Name: Simple Dynamic Allocation of groups array
Author: Rusty Russell
Status: Experimental

D: This is a safe, naive approach to group addition.  It applies to x86
D: and s390.

diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .9886-linux-2.4.19/arch/i386/kernel/init_task.c .9886-linux-2.4.19.updated/arch/i386/kernel/init_task.c
--- .9886-linux-2.4.19/arch/i386/kernel/init_task.c	2003-02-27 14:46:17.000000000 +1100
+++ .9886-linux-2.4.19.updated/arch/i386/kernel/init_task.c	2003-09-18 17:44:43.000000000 +1000
@@ -10,6 +10,7 @@ static struct fs_struct init_fs = INIT_F
 static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS;
 struct mm_struct init_mm = INIT_MM(init_mm);
+static gid_t init_groups[NGROUPS];
 
 /*
  * Initial task structure.
@@ -20,7 +21,7 @@ struct mm_struct init_mm = INIT_MM(init_
  */
 union task_union init_task_union 
 	__attribute__((__section__(".data.init_task"))) =
-		{ INIT_TASK(init_task_union.task) };
+		{ INIT_TASK(init_task_union.task,init_groups) };
 
 /*
  * per-CPU TSS segments. Threads are completely 'soft' on Linux,
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .9886-linux-2.4.19/arch/s390/kernel/init_task.c .9886-linux-2.4.19.updated/arch/s390/kernel/init_task.c
--- .9886-linux-2.4.19/arch/s390/kernel/init_task.c	2003-02-27 14:51:56.000000000 +1100
+++ .9886-linux-2.4.19.updated/arch/s390/kernel/init_task.c	2003-09-18 17:44:43.000000000 +1000
@@ -16,6 +16,7 @@ static struct fs_struct init_fs = INIT_F
 static struct files_struct init_files = INIT_FILES;
 static struct signal_struct init_signals = INIT_SIGNALS;
 struct mm_struct init_mm = INIT_MM(init_mm);
+static gid_t init_groups[NGROUPS];
 
 /*
  * Initial task structure.
@@ -28,4 +29,4 @@ struct mm_struct init_mm = INIT_MM(init_
  * The things we do for performance..
  */
 union task_union init_task_union __attribute__((aligned(8192))) = 
-  { INIT_TASK(init_task_union.task) };
+  { INIT_TASK(init_task_union.task,init_groups) };
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .9886-linux-2.4.19/include/asm-i386/param.h .9886-linux-2.4.19.updated/include/asm-i386/param.h
--- .9886-linux-2.4.19/include/asm-i386/param.h	2000-10-28 05:04:43.000000000 +1100
+++ .9886-linux-2.4.19.updated/include/asm-i386/param.h	2003-09-18 17:44:43.000000000 +1000
@@ -8,7 +8,7 @@
 #define EXEC_PAGESIZE	4096
 
 #ifndef NGROUPS
-#define NGROUPS		32
+#define NGROUPS		256
 #endif
 
 #ifndef NOGROUP
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .9886-linux-2.4.19/include/asm-i386/processor.h .9886-linux-2.4.19.updated/include/asm-i386/processor.h
--- .9886-linux-2.4.19/include/asm-i386/processor.h	2003-03-18 04:59:15.000000000 +1100
+++ .9886-linux-2.4.19.updated/include/asm-i386/processor.h	2003-09-18 17:44:43.000000000 +1000
@@ -452,8 +452,8 @@ unsigned long get_wchan(struct task_stru
 #define KSTK_ESP(tsk)	(((unsigned long *)(4096+(unsigned long)(tsk)))[1022])
 
 #define THREAD_SIZE (2*PAGE_SIZE)
-#define alloc_task_struct() ((struct task_struct *) __get_free_pages(GFP_KERNEL,1))
-#define free_task_struct(p) free_pages((unsigned long) (p), 1)
+#define __alloc_task_struct() ((struct task_struct *) __get_free_pages(GFP_KERNEL,1))
+#define __free_task_struct(p) free_pages((unsigned long) (p), 1)
 #define get_task_struct(tsk)      atomic_inc(&virt_to_page(tsk)->count)
 
 #define init_task	(init_task_union.task)
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .9886-linux-2.4.19/include/asm-s390/param.h .9886-linux-2.4.19.updated/include/asm-s390/param.h
--- .9886-linux-2.4.19/include/asm-s390/param.h	2001-02-14 09:13:44.000000000 +1100
+++ .9886-linux-2.4.19.updated/include/asm-s390/param.h	2003-09-18 17:44:43.000000000 +1000
@@ -16,7 +16,7 @@
 #define EXEC_PAGESIZE	4096
 
 #ifndef NGROUPS
-#define NGROUPS		32
+#define NGROUPS		256
 #endif
 
 #ifndef NOGROUP
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .9886-linux-2.4.19/include/asm-s390/processor.h .9886-linux-2.4.19.updated/include/asm-s390/processor.h
--- .9886-linux-2.4.19/include/asm-s390/processor.h	2003-03-18 04:59:20.000000000 +1100
+++ .9886-linux-2.4.19.updated/include/asm-s390/processor.h	2003-09-18 17:44:43.000000000 +1000
@@ -144,9 +144,9 @@ unsigned long get_wchan(struct task_stru
 /*
  * NOTE! The task struct and the stack go together
  */
-#define alloc_task_struct() \
+#define __alloc_task_struct() \
         ((struct task_struct *) __get_free_pages(GFP_KERNEL,1))
-#define free_task_struct(p)     free_pages((unsigned long)(p),1)
+#define __free_task_struct(p)     free_pages((unsigned long)(p),1)
 #define get_task_struct(tsk)      atomic_inc(&virt_to_page(tsk)->count)
 
 #define init_task       (init_task_union.task)
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .9886-linux-2.4.19/include/linux/limits.h .9886-linux-2.4.19.updated/include/linux/limits.h
--- .9886-linux-2.4.19/include/linux/limits.h	2003-02-27 14:52:03.000000000 +1100
+++ .9886-linux-2.4.19.updated/include/linux/limits.h	2003-09-18 17:44:43.000000000 +1000
@@ -3,7 +3,7 @@
 
 #define NR_OPEN	        1024
 
-#define NGROUPS_MAX       32	/* supplemental group IDs are available */
+#define NGROUPS_MAX      256	/* supplemental group IDs are available */
 #define ARG_MAX       131072	/* # bytes of args + environ for exec() */
 #define CHILD_MAX        999    /* no limit :-) */
 #define OPEN_MAX         256	/* # open files a process may have */
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .9886-linux-2.4.19/include/linux/mm.h .9886-linux-2.4.19.updated/include/linux/mm.h
--- .9886-linux-2.4.19/include/linux/mm.h	2003-03-18 04:59:22.000000000 +1100
+++ .9886-linux-2.4.19.updated/include/linux/mm.h	2003-09-18 17:44:43.000000000 +1000
@@ -454,8 +454,8 @@ extern unsigned long FASTCALL(get_zeroed
 /*
  * There is only one 'core' page-freeing function.
  */
-extern void FASTCALL(__free_pages(struct page *page, unsigned int order));
-extern void FASTCALL(free_pages(unsigned long addr, unsigned int order));
+extern int FASTCALL(__free_pages(struct page *page, unsigned int order));
+extern int FASTCALL(free_pages(unsigned long addr, unsigned int order));
 
 #define __free_page(page) __free_pages((page), 0)
 #define free_page(addr) free_pages((addr),0)
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .9886-linux-2.4.19/include/linux/sched.h .9886-linux-2.4.19.updated/include/linux/sched.h
--- .9886-linux-2.4.19/include/linux/sched.h	2003-03-18 04:59:22.000000000 +1100
+++ .9886-linux-2.4.19.updated/include/linux/sched.h	2003-09-18 17:44:51.000000000 +1000
@@ -374,7 +374,7 @@ struct task_struct {
 	uid_t uid,euid,suid,fsuid;
 	gid_t gid,egid,sgid,fsgid;
 	int ngroups;
-	gid_t	groups[NGROUPS];
+	gid_t	*groups;
 	kernel_cap_t   cap_effective, cap_inheritable, cap_permitted;
 	int keep_capabilities:1;
 	struct user_struct *user;
@@ -470,7 +470,7 @@ extern struct exec_domain	default_exec_d
  *  INIT_TASK is used to set up the first task table, touch at
  * your own risk!. Base=0, limit=0x1fffff (=2MB)
  */
-#define INIT_TASK(tsk)	\
+#define INIT_TASK(tsk,_groups)	\
 {									\
     state:		0,						\
     flags:		0,						\
@@ -511,6 +511,7 @@ extern struct exec_domain	default_exec_d
     blocked:		{{0}},						\
     alloc_lock:		SPIN_LOCK_UNLOCKED,				\
     journal_info:	NULL,						\
+    groups:		_groups,					\
 }
 
 
@@ -946,4 +947,7 @@ static inline char * d_path(struct dentr
 
 #endif /* __KERNEL__ */
 
+struct task_struct *alloc_task_struct(void);
+void free_task_struct(struct task_struct *p);
+
 #endif
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .9886-linux-2.4.19/kernel/fork.c .9886-linux-2.4.19.updated/kernel/fork.c
--- .9886-linux-2.4.19/kernel/fork.c	2003-03-18 04:59:25.000000000 +1100
+++ .9886-linux-2.4.19.updated/kernel/fork.c	2003-09-18 17:44:43.000000000 +1000
@@ -580,6 +580,7 @@ int do_fork(unsigned long clone_flags, u
 	int retval;
 	struct task_struct *p;
 	struct completion vfork;
+	gid_t *newgroups;
 
 	if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
 		return -EINVAL;
@@ -600,7 +601,11 @@ int do_fork(unsigned long clone_flags, u
 	if (!p)
 		goto fork_out;
 
+	/* Preserve group pointer, and copy across */
+	newgroups = p->groups;
 	*p = *current;
+	p->groups = newgroups;
+	memcpy(p->groups, current->groups, sizeof(p->groups[0])*NGROUPS);
 
 	retval = -EAGAIN;
 	/*
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .9886-linux-2.4.19/kernel/sched.c .9886-linux-2.4.19.updated/kernel/sched.c
--- .9886-linux-2.4.19/kernel/sched.c	2003-03-18 04:59:25.000000000 +1100
+++ .9886-linux-2.4.19.updated/kernel/sched.c	2003-09-18 17:44:43.000000000 +1000
@@ -1314,6 +1314,28 @@ void __init init_idle(void)
 	clear_bit(current->processor, &wait_init_idle);
 }
 
+struct task_struct *alloc_task_struct(void)
+{
+	struct task_struct *p = __alloc_task_struct();
+	if (p) {
+		p->groups = kmalloc(sizeof(p->groups[0])*NGROUPS, GFP_KERNEL);
+		if (!p->groups) {
+			__free_task_struct(p);
+			p = NULL;
+		}
+	}
+	return p;
+}
+
+void free_task_struct(struct task_struct *p)
+{
+	if (p) {
+		gid_t *groups = p->groups;
+		if (__free_task_struct(p))
+			kfree(groups);
+	}
+}
+
 extern void init_timervecs (void);
 
 void __init sched_init(void)
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .9886-linux-2.4.19/mm/page_alloc.c .9886-linux-2.4.19.updated/mm/page_alloc.c
--- .9886-linux-2.4.19/mm/page_alloc.c	2003-03-18 04:59:25.000000000 +1100
+++ .9886-linux-2.4.19.updated/mm/page_alloc.c	2003-09-18 17:44:43.000000000 +1000
@@ -439,16 +439,22 @@ unsigned long get_zeroed_page(unsigned i
 	return 0;
 }
 
-void __free_pages(struct page *page, unsigned int order)
+/* Return true if refcount hit zero. */
+int __free_pages(struct page *page, unsigned int order)
 {
-	if (!PageReserved(page) && put_page_testzero(page))
+	if (!PageReserved(page) && put_page_testzero(page)) {
 		__free_pages_ok(page, order);
+		return 1;
+	}
+	return 0;
 }
 
-void free_pages(unsigned long addr, unsigned int order)
+/* Return true if refcount hit zero. */
+int free_pages(unsigned long addr, unsigned int order)
 {
 	if (addr != 0)
-		__free_pages(virt_to_page(addr), order);
+		return __free_pages(virt_to_page(addr), order);
+	return 0;
 }
 
 /*