Re: 2.6.8-rc4-mm1

[Robert Picco]

copy_thread expects a switch_stack below pt_regs  on the stack.  the 
switch_stack would have the parent's bspstore value for computing how 
much register backing store to copy into child.  there isn't a 
switch_stack and the resultant bspstore size computed is enormous 
(depends on what there is on stack).  i suspect printk has changed stack 
and the code layout changed too.

diff -ruN -X /home/picco/losl/dontdiff linux-2.6.8-rc3-mm2-orig/arch/ia64/kernel/process.c linux-2.6.8-rc3-mm2/arch/ia64/kernel/process.c
--- linux-2.6.8-rc3-mm2-orig/arch/ia64/kernel/process.c	2004-08-10 17:24:51.000000000 -0400
+++ linux-2.6.8-rc3-mm2/arch/ia64/kernel/process.c	2004-08-10 17:33:51.000000000 -0400
@@ -352,7 +352,7 @@
	 * For SMP idle threads, fork_by_hand() calls do_fork with
	 * NULL regs.
	 */
-	if (!regs)
+	if (clone_flags & CLONE_IDLETASK)
		return 0;
#endif

diff -ruN -X /home/picco/losl/dontdiff linux-2.6.8-rc3-mm2-orig/include/linux/sched.h linux-2.6.8-rc3-mm2/include/linux/sched.h
--- linux-2.6.8-rc3-mm2-orig/include/linux/sched.h	2004-08-10 17:25:07.000000000 -0400
+++ linux-2.6.8-rc3-mm2/include/linux/sched.h	2004-08-10 17:31:56.000000000 -0400
@@ -40,6 +40,7 @@
#define CLONE_FS	0x00000200	/* set if fs info shared between processes */
#define CLONE_FILES	0x00000400	/* set if open files shared between processes */
#define CLONE_SIGHAND	0x00000800	/* set if signal handlers and blocked signals shared */
+#define CLONE_IDLETASK	0x00001000	/* set if new pid should be 0 (kernel only)*/
#define CLONE_PTRACE	0x00002000	/* set if we want to let tracing continue on the child too */
#define CLONE_VFORK	0x00004000	/* set if the parent wants the child to wake it up on mm_release */
#define CLONE_PARENT	0x00008000	/* set if we want to have the same parent as the cloner */
diff -ruN -X /home/picco/losl/dontdiff linux-2.6.8-rc3-mm2-orig/kernel/fork.c linux-2.6.8-rc3-mm2/kernel/fork.c
--- linux-2.6.8-rc3-mm2-orig/kernel/fork.c	2004-08-10 17:25:10.000000000 -0400
+++ linux-2.6.8-rc3-mm2/kernel/fork.c	2004-08-10 17:32:56.000000000 -0400
@@ -1196,7 +1196,7 @@
	struct pt_regs regs;

	memset(&regs, 0, sizeof(struct pt_regs));
-	task = copy_process(CLONE_VM, 0, &regs, 0, NULL, NULL, 0);
+	task = copy_process(CLONE_VM|CLONE_IDLETASK, 0, &regs, 0, NULL, NULL, 0);
	if (!task)
		return ERR_PTR(-ENOMEM);
	init_idle(task, cpu);


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