* [PATCH 1/3] sched: fix confusing PFA_NO_NEW_PRIVS constant
@ 2014-09-22 3:50 Zefan Li
2014-09-22 3:51 ` [PATCH 2/3] sched: add a macro to define bitops for task atomic flags Zefan Li
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Zefan Li @ 2014-09-22 3:50 UTC (permalink / raw)
To: Tejun Heo
Cc: LKML, Cgroups, Ingo Molnar, Peter Zijlstra, keescook, Tetsuo Handa
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.
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Kees Cook <keescook@chromium.org>
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
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH 2/3] sched: add a macro to define bitops for task atomic flags
2014-09-22 3:50 [PATCH 1/3] sched: fix confusing PFA_NO_NEW_PRIVS constant Zefan Li
@ 2014-09-22 3:51 ` Zefan Li
2014-09-22 11:45 ` Peter Zijlstra
2014-09-22 3:52 ` [PATCH 3/3] cpuset: PF_SPREAD_PAGE and PF_SPREAD_SLAB should be " Zefan Li
2014-09-22 4:02 ` [PATCH 1/3] sched: fix confusing PFA_NO_NEW_PRIVS constant Tejun Heo
2 siblings, 1 reply; 6+ messages in thread
From: Zefan Li @ 2014-09-22 3:51 UTC (permalink / raw)
To: Tejun Heo
Cc: LKML, Cgroups, Ingo Molnar, Peter Zijlstra, keescook, Tetsuo Handa
This will simplify code when we add new flags.
Signed-off-by: Zefan Li <lizefan@huawei.com>
---
include/linux/sched.h | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 4557765..04a2ae2 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1959,15 +1959,17 @@ 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_BITOPS(name, func) \
+static inline bool task_##func(struct task_struct *p) \
+{ return test_bit(PFA_##name, &p->atomic_flags); } \
+ \
+static inline void task_set_##func(struct task_struct *p) \
+{ set_bit(PFA_##name, &p->atomic_flags); } \
+ \
+static inline void task_clear_##func(struct task_struct *p) \
+{ clear_bit(PFA_##name, &p->atomic_flags); }
+
+TASK_PFA_BITOPS(NO_NEW_PRIVS, no_new_privs)
/*
* task->jobctl flags
--
1.8.0.2
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH 3/3] cpuset: PF_SPREAD_PAGE and PF_SPREAD_SLAB should be atomic flags
2014-09-22 3:50 [PATCH 1/3] sched: fix confusing PFA_NO_NEW_PRIVS constant Zefan Li
2014-09-22 3:51 ` [PATCH 2/3] sched: add a macro to define bitops for task atomic flags Zefan Li
@ 2014-09-22 3:52 ` Zefan Li
2014-09-22 4:02 ` [PATCH 1/3] sched: fix confusing PFA_NO_NEW_PRIVS constant Tejun Heo
2 siblings, 0 replies; 6+ messages in thread
From: Zefan Li @ 2014-09-22 3:52 UTC (permalink / raw)
To: Tejun Heo
Cc: LKML, Cgroups, Ingo Molnar, Peter Zijlstra, keescook, Tetsuo Handa
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.
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 | 6 ++++--
kernel/cpuset.c | 9 +++++----
3 files changed, 11 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 04a2ae2..ee634d1 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 +1956,8 @@ 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_BITOPS(name, func) \
static inline bool task_##func(struct task_struct *p) \
@@ -1970,6 +1970,8 @@ static inline void task_clear_##func(struct task_struct *p) \
{ clear_bit(PFA_##name, &p->atomic_flags); }
TASK_PFA_BITOPS(NO_NEW_PRIVS, no_new_privs)
+TASK_PFA_BITOPS(SPREAD_PAGE, spread_page)
+TASK_PFA_BITOPS(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
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH 1/3] sched: fix confusing PFA_NO_NEW_PRIVS constant
2014-09-22 3:50 [PATCH 1/3] sched: fix confusing PFA_NO_NEW_PRIVS constant Zefan Li
2014-09-22 3:51 ` [PATCH 2/3] sched: add a macro to define bitops for task atomic flags Zefan Li
2014-09-22 3:52 ` [PATCH 3/3] cpuset: PF_SPREAD_PAGE and PF_SPREAD_SLAB should be " Zefan Li
@ 2014-09-22 4:02 ` Tejun Heo
2014-09-22 4:44 ` Zefan Li
2 siblings, 1 reply; 6+ messages in thread
From: Tejun Heo @ 2014-09-22 4:02 UTC (permalink / raw)
To: Zefan Li
Cc: LKML, Cgroups, Ingo Molnar, Peter Zijlstra, keescook, Tetsuo Handa
On Mon, Sep 22, 2014 at 11:50:46AM +0800, Zefan Li wrote:
> 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.
It's also changing the bit position, which is fine but should be
mentioned in the description.
Thanks.
--
tejun
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 1/3] sched: fix confusing PFA_NO_NEW_PRIVS constant
2014-09-22 4:02 ` [PATCH 1/3] sched: fix confusing PFA_NO_NEW_PRIVS constant Tejun Heo
@ 2014-09-22 4:44 ` Zefan Li
0 siblings, 0 replies; 6+ messages in thread
From: Zefan Li @ 2014-09-22 4:44 UTC (permalink / raw)
To: Tejun Heo
Cc: LKML, Cgroups, Ingo Molnar, Peter Zijlstra, keescook, Tetsuo Handa
On 2014/9/22 12:02, Tejun Heo wrote:
> On Mon, Sep 22, 2014 at 11:50:46AM +0800, Zefan Li wrote:
>> 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.
>
> It's also changing the bit position, which is fine but should be
> mentioned in the description.
>
I've resent the patch with changelog updated.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 2/3] sched: add a macro to define bitops for task atomic flags
2014-09-22 3:51 ` [PATCH 2/3] sched: add a macro to define bitops for task atomic flags Zefan Li
@ 2014-09-22 11:45 ` Peter Zijlstra
0 siblings, 0 replies; 6+ messages in thread
From: Peter Zijlstra @ 2014-09-22 11:45 UTC (permalink / raw)
To: Zefan Li; +Cc: Tejun Heo, LKML, Cgroups, Ingo Molnar, keescook, Tetsuo Handa
On Mon, Sep 22, 2014 at 11:51:48AM +0800, Zefan Li wrote:
> This will simplify code when we add new flags.
>
> Signed-off-by: Zefan Li <lizefan@huawei.com>
> ---
> include/linux/sched.h | 20 +++++++++++---------
> 1 file changed, 11 insertions(+), 9 deletions(-)
>
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 4557765..04a2ae2 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -1959,15 +1959,17 @@ 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_BITOPS(name, func) \
> +static inline bool task_##func(struct task_struct *p) \
> +{ return test_bit(PFA_##name, &p->atomic_flags); } \
> + \
> +static inline void task_set_##func(struct task_struct *p) \
> +{ set_bit(PFA_##name, &p->atomic_flags); } \
> + \
> +static inline void task_clear_##func(struct task_struct *p) \
> +{ clear_bit(PFA_##name, &p->atomic_flags); }
> +
> +TASK_PFA_BITOPS(NO_NEW_PRIVS, no_new_privs)
This could really do with a corresponding script/tags.sh update.
--regex-c++='TASK_PFA_BITOPS\([^,]*,([^)]*)\)/task_\1/'
--regex-c++='TASK_PFA_BITOPS\([^,]*,([^)]*)\)/task_set_\1/'
--regex-c++='TASK_PFA_BITOPS\([^,]*,([^)]*)\)/task_clear_\1/'
For exhuberant and matching bits for emacs.
^ permalink raw reply [flat|nested] 6+ messages in thread
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2014-09-22 3:50 [PATCH 1/3] sched: fix confusing PFA_NO_NEW_PRIVS constant Zefan Li
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2014-09-22 11:45 ` Peter Zijlstra
2014-09-22 3:52 ` [PATCH 3/3] cpuset: PF_SPREAD_PAGE and PF_SPREAD_SLAB should be " Zefan Li
2014-09-22 4:02 ` [PATCH 1/3] sched: fix confusing PFA_NO_NEW_PRIVS constant Tejun Heo
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