From: William Lee Irwin III <wli@holomorphy.com>
To: Anton Blanchard <anton@samba.org>
Cc: linux-kernel@vger.kernel.org, mingo@elte.hu,
viro@parcelfarce.linux.theplanet.co.uk
Subject: Re: /proc/sys/kernel/pid_max issues
Date: Sun, 12 Sep 2004 02:58:05 -0700 [thread overview]
Message-ID: <20040912095805.GL2660@holomorphy.com> (raw)
In-Reply-To: <20040912093605.GJ2660@holomorphy.com>
On Sun, Sep 12, 2004 at 02:36:05AM -0700, William Lee Irwin III wrote:
> + if (map > &pidmap_array[pid_max/BITS_PER_PAGE])
> + map = pidmap_array;
> if (unlikely(!map->page)) {
> unsigned long page = get_zeroed_page(GFP_KERNEL);
If pid_max == BITS_PER_PAGE*n, none of &pidmap_array[pid_max/BITS_PER_PAGE]
is usable, so if we must complete a full revolution around pidmap_array[]
to discover a free pid slightly less than last_pid we will miss it. Hence:
-- wli
Index: mm4-2.6.9-rc1/kernel/pid.c
===================================================================
--- mm4-2.6.9-rc1.orig/kernel/pid.c 2004-09-08 05:46:18.000000000 -0700
+++ mm4-2.6.9-rc1/kernel/pid.c 2004-09-12 02:46:17.426981200 -0700
@@ -75,6 +75,8 @@
while (--*max_steps) {
if (++map == map_limit)
map = pidmap_array;
+ if (map > &pidmap_array[(pid_max-1)/BITS_PER_PAGE])
+ map = pidmap_array;
if (unlikely(!map->page)) {
unsigned long page = get_zeroed_page(GFP_KERNEL);
/*
@@ -135,13 +137,12 @@
*/
scan_more:
offset = find_next_zero_bit(map->page, BITS_PER_PAGE, offset);
- if (offset >= BITS_PER_PAGE)
+ pid = (map - pidmap_array) * BITS_PER_PAGE + offset;
+ if (offset >= BITS_PER_PAGE || pid >= pid_max)
goto next_map;
if (test_and_set_bit(offset, map->page))
goto scan_more;
-
/* we got the PID: */
- pid = (map - pidmap_array) * BITS_PER_PAGE + offset;
goto return_pid;
failure:
next prev parent reply other threads:[~2004-09-12 9:58 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-12 8:56 /proc/sys/kernel/pid_max issues Anton Blanchard
2004-09-12 9:36 ` William Lee Irwin III
2004-09-12 9:51 ` Ingo Molnar
2004-09-12 9:58 ` William Lee Irwin III [this message]
2004-09-12 10:10 ` William Lee Irwin III
2004-09-12 10:13 ` Ingo Molnar
2004-09-12 10:43 ` William Lee Irwin III
2004-09-12 10:45 ` William Lee Irwin III
2004-09-12 11:08 ` William Lee Irwin III
2004-09-12 11:20 ` Ingo Molnar
2004-09-12 17:13 ` William Lee Irwin III
2004-09-12 18:02 ` Chris Wedgwood
2004-09-12 23:06 ` William Lee Irwin III
2004-09-13 1:46 ` [pidhashing] rewrite alloc_pidmap() William Lee Irwin III
2004-09-12 9:39 ` /proc/sys/kernel/pid_max issues Ingo Molnar
2004-09-12 9:43 ` William Lee Irwin III
2004-09-12 12:18 ` Arjan van de Ven
2004-09-12 12:30 ` Anton Blanchard
2004-09-12 12:44 ` Arjan van de Ven
2004-09-12 13:34 ` Anton Blanchard
2004-09-12 13:41 ` Ingo Molnar
-- strict thread matches above, loose matches on Subject: below --
2004-09-13 3:20 Albert Cahalan
2004-09-13 7:42 ` William Lee Irwin III
2004-09-13 14:11 ` Albert Cahalan
2004-09-13 14:27 ` William Lee Irwin III
2004-09-13 14:51 ` Herbert Poetzl
2004-09-14 2:13 ` William Lee Irwin III
2004-09-23 13:13 ` Pavel Machek
2004-09-24 16:02 ` Martin Mares
2004-09-23 13:11 ` Pavel Machek
2004-09-13 7:57 ` Ingo Molnar
2004-09-13 13:54 ` Albert Cahalan
2004-09-13 14:24 ` William Lee Irwin III
2004-09-13 14:54 ` Albert Cahalan
2004-09-14 2:02 ` William Lee Irwin III
2004-09-14 15:32 ` Ingo Molnar
2004-09-18 18:32 ` Pavel Machek
2004-09-23 13:18 ` Pavel Machek
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