[linux-yocto] [PATCH 1/1] 4.1.28 Fix bad backport of 8f182270dfec "mm/swap.c: flush lru, pvecs on compound page arrival"

[Bruce Ashfield]

On 2016-07-25 04:43 PM, Chris Sykes wrote:
>  From 74225a4cbea38034034add5da67a2f7ee23251c0 Mon Sep 17 00:00:00 2001
> From: Steven Rostedt <rostedt at goodmis.org>
>
> When I pulled in 4.1.28 into my stable 4.1-rt tree and ran the tests,
> it crashed with a severe OOM killing everything. I then tested 4.1.28
> without -rt and it had the same issue. I did a bisect between 4.1.27
> and 4.1.28 and found that the bug started at:
>
> commit 8f182270dfec "mm/swap.c: flush lru pvecs on compound page
> arrival"
>
> Looking at that patch and what's in mainline, I see that there's a
> mismatch in one of the hunks:

I expect that 4.1.29 will drop any day now, but I went ahead and
integrated this change.

The patch was slightly corrupted, so I grabbed it directly off the
4.1.y stable queue.

SRCREV updates will be out shortly for this (but it is in the tree
now).

Bruce

>
> Mainline:
>
> @@ -391,9 +391,8 @@ static void __lru_cache_add(struct page *page)
>          struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
>
>          get_page(page);
> -       if (!pagevec_space(pvec))
> +       if (!pagevec_add(pvec, page) || PageCompound(page))
>                  __pagevec_lru_add(pvec);
> -       pagevec_add(pvec, page);
>          put_cpu_var(lru_add_pvec);
>   }
>
> Stable 4.1.28:
>
> @@ -631,9 +631,8 @@ static void __lru_cache_add(struct page *page)
>          struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
>
>          page_cache_get(page);
> -       if (!pagevec_space(pvec))
> +       if (!pagevec_space(pvec) || PageCompound(page))
>                  __pagevec_lru_add(pvec);
> -       pagevec_add(pvec, page);
>          put_cpu_var(lru_add_pvec);
>   }
>
> Where mainline replace pagevec_space() with pagevec_add, and stable did
> not.
>
> Fixing this makes the OOM go away.
>
> Note, 3.18 has the same bug.
>
> Signed-off-by: Steven Rostedt <rostedt at goodmis.org>
> Signed-off-by: Sasha Levin <alexander.levin at verizon.com>
> ---
>   mm/swap.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/swap.c b/mm/swap.c
> index b523f0a..ab3b9c2 100644
> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -631,7 +631,7 @@ static void __lru_cache_add(struct page *page)
>       struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
>
>       page_cache_get(page);
> -    if (!pagevec_space(pvec) || PageCompound(page))
> +    if (!pagevec_add(pvec, page) || PageCompound(page))
>           __pagevec_lru_add(pvec);
>       put_cpu_var(lru_add_pvec);
>   }