[PATCH] kretprobe instance recycled by parent process

[PATCH] kretprobe instance recycled by parent process

[bibo mao]

[-- Attachment #1: Type: text/plain, Size: 6335 bytes --]

When kretprobe probe schedule() function, if probed process exit then 
schedule() function will never return, so some kretprobe instance will 
never be recycled. By this patch the parent process will recycle 
retprobe instance of probed function, there will be no memory leak of 
kretprobe instance. This patch is based on 2.6.16-rc3.

Signed-off-by: bibo mao <bibo.mao@intel.com>

  arch/i386/kernel/process.c    |    8 --------
  arch/ia64/kernel/process.c    |    8 --------
  arch/powerpc/kernel/process.c |    2 --
  arch/x86_64/kernel/process.c  |    8 --------
  kernel/kprobes.c              |   10 +++++-----
  kernel/sched.c                |    9 ++++++++-
  6 files changed, 13 insertions(+), 32 deletions(-)
diff -Nruap linux-2.6.16-rc3.org/arch/i386/kernel/process.c 
linux-2.6.16-rc3/arch/i386/kernel/process.c
--- linux-2.6.16-rc3.org/arch/i386/kernel/process.c	2006-02-14 
05:46:38.000000000 +0800
+++ linux-2.6.16-rc3/arch/i386/kernel/process.c	2006-02-14 
05:48:06.000000000 +0800
@@ -38,7 +38,6 @@
  #include <linux/kallsyms.h>
  #include <linux/ptrace.h>
  #include <linux/random.h>
-#include <linux/kprobes.h>

  #include <asm/uaccess.h>
  #include <asm/pgtable.h>
@@ -364,13 +363,6 @@ void exit_thread(void)
  	struct task_struct *tsk = current;
  	struct thread_struct *t = &tsk->thread;

-	/*
-	 * Remove function-return probe instances associated with this task
-	 * and put them back on the free list. Do not insert an exit probe for
-	 * this function, it will be disabled by kprobe_flush_task if you do.
-	 */
-	kprobe_flush_task(tsk);
-
  	/* The process may have allocated an io port bitmap... nuke it. */
  	if (unlikely(NULL != t->io_bitmap_ptr)) {
  		int cpu = get_cpu();
diff -Nruap linux-2.6.16-rc3.org/arch/ia64/kernel/process.c 
linux-2.6.16-rc3/arch/ia64/kernel/process.c
--- linux-2.6.16-rc3.org/arch/ia64/kernel/process.c	2006-02-14 
05:46:38.000000000 +0800
+++ linux-2.6.16-rc3/arch/ia64/kernel/process.c	2006-02-14 
05:48:40.000000000 +0800
@@ -30,7 +30,6 @@
  #include <linux/efi.h>
  #include <linux/interrupt.h>
  #include <linux/delay.h>
-#include <linux/kprobes.h>

  #include <asm/cpu.h>
  #include <asm/delay.h>
@@ -738,13 +737,6 @@ void
  exit_thread (void)
  {

-	/*
-	 * Remove function-return probe instances associated with this task
-	 * and put them back on the free list. Do not insert an exit probe for
-	 * this function, it will be disabled by kprobe_flush_task if you do.
-	 */
-	kprobe_flush_task(current);
-
  	ia64_drop_fpu(current);
  #ifdef CONFIG_PERFMON
         /* if needed, stop monitoring and flush state to perfmon context */
diff -Nruap linux-2.6.16-rc3.org/arch/powerpc/kernel/process.c 
linux-2.6.16-rc3/arch/powerpc/kernel/process.c
--- linux-2.6.16-rc3.org/arch/powerpc/kernel/process.c	2006-02-14 
05:46:38.000000000 +0800
+++ linux-2.6.16-rc3/arch/powerpc/kernel/process.c	2006-02-14 
05:49:33.000000000 +0800
@@ -37,7 +37,6 @@
  #include <linux/mqueue.h>
  #include <linux/hardirq.h>
  #include <linux/utsname.h>
-#include <linux/kprobes.h>

  #include <asm/pgtable.h>
  #include <asm/uaccess.h>
@@ -457,7 +456,6 @@ void show_regs(struct pt_regs * regs)

  void exit_thread(void)
  {
-	kprobe_flush_task(current);
  	discard_lazy_cpu_state();
  }

diff -Nruap linux-2.6.16-rc3.org/arch/x86_64/kernel/process.c 
linux-2.6.16-rc3/arch/x86_64/kernel/process.c
--- linux-2.6.16-rc3.org/arch/x86_64/kernel/process.c	2006-02-14 
05:46:38.000000000 +0800
+++ linux-2.6.16-rc3/arch/x86_64/kernel/process.c	2006-02-14 
05:50:02.000000000 +0800
@@ -35,7 +35,6 @@
  #include <linux/ptrace.h>
  #include <linux/utsname.h>
  #include <linux/random.h>
-#include <linux/kprobes.h>
  #include <linux/notifier.h>

  #include <asm/uaccess.h>
@@ -353,13 +352,6 @@ void exit_thread(void)
  	struct task_struct *me = current;
  	struct thread_struct *t = &me->thread;

-	/*
-	 * Remove function-return probe instances associated with this task
-	 * and put them back on the free list. Do not insert an exit probe for
-	 * this function, it will be disabled by kprobe_flush_task if you do.
-	 */
-	kprobe_flush_task(me);
-
  	if (me->thread.io_bitmap_ptr) {
  		struct tss_struct *tss = &per_cpu(init_tss, get_cpu());

diff -Nruap linux-2.6.16-rc3.org/kernel/kprobes.c 
linux-2.6.16-rc3/kernel/kprobes.c
--- linux-2.6.16-rc3.org/kernel/kprobes.c	2006-02-14 05:46:38.000000000 
+0800
+++ linux-2.6.16-rc3/kernel/kprobes.c	2006-02-14 08:16:55.000000000 +0800
@@ -323,10 +323,10 @@ struct hlist_head __kprobes *kretprobe_i
  }

  /*
- * This function is called from exit_thread or flush_thread when task tk's
- * stack is being recycled so that we can recycle any function-return probe
- * instances associated with this task. These left over instances represent
- * probed functions that have been called but will never return.
+ * This function is called from finish_task_switch when task tk becomes 
dead,
+ * so that we can recycle any function-return probe instances associated
+ * with this task. These left over instances represent probed functions
+ * that have been called but will never return.
   */
  void __kprobes kprobe_flush_task(struct task_struct *tk)
  {
@@ -336,7 +336,7 @@ void __kprobes kprobe_flush_task(struct
  	unsigned long flags = 0;

  	spin_lock_irqsave(&kretprobe_lock, flags);
-        head = kretprobe_inst_table_head(current);
+        head = kretprobe_inst_table_head(tk);
          hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
                  if (ri->task == tk)
                          recycle_rp_inst(ri);
diff -Nruap linux-2.6.16-rc3.org/kernel/sched.c 
linux-2.6.16-rc3/kernel/sched.c
--- linux-2.6.16-rc3.org/kernel/sched.c	2006-02-14 05:46:38.000000000 +0800
+++ linux-2.6.16-rc3/kernel/sched.c	2006-02-14 06:11:57.000000000 +0800
@@ -49,6 +49,7 @@
  #include <linux/syscalls.h>
  #include <linux/times.h>
  #include <linux/acct.h>
+#include <linux/kprobes.h>
  #include <asm/tlb.h>

  #include <asm/unistd.h>
@@ -1566,8 +1567,14 @@ static inline void finish_task_switch(ru
  	finish_lock_switch(rq, prev);
  	if (mm)
  		mmdrop(mm);
-	if (unlikely(prev_task_flags & PF_DEAD))
+	if (unlikely(prev_task_flags & PF_DEAD)){
+		/*
+	 	 * Remove function-return probe instances associated with this task
+	 	 * and put them back on the free list.
+	 	 */
+		kprobe_flush_task(prev);
  		put_task_struct(prev);
+	}
  }

  /**

[-- Attachment #2: kretprobe_instance_patch_2.6.16-rc3 --]
[-- Type: text/plain, Size: 5889 bytes --]

 arch/i386/kernel/process.c    |    8 --------
 arch/ia64/kernel/process.c    |    8 --------
 arch/powerpc/kernel/process.c |    2 --
 arch/x86_64/kernel/process.c  |    8 --------
 kernel/kprobes.c              |   10 +++++-----
 kernel/sched.c                |    9 ++++++++-
 6 files changed, 13 insertions(+), 32 deletions(-)
diff -Nruap linux-2.6.16-rc3.org/arch/i386/kernel/process.c linux-2.6.16-rc3/arch/i386/kernel/process.c
--- linux-2.6.16-rc3.org/arch/i386/kernel/process.c	2006-02-14 05:46:38.000000000 +0800
+++ linux-2.6.16-rc3/arch/i386/kernel/process.c	2006-02-14 05:48:06.000000000 +0800
@@ -38,7 +38,6 @@
 #include <linux/kallsyms.h>
 #include <linux/ptrace.h>
 #include <linux/random.h>
-#include <linux/kprobes.h>
 
 #include <asm/uaccess.h>
 #include <asm/pgtable.h>
@@ -364,13 +363,6 @@ void exit_thread(void)
 	struct task_struct *tsk = current;
 	struct thread_struct *t = &tsk->thread;
 
-	/*
-	 * Remove function-return probe instances associated with this task
-	 * and put them back on the free list. Do not insert an exit probe for
-	 * this function, it will be disabled by kprobe_flush_task if you do.
-	 */
-	kprobe_flush_task(tsk);
-
 	/* The process may have allocated an io port bitmap... nuke it. */
 	if (unlikely(NULL != t->io_bitmap_ptr)) {
 		int cpu = get_cpu();
diff -Nruap linux-2.6.16-rc3.org/arch/ia64/kernel/process.c linux-2.6.16-rc3/arch/ia64/kernel/process.c
--- linux-2.6.16-rc3.org/arch/ia64/kernel/process.c	2006-02-14 05:46:38.000000000 +0800
+++ linux-2.6.16-rc3/arch/ia64/kernel/process.c	2006-02-14 05:48:40.000000000 +0800
@@ -30,7 +30,6 @@
 #include <linux/efi.h>
 #include <linux/interrupt.h>
 #include <linux/delay.h>
-#include <linux/kprobes.h>
 
 #include <asm/cpu.h>
 #include <asm/delay.h>
@@ -738,13 +737,6 @@ void
 exit_thread (void)
 {
 
-	/*
-	 * Remove function-return probe instances associated with this task
-	 * and put them back on the free list. Do not insert an exit probe for
-	 * this function, it will be disabled by kprobe_flush_task if you do.
-	 */
-	kprobe_flush_task(current);
-
 	ia64_drop_fpu(current);
 #ifdef CONFIG_PERFMON
        /* if needed, stop monitoring and flush state to perfmon context */
diff -Nruap linux-2.6.16-rc3.org/arch/powerpc/kernel/process.c linux-2.6.16-rc3/arch/powerpc/kernel/process.c
--- linux-2.6.16-rc3.org/arch/powerpc/kernel/process.c	2006-02-14 05:46:38.000000000 +0800
+++ linux-2.6.16-rc3/arch/powerpc/kernel/process.c	2006-02-14 05:49:33.000000000 +0800
@@ -37,7 +37,6 @@
 #include <linux/mqueue.h>
 #include <linux/hardirq.h>
 #include <linux/utsname.h>
-#include <linux/kprobes.h>
 
 #include <asm/pgtable.h>
 #include <asm/uaccess.h>
@@ -457,7 +456,6 @@ void show_regs(struct pt_regs * regs)
 
 void exit_thread(void)
 {
-	kprobe_flush_task(current);
 	discard_lazy_cpu_state();
 }
 
diff -Nruap linux-2.6.16-rc3.org/arch/x86_64/kernel/process.c linux-2.6.16-rc3/arch/x86_64/kernel/process.c
--- linux-2.6.16-rc3.org/arch/x86_64/kernel/process.c	2006-02-14 05:46:38.000000000 +0800
+++ linux-2.6.16-rc3/arch/x86_64/kernel/process.c	2006-02-14 05:50:02.000000000 +0800
@@ -35,7 +35,6 @@
 #include <linux/ptrace.h>
 #include <linux/utsname.h>
 #include <linux/random.h>
-#include <linux/kprobes.h>
 #include <linux/notifier.h>
 
 #include <asm/uaccess.h>
@@ -353,13 +352,6 @@ void exit_thread(void)
 	struct task_struct *me = current;
 	struct thread_struct *t = &me->thread;
 
-	/*
-	 * Remove function-return probe instances associated with this task
-	 * and put them back on the free list. Do not insert an exit probe for
-	 * this function, it will be disabled by kprobe_flush_task if you do.
-	 */
-	kprobe_flush_task(me);
-
 	if (me->thread.io_bitmap_ptr) { 
 		struct tss_struct *tss = &per_cpu(init_tss, get_cpu());
 
diff -Nruap linux-2.6.16-rc3.org/kernel/kprobes.c linux-2.6.16-rc3/kernel/kprobes.c
--- linux-2.6.16-rc3.org/kernel/kprobes.c	2006-02-14 05:46:38.000000000 +0800
+++ linux-2.6.16-rc3/kernel/kprobes.c	2006-02-14 08:16:55.000000000 +0800
@@ -323,10 +323,10 @@ struct hlist_head __kprobes *kretprobe_i
 }
 
 /*
- * This function is called from exit_thread or flush_thread when task tk's
- * stack is being recycled so that we can recycle any function-return probe
- * instances associated with this task. These left over instances represent
- * probed functions that have been called but will never return.
+ * This function is called from finish_task_switch when task tk becomes dead,
+ * so that we can recycle any function-return probe instances associated 
+ * with this task. These left over instances represent probed functions 
+ * that have been called but will never return.
  */
 void __kprobes kprobe_flush_task(struct task_struct *tk)
 {
@@ -336,7 +336,7 @@ void __kprobes kprobe_flush_task(struct 
 	unsigned long flags = 0;
 
 	spin_lock_irqsave(&kretprobe_lock, flags);
-        head = kretprobe_inst_table_head(current);
+        head = kretprobe_inst_table_head(tk);
         hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
                 if (ri->task == tk)
                         recycle_rp_inst(ri);
diff -Nruap linux-2.6.16-rc3.org/kernel/sched.c linux-2.6.16-rc3/kernel/sched.c
--- linux-2.6.16-rc3.org/kernel/sched.c	2006-02-14 05:46:38.000000000 +0800
+++ linux-2.6.16-rc3/kernel/sched.c	2006-02-14 06:11:57.000000000 +0800
@@ -49,6 +49,7 @@
 #include <linux/syscalls.h>
 #include <linux/times.h>
 #include <linux/acct.h>
+#include <linux/kprobes.h>
 #include <asm/tlb.h>
 
 #include <asm/unistd.h>
@@ -1566,8 +1567,14 @@ static inline void finish_task_switch(ru
 	finish_lock_switch(rq, prev);
 	if (mm)
 		mmdrop(mm);
-	if (unlikely(prev_task_flags & PF_DEAD))
+	if (unlikely(prev_task_flags & PF_DEAD)){
+		/*
+	 	 * Remove function-return probe instances associated with this task
+	 	 * and put them back on the free list.
+	 	 */
+		kprobe_flush_task(prev);
 		put_task_struct(prev);
+	}
 }
 
 /**

Fwd: [PATCH] kretprobe instance recycled by parent process

[Zhou Yingchao]

2006/2/15, bibo mao <bibo_mao@linux.intel.com>:
> When kretprobe probe schedule() function, if probed process exit then
> schedule() function will never return, so some kretprobe instance will
> never be recycled. By this patch the parent process will recycle
> retprobe instance of probed function, there will be no memory leak of
> kretprobe instance. This patch is based on 2.6.16-rc3.

Is there any process which can exit without go through the do_exit() path?
--
Yingchao Zhou
***********************************************
 Institute Of Computing Technology
 Chinese Academy of Sciences
 Tel(O) : 010-62613792-28
***********************************************


--
Yingchao Zhou
***********************************************
 Institute Of Computing Technology
 Chinese Academy of Sciences
 Tel(O) : 010-62613792-28
***********************************************

Re: Fwd: [PATCH] kretprobe instance recycled by parent process

[bibo mao]

Zhou Yingchao wrote:
> 2006/2/15, bibo mao <bibo_mao@linux.intel.com>:
>> When kretprobe probe schedule() function, if probed process exit then
>> schedule() function will never return, so some kretprobe instance will
>> never be recycled. By this patch the parent process will recycle
>> retprobe instance of probed function, there will be no memory leak of
>> kretprobe instance. This patch is based on 2.6.16-rc3.
> 
> Is there any process which can exit without go through the do_exit() path?
> --
When process exits through do_exit() function, it will call schedule() 
function. But if schedule() function is probed by kretprobe, this time 
schedule() function will not return never because process has exited.

bibo,mao

Re: Fwd: [PATCH] kretprobe instance recycled by parent process

[Zhou Yingchao]

> >> When kretprobe probe schedule() function, if probed process exit then
> >> schedule() function will never return, so some kretprobe instance will
> >> never be recycled. By this patch the parent process will recycle
> >> retprobe instance of probed function, there will be no memory leak of
> >> kretprobe instance. This patch is based on 2.6.16-rc3.
> >
> > Is there any process which can exit without go through the do_exit() path?
> > --
> When process exits through do_exit() function, it will call schedule()
> function. But if schedule() function is probed by kretprobe, this time
> schedule() function will not return never because process has exited.
>
> bibo,mao
>

In the original path, doesn't the call path of
do_exit()->exit_thread()->kprobe_flush_task(current) recycle the
kretprobe instance? Is there anything misundstood?
--
Yingchao Zhou
***********************************************
 Institute Of Computing Technology
 Chinese Academy of Sciences
 Tel(O) : 010-62613792-28
***********************************************

Re: Fwd: [PATCH] kretprobe instance recycled by parent process

[bibo mao]

Zhou Yingchao wrote:
>>>> When kretprobe probe schedule() function, if probed process exit then
>>>> schedule() function will never return, so some kretprobe instance will
>>>> never be recycled. By this patch the parent process will recycle
>>>> retprobe instance of probed function, there will be no memory leak of
>>>> kretprobe instance. This patch is based on 2.6.16-rc3.
>>> Is there any process which can exit without go through the do_exit() path?
>>> --
>> When process exits through do_exit() function, it will call schedule()
>> function. But if schedule() function is probed by kretprobe, this time
>> schedule() function will not return never because process has exited.
>>
>> bibo,mao
>>
> 
> In the original path, doesn't the call path of
> do_exit()->exit_thread()->kprobe_flush_task(current) recycle the
> kretprobe instance? Is there anything misundstood?
> --
yes, it is right. The old recycle method is
    do_exit()->exit_thread()->kprobe_flush_task(current)
             ->schedule()
At last line of do_exit() it will call schedule() function, and this 
time it will never return. But if schedule function is probed, who is 
responsible for recycling it?

bibo,mao