[PATCH v3 1/3] sched: fix confusing PFA_NO_NEW_PRIVS constant

[PATCH v3 1/3] sched: fix confusing PFA_NO_NEW_PRIVS constant

[Zefan Li]

From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>

Commit 1d4457f99928 ("sched: move no_new_privs into new atomic flags")
defined PFA_NO_NEW_PRIVS as hexadecimal value, but it is confusing
because it is used as bit number. Redefine it as decimal bit number.

Note this changes the bit position of PFA_NOW_NEW_PRIVS from 1 to 0.

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Miao Xie <miaox@cn.fujitsu.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Kees Cook <keescook@chromium.org>
[ lizf: slightly modified subject and changelog ]
Signed-off-by: Zefan Li <lizefan@huawei.com>
---
 include/linux/sched.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 5c2c885..4557765 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1957,7 +1957,7 @@ static inline void memalloc_noio_restore(unsigned int flags)
 }
 
 /* Per-process atomic flags. */
-#define PFA_NO_NEW_PRIVS 0x00000001	/* May not gain new privileges. */
+#define PFA_NO_NEW_PRIVS 0	/* May not gain new privileges. */
 
 static inline bool task_no_new_privs(struct task_struct *p)
 {
-- 
1.8.0.2

[PATCH v3 2/3] sched: add macros to define bitops for task atomic flags

[Zefan Li]

This will simplify code when we add new flags.

v3:
- Kees pointed out that no_new_privs should never be cleared, so we
shouldn't define task_clear_no_new_privs(). we define 3 macros instead
of a single one.

v2:
- updated scripts/tags.sh, suggested by Peter.

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Miao Xie <miaox@cn.fujitsu.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Zefan Li <lizefan@huawei.com>
---
 include/linux/sched.h | 21 ++++++++++++---------
 scripts/tags.sh       |  6 ++++++
 2 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 4557765..5630763 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1959,15 +1959,18 @@ static inline void memalloc_noio_restore(unsigned int flags)
 /* Per-process atomic flags. */
 #define PFA_NO_NEW_PRIVS 0	/* May not gain new privileges. */
 
-static inline bool task_no_new_privs(struct task_struct *p)
-{
-	return test_bit(PFA_NO_NEW_PRIVS, &p->atomic_flags);
-}
-
-static inline void task_set_no_new_privs(struct task_struct *p)
-{
-	set_bit(PFA_NO_NEW_PRIVS, &p->atomic_flags);
-}
+#define TASK_PFA_TEST(name, func)					\
+	static inline bool task_##func(struct task_struct *p)		\
+	{ return test_bit(PFA_##name, &p->atomic_flags); }
+#define TASK_PFA_SET(name, func)					\
+	static inline void task_set_##func(struct task_struct *p)	\
+	{ set_bit(PFA_##name, &p->atomic_flags); }
+#define TASK_PFA_CLEAR(name, func)					\
+	static inline void task_clear_##func(struct task_struct *p)	\
+	{ clear_bit(PFA_##name, &p->atomic_flags); }
+
+TASK_PFA_TEST(NO_NEW_PRIVS, no_new_privs)
+TASK_PFA_SET(NO_NEW_PRIVS, no_new_privs)
 
 /*
  * task->jobctl flags
diff --git a/scripts/tags.sh b/scripts/tags.sh
index cbfd269..293828b 100755
--- a/scripts/tags.sh
+++ b/scripts/tags.sh
@@ -197,6 +197,9 @@ exuberant()
 	--regex-c++='/SETPCGFLAG\(([^,)]*).*/SetPageCgroup\1/'		\
 	--regex-c++='/CLEARPCGFLAG\(([^,)]*).*/ClearPageCgroup\1/'	\
 	--regex-c++='/TESTCLEARPCGFLAG\(([^,)]*).*/TestClearPageCgroup\1/' \
+	--regex-c++='/TASK_PFA_TEST\([^,]*,\s*([^)]*)\)/task_\1/'	\
+	--regex-c++='/TASK_PFA_SET\([^,]*,\s*([^)]*)\)/task_set_\1/'	\
+	--regex-c++='/TASK_PFA_CLEAR\([^,]*,\s*([^)]*)\)/task_clear_\1/'\
 	--regex-c='/PCI_OP_READ\((\w*).*[1-4]\)/pci_bus_read_config_\1/' \
 	--regex-c='/PCI_OP_WRITE\((\w*).*[1-4]\)/pci_bus_write_config_\1/' \
 	--regex-c='/DEFINE_(MUTEX|SEMAPHORE|SPINLOCK)\((\w*)/\2/v/'	\
@@ -260,6 +263,9 @@ emacs()
 	--regex='/SETPCGFLAG\(([^,)]*).*/SetPageCgroup\1/'	\
 	--regex='/CLEARPCGFLAG\(([^,)]*).*/ClearPageCgroup\1/'	\
 	--regex='/TESTCLEARPCGFLAG\(([^,)]*).*/TestClearPageCgroup\1/' \
+	--regex='/TASK_PFA_TEST\([^,]*,\s*([^)]*)\)/task_\1/'		\
+	--regex='/TASK_PFA_SET\([^,]*,\s*([^)]*)\)/task_set_\1/'	\
+	--regex='/TASK_PFA_CLEAR\([^,]*,\s*([^)]*)\)/task_clear_\1/'	\
 	--regex='/_PE(\([^,)]*\).*/PEVENT_ERRNO__\1/'		\
 	--regex='/PCI_OP_READ(\([a-z]*[a-z]\).*[1-4])/pci_bus_read_config_\1/' \
 	--regex='/PCI_OP_WRITE(\([a-z]*[a-z]\).*[1-4])/pci_bus_write_config_\1/'\
-- 
1.8.0.2

Re: [PATCH v3 2/3] sched: add macros to define bitops for task atomic flags

[Peter Zijlstra]

On Tue, Sep 23, 2014 at 03:44:59PM +0800, Zefan Li wrote:
> This will simplify code when we add new flags.
> 
> v3:
> - Kees pointed out that no_new_privs should never be cleared, so we
> shouldn't define task_clear_no_new_privs(). we define 3 macros instead
> of a single one.
> 
> v2:
> - updated scripts/tags.sh, suggested by Peter.
> 
> Cc: Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
> Cc: Ingo Molnar <mingo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
> Cc: Miao Xie <miaox-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
> Cc: Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
> Cc: Tetsuo Handa <penguin-kernel-JPay3/Yim36HaxMnTkn67Xf5DAMn2ifp@public.gmane.org>
> Signed-off-by: Zefan Li <lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>

Acked-by: Peter Zijlstra (Intel) <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>

Re: [PATCH v3 2/3] sched: add macros to define bitops for task atomic flags

[Kees Cook]

On Tue, Sep 23, 2014 at 3:01 AM, Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org> wrote:
> On Tue, Sep 23, 2014 at 03:44:59PM +0800, Zefan Li wrote:
>> This will simplify code when we add new flags.
>>
>> v3:
>> - Kees pointed out that no_new_privs should never be cleared, so we
>> shouldn't define task_clear_no_new_privs(). we define 3 macros instead
>> of a single one.

Thanks! This looks good to me.

>>
>> v2:
>> - updated scripts/tags.sh, suggested by Peter.
>>
>> Cc: Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
>> Cc: Ingo Molnar <mingo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
>> Cc: Miao Xie <miaox-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
>> Cc: Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
>> Cc: Tetsuo Handa <penguin-kernel-JPay3/Yim36HaxMnTkn67Xf5DAMn2ifp@public.gmane.org>
>> Signed-off-by: Zefan Li <lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
>
> Acked-by: Peter Zijlstra (Intel) <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>

Acked-by: Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>

-Kees

-- 
Kees Cook
Chrome OS Security

[PATCH v3 3/3] cpuset: PF_SPREAD_PAGE and PF_SPREAD_SLAB should be atomic flags

[Zefan Li]

When we change cpuset.memory_spread_{page,slab}, cpuset will flip
PF_SPREAD_{PAGE,SLAB} bit of tsk->flags for each task in that cpuset.
This should be done using atomic bitops, but currently we don't,
which is broken.

Tetsuo reported a hard-to-reproduce kernel crash on RHEL6, which happend
when one thread tried to clear PF_USED_MATH while at the same time another
thread tried to flip PF_SPREAD_PAGE/PF_SPREAD_SLAB. They both operate on
the same task.

Here's the full report:
https://lkml.org/lkml/2014/9/19/230

To fix this, we make PF_SPREAD_PAGE and PF_SPARED_SLAB atomic flags.

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Miao Xie <miaox@cn.fujitsu.com>
Cc: Kees Cook <keescook@chromium.org>
Fixes: 950592f7b991 ("cpusets: update tasks' page/slab spread flags in time")
Cc: <stable@vger.kernel.org> # 2.6.31+
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Zefan Li <lizefan@huawei.com>
---
 include/linux/cpuset.h |  4 ++--
 include/linux/sched.h  | 13 +++++++++++--
 kernel/cpuset.c        |  9 +++++----
 3 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
index 0d4e067..2f073db 100644
--- a/include/linux/cpuset.h
+++ b/include/linux/cpuset.h
@@ -94,12 +94,12 @@ extern int cpuset_slab_spread_node(void);
 
 static inline int cpuset_do_page_mem_spread(void)
 {
-	return current->flags & PF_SPREAD_PAGE;
+	return task_spread_page(current);
 }
 
 static inline int cpuset_do_slab_mem_spread(void)
 {
-	return current->flags & PF_SPREAD_SLAB;
+	return task_spread_slab(current);
 }
 
 extern int current_cpuset_is_being_rebound(void);
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 5630763..7b1cafe 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1903,8 +1903,6 @@ extern void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut,
 #define PF_KTHREAD	0x00200000	/* I am a kernel thread */
 #define PF_RANDOMIZE	0x00400000	/* randomize virtual address space */
 #define PF_SWAPWRITE	0x00800000	/* Allowed to write to swap */
-#define PF_SPREAD_PAGE	0x01000000	/* Spread page cache over cpuset */
-#define PF_SPREAD_SLAB	0x02000000	/* Spread some slab caches over cpuset */
 #define PF_NO_SETAFFINITY 0x04000000	/* Userland is not allowed to meddle with cpus_allowed */
 #define PF_MCE_EARLY    0x08000000      /* Early kill for mce process policy */
 #define PF_MUTEX_TESTER	0x20000000	/* Thread belongs to the rt mutex tester */
@@ -1958,6 +1956,9 @@ static inline void memalloc_noio_restore(unsigned int flags)
 
 /* Per-process atomic flags. */
 #define PFA_NO_NEW_PRIVS 0	/* May not gain new privileges. */
+#define PFA_SPREAD_PAGE  1      /* Spread page cache over cpuset */
+#define PFA_SPREAD_SLAB  2      /* Spread some slab caches over cpuset */
+
 
 #define TASK_PFA_TEST(name, func)					\
 	static inline bool task_##func(struct task_struct *p)		\
@@ -1972,6 +1973,14 @@ static inline void memalloc_noio_restore(unsigned int flags)
 TASK_PFA_TEST(NO_NEW_PRIVS, no_new_privs)
 TASK_PFA_SET(NO_NEW_PRIVS, no_new_privs)
 
+TASK_PFA_TEST(SPREAD_PAGE, spread_page)
+TASK_PFA_SET(SPREAD_PAGE, spread_page)
+TASK_PFA_CLEAR(SPREAD_PAGE, spread_page)
+
+TASK_PFA_TEST(SPREAD_SLAB, spread_slab)
+TASK_PFA_SET(SPREAD_SLAB, spread_slab)
+TASK_PFA_CLEAR(SPREAD_SLAB, spread_slab)
+
 /*
  * task->jobctl flags
  */
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index a37f4ed..1f107c7 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -365,13 +365,14 @@ static void cpuset_update_task_spread_flag(struct cpuset *cs,
 					struct task_struct *tsk)
 {
 	if (is_spread_page(cs))
-		tsk->flags |= PF_SPREAD_PAGE;
+		task_set_spread_page(tsk);
 	else
-		tsk->flags &= ~PF_SPREAD_PAGE;
+		task_clear_spread_page(tsk);
+
 	if (is_spread_slab(cs))
-		tsk->flags |= PF_SPREAD_SLAB;
+		task_set_spread_slab(tsk);
 	else
-		tsk->flags &= ~PF_SPREAD_SLAB;
+		task_clear_spread_slab(tsk);
 }
 
 /*
-- 
1.8.0.2

Re: [PATCH v3 3/3] cpuset: PF_SPREAD_PAGE and PF_SPREAD_SLAB should be atomic flags

[David Rientjes]

On Tue, 23 Sep 2014, Zefan Li wrote:

> When we change cpuset.memory_spread_{page,slab}, cpuset will flip
> PF_SPREAD_{PAGE,SLAB} bit of tsk->flags for each task in that cpuset.
> This should be done using atomic bitops, but currently we don't,
> which is broken.
> 
> Tetsuo reported a hard-to-reproduce kernel crash on RHEL6, which happend
> when one thread tried to clear PF_USED_MATH while at the same time another
> thread tried to flip PF_SPREAD_PAGE/PF_SPREAD_SLAB. They both operate on
> the same task.
> 
> Here's the full report:
> https://lkml.org/lkml/2014/9/19/230
> 
> To fix this, we make PF_SPREAD_PAGE and PF_SPARED_SLAB atomic flags.
> 

s/SPARED/SPREAD/

> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Ingo Molnar <mingo@kernel.org>
> Cc: Miao Xie <miaox@cn.fujitsu.com>
> Cc: Kees Cook <keescook@chromium.org>
> Fixes: 950592f7b991 ("cpusets: update tasks' page/slab spread flags in time")
> Cc: <stable@vger.kernel.org> # 2.6.31+
> Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> Signed-off-by: Zefan Li <lizefan@huawei.com>
> ---
>  include/linux/cpuset.h |  4 ++--
>  include/linux/sched.h  | 13 +++++++++++--
>  kernel/cpuset.c        |  9 +++++----
>  3 files changed, 18 insertions(+), 8 deletions(-)
> 
> diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
> index 0d4e067..2f073db 100644
> --- a/include/linux/cpuset.h
> +++ b/include/linux/cpuset.h
> @@ -94,12 +94,12 @@ extern int cpuset_slab_spread_node(void);
>  
>  static inline int cpuset_do_page_mem_spread(void)
>  {
> -	return current->flags & PF_SPREAD_PAGE;
> +	return task_spread_page(current);
>  }
>  
>  static inline int cpuset_do_slab_mem_spread(void)
>  {
> -	return current->flags & PF_SPREAD_SLAB;
> +	return task_spread_slab(current);
>  }
>  
>  extern int current_cpuset_is_being_rebound(void);
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 5630763..7b1cafe 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -1903,8 +1903,6 @@ extern void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut,
>  #define PF_KTHREAD	0x00200000	/* I am a kernel thread */
>  #define PF_RANDOMIZE	0x00400000	/* randomize virtual address space */
>  #define PF_SWAPWRITE	0x00800000	/* Allowed to write to swap */
> -#define PF_SPREAD_PAGE	0x01000000	/* Spread page cache over cpuset */
> -#define PF_SPREAD_SLAB	0x02000000	/* Spread some slab caches over cpuset */
>  #define PF_NO_SETAFFINITY 0x04000000	/* Userland is not allowed to meddle with cpus_allowed */
>  #define PF_MCE_EARLY    0x08000000      /* Early kill for mce process policy */
>  #define PF_MUTEX_TESTER	0x20000000	/* Thread belongs to the rt mutex tester */
> @@ -1958,6 +1956,9 @@ static inline void memalloc_noio_restore(unsigned int flags)
>  
>  /* Per-process atomic flags. */
>  #define PFA_NO_NEW_PRIVS 0	/* May not gain new privileges. */
> +#define PFA_SPREAD_PAGE  1      /* Spread page cache over cpuset */
> +#define PFA_SPREAD_SLAB  2      /* Spread some slab caches over cpuset */
> +
>  
>  #define TASK_PFA_TEST(name, func)					\
>  	static inline bool task_##func(struct task_struct *p)		\
> @@ -1972,6 +1973,14 @@ static inline void memalloc_noio_restore(unsigned int flags)
>  TASK_PFA_TEST(NO_NEW_PRIVS, no_new_privs)
>  TASK_PFA_SET(NO_NEW_PRIVS, no_new_privs)
>  
> +TASK_PFA_TEST(SPREAD_PAGE, spread_page)
> +TASK_PFA_SET(SPREAD_PAGE, spread_page)
> +TASK_PFA_CLEAR(SPREAD_PAGE, spread_page)
> +
> +TASK_PFA_TEST(SPREAD_SLAB, spread_slab)
> +TASK_PFA_SET(SPREAD_SLAB, spread_slab)
> +TASK_PFA_CLEAR(SPREAD_SLAB, spread_slab)
> +
>  /*
>   * task->jobctl flags
>   */
> diff --git a/kernel/cpuset.c b/kernel/cpuset.c
> index a37f4ed..1f107c7 100644
> --- a/kernel/cpuset.c
> +++ b/kernel/cpuset.c
> @@ -365,13 +365,14 @@ static void cpuset_update_task_spread_flag(struct cpuset *cs,
>  					struct task_struct *tsk)
>  {
>  	if (is_spread_page(cs))
> -		tsk->flags |= PF_SPREAD_PAGE;
> +		task_set_spread_page(tsk);
>  	else
> -		tsk->flags &= ~PF_SPREAD_PAGE;
> +		task_clear_spread_page(tsk);
> +
>  	if (is_spread_slab(cs))
> -		tsk->flags |= PF_SPREAD_SLAB;
> +		task_set_spread_slab(tsk);
>  	else
> -		tsk->flags &= ~PF_SPREAD_SLAB;
> +		task_clear_spread_slab(tsk);
>  }
>  
>  /*

This most certainly needs commentary to specify why these have to be 
atomic ops.

Re: [PATCH v3 3/3] cpuset: PF_SPREAD_PAGE and PF_SPREAD_SLAB should be atomic flags

[Zefan Li]

于 2014/9/24 6:10, David Rientjes wrote:
> On Tue, 23 Sep 2014, Zefan Li wrote:
> 
>> When we change cpuset.memory_spread_{page,slab}, cpuset will flip
>> PF_SPREAD_{PAGE,SLAB} bit of tsk->flags for each task in that cpuset.
>> This should be done using atomic bitops, but currently we don't,
>> which is broken.
>>
>> Tetsuo reported a hard-to-reproduce kernel crash on RHEL6, which happend
>> when one thread tried to clear PF_USED_MATH while at the same time another
>> thread tried to flip PF_SPREAD_PAGE/PF_SPREAD_SLAB. They both operate on
>> the same task.
>>
>> Here's the full report:
>> https://lkml.org/lkml/2014/9/19/230
>>
>> To fix this, we make PF_SPREAD_PAGE and PF_SPARED_SLAB atomic flags.
>>
> 
> s/SPARED/SPREAD/
> 
>> Cc: Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
>> Cc: Ingo Molnar <mingo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
>> Cc: Miao Xie <miaox-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
>> Cc: Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
>> Fixes: 950592f7b991 ("cpusets: update tasks' page/slab spread flags in time")
>> Cc: <stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org> # 2.6.31+
>> Reported-by: Tetsuo Handa <penguin-kernel-JPay3/Yim36HaxMnTkn67Xf5DAMn2ifp@public.gmane.org>
>> Signed-off-by: Zefan Li <lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
>> ---
>>  include/linux/cpuset.h |  4 ++--
>>  include/linux/sched.h  | 13 +++++++++++--
>>  kernel/cpuset.c        |  9 +++++----
>>  3 files changed, 18 insertions(+), 8 deletions(-)
>>
>> diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h
>> index 0d4e067..2f073db 100644
>> --- a/include/linux/cpuset.h
>> +++ b/include/linux/cpuset.h
>> @@ -94,12 +94,12 @@ extern int cpuset_slab_spread_node(void);
>>  
>>  static inline int cpuset_do_page_mem_spread(void)
>>  {
>> -	return current->flags & PF_SPREAD_PAGE;
>> +	return task_spread_page(current);
>>  }
>>  
>>  static inline int cpuset_do_slab_mem_spread(void)
>>  {
>> -	return current->flags & PF_SPREAD_SLAB;
>> +	return task_spread_slab(current);
>>  }
>>  
>>  extern int current_cpuset_is_being_rebound(void);
>> diff --git a/include/linux/sched.h b/include/linux/sched.h
>> index 5630763..7b1cafe 100644
>> --- a/include/linux/sched.h
>> +++ b/include/linux/sched.h
>> @@ -1903,8 +1903,6 @@ extern void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut,
>>  #define PF_KTHREAD	0x00200000	/* I am a kernel thread */
>>  #define PF_RANDOMIZE	0x00400000	/* randomize virtual address space */
>>  #define PF_SWAPWRITE	0x00800000	/* Allowed to write to swap */
>> -#define PF_SPREAD_PAGE	0x01000000	/* Spread page cache over cpuset */
>> -#define PF_SPREAD_SLAB	0x02000000	/* Spread some slab caches over cpuset */
>>  #define PF_NO_SETAFFINITY 0x04000000	/* Userland is not allowed to meddle with cpus_allowed */
>>  #define PF_MCE_EARLY    0x08000000      /* Early kill for mce process policy */
>>  #define PF_MUTEX_TESTER	0x20000000	/* Thread belongs to the rt mutex tester */
>> @@ -1958,6 +1956,9 @@ static inline void memalloc_noio_restore(unsigned int flags)
>>  
>>  /* Per-process atomic flags. */
>>  #define PFA_NO_NEW_PRIVS 0	/* May not gain new privileges. */
>> +#define PFA_SPREAD_PAGE  1      /* Spread page cache over cpuset */
>> +#define PFA_SPREAD_SLAB  2      /* Spread some slab caches over cpuset */
>> +
>>  
>>  #define TASK_PFA_TEST(name, func)					\
>>  	static inline bool task_##func(struct task_struct *p)		\
>> @@ -1972,6 +1973,14 @@ static inline void memalloc_noio_restore(unsigned int flags)
>>  TASK_PFA_TEST(NO_NEW_PRIVS, no_new_privs)
>>  TASK_PFA_SET(NO_NEW_PRIVS, no_new_privs)
>>  
>> +TASK_PFA_TEST(SPREAD_PAGE, spread_page)
>> +TASK_PFA_SET(SPREAD_PAGE, spread_page)
>> +TASK_PFA_CLEAR(SPREAD_PAGE, spread_page)
>> +
>> +TASK_PFA_TEST(SPREAD_SLAB, spread_slab)
>> +TASK_PFA_SET(SPREAD_SLAB, spread_slab)
>> +TASK_PFA_CLEAR(SPREAD_SLAB, spread_slab)
>> +
>>  /*
>>   * task->jobctl flags
>>   */
>> diff --git a/kernel/cpuset.c b/kernel/cpuset.c
>> index a37f4ed..1f107c7 100644
>> --- a/kernel/cpuset.c
>> +++ b/kernel/cpuset.c
>> @@ -365,13 +365,14 @@ static void cpuset_update_task_spread_flag(struct cpuset *cs,
>>  					struct task_struct *tsk)
>>  {
>>  	if (is_spread_page(cs))
>> -		tsk->flags |= PF_SPREAD_PAGE;
>> +		task_set_spread_page(tsk);
>>  	else
>> -		tsk->flags &= ~PF_SPREAD_PAGE;
>> +		task_clear_spread_page(tsk);
>> +
>>  	if (is_spread_slab(cs))
>> -		tsk->flags |= PF_SPREAD_SLAB;
>> +		task_set_spread_slab(tsk);
>>  	else
>> -		tsk->flags &= ~PF_SPREAD_SLAB;
>> +		task_clear_spread_slab(tsk);
>>  }
>>  
>>  /*
> 
> This most certainly needs commentary to specify why these have to be 
> atomic ops.
> .

It won't hurt to add more comment, but I don't think it's necessary, because
the reason to use atomic bitops seems obvious to me. Besides there's no such
comment for no_new_privs, which was tsk->atomic_flags introduced for.

Re: [PATCH v3 1/3] sched: fix confusing PFA_NO_NEW_PRIVS constant

[Tejun Heo]

On Tue, Sep 23, 2014 at 03:44:19PM +0800, Zefan Li wrote:
> From: Tetsuo Handa <penguin-kernel-JPay3/Yim36HaxMnTkn67Xf5DAMn2ifp@public.gmane.org>
> 
> Commit 1d4457f99928 ("sched: move no_new_privs into new atomic flags")
> defined PFA_NO_NEW_PRIVS as hexadecimal value, but it is confusing
> because it is used as bit number. Redefine it as decimal bit number.
> 
> Note this changes the bit position of PFA_NOW_NEW_PRIVS from 1 to 0.
> 
> Cc: Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
> Cc: Ingo Molnar <mingo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
> Cc: Miao Xie <miaox-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
> Cc: Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
> Signed-off-by: Tetsuo Handa <penguin-kernel-JPay3/Yim36HaxMnTkn67Xf5DAMn2ifp@public.gmane.org>
> Acked-by: Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
> [ lizf: slightly modified subject and changelog ]
> Signed-off-by: Zefan Li <lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>

Applied 1-3 to cgroup/for-3.17-fixes w/ the typo spotted by davidr
fixed.

Thanks.

-- 
tejun

Re: [PATCH v3 1/3] sched: fix confusing PFA_NO_NEW_PRIVS constant

[Tejun Heo]

On Wed, Sep 24, 2014 at 09:22:18AM -0400, Tejun Heo wrote:
> On Tue, Sep 23, 2014 at 03:44:19PM +0800, Zefan Li wrote:
> > From: Tetsuo Handa <penguin-kernel-JPay3/Yim36HaxMnTkn67Xf5DAMn2ifp@public.gmane.org>
> > 
> > Commit 1d4457f99928 ("sched: move no_new_privs into new atomic flags")
> > defined PFA_NO_NEW_PRIVS as hexadecimal value, but it is confusing
> > because it is used as bit number. Redefine it as decimal bit number.
> > 
> > Note this changes the bit position of PFA_NOW_NEW_PRIVS from 1 to 0.
> > 
> > Cc: Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
> > Cc: Ingo Molnar <mingo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
> > Cc: Miao Xie <miaox-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
> > Cc: Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
> > Signed-off-by: Tetsuo Handa <penguin-kernel-JPay3/Yim36HaxMnTkn67Xf5DAMn2ifp@public.gmane.org>
> > Acked-by: Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
> > [ lizf: slightly modified subject and changelog ]
> > Signed-off-by: Zefan Li <lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
> 
> Applied 1-3 to cgroup/for-3.17-fixes w/ the typo spotted by davidr
> fixed.

Reverted due to build failure.  Will wait for a refreshed version. :(

Thanks.

-- 
tejun

Re: [PATCH v3 1/3] sched: fix confusing PFA_NO_NEW_PRIVS constant

[Tetsuo Handa]

Tejun Heo wrote:
> > Applied 1-3 to cgroup/for-3.17-fixes w/ the typo spotted by davidr
> > fixed.

s/happend/happened/

> 
> Reverted due to build failure.  Will wait for a refreshed version. :(

I can build with 1-3 patches using HEAD of linux.git. What failure did you see?

$ make kernel/seccomp.o kernel/sys.o security/apparmor/domain.o kernel/cpuset.o

Re: [PATCH v3 1/3] sched: fix confusing PFA_NO_NEW_PRIVS constant

[Tejun Heo]

On Wed, Sep 24, 2014 at 11:09:25PM +0900, Tetsuo Handa wrote:
> Tejun Heo wrote:
> > > Applied 1-3 to cgroup/for-3.17-fixes w/ the typo spotted by davidr
> > > fixed.
> 
> s/happend/happened/
> 
> > 
> > Reverted due to build failure.  Will wait for a refreshed version. :(
> 
> I can build with 1-3 patches using HEAD of linux.git. What failure did you see?
> 
> $ make kernel/seccomp.o kernel/sys.o security/apparmor/domain.o kernel/cpuset.o

Got the following failure report from the build bot.

tree:   git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git for-3.17-fixes
head:   ed91a06989e253cde811d492414adcf94f34eb03
commit: ed91a06989e253cde811d492414adcf94f34eb03 [8/8] cpuset: PF_SPREAD_PAGE and PF_SPREAD_SLAB
+should be atomic flags
config: x86_64-randconfig-hxb2-0924 (attached as .config)
reproduce:
  git checkout ed91a06989e253cde811d492414adcf94f34eb03
  # save the attached .config to linux build tree
  make ARCH=x86_64

All error/warnings:

   In file included from include/linux/linkage.h:4:0,
                    from include/linux/preempt.h:9,
                    from include/linux/spinlock.h:50,
                    from include/linux/mmzone.h:7,
                    from include/linux/gfp.h:5,
                    from include/linux/slab.h:14,
                    from mm/slab.c:89:
   mm/slab.c: In function '__do_cache_alloc':
>> mm/slab.c:3229:54: error: 'PF_SPREAD_SLAB' undeclared (first use in this function)
     if (current->mempolicy || unlikely(current->flags & PF_SPREAD_SLAB)) {
                                                         ^
   include/linux/compiler.h:131:45: note: in definition of macro 'unlikely'
    #  define unlikely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0))
                                               	^
   mm/slab.c:3229:54: note: each undeclared identifier is reported only once for each function it ap
+pears in
     if (current->mempolicy || unlikely(current->flags & PF_SPREAD_SLAB)) {
                                                         ^
   include/linux/compiler.h:131:45: note: in definition of macro 'unlikely'
    #  define unlikely(x) (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0))
                                               	^

vim +/PF_SPREAD_SLAB +3229 mm/slab.c

8c8cc2c1 Pekka Enberg   2007-02-10  3223
8c8cc2c1 Pekka Enberg   2007-02-10  3224  static __always_inline void *
8c8cc2c1 Pekka Enberg   2007-02-10  3225  __do_cache_alloc(struct kmem_cache *cache, gfp_t flags)
8c8cc2c1 Pekka Enberg   2007-02-10  3226  {
8c8cc2c1 Pekka Enberg   2007-02-10  3227        void *objp;
8c8cc2c1 Pekka Enberg   2007-02-10  3228
f0432d15 David Rientjes 2014-04-07 @3229        if (current->mempolicy || unlikely(current->flags &
+PF_SPREAD_SLAB)) {
8c8cc2c1 Pekka Enberg   2007-02-10  3230                objp = alternate_node_alloc(cache, flags);
8c8cc2c1 Pekka Enberg   2007-02-10  3231                if (objp)
8c8cc2c1 Pekka Enberg   2007-02-10  3232                        goto out;

-- 
tejun

Re: [PATCH v3 1/3] sched: fix confusing PFA_NO_NEW_PRIVS constant

[Zefan Li]

On 2014/9/24 21:35, Tejun Heo wrote:
> On Wed, Sep 24, 2014 at 09:22:18AM -0400, Tejun Heo wrote:
>> On Tue, Sep 23, 2014 at 03:44:19PM +0800, Zefan Li wrote:
>>> From: Tetsuo Handa <penguin-kernel-JPay3/Yim36HaxMnTkn67Xf5DAMn2ifp@public.gmane.org>
>>>
>>> Commit 1d4457f99928 ("sched: move no_new_privs into new atomic flags")
>>> defined PFA_NO_NEW_PRIVS as hexadecimal value, but it is confusing
>>> because it is used as bit number. Redefine it as decimal bit number.
>>>
>>> Note this changes the bit position of PFA_NOW_NEW_PRIVS from 1 to 0.
>>>
>>> Cc: Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
>>> Cc: Ingo Molnar <mingo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
>>> Cc: Miao Xie <miaox-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org>
>>> Cc: Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
>>> Signed-off-by: Tetsuo Handa <penguin-kernel-JPay3/Yim36HaxMnTkn67Xf5DAMn2ifp@public.gmane.org>
>>> Acked-by: Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
>>> [ lizf: slightly modified subject and changelog ]
>>> Signed-off-by: Zefan Li <lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
>>
>> Applied 1-3 to cgroup/for-3.17-fixes w/ the typo spotted by davidr
>> fixed.
> 
> Reverted due to build failure.  Will wait for a refreshed version. :(
> 

Didn't notice mm/slab.c uses PF_SPREAD_SLAB without the cpuset wrapper...