On Mon, Aug 13, 2012 at 06:28:46PM -0700, Julian Elischer wrote:
> On 8/13/12 3:33 PM, Dan Plassche wrote:
> >Konstantin,
> >
> >My apologies for any confusion.  Your patch solved the problem on
> >8.2.  Static and dynamic a.out binaries from 1.1.5.1 are working
> >normally in a chroot environment now.
> 
> you will also have to change PID_MAX (spelling?) to be 60000
> I have considered making this a tunable..
> If you don't then the shell in the 1.1.5.1 environment will not be 
> able to handle when a child
> get s a pid of > 16 bits and it will not be able to wait on it. so it 
> will suspend for ever.
> teh result is that you can not complete  a "make world".
> 
> last time I tried a "make world" completed in about 1 minute and a kernel
> (1.1.5.1 GENERIC) compiled in way less than a minute. that was in 7.x 
> days.
> 
> I'd like to see results under 9.2 on a modern machine.

I committed today a batch of changes that allowed me to run most of
the binaries from 1.1.5.1 CD on real amd64 machine.

Below is the pid_max tunable patch. I first thought that it cannot be
made a writeable sysctl, but then realized that there is nothing wrong
with having existing process pid be greater then pid_max, as far as it
is less then PID_MAX.

diff --git a/sys/compat/linprocfs/linprocfs.c b/sys/compat/linprocfs/linprocfs.c
index 3adbe96..03db81a 100644
--- a/sys/compat/linprocfs/linprocfs.c
+++ b/sys/compat/linprocfs/linprocfs.c
@@ -1230,7 +1230,7 @@ static int
 linprocfs_dopid_max(PFS_FILL_ARGS)
 {
 
-       sbuf_printf(sb, "%i\n", PID_MAX);
+       sbuf_printf(sb, "%i\n", pid_max);
        return (0);
 }
 
diff --git a/sys/compat/svr4/svr4_misc.c b/sys/compat/svr4/svr4_misc.c
index 8456e10..dd4a24f 100644
--- a/sys/compat/svr4/svr4_misc.c
+++ b/sys/compat/svr4/svr4_misc.c
@@ -824,7 +824,7 @@ svr4_sys_sysconfig(td, uap)
                *retval = 1;    /* XXX */
                break;
        case SVR4_CONFIG_MAXPID:
-               *retval = PID_MAX;
+               *retval = pid_max;
                break;
        case SVR4_CONFIG_STACK_PROT:
                *retval = PROT_READ|PROT_WRITE|PROT_EXEC;
diff --git a/sys/fs/pseudofs/pseudofs_vnops.c b/sys/fs/pseudofs/pseudofs_vnops.c
index 9f97cd3..9600e9a 100644
--- a/sys/fs/pseudofs/pseudofs_vnops.c
+++ b/sys/fs/pseudofs/pseudofs_vnops.c
@@ -531,7 +531,7 @@ pfs_lookup(struct vop_cachedlookup_args *va)
        if ((pn = pdn) != NULL) {
                pid = 0;
                for (pid = 0, i = 0; i < namelen && isdigit(pname[i]); ++i)
-                       if ((pid = pid * 10 + pname[i] - '0') > PID_MAX)
+                       if ((pid = pid * 10 + pname[i] - '0') > pid_max)
                                break;
                if (i == cnp->cn_namelen) {
                        pfs_unlock(pd);
diff --git a/sys/kern/init_main.c b/sys/kern/init_main.c
index ba905e0..3174a34 100644
--- a/sys/kern/init_main.c
+++ b/sys/kern/init_main.c
@@ -476,6 +476,7 @@ proc0_init(void *dummy __unused)
        knlist_init_mtx(&p->p_klist, &p->p_mtx);
        STAILQ_INIT(&p->p_ktr);
        p->p_nice = NZERO;
+       /* pid_max cannot be greater then PID_MAX */
        td->td_tid = PID_MAX + 1;
        LIST_INSERT_HEAD(TIDHASH(td->td_tid), td, td_hash);
        td->td_state = TDS_RUNNING;
diff --git a/sys/kern/kern_fork.c b/sys/kern/kern_fork.c
index 6cb95cd..69abb23 100644
--- a/sys/kern/kern_fork.c
+++ b/sys/kern/kern_fork.c
@@ -209,8 +209,8 @@ sysctl_kern_randompid(SYSCTL_HANDLER_ARGS)
        pid = randompid;
        error = sysctl_handle_int(oidp, &pid, 0, req);
        if (error == 0 && req->newptr != NULL) {
-               if (pid < 0 || pid > PID_MAX - 100)     /* out of range */
-                       pid = PID_MAX - 100;
+               if (pid < 0 || pid > pid_max - 100)     /* out of range */
+                       pid = pid_max - 100;
                else if (pid < 2)                       /* NOP */
                        pid = 0;
                else if (pid < 100)                     /* Make it reasonable */
@@ -259,8 +259,8 @@ retry:
         * restart somewhat above 0, as the low-numbered procs
         * tend to include daemons that don't exit.
         */
-       if (trypid >= PID_MAX) {
-               trypid = trypid % PID_MAX;
+       if (trypid >= pid_max) {
+               trypid = trypid % pid_max;
                if (trypid < 100)
                        trypid += 100;
                pidchecked = 0;
@@ -268,7 +268,7 @@ retry:
        if (trypid >= pidchecked) {
                int doingzomb = 0;
 
-               pidchecked = PID_MAX;
+               pidchecked = pid_max;
                /*
                 * Scan the active and zombie procs to check whether this pid
                 * is in use.  Remember the lowest pid that's greater
diff --git a/sys/kern/kern_mib.c b/sys/kern/kern_mib.c
index 75b3af9..dfc8695 100644
--- a/sys/kern/kern_mib.c
+++ b/sys/kern/kern_mib.c
@@ -499,6 +499,30 @@ SYSCTL_INT(_debug_sizeof, OID_AUTO, vnode, CTLFLAG_RD,
 SYSCTL_INT(_debug_sizeof, OID_AUTO, proc, CTLFLAG_RD,
     0, sizeof(struct proc), "sizeof(struct proc)");
 
+static int
+sysctl_kern_pid_max(SYSCTL_HANDLER_ARGS)
+{
+       int error, pm;
+
+       pm = pid_max;
+       error = sysctl_handle_int(oidp, &pm, 0, req);
+       if (error || !req->newptr)
+               return (error);
+       /* Permit update only if the new securelevel exceeds the old. */
+       sx_xlock(&proctree_lock);
+       sx_xlock(&allproc_lock);
+       if (pm > PID_MAX)
+               error = EINVAL;
+       else
+               pid_max = pm;
+       sx_xunlock(&allproc_lock);
+       sx_xunlock(&proctree_lock);
+       return (error);
+}
+SYSCTL_PROC(_kern, OID_AUTO, pid_max, CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_TUN |
+    CTLFLAG_MPSAFE, 0, 0, sysctl_kern_pid_max, "I",
+    "Maximum allowed pid");
+
 #include <sys/bio.h>
 #include <sys/buf.h>
 SYSCTL_INT(_debug_sizeof, OID_AUTO, bio, CTLFLAG_RD,
diff --git a/sys/kern/kern_thread.c b/sys/kern/kern_thread.c
index 69a416e..d21763c 100644
--- a/sys/kern/kern_thread.c
+++ b/sys/kern/kern_thread.c
@@ -269,7 +269,11 @@ threadinit(void)
 {
 
        mtx_init(&tid_lock, "TID lock", NULL, MTX_DEF);
-       /* leave one number for thread0 */
+
+       /*
+        * pid_max cannot be greater then PID_MAX.
+        * leave one number for thread0.
+        */
        tid_unrhdr = new_unrhdr(PID_MAX + 2, INT_MAX, &tid_lock);
 
        thread_zone = uma_zcreate("THREAD", sched_sizeof_thread(),
diff --git a/sys/kern/subr_param.c b/sys/kern/subr_param.c
index 8c13336..1c6b867 100644
--- a/sys/kern/subr_param.c
+++ b/sys/kern/subr_param.c
@@ -41,12 +41,13 @@ __FBSDID("$FreeBSD$");
 #include "opt_msgbuf.h"
 #include "opt_maxusers.h"
 
-#include <sys/limits.h>
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/kernel.h>
-#include <sys/sysctl.h>
+#include <sys/limits.h>
 #include <sys/msgbuf.h>
+#include <sys/sysctl.h>
+#include <sys/proc.h>
 
 #include <vm/vm.h>
 #include <vm/vm_param.h>
@@ -92,6 +93,7 @@ int   ncallout;                       /* maximum # of timer 
events */
 int    nbuf;
 int    ngroups_max;                    /* max # groups per process */
 int    nswbuf;
+pid_t  pid_max = PID_MAX;
 long   maxswzone;                      /* max swmeta KVA storage */
 long   maxbcache;                      /* max buffer cache KVA storage */
 long   maxpipekva;                     /* Limit on pipe KVA */
@@ -250,6 +252,13 @@ init_param1(void)
        TUNABLE_INT_FETCH("kern.ngroups", &ngroups_max);
        if (ngroups_max < NGROUPS_MAX)
                ngroups_max = NGROUPS_MAX;
+
+       /*
+        * Only allow to lower the maximal pid.
+        */
+       TUNABLE_INT_FETCH("kern.pid_max", &pid_max);
+       if (pid_max > PID_MAX)
+               pid_max = PID_MAX;
 }
 
 /*
diff --git a/sys/kern/sys_process.c b/sys/kern/sys_process.c
index 3883fe4..39e2a58 100644
--- a/sys/kern/sys_process.c
+++ b/sys/kern/sys_process.c
@@ -673,7 +673,7 @@ kern_ptrace(struct thread *td, int req, pid_t pid, void 
*addr, int data)
                p = td->td_proc;
                PROC_LOCK(p);
        } else {
-               if (pid <= PID_MAX) {
+               if (pid <= pid_max) {
                        if ((p = pfind(pid)) == NULL) {
                                if (proctree_locked)
                                        sx_xunlock(&proctree_lock);
diff --git a/sys/nlm/nlm_advlock.c b/sys/nlm/nlm_advlock.c
index 416cd1d..0c53be1 100644
--- a/sys/nlm/nlm_advlock.c
+++ b/sys/nlm/nlm_advlock.c
@@ -98,6 +98,7 @@ nlm_client_init(void *dummy)
        int i;
 
        mtx_init(&nlm_svid_lock, "NLM svid lock", NULL, MTX_DEF);
+       /* pid_max cannot be greater then PID_MAX */
        nlm_svid_allocator = new_unrhdr(PID_MAX + 2, INT_MAX, &nlm_svid_lock);
        for (i = 0; i < NLM_SVID_HASH_SIZE; i++)
                LIST_INIT(&nlm_file_svids[i]);
diff --git a/sys/sys/proc.h b/sys/sys/proc.h
index 06df632..4c4aa2f 100644
--- a/sys/sys/proc.h
+++ b/sys/sys/proc.h
@@ -696,11 +696,12 @@ MALLOC_DECLARE(M_SUBPROC);
 #define        FIRST_THREAD_IN_PROC(p) TAILQ_FIRST(&(p)->p_threads)
 
 /*
- * We use process IDs <= PID_MAX; PID_MAX + 1 must also fit in a pid_t,
- * as it is used to represent "no process group".
+ * We use process IDs <= pid_max <= PID_MAX; PID_MAX + 1 must also fit
+ * in a pid_t, as it is used to represent "no process group".
  */
 #define        PID_MAX         99999
 #define        NO_PID          100000
+extern pid_t pid_max;
 
 #define        SESS_LEADER(p)  ((p)->p_session->s_leader == (p))
 

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