Revision ee297209bf0a25c6717b7c063e76795142d32f37 authored by Xiaotian Feng on 20 December 2012, 23:05:44 UTC, committed by Linus Torvalds on 21 December 2012, 01:40:20 UTC
Lockdep found an inconsistent lock state when rcu is processing delayed work in softirq. Currently, kernel is using spin_lock/spin_unlock to protect proc_inum_ida, but proc_free_inum is called by rcu in softirq context. Use spin_lock_bh/spin_unlock_bh fix following lockdep warning. ================================= [ INFO: inconsistent lock state ] 3.7.0 #36 Not tainted --------------------------------- inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. swapper/1/0 [HC0[0]:SC1[1]:HE1:SE0] takes: (proc_inum_lock){+.?...}, at: proc_free_inum+0x1c/0x50 {SOFTIRQ-ON-W} state was registered at: __lock_acquire+0x8ae/0xca0 lock_acquire+0x199/0x200 _raw_spin_lock+0x41/0x50 proc_alloc_inum+0x4c/0xd0 alloc_mnt_ns+0x49/0xc0 create_mnt_ns+0x25/0x70 mnt_init+0x161/0x1c7 vfs_caches_init+0x107/0x11a start_kernel+0x348/0x38c x86_64_start_reservations+0x131/0x136 x86_64_start_kernel+0x103/0x112 irq event stamp: 2993422 hardirqs last enabled at (2993422): _raw_spin_unlock_irqrestore+0x55/0x80 hardirqs last disabled at (2993421): _raw_spin_lock_irqsave+0x29/0x70 softirqs last enabled at (2993394): _local_bh_enable+0x13/0x20 softirqs last disabled at (2993395): call_softirq+0x1c/0x30 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(proc_inum_lock); <Interrupt> lock(proc_inum_lock); *** DEADLOCK *** no locks held by swapper/1/0. stack backtrace: Pid: 0, comm: swapper/1 Not tainted 3.7.0 #36 Call Trace: <IRQ> [<ffffffff810a40f1>] ? vprintk_emit+0x471/0x510 print_usage_bug+0x2a5/0x2c0 mark_lock+0x33b/0x5e0 __lock_acquire+0x813/0xca0 lock_acquire+0x199/0x200 _raw_spin_lock+0x41/0x50 proc_free_inum+0x1c/0x50 free_pid_ns+0x1c/0x50 put_pid_ns+0x2e/0x50 put_pid+0x4a/0x60 delayed_put_pid+0x12/0x20 rcu_process_callbacks+0x462/0x790 __do_softirq+0x1b4/0x3b0 call_softirq+0x1c/0x30 do_softirq+0x59/0xd0 irq_exit+0x54/0xd0 smp_apic_timer_interrupt+0x95/0xa3 apic_timer_interrupt+0x72/0x80 cpuidle_enter_tk+0x10/0x20 cpuidle_enter_state+0x17/0x50 cpuidle_idle_call+0x287/0x520 cpu_idle+0xba/0x130 start_secondary+0x2b3/0x2bc Signed-off-by: Xiaotian Feng <dannyfeng@tencent.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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binfmt_script.c
/*
* linux/fs/binfmt_script.c
*
* Copyright (C) 1996 Martin von Löwis
* original #!-checking implemented by tytso.
*/
#include <linux/module.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/binfmts.h>
#include <linux/init.h>
#include <linux/file.h>
#include <linux/err.h>
#include <linux/fs.h>
static int load_script(struct linux_binprm *bprm)
{
const char *i_arg, *i_name;
char *cp;
struct file *file;
char interp[BINPRM_BUF_SIZE];
int retval;
if ((bprm->buf[0] != '#') || (bprm->buf[1] != '!'))
return -ENOEXEC;
/*
* This section does the #! interpretation.
* Sorta complicated, but hopefully it will work. -TYT
*/
allow_write_access(bprm->file);
fput(bprm->file);
bprm->file = NULL;
bprm->buf[BINPRM_BUF_SIZE - 1] = '\0';
if ((cp = strchr(bprm->buf, '\n')) == NULL)
cp = bprm->buf+BINPRM_BUF_SIZE-1;
*cp = '\0';
while (cp > bprm->buf) {
cp--;
if ((*cp == ' ') || (*cp == '\t'))
*cp = '\0';
else
break;
}
for (cp = bprm->buf+2; (*cp == ' ') || (*cp == '\t'); cp++);
if (*cp == '\0')
return -ENOEXEC; /* No interpreter name found */
i_name = cp;
i_arg = NULL;
for ( ; *cp && (*cp != ' ') && (*cp != '\t'); cp++)
/* nothing */ ;
while ((*cp == ' ') || (*cp == '\t'))
*cp++ = '\0';
if (*cp)
i_arg = cp;
strcpy (interp, i_name);
/*
* OK, we've parsed out the interpreter name and
* (optional) argument.
* Splice in (1) the interpreter's name for argv[0]
* (2) (optional) argument to interpreter
* (3) filename of shell script (replace argv[0])
*
* This is done in reverse order, because of how the
* user environment and arguments are stored.
*/
retval = remove_arg_zero(bprm);
if (retval)
return retval;
retval = copy_strings_kernel(1, &bprm->interp, bprm);
if (retval < 0) return retval;
bprm->argc++;
if (i_arg) {
retval = copy_strings_kernel(1, &i_arg, bprm);
if (retval < 0) return retval;
bprm->argc++;
}
retval = copy_strings_kernel(1, &i_name, bprm);
if (retval) return retval;
bprm->argc++;
retval = bprm_change_interp(interp, bprm);
if (retval < 0)
return retval;
/*
* OK, now restart the process with the interpreter's dentry.
*/
file = open_exec(interp);
if (IS_ERR(file))
return PTR_ERR(file);
bprm->file = file;
retval = prepare_binprm(bprm);
if (retval < 0)
return retval;
return search_binary_handler(bprm);
}
static struct linux_binfmt script_format = {
.module = THIS_MODULE,
.load_binary = load_script,
};
static int __init init_script_binfmt(void)
{
register_binfmt(&script_format);
return 0;
}
static void __exit exit_script_binfmt(void)
{
unregister_binfmt(&script_format);
}
core_initcall(init_script_binfmt);
module_exit(exit_script_binfmt);
MODULE_LICENSE("GPL");
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