Re: [PATCH 1/6] oom: Make find_lock_task_mm() sparse-aware

From: Greg KH
Date: Mon Feb 06 2012 - 11:37:09 EST


On Mon, Feb 06, 2012 at 08:29:30PM +0400, Anton Vorontsov wrote:
> This is needed so that callers would not get 'context imbalance'
> warnings from the sparse tool.
>
> As a side effect, this patch fixes the following sparse warnings:
>
> CHECK mm/oom_kill.c
> mm/oom_kill.c:201:28: warning: context imbalance in 'oom_badness' -
> unexpected unlock
> include/linux/rcupdate.h:249:30: warning: context imbalance in
> 'dump_tasks' - unexpected unlock
> mm/oom_kill.c:453:9: warning: context imbalance in 'oom_kill_task' -
> unexpected unlock
> CHECK mm/memcontrol.c
> ...
> mm/memcontrol.c:1130:17: warning: context imbalance in
> 'task_in_mem_cgroup' - unexpected unlock
>
> Signed-off-by: Anton Vorontsov <anton.vorontsov@xxxxxxxxxx>
> ---
> include/linux/oom.h | 11 ++++++++++-
> mm/oom_kill.c | 2 +-
> 2 files changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/oom.h b/include/linux/oom.h
> index 552fba9..e64bfd2 100644
> --- a/include/linux/oom.h
> +++ b/include/linux/oom.h
> @@ -21,6 +21,7 @@
>
> #ifdef __KERNEL__
>
> +#include <linux/compiler.h>
> #include <linux/sched.h>
> #include <linux/types.h>
> #include <linux/nodemask.h>
> @@ -65,7 +66,15 @@ static inline void oom_killer_enable(void)
> oom_killer_disabled = false;
> }
>
> -extern struct task_struct *find_lock_task_mm(struct task_struct *p);
> +extern struct task_struct *__find_lock_task_mm(struct task_struct *p);
> +
> +#define find_lock_task_mm(p) \
> +({ \
> + struct task_struct *__ret; \
> + \
> + __cond_lock(&(p)->alloc_lock, __ret = __find_lock_task_mm(p)); \
> + __ret; \
> +})

Please use the proper "do...while" style thing here for multi-line,
complex #defines like the rest of the kernel does so that you don't end
up debugging horrible problems later.

And I would need acks from the -mm developers before I could apply any
of this.

thanks,

greg k-h
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