mm/vmscan.c: reclaim unevictable pages

[Pankaj Suryawanshi]

Hello ,


shrink_page_list() returns , number of pages reclaimed, when pages is unevictable it returns VM_BUG_ON_PAGE(PageLRU(page) || PageUnevicatble(page),page);


We can add the unevictable pages in reclaim list in shrink_page_list(), return total number of reclaim pages including unevictable pages, let the caller handle unevictable pages.



Below is the Error Msg/Kerenl Crash :

[   24.718792] page dumped because: VM_BUG_ON_PAGE(PageLRU(page) || PageUnevictable(page))
[   24.726949] page->mem_cgroup:bd008c00
[   24.730693] ------------[ cut here ]------------
[   24.735304] kernel BUG at mm/vmscan.c:1350!
[   24.739478] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM


Solved the issue by below 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
************************************************************************************************************************************************************* eInfochips Business Disclaimer: This e-mail message and all attachments transmitted with it are intended solely for the use of the addressee and may contain legally privileged and confidential information. If the reader of this message is not the intended recipient, or an employee or agent responsible for delivering this message to the intended recipient, you are hereby notified that any dissemination, distribution, copying, or other use of this message or its attachments is strictly prohibited. If you have received this message in error, please notify the sender immediately by replying to this message and please delete it from your computer. Any views expressed in this message are those of the individual sender unless otherwise stated. Company has taken enough precautions to prevent the spread of viruses. However the company accepts no liability for any damage caused by any virus transmitted by this email. *************************************************************************************************************************************************************