* [PATCH bpf-next] bpf: check that BPF programs run with preemption disabled
@ 2019-01-29 1:21 Alexei Starovoitov
2019-01-29 7:00 ` Song Liu
2019-01-31 22:29 ` Daniel Borkmann
0 siblings, 2 replies; 4+ messages in thread
From: Alexei Starovoitov @ 2019-01-29 1:21 UTC (permalink / raw)
To: davem
Cc: daniel, peterz, jannh, paulmck, will.deacon, mingo, netdev, kernel-team
From: Peter Zijlstra <peterz@infradead.org>
Introduce cant_sleep() macro for annotation of functions that cannot sleep.
Use it in BPF_PROG_RUN to catch execution of BPF programs
in preemptable context.
Suggested-by: Jann Horn <jannh@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
include/linux/filter.h | 2 +-
include/linux/kernel.h | 14 ++++++++++++--
kernel/sched/core.c | 28 ++++++++++++++++++++++++++++
3 files changed, 41 insertions(+), 3 deletions(-)
diff --git a/include/linux/filter.h b/include/linux/filter.h
index e4b473f85b46..7e87863617b3 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -533,7 +533,7 @@ struct sk_filter {
struct bpf_prog *prog;
};
-#define BPF_PROG_RUN(filter, ctx) (*(filter)->bpf_func)(ctx, (filter)->insnsi)
+#define BPF_PROG_RUN(filter, ctx) ({ cant_sleep(); (*(filter)->bpf_func)(ctx, (filter)->insnsi); })
#define BPF_SKB_CB_LEN QDISC_CB_PRIV_LEN
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 8f0e68e250a7..a8868a32098c 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -245,8 +245,10 @@ extern int _cond_resched(void);
#endif
#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
- void ___might_sleep(const char *file, int line, int preempt_offset);
- void __might_sleep(const char *file, int line, int preempt_offset);
+extern void ___might_sleep(const char *file, int line, int preempt_offset);
+extern void __might_sleep(const char *file, int line, int preempt_offset);
+extern void __cant_sleep(const char *file, int line, int preempt_offset);
+
/**
* might_sleep - annotation for functions that can sleep
*
@@ -259,6 +261,13 @@ extern int _cond_resched(void);
*/
# define might_sleep() \
do { __might_sleep(__FILE__, __LINE__, 0); might_resched(); } while (0)
+/**
+ * cant_sleep - annotation for functions that cannot sleep
+ *
+ * this macro will print a stack trace if it is executed with preemption enabled
+ */
+# define cant_sleep() \
+ do { __cant_sleep(__FILE__, __LINE__, 0); } while (0)
# define sched_annotate_sleep() (current->task_state_change = 0)
#else
static inline void ___might_sleep(const char *file, int line,
@@ -266,6 +275,7 @@ extern int _cond_resched(void);
static inline void __might_sleep(const char *file, int line,
int preempt_offset) { }
# define might_sleep() do { might_resched(); } while (0)
+# define cant_sleep() do { } while (0)
# define sched_annotate_sleep() do { } while (0)
#endif
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index a674c7db2f29..1dcbff62f973 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6149,6 +6149,34 @@ void ___might_sleep(const char *file, int line, int preempt_offset)
add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
}
EXPORT_SYMBOL(___might_sleep);
+
+void __cant_sleep(const char *file, int line, int preempt_offset)
+{
+ static unsigned long prev_jiffy;
+
+ if (irqs_disabled())
+ return;
+
+ if (!IS_ENABLED(CONFIG_PREEMPT_COUNT))
+ return;
+
+ if (preempt_count() > preempt_offset)
+ return;
+
+ if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
+ return;
+ prev_jiffy = jiffies;
+
+ printk(KERN_ERR "BUG: assuming atomic context at %s:%d\n", file, line);
+ printk(KERN_ERR "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
+ in_atomic(), irqs_disabled(),
+ current->pid, current->comm);
+
+ debug_show_held_locks(current);
+ dump_stack();
+ add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
+}
+EXPORT_SYMBOL_GPL(__cant_sleep);
#endif
#ifdef CONFIG_MAGIC_SYSRQ
--
2.20.0
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH bpf-next] bpf: check that BPF programs run with preemption disabled
2019-01-29 1:21 [PATCH bpf-next] bpf: check that BPF programs run with preemption disabled Alexei Starovoitov
@ 2019-01-29 7:00 ` Song Liu
2019-01-31 22:29 ` Daniel Borkmann
1 sibling, 0 replies; 4+ messages in thread
From: Song Liu @ 2019-01-29 7:00 UTC (permalink / raw)
To: Alexei Starovoitov
Cc: David Miller, Daniel Borkmann, peterz, jannh, paulmck,
will.deacon, mingo, netdev, Kernel Team
> On Jan 28, 2019, at 5:21 PM, Alexei Starovoitov <ast@kernel.org> wrote:
>
> From: Peter Zijlstra <peterz@infradead.org>
>
> Introduce cant_sleep() macro for annotation of functions that cannot sleep.
>
> Use it in BPF_PROG_RUN to catch execution of BPF programs
> in preemptable context.
>
> Suggested-by: Jann Horn <jannh@google.com>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
> ---
> include/linux/filter.h | 2 +-
> include/linux/kernel.h | 14 ++++++++++++--
> kernel/sched/core.c | 28 ++++++++++++++++++++++++++++
> 3 files changed, 41 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/filter.h b/include/linux/filter.h
> index e4b473f85b46..7e87863617b3 100644
> --- a/include/linux/filter.h
> +++ b/include/linux/filter.h
> @@ -533,7 +533,7 @@ struct sk_filter {
> struct bpf_prog *prog;
> };
>
> -#define BPF_PROG_RUN(filter, ctx) (*(filter)->bpf_func)(ctx, (filter)->insnsi)
> +#define BPF_PROG_RUN(filter, ctx) ({ cant_sleep(); (*(filter)->bpf_func)(ctx, (filter)->insnsi); })
>
> #define BPF_SKB_CB_LEN QDISC_CB_PRIV_LEN
>
> diff --git a/include/linux/kernel.h b/include/linux/kernel.h
> index 8f0e68e250a7..a8868a32098c 100644
> --- a/include/linux/kernel.h
> +++ b/include/linux/kernel.h
> @@ -245,8 +245,10 @@ extern int _cond_resched(void);
> #endif
>
> #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
> - void ___might_sleep(const char *file, int line, int preempt_offset);
> - void __might_sleep(const char *file, int line, int preempt_offset);
> +extern void ___might_sleep(const char *file, int line, int preempt_offset);
> +extern void __might_sleep(const char *file, int line, int preempt_offset);
> +extern void __cant_sleep(const char *file, int line, int preempt_offset);
> +
> /**
> * might_sleep - annotation for functions that can sleep
> *
> @@ -259,6 +261,13 @@ extern int _cond_resched(void);
> */
> # define might_sleep() \
> do { __might_sleep(__FILE__, __LINE__, 0); might_resched(); } while (0)
> +/**
> + * cant_sleep - annotation for functions that cannot sleep
> + *
> + * this macro will print a stack trace if it is executed with preemption enabled
> + */
> +# define cant_sleep() \
> + do { __cant_sleep(__FILE__, __LINE__, 0); } while (0)
> # define sched_annotate_sleep() (current->task_state_change = 0)
> #else
> static inline void ___might_sleep(const char *file, int line,
> @@ -266,6 +275,7 @@ extern int _cond_resched(void);
> static inline void __might_sleep(const char *file, int line,
> int preempt_offset) { }
> # define might_sleep() do { might_resched(); } while (0)
> +# define cant_sleep() do { } while (0)
> # define sched_annotate_sleep() do { } while (0)
> #endif
>
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index a674c7db2f29..1dcbff62f973 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -6149,6 +6149,34 @@ void ___might_sleep(const char *file, int line, int preempt_offset)
> add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
> }
> EXPORT_SYMBOL(___might_sleep);
> +
> +void __cant_sleep(const char *file, int line, int preempt_offset)
> +{
> + static unsigned long prev_jiffy;
> +
> + if (irqs_disabled())
> + return;
> +
> + if (!IS_ENABLED(CONFIG_PREEMPT_COUNT))
> + return;
> +
> + if (preempt_count() > preempt_offset)
> + return;
> +
> + if (time_before(jiffies, prev_jiffy + HZ) && prev_jiffy)
> + return;
> + prev_jiffy = jiffies;
> +
> + printk(KERN_ERR "BUG: assuming atomic context at %s:%d\n", file, line);
> + printk(KERN_ERR "in_atomic(): %d, irqs_disabled(): %d, pid: %d, name: %s\n",
> + in_atomic(), irqs_disabled(),
> + current->pid, current->comm);
> +
> + debug_show_held_locks(current);
> + dump_stack();
> + add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
> +}
> +EXPORT_SYMBOL_GPL(__cant_sleep);
> #endif
>
> #ifdef CONFIG_MAGIC_SYSRQ
> --
> 2.20.0
>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH bpf-next] bpf: check that BPF programs run with preemption disabled
2019-01-29 1:21 [PATCH bpf-next] bpf: check that BPF programs run with preemption disabled Alexei Starovoitov
2019-01-29 7:00 ` Song Liu
@ 2019-01-31 22:29 ` Daniel Borkmann
2019-02-19 20:58 ` Daniel Borkmann
1 sibling, 1 reply; 4+ messages in thread
From: Daniel Borkmann @ 2019-01-31 22:29 UTC (permalink / raw)
To: Alexei Starovoitov, davem
Cc: peterz, jannh, paulmck, will.deacon, mingo, netdev, kernel-team
On 01/29/2019 02:21 AM, Alexei Starovoitov wrote:
> From: Peter Zijlstra <peterz@infradead.org>
>
> Introduce cant_sleep() macro for annotation of functions that cannot sleep.
>
> Use it in BPF_PROG_RUN to catch execution of BPF programs
> in preemptable context.
>
> Suggested-by: Jann Horn <jannh@google.com>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
(Just fyi, will let this sit in patchwork till the preemption fixes have been
merged back from bpf into bpf-next as otherwise people will yell that they
hit this frequently.)
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH bpf-next] bpf: check that BPF programs run with preemption disabled
2019-01-31 22:29 ` Daniel Borkmann
@ 2019-02-19 20:58 ` Daniel Borkmann
0 siblings, 0 replies; 4+ messages in thread
From: Daniel Borkmann @ 2019-02-19 20:58 UTC (permalink / raw)
To: Alexei Starovoitov, davem
Cc: peterz, jannh, paulmck, will.deacon, mingo, netdev, kernel-team
On 01/31/2019 11:29 PM, Daniel Borkmann wrote:
> On 01/29/2019 02:21 AM, Alexei Starovoitov wrote:
>> From: Peter Zijlstra <peterz@infradead.org>
>>
>> Introduce cant_sleep() macro for annotation of functions that cannot sleep.
>>
>> Use it in BPF_PROG_RUN to catch execution of BPF programs
>> in preemptable context.
>>
>> Suggested-by: Jann Horn <jannh@google.com>
>> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
>> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
>
> (Just fyi, will let this sit in patchwork till the preemption fixes have been
> merged back from bpf into bpf-next as otherwise people will yell that they
> hit this frequently.)
Pushed out now, thanks!
^ permalink raw reply [flat|nested] 4+ messages in thread
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2019-01-29 1:21 [PATCH bpf-next] bpf: check that BPF programs run with preemption disabled Alexei Starovoitov
2019-01-29 7:00 ` Song Liu
2019-01-31 22:29 ` Daniel Borkmann
2019-02-19 20:58 ` Daniel Borkmann
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