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#include <linux/types.h>
13#include <linux/module.h>
14#include <linux/proc_fs.h>
15#include <linux/kernel.h>
16#include <linux/syscalls.h>
17#include <linux/stackprotector.h>
18#include <linux/string.h>
19#include <linux/ctype.h>
20#include <linux/delay.h>
21#include <linux/ioport.h>
22#include <linux/init.h>
23#include <linux/initrd.h>
24#include <linux/bootmem.h>
25#include <linux/acpi.h>
26#include <linux/tty.h>
27#include <linux/percpu.h>
28#include <linux/kmod.h>
29#include <linux/vmalloc.h>
30#include <linux/kernel_stat.h>
31#include <linux/start_kernel.h>
32#include <linux/security.h>
33#include <linux/smp.h>
34#include <linux/profile.h>
35#include <linux/rcupdate.h>
36#include <linux/moduleparam.h>
37#include <linux/kallsyms.h>
38#include <linux/writeback.h>
39#include <linux/cpu.h>
40#include <linux/cpuset.h>
41#include <linux/cgroup.h>
42#include <linux/efi.h>
43#include <linux/tick.h>
44#include <linux/interrupt.h>
45#include <linux/taskstats_kern.h>
46#include <linux/delayacct.h>
47#include <linux/unistd.h>
48#include <linux/rmap.h>
49#include <linux/mempolicy.h>
50#include <linux/key.h>
51#include <linux/buffer_head.h>
52#include <linux/page_cgroup.h>
53#include <linux/debug_locks.h>
54#include <linux/debugobjects.h>
55#include <linux/lockdep.h>
56#include <linux/kmemleak.h>
57#include <linux/pid_namespace.h>
58#include <linux/device.h>
59#include <linux/kthread.h>
60#include <linux/sched.h>
61#include <linux/signal.h>
62#include <linux/idr.h>
63#include <linux/kgdb.h>
64#include <linux/ftrace.h>
65#include <linux/async.h>
66#include <linux/kmemcheck.h>
67#include <linux/sfi.h>
68#include <linux/shmem_fs.h>
69#include <linux/slab.h>
70#include <linux/perf_event.h>
71#include <linux/file.h>
72#include <linux/ptrace.h>
73#include <linux/blkdev.h>
74#include <linux/elevator.h>
75
76#include <asm/io.h>
77#include <asm/bugs.h>
78#include <asm/setup.h>
79#include <asm/sections.h>
80#include <asm/cacheflush.h>
81
82#ifdef CONFIG_X86_LOCAL_APIC
83#include <asm/smp.h>
84#endif
85
86static int kernel_init(void *);
87
88extern void init_IRQ(void);
89extern void fork_init(unsigned long);
90extern void mca_init(void);
91extern void sbus_init(void);
92extern void radix_tree_init(void);
93#ifndef CONFIG_DEBUG_RODATA
94static inline void mark_rodata_ro(void) { }
95#endif
96
97#ifdef CONFIG_TC
98extern void tc_init(void);
99#endif
100
101/*
102 * Debug helper: via this flag we know that we are in 'early bootup code'
103 * where only the boot processor is running with IRQ disabled. This means
104 * two things - IRQ must not be enabled before the flag is cleared and some
105 * operations which are not allowed with IRQ disabled are allowed while the
106 * flag is set.
107 */
108bool early_boot_irqs_disabled __read_mostly;
109
110enum system_states system_state __read_mostly;
111EXPORT_SYMBOL(system_state);
112
113/*
114 * Boot command-line arguments
115 */
116#define MAX_INIT_ARGS CONFIG_INIT_ENV_ARG_LIMIT
117#define MAX_INIT_ENVS CONFIG_INIT_ENV_ARG_LIMIT
118
119extern void time_init(void);
120/* Default late time init is NULL. archs can override this later. */
121void (*__initdata late_time_init)(void);
122extern void softirq_init(void);
123
124/* Untouched command line saved by arch-specific code. */
125char __initdata boot_command_line[COMMAND_LINE_SIZE];
126/* Untouched saved command line (eg. for /proc) */
127char *saved_command_line;
128/* Command line for parameter parsing */
129static char *static_command_line;
130
131static char *execute_command;
132static char *ramdisk_execute_command;
133
134/*
135 * If set, this is an indication to the drivers that reset the underlying
136 * device before going ahead with the initialization otherwise driver might
137 * rely on the BIOS and skip the reset operation.
138 *
139 * This is useful if kernel is booting in an unreliable environment.
140 * For ex. kdump situaiton where previous kernel has crashed, BIOS has been
141 * skipped and devices will be in unknown state.
142 */
143unsigned int reset_devices;
144EXPORT_SYMBOL(reset_devices);
145
146static int __init set_reset_devices(char *str)
147{
148    reset_devices = 1;
149    return 1;
150}
151
152__setup("reset_devices", set_reset_devices);
153
154static const char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
155const char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=linux", NULL, };
156static const char *panic_later, *panic_param;
157
158extern const struct obs_kernel_param __setup_start[], __setup_end[];
159
160static int __init obsolete_checksetup(char *line)
161{
162    const struct obs_kernel_param *p;
163    int had_early_param = 0;
164
165    p = __setup_start;
166    do {
167        int n = strlen(p->str);
168        if (parameqn(line, p->str, n)) {
169            if (p->early) {
170                /* Already done in parse_early_param?
171                 * (Needs exact match on param part).
172                 * Keep iterating, as we can have early
173                 * params and __setups of same names 8( */
174                if (line[n] == '\0' || line[n] == '=')
175                    had_early_param = 1;
176            } else if (!p->setup_func) {
177                printk(KERN_WARNING "Parameter %s is obsolete,"
178                       " ignored\n", p->str);
179                return 1;
180            } else if (p->setup_func(line + n))
181                return 1;
182        }
183        p++;
184    } while (p < __setup_end);
185
186    return had_early_param;
187}
188
189/*
190 * This should be approx 2 Bo*oMips to start (note initial shift), and will
191 * still work even if initially too large, it will just take slightly longer
192 */
193unsigned long loops_per_jiffy = (1<<12);
194
195EXPORT_SYMBOL(loops_per_jiffy);
196
197static int __init debug_kernel(char *str)
198{
199    console_loglevel = 10;
200    return 0;
201}
202
203static int __init quiet_kernel(char *str)
204{
205    console_loglevel = 4;
206    return 0;
207}
208
209early_param("debug", debug_kernel);
210early_param("quiet", quiet_kernel);
211
212static int __init loglevel(char *str)
213{
214    int newlevel;
215
216    /*
217     * Only update loglevel value when a correct setting was passed,
218     * to prevent blind crashes (when loglevel being set to 0) that
219     * are quite hard to debug
220     */
221    if (get_option(&str, &newlevel)) {
222        console_loglevel = newlevel;
223        return 0;
224    }
225
226    return -EINVAL;
227}
228
229early_param("loglevel", loglevel);
230
231/* Change NUL term back to "=", to make "param" the whole string. */
232static int __init repair_env_string(char *param, char *val, const char *unused)
233{
234    if (val) {
235        /* param=val or param="val"? */
236        if (val == param+strlen(param)+1)
237            val[-1] = '=';
238        else if (val == param+strlen(param)+2) {
239            val[-2] = '=';
240            memmove(val-1, val, strlen(val)+1);
241            val--;
242        } else
243            BUG();
244    }
245    return 0;
246}
247
248/*
249 * Unknown boot options get handed to init, unless they look like
250 * unused parameters (modprobe will find them in /proc/cmdline).
251 */
252static int __init unknown_bootoption(char *param, char *val, const char *unused)
253{
254    repair_env_string(param, val, unused);
255
256    /* Handle obsolete-style parameters */
257    if (obsolete_checksetup(param))
258        return 0;
259
260    /* Unused module parameter. */
261    if (strchr(param, '.') && (!val || strchr(param, '.') < val))
262        return 0;
263
264    if (panic_later)
265        return 0;
266
267    if (val) {
268        /* Environment option */
269        unsigned int i;
270        for (i = 0; envp_init[i]; i++) {
271            if (i == MAX_INIT_ENVS) {
272                panic_later = "Too many boot env vars at `%s'";
273                panic_param = param;
274            }
275            if (!strncmp(param, envp_init[i], val - param))
276                break;
277        }
278        envp_init[i] = param;
279    } else {
280        /* Command line option */
281        unsigned int i;
282        for (i = 0; argv_init[i]; i++) {
283            if (i == MAX_INIT_ARGS) {
284                panic_later = "Too many boot init vars at `%s'";
285                panic_param = param;
286            }
287        }
288        argv_init[i] = param;
289    }
290    return 0;
291}
292
293static int __init init_setup(char *str)
294{
295    unsigned int i;
296
297    execute_command = str;
298    /*
299     * In case LILO is going to boot us with default command line,
300     * it prepends "auto" before the whole cmdline which makes
301     * the shell think it should execute a script with such name.
302     * So we ignore all arguments entered _before_ init=... [MJ]
303     */
304    for (i = 1; i < MAX_INIT_ARGS; i++)
305        argv_init[i] = NULL;
306    return 1;
307}
308__setup("init=", init_setup);
309
310static int __init rdinit_setup(char *str)
311{
312    unsigned int i;
313
314    ramdisk_execute_command = str;
315    /* See "auto" comment in init_setup */
316    for (i = 1; i < MAX_INIT_ARGS; i++)
317        argv_init[i] = NULL;
318    return 1;
319}
320__setup("rdinit=", rdinit_setup);
321
322#ifndef CONFIG_SMP
323static const unsigned int setup_max_cpus = NR_CPUS;
324#ifdef CONFIG_X86_LOCAL_APIC
325static void __init smp_init(void)
326{
327    APIC_init_uniprocessor();
328}
329#else
330#define smp_init() do { } while (0)
331#endif
332
333static inline void setup_nr_cpu_ids(void) { }
334static inline void smp_prepare_cpus(unsigned int maxcpus) { }
335#endif
336
337/*
338 * We need to store the untouched command line for future reference.
339 * We also need to store the touched command line since the parameter
340 * parsing is performed in place, and we should allow a component to
341 * store reference of name/value for future reference.
342 */
343static void __init setup_command_line(char *command_line)
344{
345    saved_command_line = alloc_bootmem(strlen (boot_command_line)+1);
346    static_command_line = alloc_bootmem(strlen (command_line)+1);
347    strcpy (saved_command_line, boot_command_line);
348    strcpy (static_command_line, command_line);
349}
350
351/*
352 * We need to finalize in a non-__init function or else race conditions
353 * between the root thread and the init thread may cause start_kernel to
354 * be reaped by free_initmem before the root thread has proceeded to
355 * cpu_idle.
356 *
357 * gcc-3.4 accidentally inlines this function, so use noinline.
358 */
359
360static __initdata DECLARE_COMPLETION(kthreadd_done);
361
362static noinline void __init_refok rest_init(void)
363{
364    int pid;
365
366    rcu_scheduler_starting();
367    /*
368     * We need to spawn init first so that it obtains pid 1, however
369     * the init task will end up wanting to create kthreads, which, if
370     * we schedule it before we create kthreadd, will OOPS.
371     */
372    kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND);
373    numa_default_policy();
374    pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES);
375    rcu_read_lock();
376    kthreadd_task = find_task_by_pid_ns(pid, &init_pid_ns);
377    rcu_read_unlock();
378    complete(&kthreadd_done);
379
380    /*
381     * The boot idle thread must execute schedule()
382     * at least once to get things moving:
383     */
384    init_idle_bootup_task(current);
385    schedule_preempt_disabled();
386    /* Call into cpu_idle with preempt disabled */
387    cpu_idle();
388}
389
390/* Check for early params. */
391static int __init do_early_param(char *param, char *val, const char *unused)
392{
393    const struct obs_kernel_param *p;
394
395    for (p = __setup_start; p < __setup_end; p++) {
396        if ((p->early && parameq(param, p->str)) ||
397            (strcmp(param, "console") == 0 &&
398             strcmp(p->str, "earlycon") == 0)
399        ) {
400            if (p->setup_func(val) != 0)
401                printk(KERN_WARNING
402                       "Malformed early option '%s'\n", param);
403        }
404    }
405    /* We accept everything at this stage. */
406    return 0;
407}
408
409void __init parse_early_options(char *cmdline)
410{
411    parse_args("early options", cmdline, NULL, 0, 0, 0, do_early_param);
412}
413
414/* Arch code calls this early on, or if not, just before other parsing. */
415void __init parse_early_param(void)
416{
417    static __initdata int done = 0;
418    static __initdata char tmp_cmdline[COMMAND_LINE_SIZE];
419
420    if (done)
421        return;
422
423    /* All fall through to do_early_param. */
424    strlcpy(tmp_cmdline, boot_command_line, COMMAND_LINE_SIZE);
425    parse_early_options(tmp_cmdline);
426    done = 1;
427}
428
429/*
430 * Activate the first processor.
431 */
432
433static void __init boot_cpu_init(void)
434{
435    int cpu = smp_processor_id();
436    /* Mark the boot cpu "present", "online" etc for SMP and UP case */
437    set_cpu_online(cpu, true);
438    set_cpu_active(cpu, true);
439    set_cpu_present(cpu, true);
440    set_cpu_possible(cpu, true);
441}
442
443void __init __weak smp_setup_processor_id(void)
444{
445}
446
447# if THREAD_SIZE >= PAGE_SIZE
448void __init __weak thread_info_cache_init(void)
449{
450}
451#endif
452
453/*
454 * Set up kernel memory allocators
455 */
456static void __init mm_init(void)
457{
458    /*
459     * page_cgroup requires contiguous pages,
460     * bigger than MAX_ORDER unless SPARSEMEM.
461     */
462    page_cgroup_init_flatmem();
463    mem_init();
464    kmem_cache_init();
465    percpu_init_late();
466    pgtable_cache_init();
467    vmalloc_init();
468}
469
470asmlinkage void __init start_kernel(void)
471{
472    char * command_line;
473    extern const struct kernel_param __start___param[], __stop___param[];
474
475    /*
476     * Need to run as early as possible, to initialize the
477     * lockdep hash:
478     */
479    lockdep_init();
480    smp_setup_processor_id();
481    debug_objects_early_init();
482
483    /*
484     * Set up the the initial canary ASAP:
485     */
486    boot_init_stack_canary();
487
488    cgroup_init_early();
489
490    local_irq_disable();
491    early_boot_irqs_disabled = true;
492
493/*
494 * Interrupts are still disabled. Do necessary setups, then
495 * enable them
496 */
497    tick_init();
498    boot_cpu_init();
499    page_address_init();
500    printk(KERN_NOTICE "%s", linux_banner);
501    setup_arch(&command_line);
502    mm_init_owner(&init_mm, &init_task);
503    mm_init_cpumask(&init_mm);
504    setup_command_line(command_line);
505    setup_nr_cpu_ids();
506    setup_per_cpu_areas();
507    smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
508
509    build_all_zonelists(NULL, NULL);
510    page_alloc_init();
511
512    printk(KERN_NOTICE "Kernel command line: %s\n", boot_command_line);
513    parse_early_param();
514    parse_args("Booting kernel", static_command_line, __start___param,
515           __stop___param - __start___param,
516           -1, -1, &unknown_bootoption);
517
518    jump_label_init();
519
520    /*
521     * These use large bootmem allocations and must precede
522     * kmem_cache_init()
523     */
524    setup_log_buf(0);
525    pidhash_init();
526    vfs_caches_init_early();
527    sort_main_extable();
528    trap_init();
529    mm_init();
530
531    /*
532     * Set up the scheduler prior starting any interrupts (such as the
533     * timer interrupt). Full topology setup happens at smp_init()
534     * time - but meanwhile we still have a functioning scheduler.
535     */
536    sched_init();
537    /*
538     * Disable preemption - early bootup scheduling is extremely
539     * fragile until we cpu_idle() for the first time.
540     */
541    preempt_disable();
542    if (!irqs_disabled()) {
543        printk(KERN_WARNING "start_kernel(): bug: interrupts were "
544                "enabled *very* early, fixing it\n");
545        local_irq_disable();
546    }
547    idr_init_cache();
548    perf_event_init();
549    rcu_init();
550    radix_tree_init();
551    /* init some links before init_ISA_irqs() */
552    early_irq_init();
553    init_IRQ();
554    init_timers();
555    hrtimers_init();
556    softirq_init();
557    timekeeping_init();
558    time_init();
559    profile_init();
560    call_function_init();
561    if (!irqs_disabled())
562        printk(KERN_CRIT "start_kernel(): bug: interrupts were "
563                 "enabled early\n");
564    early_boot_irqs_disabled = false;
565    local_irq_enable();
566
567    kmem_cache_init_late();
568
569    /*
570     * HACK ALERT! This is early. We're enabling the console before
571     * we've done PCI setups etc, and console_init() must be aware of
572     * this. But we do want output early, in case something goes wrong.
573     */
574    console_init();
575    if (panic_later)
576        panic(panic_later, panic_param);
577
578    lockdep_info();
579
580    /*
581     * Need to run this when irqs are enabled, because it wants
582     * to self-test [hard/soft]-irqs on/off lock inversion bugs
583     * too:
584     */
585    locking_selftest();
586
587#ifdef CONFIG_BLK_DEV_INITRD
588    if (initrd_start && !initrd_below_start_ok &&
589        page_to_pfn(virt_to_page((void *)initrd_start)) < min_low_pfn) {
590        printk(KERN_CRIT "initrd overwritten (0x%08lx < 0x%08lx) - "
591            "disabling it.\n",
592            page_to_pfn(virt_to_page((void *)initrd_start)),
593            min_low_pfn);
594        initrd_start = 0;
595    }
596#endif
597    page_cgroup_init();
598    debug_objects_mem_init();
599    kmemleak_init();
600    setup_per_cpu_pageset();
601    numa_policy_init();
602    if (late_time_init)
603        late_time_init();
604    sched_clock_init();
605    calibrate_delay();
606    pidmap_init();
607    anon_vma_init();
608#ifdef CONFIG_X86
609    if (efi_enabled(EFI_RUNTIME_SERVICES))
610        efi_enter_virtual_mode();
611#endif
612    thread_info_cache_init();
613    cred_init();
614    fork_init(totalram_pages);
615    proc_caches_init();
616    buffer_init();
617    key_init();
618    security_init();
619    dbg_late_init();
620    vfs_caches_init(totalram_pages);
621    signals_init();
622    /* rootfs populating might need page-writeback */
623    page_writeback_init();
624#ifdef CONFIG_PROC_FS
625    proc_root_init();
626#endif
627    cgroup_init();
628    cpuset_init();
629    taskstats_init_early();
630    delayacct_init();
631
632    check_bugs();
633
634    acpi_early_init(); /* before LAPIC and SMP init */
635    sfi_init_late();
636
637    if (efi_enabled(EFI_RUNTIME_SERVICES)) {
638        efi_late_init();
639        efi_free_boot_services();
640    }
641
642    ftrace_init();
643
644    /* Do the rest non-__init'ed, we're now alive */
645    rest_init();
646}
647
648/* Call all constructor functions linked into the kernel. */
649static void __init do_ctors(void)
650{
651#ifdef CONFIG_CONSTRUCTORS
652    ctor_fn_t *fn = (ctor_fn_t *) __ctors_start;
653
654    for (; fn < (ctor_fn_t *) __ctors_end; fn++)
655        (*fn)();
656#endif
657}
658
659bool initcall_debug;
660core_param(initcall_debug, initcall_debug, bool, 0644);
661
662static char msgbuf[64];
663
664static int __init_or_module do_one_initcall_debug(initcall_t fn)
665{
666    ktime_t calltime, delta, rettime;
667    unsigned long long duration;
668    int ret;
669
670    printk(KERN_DEBUG "calling %pF @ %i\n", fn, task_pid_nr(current));
671    calltime = ktime_get();
672    ret = fn();
673    rettime = ktime_get();
674    delta = ktime_sub(rettime, calltime);
675    duration = (unsigned long long) ktime_to_ns(delta) >> 10;
676    printk(KERN_DEBUG "initcall %pF returned %d after %lld usecs\n", fn,
677        ret, duration);
678
679    return ret;
680}
681
682int __init_or_module do_one_initcall(initcall_t fn)
683{
684    int count = preempt_count();
685    int ret;
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 (ret && ret != -ENODEV && initcall_debug)
695        sprintf(msgbuf, "error code %d ", ret);
696
697    if (preempt_count() != count) {
698        strlcat(msgbuf, "preemption imbalance ", sizeof(msgbuf));
699        preempt_count() = count;
700    }
701    if (irqs_disabled()) {
702        strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
703        local_irq_enable();
704    }
705    if (msgbuf[0]) {
706        printk("initcall %pF returned with %s\n", fn, msgbuf);
707    }
708
709    return ret;
710}
711
712
713extern initcall_t __initcall_start[];
714extern initcall_t __initcall0_start[];
715extern initcall_t __initcall1_start[];
716extern initcall_t __initcall2_start[];
717extern initcall_t __initcall3_start[];
718extern initcall_t __initcall4_start[];
719extern initcall_t __initcall5_start[];
720extern initcall_t __initcall6_start[];
721extern initcall_t __initcall7_start[];
722extern initcall_t __initcall_end[];
723
724static initcall_t *initcall_levels[] __initdata = {
725    __initcall0_start,
726    __initcall1_start,
727    __initcall2_start,
728    __initcall3_start,
729    __initcall4_start,
730    __initcall5_start,
731    __initcall6_start,
732    __initcall7_start,
733    __initcall_end,
734};
735
736/* Keep these in sync with initcalls in include/linux/init.h */
737static char *initcall_level_names[] __initdata = {
738    "early",
739    "core",
740    "postcore",
741    "arch",
742    "subsys",
743    "fs",
744    "device",
745    "late",
746};
747
748static void __init do_initcall_level(int level)
749{
750    extern const struct kernel_param __start___param[], __stop___param[];
751    initcall_t *fn;
752
753    strcpy(static_command_line, saved_command_line);
754    parse_args(initcall_level_names[level],
755           static_command_line, __start___param,
756           __stop___param - __start___param,
757           level, level,
758           &repair_env_string);
759
760    for (fn = initcall_levels[level]; fn < initcall_levels[level+1]; fn++)
761        do_one_initcall(*fn);
762}
763
764static void __init do_initcalls(void)
765{
766    int level;
767
768    for (level = 0; level < ARRAY_SIZE(initcall_levels) - 1; level++)
769        do_initcall_level(level);
770}
771
772/*
773 * Ok, the machine is now initialized. None of the devices
774 * have been touched yet, but the CPU subsystem is up and
775 * running, and memory and process management works.
776 *
777 * Now we can finally start doing some real work..
778 */
779static void __init do_basic_setup(void)
780{
781    cpuset_init_smp();
782    usermodehelper_init();
783    shmem_init();
784    driver_init();
785    init_irq_proc();
786    do_ctors();
787    usermodehelper_enable();
788    do_initcalls();
789}
790
791static void __init do_pre_smp_initcalls(void)
792{
793    initcall_t *fn;
794
795    for (fn = __initcall_start; fn < __initcall0_start; fn++)
796        do_one_initcall(*fn);
797}
798
799/*
800 * This function requests modules which should be loaded by default and is
801 * called twice right after initrd is mounted and right before init is
802 * exec'd. If such modules are on either initrd or rootfs, they will be
803 * loaded before control is passed to userland.
804 */
805void __init load_default_modules(void)
806{
807    load_default_elevator_module();
808}
809
810static int run_init_process(const char *init_filename)
811{
812    argv_init[0] = init_filename;
813    return do_execve(init_filename,
814        (const char __user *const __user *)argv_init,
815        (const char __user *const __user *)envp_init);
816}
817
818static noinline void __init kernel_init_freeable(void);
819
820static int __ref kernel_init(void *unused)
821{
822    kernel_init_freeable();
823    /* need to finish all async __init code before freeing the memory */
824    async_synchronize_full();
825    free_initmem();
826    mark_rodata_ro();
827    system_state = SYSTEM_RUNNING;
828    numa_default_policy();
829
830    flush_delayed_fput();
831
832    if (ramdisk_execute_command) {
833        if (!run_init_process(ramdisk_execute_command))
834            return 0;
835        printk(KERN_WARNING "Failed to execute %s\n",
836                ramdisk_execute_command);
837    }
838
839    /*
840     * We try each of these until one succeeds.
841     *
842     * The Bourne shell can be used instead of init if we are
843     * trying to recover a really broken machine.
844     */
845    if (execute_command) {
846        if (!run_init_process(execute_command))
847            return 0;
848        printk(KERN_WARNING "Failed to execute %s. Attempting "
849                    "defaults...\n", execute_command);
850    }
851    if (!run_init_process("/sbin/init") ||
852        !run_init_process("/etc/init") ||
853        !run_init_process("/bin/init") ||
854        !run_init_process("/bin/sh"))
855        return 0;
856
857    panic("No init found. Try passing init= option to kernel. "
858          "See Linux Documentation/init.txt for guidance.");
859}
860
861static noinline void __init kernel_init_freeable(void)
862{
863    /*
864     * Wait until kthreadd is all set-up.
865     */
866    wait_for_completion(&kthreadd_done);
867
868    /* Now the scheduler is fully set up and can do blocking allocations */
869    gfp_allowed_mask = __GFP_BITS_MASK;
870
871    /*
872     * init can allocate pages on any node
873     */
874    set_mems_allowed(node_states[N_MEMORY]);
875    /*
876     * init can run on any cpu.
877     */
878    set_cpus_allowed_ptr(current, cpu_all_mask);
879
880    cad_pid = task_pid(current);
881
882    smp_prepare_cpus(setup_max_cpus);
883
884    do_pre_smp_initcalls();
885    lockup_detector_init();
886
887    smp_init();
888    sched_init_smp();
889
890    do_basic_setup();
891
892    /* Open the /dev/console on the rootfs, this should never fail */
893    if (sys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0)
894        printk(KERN_WARNING "Warning: unable to open an initial console.\n");
895
896    (void) sys_dup(0);
897    (void) sys_dup(0);
898    /*
899     * check if there is an early userspace init. If yes, let it do all
900     * the work
901     */
902
903    if (!ramdisk_execute_command)
904        ramdisk_execute_command = "/init";
905
906    if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {
907        ramdisk_execute_command = NULL;
908        prepare_namespace();
909    }
910
911    /*
912     * Ok, we have completed the initial bootup, and
913     * we're essentially up and running. Get rid of the
914     * initmem segments and start the user-mode stuff..
915     */
916
917    /* rootfs is available now, try loading default modules */
918    load_default_modules();
919}
920

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