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Re: [PATCH 4/5] ftrace: limit trace entries

Previous thread: [PATCH 5/5] ftrace: comment code by Steven Rostedt on Friday, April 18, 2008 - 4:05 pm. (1 message)

Next thread: Huge lockdep trace then system freeze after docking laptop by Chuck Ebbert on Friday, April 18, 2008 - 4:22 pm. (1 message)
[view original message]
From: Steven Rostedt <rostedt@...>
To: <linux-kernel@...>
Cc: Ingo Molnar <mingo@...>, Steven Rostedt <rostedt@...>, <akpm@...>, Peter Zijlstra <peterz@...>, Soeren Sandmann Pedersen <sandmann@...>, Pekka Paalanen <pq@...>, Steven Rostedt <srostedt@...>
Subject: [PATCH 4/5] ftrace: limit trace entries
Date: Friday, April 18, 2008 - 4:05 pm

Currently there is no protection from the root user to use up all of

memory for trace buffers. If the root user allocates too many entries,

the OOM killer might start kill off all tasks.


This patch adds an algorith to check the following condition:


 pages_requested > (freeable_memory + current_trace_buffer_pages) / 4


If the above is met then the allocation fails. The above prevents more

than 1/4th of freeable memory from being used by trace buffers.


To determine the freeable_memory, I made determine_dirtyable_memory in

mm/page-writeback.c global.


Special thanks goes to Peter Zijlstra for suggesting the above calculation.


Signed-off-by: Steven Rostedt <srostedt@redhat.com>

---

 include/linux/writeback.h |    2 ++

 kernel/trace/trace.c      |   38 ++++++++++++++++++++++++++++++++++++++

 mm/page-writeback.c       |   10 +++++++---

 3 files changed, 47 insertions(+), 3 deletions(-)


Index: linux-sched-devel.git/include/linux/writeback.h

===================================================================

--- linux-sched-devel.git.orig/include/linux/writeback.h	2008-04-18 15:47:21.000000000 -0400

+++ linux-sched-devel.git/include/linux/writeback.h	2008-04-18 15:53:08.000000000 -0400

@@ -105,6 +105,8 @@ extern int vm_highmem_is_dirtyable;

 extern int block_dump;

 extern int laptop_mode;


+extern unsigned long determine_dirtyable_memory(void);

+

 extern int dirty_ratio_handler(struct ctl_table *table, int write,

 		struct file *filp, void __user *buffer, size_t *lenp,

 		loff_t *ppos);

Index: linux-sched-devel.git/kernel/trace/trace.c

===================================================================

--- linux-sched-devel.git.orig/kernel/trace/trace.c	2008-04-18 15:50:47.000000000 -0400

+++ linux-sched-devel.git/kernel/trace/trace.c	2008-04-18 15:53:08.000000000 -0400

@@ -27,6 +27,7 @@

 #include <linux/poll.h>

 #include <linux/gfp.h>

 #include <linux/fs.h>

+#include <linux/writeback.h>


 #include <linux/stacktrace.h>


@@ -51,...
[ message continues ]
[view original message]
From: Andrew Morton <akpm@...>
To: Steven Rostedt <rostedt@...>
Cc: <linux-kernel@...>, <mingo@...>, <rostedt@...>, <peterz@...>, <sandmann@...>, <pq@...>, <srostedt@...>
Subject: Re: [PATCH 4/5] ftrace: limit trace entries
Date: Friday, April 18, 2008 - 4:19 pm

On Fri, 18 Apr 2008 16:05:42 -0400


tpyo

--
[view original message]
From: Ingo Molnar <mingo@...>
To: Andrew Morton <akpm@...>
Cc: Steven Rostedt <rostedt@...>, <linux-kernel@...>, <peterz@...>, <sandmann@...>, <pq@...>, <srostedt@...>
Subject: Re: [PATCH 4/5] ftrace: limit trace entries
Date: Saturday, April 19, 2008 - 2:10 am

thanks, fixed.


	Ingo

--
[view original message]
From: Steven Rostedt <rostedt@...>
To: Andrew Morton <akpm@...>
Cc: LKML <linux-kernel@...>, Ingo Molnar <mingo@...>, Peter Zijlstra <peterz@...>, <sandmann@...>, <pq@...>, <srostedt@...>
Subject: [PATCH 4/5 -v2] ftrace: limit trace entries
Date: Friday, April 18, 2008 - 11:17 pm

Currently there is no protection from the root user to use up all of

memory for trace buffers. If the root user allocates too many entries,

the OOM killer might start killing off all tasks.


This patch adds an algorithm to check the following condition:


 pages_requested > (freeable_memory + current_trace_buffer_pages) / 4


If the above is met then the allocation fails. The above prevents more

than 1/4th of freeable memory from being used by trace buffers.


To determine the freeable_memory, I made determine_dirtyable_memory in

mm/page-writeback.c global.


Special thanks goes to Peter Zijlstra for suggesting the above calculation.


Signed-off-by: Steven Rostedt <srostedt@redhat.com>

---

 include/linux/writeback.h |    2 ++

 kernel/trace/trace.c      |   38 ++++++++++++++++++++++++++++++++++++++

 mm/page-writeback.c       |   10 +++++++---

 3 files changed, 47 insertions(+), 3 deletions(-)


Index: linux-sched-devel.git/include/linux/writeback.h

===================================================================

--- linux-sched-devel.git.orig/include/linux/writeback.h	2008-04-18 23:01:57.000000000 -0400

+++ linux-sched-devel.git/include/linux/writeback.h	2008-04-18 23:06:43.000000000 -0400

@@ -105,6 +105,8 @@ extern int vm_highmem_is_dirtyable;

 extern int block_dump;

 extern int laptop_mode;


+extern unsigned long determine_dirtyable_memory(void);

+

 extern int dirty_ratio_handler(struct ctl_table *table, int write,

 		struct file *filp, void __user *buffer, size_t *lenp,

 		loff_t *ppos);

Index: linux-sched-devel.git/kernel/trace/trace.c

===================================================================

--- linux-sched-devel.git.orig/kernel/trace/trace.c	2008-04-18 23:06:40.000000000 -0400

+++ linux-sched-devel.git/kernel/trace/trace.c	2008-04-18 23:06:43.000000000 -0400

@@ -27,6 +27,7 @@

 #include <linux/poll.h>

 #include <linux/gfp.h>

 #include <linux/fs.h>

+#include <linux/writeback.h>


 #include <linux/stacktrace.h>


@@ -...
[ message continues ]
[view original message]
From: Steven Rostedt <rostedt@...>
To: Andrew Morton <akpm@...>
Cc: <linux-kernel@...>, <mingo@...>, <peterz@...>, <sandmann@...>, <pq@...>, <srostedt@...>
Subject: Re: [PATCH 4/5] ftrace: limit trace entries
Date: Friday, April 18, 2008 - 11:12 pm

Damn! You don't miss a thing. Are you sure your name isn't Monk?


New patch coming.


Thanks,


-- Steve


--
[view original message]
From: Andrew Morton <akpm@...>
To: Steven Rostedt <rostedt@...>
Cc: <linux-kernel@...>, <mingo@...>, <peterz@...>, <sandmann@...>, <pq@...>, <srostedt@...>
Subject: Re: [PATCH 4/5] ftrace: limit trace entries
Date: Friday, April 18, 2008 - 11:32 pm

We could do this all day at this level of detail :)

--
Previous thread: [PATCH 5/5] ftrace: comment code by Steven Rostedt on Friday, April 18, 2008 - 4:05 pm. (1 message)

Next thread: Huge lockdep trace then system freeze after docking laptop by Chuck Ebbert on Friday, April 18, 2008 - 4:22 pm. (1 message)