linux-kernel - Re: [External] Re: vmscan: Reclaim unevictable pages

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Date:   Mon, 18 Mar 2019 09:42:50 +0100
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Pankaj Suryawanshi <pankaj.suryawanshi@...fochips.com>,
        Kirill Tkhai <ktkhai@...tuozzo.com>,
        Michal Hocko <mhocko@...nel.org>,
        "aneesh.kumar@...ux.ibm.com" <aneesh.kumar@...ux.ibm.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "minchan@...nel.org" <minchan@...nel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "khandual@...ux.vnet.ibm.com" <khandual@...ux.vnet.ibm.com>,
        "hillf.zj@...baba-inc.com" <hillf.zj@...baba-inc.com>
Subject: Re: [External] Re: vmscan: Reclaim unevictable pages

On 3/15/19 11:11 AM, Pankaj Suryawanshi wrote:
> 
> [ cc Aneesh kumar, Anshuman, Hillf, Vlastimil]

Can you send a proper patch with changelog explaining the change? I
don't know the context of this thread.

> From: Pankaj Suryawanshi
> Sent: 15 March 2019 11:35:05
> To: Kirill Tkhai; Michal Hocko
> Cc: linux-kernel@...r.kernel.org; minchan@...nel.org; linux-mm@...ck.org
> Subject: Re: Re: [External] Re: vmscan: Reclaim unevictable pages
> 
> 
> 
> [ cc linux-mm ]
> 
> 
> From: Pankaj Suryawanshi
> Sent: 14 March 2019 19:14:40
> To: Kirill Tkhai; Michal Hocko
> Cc: linux-kernel@...r.kernel.org; minchan@...nel.org
> Subject: Re: Re: [External] Re: vmscan: Reclaim unevictable pages
> 
> 
> 
> Hello ,
> 
> Please ignore the curly braces, they are just for debugging.
> 
> Below is the updated patch.
> 
> 
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index be56e2e..12ac353 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -998,7 +998,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
>                 sc->nr_scanned++;
> 
>                 if (unlikely(!page_evictable(page)))
> -                       goto activate_locked;
> +                      goto cull_mlocked;
> 
>                 if (!sc->may_unmap && page_mapped(page))
>                         goto keep_locked;
> @@ -1331,7 +1331,12 @@ static unsigned long shrink_page_list(struct list_head *page_list,
>                 } else
>                         list_add(&page->lru, &free_pages);
>                 continue;
> -
> +cull_mlocked:
> +                if (PageSwapCache(page))
> +                        try_to_free_swap(page);
> +                unlock_page(page);
> +                list_add(&page->lru, &ret_pages);
> +                continue;
>  activate_locked:
>                 /* Not a candidate for swapping, so reclaim swap space. */
>                 if (PageSwapCache(page) && (mem_cgroup_swap_full(page) ||
> 
> 
> 
> Regards,
> Pankaj
> 
> 
> From: Kirill Tkhai <ktkhai@...tuozzo.com>
> Sent: 14 March 2019 14:55:34
> To: Pankaj Suryawanshi; Michal Hocko
> Cc: linux-kernel@...r.kernel.org; minchan@...nel.org
> Subject: Re: Re: [External] Re: vmscan: Reclaim unevictable pages
> 
> 
> On 14.03.2019 11:52, Pankaj Suryawanshi wrote:
>>
>> I am using kernel version 4.14.65 (on Android pie [ARM]).
>>
>> No additional patches applied on top of vanilla.(Core MM).
>>
>> If  I change in the vmscan.c as below patch, it will work.
> 
> Sorry, but 4.14.65 does not have braces around trylock_page(),
> like in your patch below.
> 
> See     https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/mm/vmscan.c?h=v4.14.65
> 
> [...]
> 
>>> diff --git a/mm/vmscan.c b/mm/vmscan.c
>>> index be56e2e..2e51edc 100644
>>> --- a/mm/vmscan.c
>>> +++ b/mm/vmscan.c
>>> @@ -990,15 +990,17 @@ static unsigned long shrink_page_list(struct list_head *page_list,
>>>                  page = lru_to_page(page_list);
>>>                  list_del(&page->lru);
>>>
>>>                 if (!trylock_page(page)) {
>>>                          goto keep;
>>>                 }
> 
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