Andrew,

I had sent this patch as an RFC a few days ago and recieved no
objections/comments.  It is just a cleanup and does not change
any functionality.

Regards,

Suka

---

This is an updated version of Eric Biederman's is_init() patch.
(http://lkml.org/lkml/2006/2/6/280). It applies cleanly to 2.6.18-rc3
and replaces a few more instances of ->pid == 1 with is_init().

Further, is_init() checks pid and thus removes dependency on Eric's
other patches for now.

Eric's original description: 

	There are a lot of places in the kernel where we test for init
	because we give it special properties.  Most  significantly init
	must not die.  This results in code all over the kernel test
	->pid == 1.

	Introduce is_init to capture this case.  

	With multiple pid spaces for all of the cases affected we are
	looking for only the first process on the system, not some other
	process that has pid == 1. 

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: lxc-devel@lists.sourceforge.net


 arch/alpha/mm/fault.c                |    2 +-
 arch/arm/mm/fault.c                  |    2 +-
 arch/arm26/mm/fault.c                |    2 +-
 arch/i386/lib/usercopy.c             |    2 +-
 arch/i386/mm/fault.c                 |    2 +-
 arch/ia64/mm/fault.c                 |    2 +-
 arch/m32r/mm/fault.c                 |    2 +-
 arch/m68k/mm/fault.c                 |    2 +-
 arch/mips/mm/fault.c                 |    2 +-
 arch/powerpc/mm/fault.c              |    2 +-
 arch/powerpc/platforms/pseries/ras.c |    2 +-
 arch/ppc/kernel/traps.c              |    2 +-
 arch/ppc/mm/fault.c                  |    2 +-
 arch/s390/mm/fault.c                 |    2 +-
 arch/sh/mm/fault.c                   |    2 +-
 arch/sh64/mm/fault.c                 |    6 +++---
 arch/um/kernel/trap.c                |    2 +-
 arch/x86_64/mm/fault.c               |    4 ++--
 arch/xtensa/mm/fault.c               |    2 +-
 drivers/char/sysrq.c                 |    2 +-
 include/linux/sched.h                |   10 ++++++++++
 kernel/capability.c                  |    2 +-
 kernel/cpuset.c                      |    2 +-
 kernel/exit.c                        |    2 +-
 kernel/kexec.c                       |    2 +-
 kernel/ptrace.c                      |    1 +
 kernel/sysctl.c                      |    2 +-
 mm/oom_kill.c                        |    6 +++---
 security/commoncap.c                 |    2 +-
 security/seclvl.c                    |    9 +++++----
 30 files changed, 48 insertions(+), 36 deletions(-)

Index: linux-2.6.18-rc3/arch/alpha/mm/fault.c
===================================================================
--- linux-2.6.18-rc3.orig/arch/alpha/mm/fault.c	2006-08-08 14:10:11.000000000 -0700
+++ linux-2.6.18-rc3/arch/alpha/mm/fault.c	2006-08-08 17:23:20.000000000 -0700
@@ -193,7 +193,7 @@ do_page_fault(unsigned long address, uns
 	/* We ran out of memory, or some other thing happened to us that
 	   made us unable to handle the page fault gracefully.  */
  out_of_memory:
-	if (current->pid == 1) {
+	if (is_init(current)) {
 		yield();
 		down_read(&mm->mmap_sem);
 		goto survive;
Index: linux-2.6.18-rc3/arch/arm/mm/fault.c
===================================================================
--- linux-2.6.18-rc3.orig/arch/arm/mm/fault.c	2006-08-08 14:10:13.000000000 -0700
+++ linux-2.6.18-rc3/arch/arm/mm/fault.c	2006-08-08 17:23:20.000000000 -0700
@@ -197,7 +197,7 @@ survive:
 		return fault;
 	}
 
-	if (tsk->pid != 1)
+	if (!is_init(tsk))
 		goto out;
 
 	/*
Index: linux-2.6.18-rc3/arch/arm26/mm/fault.c
===================================================================
--- linux-2.6.18-rc3.orig/arch/arm26/mm/fault.c	2006-08-08 14:10:00.000000000 -0700
+++ linux-2.6.18-rc3/arch/arm26/mm/fault.c	2006-08-08 17:23:20.000000000 -0700
@@ -185,7 +185,7 @@ survive:
 	}
 
 	fault = -3; /* out of memory */
-	if (tsk->pid != 1)
+	if (!is_init(tsk))
 		goto out;
 
 	/*
Index: linux-2.6.18-rc3/arch/i386/lib/usercopy.c
===================================================================
--- linux-2.6.18-rc3.orig/arch/i386/lib/usercopy.c	2006-08-08 14:09:42.000000000 -0700
+++ linux-2.6.18-rc3/arch/i386/lib/usercopy.c	2006-08-08 17:23:20.000000000 -0700
@@ -739,7 +739,7 @@ survive:
 			retval = get_user_pages(current, current->mm,
 					(unsigned long )to, 1, 1, 0, &pg, NULL);
 
-			if (retval == -ENOMEM && current->pid == 1) {
+			if (retval == -ENOMEM && is_init(current)) {
 				up_read(&current->mm->mmap_sem);
 				blk_congestion_wait(WRITE, HZ/50);
 				goto survive;
Index: linux-2.6.18-rc3/arch/i386/mm/fault.c
===================================================================
--- linux-2.6.18-rc3.orig/arch/i386/mm/fault.c	2006-08-08 14:09:42.000000000 -0700
+++ linux-2.6.18-rc3/arch/i386/mm/fault.c	2006-08-08 17:23:20.000000000 -0700
@@ -598,7 +598,7 @@ no_context:
  */
 out_of_memory:
 	up_read(&mm->mmap_sem);
-	if (tsk->pid == 1) {
+	if (is_init(tsk)) {
 		yield();
 		down_read(&mm->mmap_sem);
 		goto survive;
Index: linux-2.6.18-rc3/arch/ia64/mm/fault.c
===================================================================
--- linux-2.6.18-rc3.orig/arch/ia64/mm/fault.c	2006-08-08 14:10:06.000000000 -0700
+++ linux-2.6.18-rc3/arch/ia64/mm/fault.c	2006-08-08 17:23:20.000000000 -0700
@@ -278,7 +278,7 @@ ia64_do_page_fault (unsigned long addres
 
   out_of_memory:
 	up_read(&mm->mmap_sem);
-	if (current->pid == 1) {
+	if (is_init(current)) {
 		yield();
 		down_read(&mm->mmap_sem);
 		goto survive;
Index: linux-2.6.18-rc3/arch/m32r/mm/fault.c
===================================================================
--- linux-2.6.18-rc3.orig/arch/m32r/mm/fault.c	2006-08-08 14:10:21.000000000 -0700
+++ linux-2.6.18-rc3/arch/m32r/mm/fault.c	2006-08-08 17:23:20.000000000 -0700
@@ -299,7 +299,7 @@ no_context:
  */
 out_of_memory:
 	up_read(&mm->mmap_sem);
-	if (tsk->pid == 1) {
+	if (is_init(tsk)) {
 		yield();
 		down_read(&mm->mmap_sem);
 		goto survive;
Index: linux-2.6.18-rc3/arch/m68k/mm/fault.c
===================================================================
--- linux-2.6.18-rc3.orig/arch/m68k/mm/fault.c	2006-08-08 14:10:02.000000000 -0700
+++ linux-2.6.18-rc3/arch/m68k/mm/fault.c	2006-08-08 17:23:20.000000000 -0700
@@ -181,7 +181,7 @@ good_area:
  */
 out_of_memory:
 	up_read(&mm->mmap_sem);
-	if (current->pid == 1) {
+	if (is_init(current)) {
 		yield();
 		down_read(&mm->mmap_sem);
 		goto survive;
Index: linux-2.6.18-rc3/arch/mips/mm/fault.c
===================================================================
--- linux-2.6.18-rc3.orig/arch/mips/mm/fault.c	2006-08-08 14:09:53.000000000 -0700
+++ linux-2.6.18-rc3/arch/mips/mm/fault.c	2006-08-08 17:23:20.000000000 -0700
@@ -171,7 +171,7 @@ no_context:
  */
 out_of_memory:
 	up_read(&mm->mmap_sem);
-	if (tsk->pid == 1) {
+	if (is_init(tsk)) {
 		yield();
 		down_read(&mm->mmap_sem);
 		goto survive;
Index: linux-2.6.18-rc3/arch/powerpc/mm/fault.c
===================================================================
--- linux-2.6.18-rc3.orig/arch/powerpc/mm/fault.c	2006-08-08 14:10:22.000000000 -0700
+++ linux-2.6.18-rc3/arch/powerpc/mm/fault.c	2006-08-08 17:23:21.000000000 -0700
@@ -386,7 +386,7 @@ bad_area_nosemaphore:
  */
 out_of_memory:
 	up_read(&mm->mmap_sem);
-	if (current->pid == 1) {
+	if (is_init(current)) {
 		yield();
 		down_read(&mm->mmap_sem);
 		goto survive;
Index: linux-2.6.18-rc3/arch/powerpc/platforms/pseries/ras.c
===================================================================
--- linux-2.6.18-rc3.orig/arch/powerpc/platforms/pseries/ras.c	2006-08-08 14:10:23.000000000 -0700
+++ linux-2.6.18-rc3/arch/powerpc/platforms/pseries/ras.c	2006-08-08 17:23:21.000000000 -0700
@@ -337,7 +337,7 @@ static int recover_mce(struct pt_regs *r
 		   err->disposition == RTAS_DISP_NOT_RECOVERED &&
 		   err->target == RTAS_TARGET_MEMORY &&
 		   err->type == RTAS_TYPE_ECC_UNCORR &&
-		   !(current->pid == 0 || current->pid == 1)) {
+		   !(current->pid == 0 || is_init(current))) {
 		/* Kill off a user process with an ECC error */
 		printk(KERN_ERR "MCE: uncorrectable ecc error for pid %d\n",
 		       current->pid);
Index: linux-2.6.18-rc3/arch/ppc/kernel/traps.c
===================================================================
--- linux-2.6.18-rc3.orig/arch/ppc/kernel/traps.c	2006-08-08 14:09:48.000000000 -0700
+++ linux-2.6.18-rc3/arch/ppc/kernel/traps.c	2006-08-08 17:23:21.000000000 -0700
@@ -119,7 +119,7 @@ void _exception(int signr, struct pt_reg
 	 * generate the same exception over and over again and we get
 	 * nowhere.  Better to kill it and let the kernel panic.
 	 */
-	if (current->pid == 1) {
+	if (is_init(current)) {
 		__sighandler_t handler;
 
 		spin_lock_irq(&current->sighand->siglock);
Index: linux-2.6.18-rc3/arch/ppc/mm/fault.c
===================================================================
--- linux-2.6.18-rc3.orig/arch/ppc/mm/fault.c	2006-08-08 14:09:47.000000000 -0700
+++ linux-2.6.18-rc3/arch/ppc/mm/fault.c	2006-08-08 17:23:21.000000000 -0700
@@ -291,7 +291,7 @@ bad_area:
  */
 out_of_memory:
 	up_read(&mm->mmap_sem);
-	if (current->pid == 1) {
+	if (is_init(current)) {
 		yield();
 		down_read(&mm->mmap_sem);
 		goto survive;
Index: linux-2.6.18-rc3/arch/s390/mm/fault.c
===================================================================
--- linux-2.6.18-rc3.orig/arch/s390/mm/fault.c	2006-08-08 14:10:20.000000000 -0700
+++ linux-2.6.18-rc3/arch/s390/mm/fault.c	2006-08-08 17:23:21.000000000 -0700
@@ -315,7 +315,7 @@ no_context:
 */
 out_of_memory:
 	up_read(&mm->mmap_sem);
-	if (tsk->pid == 1) {
+	if (is_init(tsk)) {
 		y