* [Bugfix] Set more than 32K pid_max
@ 2004-01-05 9:59 Zhu, Yi
2004-01-06 3:00 ` [Bugfix] Set more than 32K pid_max (reformatted) Zhu, Yi
0 siblings, 1 reply; 4+ messages in thread
From: Zhu, Yi @ 2004-01-05 9:59 UTC (permalink / raw)
To: linux-kernel
I found this is a bug in alloc_pidmap(). If one sets
/proc/sys/kernel/pid_max more than 32768, "map" will
increases 1 at (pid from 32767 to 32768)
110: map = pidmap_array + pid / BITS_PER_PAGE;
But at
126: map = next_free_map(map, &max_steps);
"map" will increase 1 again, because offset == 0.
This is not correct, but only happens when pid_max > 32k.
--- pid.c.old 2004-01-05 14:53:03.000000000 +0800
+++ pid.c 2004-01-05 17:27:53.000000000 +0800
@@ -122,6 +122,8 @@
}
if (!offset || !atomic_read(&map->nr_free)) {
+ if (!offset)
+ map--;
next_map:
map = next_free_map(map, &max_steps);
if (!map)
--
-----------------------------------------------------------------
Opinions expressed are those of the author and do not represent
Intel Corp.
Zhu Yi (Chuyee)
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^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bugfix] Set more than 32K pid_max (reformatted)
2004-01-05 9:59 [Bugfix] Set more than 32K pid_max Zhu, Yi
@ 2004-01-06 3:00 ` Zhu, Yi
2004-01-06 3:14 ` Marcos D. Marado Torres
2004-03-29 15:46 ` Marcos D. Marado Torres
0 siblings, 2 replies; 4+ messages in thread
From: Zhu, Yi @ 2004-01-06 3:00 UTC (permalink / raw)
To: Andrew Morton, Ingo Molnar; +Cc: linux-kernel
Hi Andrew and Ingo,
Would any of you review the below patch? I think it is a bug and the fix
is obvious. The bug can be reproduced as follow:
$ echo 40000 > /proc/sys/kernel/pid_max
$ # suppose current latest pid is 2198
$ for((i=2199;i<32768;i++));do ps; done
$ ps
PID TTY TIME CMD
2274 pts/0 00:00:00 bash
65536 pts/0 00:00:00 ps
$ ps
PID TTY TIME CMD
2274 pts/0 00:00:00 bash
300 pts/0 00:00:00 ps
Thanks Petri Koistinen reformatted the patch as follow.
--- linux-2.5/kernel/pid.c.orig 2004-01-05 17:54:46.000000000 +0200
+++ linux-2.5/kernel/pid.c 2004-01-05 17:55:35.000000000 +0200
@@ -122,6 +122,8 @@
}
if (!offset || !atomic_read(&map->nr_free)) {
+ if (!offser)
+ map--;
next_map:
map = next_free_map(map, &max_steps);
if (!map)
On Mon, 5 Jan 2004, Zhu, Yi wrote:
>
> I found this is a bug in alloc_pidmap(). If one sets
> /proc/sys/kernel/pid_max more than 32768, "map" will
> increases 1 at (pid from 32767 to 32768)
>
> 110: map = pidmap_array + pid / BITS_PER_PAGE;
>
> But at
>
> 126: map = next_free_map(map, &max_steps);
>
> "map" will increase 1 again, because offset == 0.
>
> This is not correct, but only happens when pid_max > 32k.
--
-----------------------------------------------------------------
Opinions expressed are those of the author and do not represent
Intel Corp.
Zhu Yi (Chuyee)
GnuPG v1.0.6 (GNU/Linux)
http://cn.geocities.com/chewie_chuyee/gpg.txt or
$ gpg --keyserver wwwkeys.pgp.net --recv-keys 71C34820
1024D/71C34820 C939 2B0B FBCE 1D51 109A 55E5 8650 DB90 71C3 4820
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Bugfix] Set more than 32K pid_max (reformatted)
2004-01-06 3:00 ` [Bugfix] Set more than 32K pid_max (reformatted) Zhu, Yi
@ 2004-01-06 3:14 ` Marcos D. Marado Torres
2004-03-29 15:46 ` Marcos D. Marado Torres
1 sibling, 0 replies; 4+ messages in thread
From: Marcos D. Marado Torres @ 2004-01-06 3:14 UTC (permalink / raw)
To: Zhu, Yi; +Cc: Andrew Morton, Ingo Molnar, linux-kernel
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On Tue, 6 Jan 2004, Zhu, Yi wrote:
> if (!offset || !atomic_read(&map->nr_free)) {
> + if (!offser)
I suppose it should be "if (!offset)"...
Mind Booster Noori
- --
==================================================
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^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Bugfix] Set more than 32K pid_max (reformatted)
2004-01-06 3:00 ` [Bugfix] Set more than 32K pid_max (reformatted) Zhu, Yi
2004-01-06 3:14 ` Marcos D. Marado Torres
@ 2004-03-29 15:46 ` Marcos D. Marado Torres
1 sibling, 0 replies; 4+ messages in thread
From: Marcos D. Marado Torres @ 2004-03-29 15:46 UTC (permalink / raw)
To: Administrator; +Cc: Andrew Morton, Ingo Molnar, linux-kernel
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On Tue, 6 Jan 2004, Zhu, Yi wrote:
> if (!offset || !atomic_read(&map->nr_free)) {
> + if (!offser)
I suppose it should be "if (!offset)"...
Mind Booster Noori
- --
==================================================
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/"\ http://student.dei.uc.pt/~marado
\ / marado@student.dei.uc.pt
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2004-01-05 9:59 [Bugfix] Set more than 32K pid_max Zhu, Yi
2004-01-06 3:00 ` [Bugfix] Set more than 32K pid_max (reformatted) Zhu, Yi
2004-01-06 3:14 ` Marcos D. Marado Torres
2004-03-29 15:46 ` Marcos D. Marado Torres
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