From: Keith Owens <kaos@sgi.com>
New pdflush threads are launched on-demand by pdflush.
It turns out that on some architectures (eg, ia64) a kernel thread inherits
its parent's stack utilisation. So after the thread-launches-a-thread
cycle has progressed sufficiently far we run out of stack space and crash.
Simple fix: convert pdflush to use kthreads. All kthreads are parented by
keventd so there is no stack windup as a result of pdflush launching
pdflush.
---
mm/pdflush.c | 8 +++++---
1 files changed, 5 insertions(+), 3 deletions(-)
diff -puN mm/pdflush.c~pdflush-use-kthread mm/pdflush.c
--- 25/mm/pdflush.c~pdflush-use-kthread 2004-02-28 21:31:37.000000000 -0800
+++ 25-akpm/mm/pdflush.c 2004-02-28 21:31:53.000000000 -0800
@@ -5,6 +5,9 @@
*
* 09Apr2002 akpm@zip.com.au
* Initial version
+ * 29Feb2004 kaos@sgi.com
+ * Move worker thread creation to kthread to avoid chewing
+ * up stack space with nested calls to kernel_thread.
*/
#include <linux/sched.h>
@@ -17,6 +20,7 @@
#include <linux/suspend.h>
#include <linux/fs.h> // Needed by writeback.h
#include <linux/writeback.h> // Prototypes pdflush_operation()
+#include <linux/kthread.h>
/*
@@ -86,8 +90,6 @@ struct pdflush_work {
static int __pdflush(struct pdflush_work *my_work)
{
- daemonize("pdflush");
-
current->flags |= PF_FLUSHER;
my_work->fn = NULL;
my_work->who = current;
@@ -207,7 +209,7 @@ int pdflush_operation(void (*fn)(unsigne
static void start_one_pdflush_thread(void)
{
- kernel_thread(pdflush, NULL, CLONE_KERNEL);
+ kthread_run(pdflush, NULL, "pdflush");
}
static int __init pdflush_init(void)
_