Re: [PATCH 07/18] mm, proc: make clear_refs killable

[Oleg Nesterov]

On 02/29, Michal Hocko wrote:
>
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -1027,11 +1027,15 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
>  		};
>
>  		if (type == CLEAR_REFS_MM_HIWATER_RSS) {
> +			if (down_write_killable(&mm->mmap_sem)) {
> +				put_task_struct(task);
> +				return -EINTR;
> +			}
> +
>  			/*
>  			 * Writing 5 to /proc/pid/clear_refs resets the peak
>  			 * resident set size to this mm's current rss value.
>  			 */
> -			down_write(&mm->mmap_sem);
>  			reset_mm_hiwater_rss(mm);
>  			up_write(&mm->mmap_sem);
>  			goto out_mm;
> @@ -1043,7 +1047,10 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
>  				if (!(vma->vm_flags & VM_SOFTDIRTY))
>  					continue;
>  				up_read(&mm->mmap_sem);
> -				down_write(&mm->mmap_sem);
> +				if (down_write_killable(&mm->mmap_sem)) {
> +					put_task_struct(task);
> +					return -EINTR;
> +				}

Both lack mmput() afaics. Don't you need "goto out_mm" rather then "return" ? In
this case you do not need put_task_struct().

Oleg.