linux/drivers/char/sysrq.c
Christoph Lameter 9b0f8b040a [PATCH] Terminate process that fails on a constrained allocation
Some allocations are restricted to a limited set of nodes (due to memory
policies or cpuset constraints).  If the page allocator is not able to find
enough memory then that does not mean that overall system memory is low.

In particular going postal and more or less randomly shooting at processes
is not likely going to help the situation but may just lead to suicide (the
whole system coming down).

It is better to signal to the process that no memory exists given the
constraints that the process (or the configuration of the process) has
placed on the allocation behavior.  The process may be killed but then the
sysadmin or developer can investigate the situation.  The solution is
similar to what we do when running out of hugepages.

This patch adds a check before we kill processes.  At that point
performance considerations do not matter much so we just scan the zonelist
and reconstruct a list of nodes.  If the list of nodes does not contain all
online nodes then this is a constrained allocation and we should kill the
current process.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-02-20 20:00:09 -08:00

471 lines
11 KiB
C

/* -*- linux-c -*-
*
* $Id: sysrq.c,v 1.15 1998/08/23 14:56:41 mj Exp $
*
* Linux Magic System Request Key Hacks
*
* (c) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
* based on ideas by Pavel Machek <pavel@atrey.karlin.mff.cuni.cz>
*
* (c) 2000 Crutcher Dunnavant <crutcher+kernel@datastacks.com>
* overhauled to use key registration
* based upon discusions in irc://irc.openprojects.net/#kernelnewbies
*/
#include <linux/config.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/tty.h>
#include <linux/mount.h>
#include <linux/kdev_t.h>
#include <linux/major.h>
#include <linux/reboot.h>
#include <linux/sysrq.h>
#include <linux/kbd_kern.h>
#include <linux/quotaops.h>
#include <linux/smp_lock.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/suspend.h>
#include <linux/writeback.h>
#include <linux/buffer_head.h> /* for fsync_bdev() */
#include <linux/swap.h>
#include <linux/spinlock.h>
#include <linux/vt_kern.h>
#include <linux/workqueue.h>
#include <linux/kexec.h>
#include <asm/ptrace.h>
/* Whether we react on sysrq keys or just ignore them */
int sysrq_enabled = 1;
/* Loglevel sysrq handler */
static void sysrq_handle_loglevel(int key, struct pt_regs *pt_regs,
struct tty_struct *tty)
{
int i;
i = key - '0';
console_loglevel = 7;
printk("Loglevel set to %d\n", i);
console_loglevel = i;
}
static struct sysrq_key_op sysrq_loglevel_op = {
.handler = sysrq_handle_loglevel,
.help_msg = "loglevel0-8",
.action_msg = "Changing Loglevel",
.enable_mask = SYSRQ_ENABLE_LOG,
};
/* SAK sysrq handler */
#ifdef CONFIG_VT
static void sysrq_handle_SAK(int key, struct pt_regs *pt_regs,
struct tty_struct *tty)
{
if (tty)
do_SAK(tty);
reset_vc(vc_cons[fg_console].d);
}
static struct sysrq_key_op sysrq_SAK_op = {
.handler = sysrq_handle_SAK,
.help_msg = "saK",
.action_msg = "SAK",
.enable_mask = SYSRQ_ENABLE_KEYBOARD,
};
#endif
#ifdef CONFIG_VT
/* unraw sysrq handler */
static void sysrq_handle_unraw(int key, struct pt_regs *pt_regs,
struct tty_struct *tty)
{
struct kbd_struct *kbd = &kbd_table[fg_console];
if (kbd)
kbd->kbdmode = VC_XLATE;
}
static struct sysrq_key_op sysrq_unraw_op = {
.handler = sysrq_handle_unraw,
.help_msg = "unRaw",
.action_msg = "Keyboard mode set to XLATE",
.enable_mask = SYSRQ_ENABLE_KEYBOARD,
};
#endif /* CONFIG_VT */
#ifdef CONFIG_KEXEC
/* crashdump sysrq handler */
static void sysrq_handle_crashdump(int key, struct pt_regs *pt_regs,
struct tty_struct *tty)
{
crash_kexec(pt_regs);
}
static struct sysrq_key_op sysrq_crashdump_op = {
.handler = sysrq_handle_crashdump,
.help_msg = "Crashdump",
.action_msg = "Trigger a crashdump",
.enable_mask = SYSRQ_ENABLE_DUMP,
};
#endif
/* reboot sysrq handler */
static void sysrq_handle_reboot(int key, struct pt_regs *pt_regs,
struct tty_struct *tty)
{
local_irq_enable();
emergency_restart();
}
static struct sysrq_key_op sysrq_reboot_op = {
.handler = sysrq_handle_reboot,
.help_msg = "reBoot",
.action_msg = "Resetting",
.enable_mask = SYSRQ_ENABLE_BOOT,
};
static void sysrq_handle_sync(int key, struct pt_regs *pt_regs,
struct tty_struct *tty)
{
emergency_sync();
}
static struct sysrq_key_op sysrq_sync_op = {
.handler = sysrq_handle_sync,
.help_msg = "Sync",
.action_msg = "Emergency Sync",
.enable_mask = SYSRQ_ENABLE_SYNC,
};
static void sysrq_handle_mountro(int key, struct pt_regs *pt_regs,
struct tty_struct *tty)
{
emergency_remount();
}
static struct sysrq_key_op sysrq_mountro_op = {
.handler = sysrq_handle_mountro,
.help_msg = "Unmount",
.action_msg = "Emergency Remount R/O",
.enable_mask = SYSRQ_ENABLE_REMOUNT,
};
/* END SYNC SYSRQ HANDLERS BLOCK */
#ifdef CONFIG_DEBUG_MUTEXES
static void
sysrq_handle_showlocks(int key, struct pt_regs *pt_regs, struct tty_struct *tty)
{
mutex_debug_show_all_locks();
}
static struct sysrq_key_op sysrq_showlocks_op = {
.handler = sysrq_handle_showlocks,
.help_msg = "show-all-locks(D)",
.action_msg = "Show Locks Held",
};
#endif
/* SHOW SYSRQ HANDLERS BLOCK */
static void sysrq_handle_showregs(int key, struct pt_regs *pt_regs,
struct tty_struct *tty)
{
if (pt_regs)
show_regs(pt_regs);
}
static struct sysrq_key_op sysrq_showregs_op = {
.handler = sysrq_handle_showregs,
.help_msg = "showPc",
.action_msg = "Show Regs",
.enable_mask = SYSRQ_ENABLE_DUMP,
};
static void sysrq_handle_showstate(int key, struct pt_regs *pt_regs,
struct tty_struct *tty)
{
show_state();
}
static struct sysrq_key_op sysrq_showstate_op = {
.handler = sysrq_handle_showstate,
.help_msg = "showTasks",
.action_msg = "Show State",
.enable_mask = SYSRQ_ENABLE_DUMP,
};
static void sysrq_handle_showmem(int key, struct pt_regs *pt_regs,
struct tty_struct *tty)
{
show_mem();
}
static struct sysrq_key_op sysrq_showmem_op = {
.handler = sysrq_handle_showmem,
.help_msg = "showMem",
.action_msg = "Show Memory",
.enable_mask = SYSRQ_ENABLE_DUMP,
};
/* SHOW SYSRQ HANDLERS BLOCK */
/* SIGNAL SYSRQ HANDLERS BLOCK */
/* signal sysrq helper function
* Sends a signal to all user processes */
static void send_sig_all(int sig)
{
struct task_struct *p;
for_each_process(p) {
if (p->mm && p->pid != 1)
/* Not swapper, init nor kernel thread */
force_sig(sig, p);
}
}
static void sysrq_handle_term(int key, struct pt_regs *pt_regs,
struct tty_struct *tty)
{
send_sig_all(SIGTERM);
console_loglevel = 8;
}
static struct sysrq_key_op sysrq_term_op = {
.handler = sysrq_handle_term,
.help_msg = "tErm",
.action_msg = "Terminate All Tasks",
.enable_mask = SYSRQ_ENABLE_SIGNAL,
};
static void moom_callback(void *ignored)
{
out_of_memory(&NODE_DATA(0)->node_zonelists[ZONE_NORMAL], GFP_KERNEL, 0);
}
static DECLARE_WORK(moom_work, moom_callback, NULL);
static void sysrq_handle_moom(int key, struct pt_regs *pt_regs,
struct tty_struct *tty)
{
schedule_work(&moom_work);
}
static struct sysrq_key_op sysrq_moom_op = {
.handler = sysrq_handle_moom,
.help_msg = "Full",
.action_msg = "Manual OOM execution",
};
static void sysrq_handle_kill(int key, struct pt_regs *pt_regs,
struct tty_struct *tty)
{
send_sig_all(SIGKILL);
console_loglevel = 8;
}
static struct sysrq_key_op sysrq_kill_op = {
.handler = sysrq_handle_kill,
.help_msg = "kIll",
.action_msg = "Kill All Tasks",
.enable_mask = SYSRQ_ENABLE_SIGNAL,
};
/* END SIGNAL SYSRQ HANDLERS BLOCK */
static void sysrq_handle_unrt(int key, struct pt_regs *pt_regs,
struct tty_struct *tty)
{
normalize_rt_tasks();
}
static struct sysrq_key_op sysrq_unrt_op = {
.handler = sysrq_handle_unrt,
.help_msg = "Nice",
.action_msg = "Nice All RT Tasks",
.enable_mask = SYSRQ_ENABLE_RTNICE,
};
/* Key Operations table and lock */
static DEFINE_SPINLOCK(sysrq_key_table_lock);
#define SYSRQ_KEY_TABLE_LENGTH 36
static struct sysrq_key_op *sysrq_key_table[SYSRQ_KEY_TABLE_LENGTH] = {
/* 0 */ &sysrq_loglevel_op,
/* 1 */ &sysrq_loglevel_op,
/* 2 */ &sysrq_loglevel_op,
/* 3 */ &sysrq_loglevel_op,
/* 4 */ &sysrq_loglevel_op,
/* 5 */ &sysrq_loglevel_op,
/* 6 */ &sysrq_loglevel_op,
/* 7 */ &sysrq_loglevel_op,
/* 8 */ &sysrq_loglevel_op,
/* 9 */ &sysrq_loglevel_op,
/* a */ NULL, /* Don't use for system provided sysrqs,
it is handled specially on the sparc
and will never arrive */
/* b */ &sysrq_reboot_op,
#ifdef CONFIG_KEXEC
/* c */ &sysrq_crashdump_op,
#else
/* c */ NULL,
#endif
#ifdef CONFIG_DEBUG_MUTEXES
/* d */ &sysrq_showlocks_op,
#else
/* d */ NULL,
#endif
/* e */ &sysrq_term_op,
/* f */ &sysrq_moom_op,
/* g */ NULL,
/* h */ NULL,
/* i */ &sysrq_kill_op,
/* j */ NULL,
#ifdef CONFIG_VT
/* k */ &sysrq_SAK_op,
#else
/* k */ NULL,
#endif
/* l */ NULL,
/* m */ &sysrq_showmem_op,
/* n */ &sysrq_unrt_op,
/* o */ NULL, /* This will often be registered
as 'Off' at init time */
/* p */ &sysrq_showregs_op,
/* q */ NULL,
#ifdef CONFIG_VT
/* r */ &sysrq_unraw_op,
#else
/* r */ NULL,
#endif
/* s */ &sysrq_sync_op,
/* t */ &sysrq_showstate_op,
/* u */ &sysrq_mountro_op,
/* v */ NULL, /* May be assigned at init time by SMP VOYAGER */
/* w */ NULL,
/* x */ NULL,
/* y */ NULL,
/* z */ NULL
};
/* key2index calculation, -1 on invalid index */
static int sysrq_key_table_key2index(int key) {
int retval;
if ((key >= '0') && (key <= '9')) {
retval = key - '0';
} else if ((key >= 'a') && (key <= 'z')) {
retval = key + 10 - 'a';
} else {
retval = -1;
}
return retval;
}
/*
* get and put functions for the table, exposed to modules.
*/
struct sysrq_key_op *__sysrq_get_key_op (int key) {
struct sysrq_key_op *op_p;
int i;
i = sysrq_key_table_key2index(key);
op_p = (i == -1) ? NULL : sysrq_key_table[i];
return op_p;
}
static void __sysrq_put_key_op (int key, struct sysrq_key_op *op_p) {
int i;
i = sysrq_key_table_key2index(key);
if (i != -1)
sysrq_key_table[i] = op_p;
}
/*
* This is the non-locking version of handle_sysrq
* It must/can only be called by sysrq key handlers,
* as they are inside of the lock
*/
void __handle_sysrq(int key, struct pt_regs *pt_regs, struct tty_struct *tty, int check_mask)
{
struct sysrq_key_op *op_p;
int orig_log_level;
int i, j;
unsigned long flags;
spin_lock_irqsave(&sysrq_key_table_lock, flags);
orig_log_level = console_loglevel;
console_loglevel = 7;
printk(KERN_INFO "SysRq : ");
op_p = __sysrq_get_key_op(key);
if (op_p) {
/* Should we check for enabled operations (/proc/sysrq-trigger should not)
* and is the invoked operation enabled? */
if (!check_mask || sysrq_enabled == 1 ||
(sysrq_enabled & op_p->enable_mask)) {
printk ("%s\n", op_p->action_msg);
console_loglevel = orig_log_level;
op_p->handler(key, pt_regs, tty);
}
else
printk("This sysrq operation is disabled.\n");
} else {
printk("HELP : ");
/* Only print the help msg once per handler */
for (i=0; i<SYSRQ_KEY_TABLE_LENGTH; i++)
if (sysrq_key_table[i]) {
for (j=0; sysrq_key_table[i] != sysrq_key_table[j]; j++);
if (j == i)
printk ("%s ", sysrq_key_table[i]->help_msg);
}
printk ("\n");
console_loglevel = orig_log_level;
}
spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
}
/*
* This function is called by the keyboard handler when SysRq is pressed
* and any other keycode arrives.
*/
void handle_sysrq(int key, struct pt_regs *pt_regs, struct tty_struct *tty)
{
if (!sysrq_enabled)
return;
__handle_sysrq(key, pt_regs, tty, 1);
}
static int __sysrq_swap_key_ops(int key, struct sysrq_key_op *insert_op_p,
struct sysrq_key_op *remove_op_p) {
int retval;
unsigned long flags;
spin_lock_irqsave(&sysrq_key_table_lock, flags);
if (__sysrq_get_key_op(key) == remove_op_p) {
__sysrq_put_key_op(key, insert_op_p);
retval = 0;
} else {
retval = -1;
}
spin_unlock_irqrestore(&sysrq_key_table_lock, flags);
return retval;
}
int register_sysrq_key(int key, struct sysrq_key_op *op_p)
{
return __sysrq_swap_key_ops(key, op_p, NULL);
}
int unregister_sysrq_key(int key, struct sysrq_key_op *op_p)
{
return __sysrq_swap_key_ops(key, NULL, op_p);
}
EXPORT_SYMBOL(handle_sysrq);
EXPORT_SYMBOL(register_sysrq_key);
EXPORT_SYMBOL(unregister_sysrq_key);