[PATCH] calculate NGROUPS_PER_BLOCK from PAGE_SIZE

[edwardsg@sgi.com (Greg Edwards)]

On ia64, EXEC_PAGESIZE (max page size) is 65536, but the default page
size is 16k.  This results in NGROUPS_PER_BLOCK in include/linux/sched.h
being calculated incorrectly when the page size is anything other than
64k.  For example, on a 16k page size kernel, a setgroups() call with a
gidsetsize of 65536 will end up walking over memory since only 1/4 of
the needed pages were allocated for the blocks[] array in the group_info
struct.

Patch below calculates NGROUPS_PER_BLOCK from PAGE_SIZE instead.

Greg


===== include/linux/sched.h 1.210 vs edited =====
--- 1.210/include/linux/sched.h	Mon May 10 06:25:34 2004
+++ edited/include/linux/sched.h	Tue May 11 11:45:29 2004
@@ -352,7 +352,7 @@
 void exit_io_context(void);
 
 #define NGROUPS_SMALL		32
-#define NGROUPS_PER_BLOCK	((int)(EXEC_PAGESIZE / sizeof(gid_t)))
+#define NGROUPS_PER_BLOCK	((int)(PAGE_SIZE / sizeof(gid_t)))
 struct group_info {
 	int ngroups;
 	atomic_t usage;