
789    initcall_t *fn;
790
791    for (fn = __initcall_start; fn < __initcall0_start; fn++)
792        do_one_initcall(*fn);
793}
794
795/*
796 * This function requests modules which should be loaded by default and is
797 * called twice right after initrd is mounted and right before init is
798 * exec'd. If such modules are on either initrd or rootfs, they will be
799 * loaded before control is passed to userland.
800 */
801void __init load_default_modules(void)
802{
803    load_default_elevator_module();
804}
805
806static int run_init_process(const char *init_filename)
807{
808    argv_init[0] = init_filename;
809    return do_execve(init_filename,
810        (const char __user *const __user *)argv_init,
811        (const char __user *const __user *)envp_init);
812}
813
814static noinline void __init kernel_init_freeable(void);
815
816static int __ref kernel_init(void *unused)
817{
818    kernel_init_freeable();
819    /* need to finish all async __init code before freeing the memory */
820    async_synchronize_full();
821    free_initmem();
822    mark_rodata_ro();
823    system_state = SYSTEM_RUNNING;
824    numa_default_policy();
825
826    flush_delayed_fput();
827
828    if (ramdisk_execute_command) {
829        if (!run_init_process(ramdisk_execute_command))
830            return 0;
831        pr_err("Failed to execute %s\n", ramdisk_execute_command);
832    }
833
834    /*
835     * We try each of these until one succeeds.
836     *
837     * The Bourne shell can be used instead of init if we are
838     * trying to recover a really broken machine.
839     */
840    if (execute_command) {
841        if (!run_init_process(execute_command))
842            return 0;
843        pr_err("Failed to execute %s. Attempting defaults...\n",
844            execute_command);
845    }
846    if (!run_init_process("/sbin/init") ||
847        !run_init_process("/etc/init") ||
848        !run_init_process("/bin/init") ||
849        !run_init_process("/bin/sh"))
850        return 0;
851
852    panic("No init found. Try passing init= option to kernel. "
853          "See Linux Documentation/init.txt for guidance.");
854}
855
856static noinline void __init kernel_init_freeable(void)
857{
858    /*
859     * Wait until kthreadd is all set-up.
860     */
861    wait_for_completion(&kthreadd_done);
862
863    /* Now the scheduler is fully set up and can do blocking allocations */
864    gfp_allowed_mask = __GFP_BITS_MASK;
865
866    /*
867     * init can allocate pages on any node
868     */
869    set_mems_allowed(node_states[N_MEMORY]);
870    /*
871     * init can run on any cpu.
872     */
873    set_cpus_allowed_ptr(current, cpu_all_mask);
874
875    cad_pid = task_pid(current);
876
877    smp_prepare_cpus(setup_max_cpus);
878
879    do_pre_smp_initcalls();
880    lockup_detector_init();
881
882    smp_init();
883    sched_init_smp();
884
885    do_basic_setup();
886
887    /* Open the /dev/console on the rootfs, this should never fail */
888    if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
889        pr_err("Warning: unable to open an initial console.\n");
890
891    (void) sys_dup(0);
892    (void) sys_dup(0);
893    /*
894     * check if there is an early userspace init. If yes, let it do all
895     * the work
896     */
897
898    if (!ramdisk_execute_command)
899        ramdisk_execute_command = "/init";
900
901    if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
902        ramdisk_execute_command = NULL;
903        prepare_namespace();
904    }
905
906    /*
907     * Ok, we have completed the initial bootup, and
908     * we're essentially up and running. Get rid of the
909     * initmem segments and start the user-mode stuff..
910     */
911
912    /* rootfs is available now, try loading default modules */
913    load_default_modules();
914}
915

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