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

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Message-ID: <SG2PR02MB3098299456FB6AE2FD822C4CE84B0@SG2PR02MB3098.apcprd02.prod.outlook.com>
Date:   Thu, 14 Mar 2019 11:09:44 +0000
From:   Pankaj Suryawanshi <pankaj.suryawanshi@...fochips.com>
To:     Kirill Tkhai <ktkhai@...tuozzo.com>,
        Michal Hocko <mhocko@...nel.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "minchan@...nel.org" <minchan@...nel.org>
Subject: Re: Re: [External] Re: vmscan: Reclaim unevictable pages

Hello ,

The curly braces are just for debugging purpose so please ignore it.

Below is the updated patch :

                if (!trylock_page(page))
                        goto keep;

                VM_BUG_ON_PAGE(PageActive(page), page);

                sc->nr_scanned++;

                if (unlikely(!page_evictable(page)))
-                       goto activate_locked;
+                      goto cull_mlocked;

                if (!sc->may_unmap && page_mapped(page))
                        goto keep_locked;
@@ -1331,6 +1333,12 @@ 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. */

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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