* [PATCH 1/2] debugobjects: Warn wrong annotation outside bucket lock
@ 2018-12-13 4:34 Dmitry Safonov
2018-12-13 4:34 ` [PATCH 2/2] debugobjects: Print warnings " Dmitry Safonov
2018-12-13 9:28 ` [PATCH 1/2] debugobjects: Warn wrong annotation " Sergey Senozhatsky
0 siblings, 2 replies; 4+ messages in thread
From: Dmitry Safonov @ 2018-12-13 4:34 UTC (permalink / raw)
To: linux-kernel
Cc: 0x7f454c46, Dmitry Safonov, kernel test robot, Andrew Morton,
Ingo Molnar, Peter Zijlstra, Sergey Senozhatsky, Thomas Gleixner,
Waiman Long
debugobjects checks during initialization where the real object resides.
Kernel must use debug_object_init() or debug_object_init_on_stack()
accordingly. I'm not sure if it's worth to check debug_object
initialization place, but it seems to be well-documented.
If initialization function finds that the debug object actually resides
in a different place than was annotated, warning is being printed.
Unfortunately, it becomes error-prone to use WARN() or printing under
debugobjects bucket lock: printk() may defer work to workqueue, and
realization of workqueues uses debugobjects. Further, console drivers
use page allocator, potentially vmalloc() or slub/slab. Which reasonably
makes lockdep to go nuts as there are debug_check_no_obj_freed() checks
in allocators.
Move printings out of debugobjets bucket lock to address the potential
lockups.
Link: lkml.kernel.org/r/20181211091154.GL23332@shao2-debian
Reported-by: kernel test robot <rong.a.chen@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
lib/debugobjects.c | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)
diff --git a/lib/debugobjects.c b/lib/debugobjects.c
index 55437fd5128b..98968219405b 100644
--- a/lib/debugobjects.c
+++ b/lib/debugobjects.c
@@ -368,13 +368,14 @@ static void debug_object_is_on_stack(void *addr, int onstack)
WARN_ON(1);
}
-static void
-__debug_object_init(void *addr, struct debug_obj_descr *descr, int onstack)
+static bool
+__debug_object_init(void *addr, struct debug_obj_descr *descr)
{
enum debug_obj_state state;
struct debug_bucket *db;
struct debug_obj *obj;
unsigned long flags;
+ bool allocated = false;
fill_pool();
@@ -389,9 +390,9 @@ __debug_object_init(void *addr, struct debug_obj_descr *descr, int onstack)
debug_objects_enabled = 0;
raw_spin_unlock_irqrestore(&db->lock, flags);
debug_objects_oom();
- return;
+ return false;
}
- debug_object_is_on_stack(addr, onstack);
+ allocated = true;
}
switch (obj->state) {
@@ -406,7 +407,7 @@ __debug_object_init(void *addr, struct debug_obj_descr *descr, int onstack)
state = obj->state;
raw_spin_unlock_irqrestore(&db->lock, flags);
debug_object_fixup(descr->fixup_init, addr, state);
- return;
+ return allocated;
case ODEBUG_STATE_DESTROYED:
debug_print_object(obj, "init");
@@ -416,6 +417,7 @@ __debug_object_init(void *addr, struct debug_obj_descr *descr, int onstack)
}
raw_spin_unlock_irqrestore(&db->lock, flags);
+ return allocated;
}
/**
@@ -428,7 +430,8 @@ void debug_object_init(void *addr, struct debug_obj_descr *descr)
if (!debug_objects_enabled)
return;
- __debug_object_init(addr, descr, 0);
+ if (__debug_object_init(addr, descr))
+ debug_object_is_on_stack(addr, 0);
}
EXPORT_SYMBOL_GPL(debug_object_init);
@@ -443,7 +446,8 @@ void debug_object_init_on_stack(void *addr, struct debug_obj_descr *descr)
if (!debug_objects_enabled)
return;
- __debug_object_init(addr, descr, 1);
+ if (__debug_object_init(addr, descr))
+ debug_object_is_on_stack(addr, 1);
}
EXPORT_SYMBOL_GPL(debug_object_init_on_stack);
--
2.20.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH 2/2] debugobjects: Print warnings outside bucket lock
2018-12-13 4:34 [PATCH 1/2] debugobjects: Warn wrong annotation outside bucket lock Dmitry Safonov
@ 2018-12-13 4:34 ` Dmitry Safonov
2018-12-13 22:04 ` Waiman Long
2018-12-13 9:28 ` [PATCH 1/2] debugobjects: Warn wrong annotation " Sergey Senozhatsky
1 sibling, 1 reply; 4+ messages in thread
From: Dmitry Safonov @ 2018-12-13 4:34 UTC (permalink / raw)
To: linux-kernel
Cc: 0x7f454c46, Dmitry Safonov, kernel test robot, Andrew Morton,
Ingo Molnar, Peter Zijlstra, Sergey Senozhatsky, Thomas Gleixner,
Waiman Long
Whenever debugobjects finds invalid pattern during life time of a kernel
object such as:
- Activation of uninitialized objects
- Initialization of active objects
- Usage of freed/destroyed objects
it prints a warning and tries to make fixup over an object.
Unfortunately, it becomes error-prone to use WARN() or printing under
debugobjects bucket lock: printk() may defer work to workqueue, and
realization of workqueues uses debugobjects. Further, console drivers
use page allocator, potentially vmalloc() or slub/slab. Which reasonably
makes lockdep to go nuts as there are debug_check_no_obj_freed() checks
in allocators.
Move printings out of debugobjets bucket lock to address the potential
lockups.
Link: lkml.kernel.org/r/20181211091154.GL23332@shao2-debian
Reported-by: kernel test robot <rong.a.chen@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
lib/debugobjects.c | 89 ++++++++++++++++++++++++----------------------
1 file changed, 47 insertions(+), 42 deletions(-)
diff --git a/lib/debugobjects.c b/lib/debugobjects.c
index 98968219405b..0c92e46cb588 100644
--- a/lib/debugobjects.c
+++ b/lib/debugobjects.c
@@ -313,7 +313,7 @@ static struct debug_bucket *get_bucket(unsigned long addr)
return &obj_hash[hash];
}
-static void debug_print_object(struct debug_obj *obj, char *msg)
+static void __debug_print_object(struct debug_obj *obj, char *msg)
{
struct debug_obj_descr *descr = obj->descr;
static int limit;
@@ -330,6 +330,14 @@ static void debug_print_object(struct debug_obj *obj, char *msg)
debug_objects_warnings++;
}
+#define debug_print_object(obj, msg, lock, flags) \
+ do { \
+ struct debug_obj tmp = *obj; \
+ \
+ raw_spin_unlock_irqrestore(lock, flags); \
+ __debug_print_object(&tmp, msg); \
+ } while(0)
+
/*
* Try to repair the damage, so we have a better chance to get useful
* debug output.
@@ -403,15 +411,14 @@ __debug_object_init(void *addr, struct debug_obj_descr *descr)
break;
case ODEBUG_STATE_ACTIVE:
- debug_print_object(obj, "init");
state = obj->state;
- raw_spin_unlock_irqrestore(&db->lock, flags);
+ debug_print_object(obj, "init", &db->lock, flags);
debug_object_fixup(descr->fixup_init, addr, state);
return allocated;
case ODEBUG_STATE_DESTROYED:
- debug_print_object(obj, "init");
- break;
+ debug_print_object(obj, "init", &db->lock, flags);
+ return allocated;
default:
break;
}
@@ -485,16 +492,14 @@ int debug_object_activate(void *addr, struct debug_obj_descr *descr)
break;
case ODEBUG_STATE_ACTIVE:
- debug_print_object(obj, "activate");
state = obj->state;
- raw_spin_unlock_irqrestore(&db->lock, flags);
+ debug_print_object(obj, "activate", &db->lock, flags);
ret = debug_object_fixup(descr->fixup_activate, addr, state);
return ret ? 0 : -EINVAL;
case ODEBUG_STATE_DESTROYED:
- debug_print_object(obj, "activate");
- ret = -EINVAL;
- break;
+ debug_print_object(obj, "activate", &db->lock, flags);
+ return -EINVAL;
default:
ret = 0;
break;
@@ -516,7 +521,7 @@ int debug_object_activate(void *addr, struct debug_obj_descr *descr)
debug_object_init(addr, descr);
debug_object_activate(addr, descr);
} else {
- debug_print_object(&o, "activate");
+ __debug_print_object(&o, "activate");
ret = debug_object_fixup(descr->fixup_activate, addr,
ODEBUG_STATE_NOTAVAILABLE);
return ret ? 0 : -EINVAL;
@@ -549,27 +554,27 @@ void debug_object_deactivate(void *addr, struct debug_obj_descr *descr)
case ODEBUG_STATE_INIT:
case ODEBUG_STATE_INACTIVE:
case ODEBUG_STATE_ACTIVE:
- if (!obj->astate)
+ if (!obj->astate) {
obj->state = ODEBUG_STATE_INACTIVE;
- else
- debug_print_object(obj, "deactivate");
- break;
-
+ break;
+ }
+ /* fallthrough */
case ODEBUG_STATE_DESTROYED:
- debug_print_object(obj, "deactivate");
- break;
+ debug_print_object(obj, "deactivate", &db->lock, flags);
+ return;
default:
break;
}
- } else {
+ }
+ raw_spin_unlock_irqrestore(&db->lock, flags);
+
+ if (!obj) {
struct debug_obj o = { .object = addr,
.state = ODEBUG_STATE_NOTAVAILABLE,
.descr = descr };
- debug_print_object(&o, "deactivate");
+ __debug_print_object(&o, "deactivate");
}
-
- raw_spin_unlock_irqrestore(&db->lock, flags);
}
EXPORT_SYMBOL_GPL(debug_object_deactivate);
@@ -603,15 +608,14 @@ void debug_object_destroy(void *addr, struct debug_obj_descr *descr)
obj->state = ODEBUG_STATE_DESTROYED;
break;
case ODEBUG_STATE_ACTIVE:
- debug_print_object(obj, "destroy");
state = obj->state;
- raw_spin_unlock_irqrestore(&db->lock, flags);
+ debug_print_object(obj, "destroy", &db->lock, flags);
debug_object_fixup(descr->fixup_destroy, addr, state);
return;
case ODEBUG_STATE_DESTROYED:
- debug_print_object(obj, "destroy");
- break;
+ debug_print_object(obj, "destroy", &db->lock, flags);
+ return;
default:
break;
}
@@ -645,9 +649,8 @@ void debug_object_free(void *addr, struct debug_obj_descr *descr)
switch (obj->state) {
case ODEBUG_STATE_ACTIVE:
- debug_print_object(obj, "free");
state = obj->state;
- raw_spin_unlock_irqrestore(&db->lock, flags);
+ debug_print_object(obj, "free", &db->lock, flags);
debug_object_fixup(descr->fixup_free, addr, state);
return;
default:
@@ -695,7 +698,7 @@ void debug_object_assert_init(void *addr, struct debug_obj_descr *descr)
/* Track this static object */
debug_object_init(addr, descr);
} else {
- debug_print_object(&o, "assert_init");
+ __debug_print_object(&o, "assert_init");
debug_object_fixup(descr->fixup_assert_init, addr,
ODEBUG_STATE_NOTAVAILABLE);
}
@@ -732,25 +735,27 @@ debug_object_active_state(void *addr, struct debug_obj_descr *descr,
if (obj) {
switch (obj->state) {
case ODEBUG_STATE_ACTIVE:
- if (obj->astate == expect)
+ if (obj->astate == expect) {
obj->astate = next;
- else
- debug_print_object(obj, "active_state");
- break;
-
+ raw_spin_unlock_irqrestore(&db->lock, flags);
+ return;
+ }
+ /* fallthrough */
default:
- debug_print_object(obj, "active_state");
- break;
+ debug_print_object(obj, "active_state",
+ &db->lock, flags);
+ return;
}
- } else {
+ }
+ raw_spin_unlock_irqrestore(&db->lock, flags);
+
+ if (!obj) {
struct debug_obj o = { .object = addr,
.state = ODEBUG_STATE_NOTAVAILABLE,
.descr = descr };
- debug_print_object(&o, "active_state");
+ __debug_print_object(&o, "active_state");
}
-
- raw_spin_unlock_irqrestore(&db->lock, flags);
}
EXPORT_SYMBOL_GPL(debug_object_active_state);
@@ -786,10 +791,10 @@ static void __debug_check_no_obj_freed(const void *address, unsigned long size)
switch (obj->state) {
case ODEBUG_STATE_ACTIVE:
- debug_print_object(obj, "free");
descr = obj->descr;
state = obj->state;
- raw_spin_unlock_irqrestore(&db->lock, flags);
+ debug_print_object(obj, "free",
+ &db->lock, flags);
debug_object_fixup(descr->fixup_free,
(void *) oaddr, state);
goto repeat;
--
2.20.0
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH 1/2] debugobjects: Warn wrong annotation outside bucket lock
2018-12-13 4:34 [PATCH 1/2] debugobjects: Warn wrong annotation outside bucket lock Dmitry Safonov
2018-12-13 4:34 ` [PATCH 2/2] debugobjects: Print warnings " Dmitry Safonov
@ 2018-12-13 9:28 ` Sergey Senozhatsky
1 sibling, 0 replies; 4+ messages in thread
From: Sergey Senozhatsky @ 2018-12-13 9:28 UTC (permalink / raw)
To: Dmitry Safonov
Cc: linux-kernel, 0x7f454c46, kernel test robot, Andrew Morton,
Ingo Molnar, Peter Zijlstra, Sergey Senozhatsky, Thomas Gleixner,
Waiman Long
On (12/13/18 04:34), Dmitry Safonov wrote:
> printk() may defer work to workqueue, and realization of workqueues
> uses debugobjects.
Sorry, not following. You mean per-CPU irq_work which printk_deferred()
is using? That one should not deal with debugobjects.
-ss
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH 2/2] debugobjects: Print warnings outside bucket lock
2018-12-13 4:34 ` [PATCH 2/2] debugobjects: Print warnings " Dmitry Safonov
@ 2018-12-13 22:04 ` Waiman Long
0 siblings, 0 replies; 4+ messages in thread
From: Waiman Long @ 2018-12-13 22:04 UTC (permalink / raw)
To: Dmitry Safonov, linux-kernel
Cc: 0x7f454c46, kernel test robot, Andrew Morton, Ingo Molnar,
Peter Zijlstra, Sergey Senozhatsky, Thomas Gleixner
On 12/12/2018 11:34 PM, Dmitry Safonov wrote:
> Whenever debugobjects finds invalid pattern during life time of a kernel
> object such as:
> - Activation of uninitialized objects
> - Initialization of active objects
> - Usage of freed/destroyed objects
> it prints a warning and tries to make fixup over an object.
>
> Unfortunately, it becomes error-prone to use WARN() or printing under
> debugobjects bucket lock: printk() may defer work to workqueue, and
> realization of workqueues uses debugobjects. Further, console drivers
> use page allocator, potentially vmalloc() or slub/slab. Which reasonably
> makes lockdep to go nuts as there are debug_check_no_obj_freed() checks
> in allocators.
>
> Move printings out of debugobjets bucket lock to address the potential
> lockups.
>
> Link: lkml.kernel.org/r/20181211091154.GL23332@shao2-debian
> Reported-by: kernel test robot <rong.a.chen@intel.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Ingo Molnar <mingo@kernel.org>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Waiman Long <longman@redhat.com>
> Signed-off-by: Dmitry Safonov <dima@arista.com>
> ---
> lib/debugobjects.c | 89 ++++++++++++++++++++++++----------------------
> 1 file changed, 47 insertions(+), 42 deletions(-)
>
> diff --git a/lib/debugobjects.c b/lib/debugobjects.c
> index 98968219405b..0c92e46cb588 100644
> --- a/lib/debugobjects.c
> +++ b/lib/debugobjects.c
> @@ -313,7 +313,7 @@ static struct debug_bucket *get_bucket(unsigned long addr)
> return &obj_hash[hash];
> }
>
> -static void debug_print_object(struct debug_obj *obj, char *msg)
> +static void __debug_print_object(struct debug_obj *obj, char *msg)
> {
> struct debug_obj_descr *descr = obj->descr;
> static int limit;
> @@ -330,6 +330,14 @@ static void debug_print_object(struct debug_obj *obj, char *msg)
> debug_objects_warnings++;
> }
>
> +#define debug_print_object(obj, msg, lock, flags) \
> + do { \
> + struct debug_obj tmp = *obj; \
> + \
> + raw_spin_unlock_irqrestore(lock, flags); \
> + __debug_print_object(&tmp, msg); \
> + } while(0)
> +
My main problem with this patch is the hiding of the unlock call in the
macro. I will prefer matching unlocks to be clearly visible in the
function bodies. Otherwise, the readers may be confused.
Cheers,
Longman
^ permalink raw reply [flat|nested] 4+ messages in thread
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2018-12-13 4:34 [PATCH 1/2] debugobjects: Warn wrong annotation outside bucket lock Dmitry Safonov
2018-12-13 4:34 ` [PATCH 2/2] debugobjects: Print warnings " Dmitry Safonov
2018-12-13 22:04 ` Waiman Long
2018-12-13 9:28 ` [PATCH 1/2] debugobjects: Warn wrong annotation " Sergey Senozhatsky
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