Re: [PATCH] sched: Avoid that __wait_on_bit_lock() hangs

[Bart Van Assche <bart.vanassche@sandisk.com>]

On 08/10/2016 03:46 AM, Oleg Nesterov wrote:
> OK. Could you  try another debugging patch below?
> 
> Oleg.
> ---
> 
> diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
> index e5a3244..9d5f892 100644
> --- a/include/linux/page-flags.h
> +++ b/include/linux/page-flags.h
> @@ -711,6 +711,15 @@ static inline int page_has_private(struct page *page)
>  	return !!(page->flags & PAGE_FLAGS_PRIVATE);
>  }
>  
> +void unlock_page(struct page *page);
> +static inline void __ClearPageLocked_x(struct page *page)
> +{
> +	if (PageLocked(compound_head(page)))
> +		unlock_page(page);
> +}
> +
> +#define __ClearPageLocked(page)	__ClearPageLocked_x(page)
> +
>  #undef PF_ANY
>  #undef PF_HEAD
>  #undef PF_NO_TAIL
 
Hi Oleg,

Are you sure that all __ClearPageLocked() users pass the compound head
to that macro? How about testing the patch below instead?

Thanks,

Bart.
 
---
 include/linux/page-flags.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index e5a3244..10d8e63 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -711,6 +711,17 @@ static inline int page_has_private(struct page *page)
 	return !!(page->flags & PAGE_FLAGS_PRIVATE);
 }
 
+void unlock_page(struct page *page);
+static inline void __ClearPageLocked_x(struct page *page)
+{
+	if (PageLocked(compound_head(page)))
+		unlock_page(page);
+	else
+		__ClearPageLocked(page);
+}
+
+#define __ClearPageLocked(page)	__ClearPageLocked_x(page)
+
 #undef PF_ANY
 #undef PF_HEAD
 #undef PF_NO_TAIL
-- 
2.9.2