[pidhashing] [3/3] enforce PID_MAX_LIMIT in sysctls

William Lee Irwin III
2004-09-14T02:41:26Z

On Mon, Sep 13, 2004 at 07:31:14PM -0700, William Lee Irwin III wrote:
> /proc/ breaks when PID_MAX_LIMIT is elevated on 32-bit, so this patch
> lowers it there. Compiletested on x86-64.

The pid_max sysctl doesn't enforce PID_MAX_LIMIT or sane lower bounds.
RESERVED_PIDS + 1 is the minimum pid_max that won't break alloc_pidmap(),
and PID_MAX_LIMIT may not be aligned to 8*PAGE_SIZE boundaries for
unusual values of PAGE_SIZE, so this also rounds up PID_MAX_LIMIT to it.
Compiletested on x86-64.

Index: mm5-2.6.9-rc1/kernel/pid.c
===================================================================
--- mm5-2.6.9-rc1.orig/kernel/pid.c 2004-09-13 16:30:21.980111568 -0700
+++ mm5-2.6.9-rc1/kernel/pid.c 2004-09-13 16:33:06.324127480 -0700
@@ -36,7 +36,10 @@

#define RESERVED_PIDS 300

-#define PIDMAP_ENTRIES (PID_MAX_LIMIT/PAGE_SIZE/8)
+int pid_max_min = RESERVED_PIDS + 1;
+int pid_max_max = PID_MAX_LIMIT;
+
+#define PIDMAP_ENTRIES ((PID_MAX_LIMIT + 8*PAGE_SIZE - 1)/PAGE_SIZE/8)
#define BITS_PER_PAGE (PAGE_SIZE*8)
#define BITS_PER_PAGE_MASK (BITS_PER_PAGE-1)
#define mk_pid(map, off) (((map) - pidmap_array)*BITS_PER_PAGE + (off))
Index: mm5-2.6.9-rc1/kernel/sysctl.c
===================================================================
--- mm5-2.6.9-rc1.orig/kernel/sysctl.c 2004-09-13 16:27:44.621033784 -0700
+++ mm5-2.6.9-rc1/kernel/sysctl.c 2004-09-13 16:40:46.358191672 -0700
@@ -68,6 +68,7 @@
extern int sched_base_timeslice;
extern int sched_min_base;
extern int sched_max_base;
+extern int pid_max_min, pid_max_max;

#if defined(CONFIG_X86_LOCAL_APIC) && defined(__i386__)
int unknown_nmi_panic;
@@ -577,7 +578,10 @@
.data = &pid_max,
.maxlen = sizeof (int),
.mode = 0644,
- .proc_handler = &proc_dointvec,
+ .proc_handler = &proc_dointvec_minmax,
+ .strategy = sysctl_intvec,
+ .extra1 = &pid_max_min,
+ .extra2 = &pid_max_max,
},
{
.ctl_name = KERN_PANIC_ON_OOPS,