commit 6ffc040a358254061fc9f1a0867945d06c2cc533
author Liam Mark <lmark@codeaurora.org> Fri Feb 27 12:59:00 2015 -0800
committer chrmhoffmann <chrmhoffmann@gmail.com> Sun Apr 05 20:16:42 2020 +0200
tree c03daae2eb4de9e11cf97c5811056cdaecacd5f6
parent 20cba1b819aee0c215de114c8a14db85059e054a

lowmemorykiller: Don't count swap cache pages twice

The lowmem_shrink function discounts all the swap cache pages from
the file cache count. The zone aware code also discounts all file
cache pages from a certain zone.  This results in some swap cache
pages being discounted twice, which can result in the low memory
killer being unnecessarily aggressive.

Fix the low memory killer to only discount the swap cache pages
once.

Change-Id: I650bbfbf0fbbabd01d82bdb3502b57ff59c3e14f
Signed-off-by: Liam Mark <lmark@codeaurora.org>
Signed-off-by: Kevin F. Haggerty <haggertk@lineageos.org>

drivers/staging/android/lowmemorykiller.c

diff --git a/drivers/staging/android/lowmemorykiller.c b/drivers/staging/android/lowmemorykiller.c
index b9c0bce..c54b54d 100644
--- a/drivers/staging/android/lowmemorykiller.c
+++ b/drivers/staging/android/lowmemorykiller.c
@@ -144,7 +144,8 @@
 			if (other_file != NULL)
 				*other_file -= zone_page_state(zone,
 							       NR_FILE_PAGES)
-					      - zone_page_state(zone, NR_SHMEM);
+					- zone_page_state(zone, NR_SHMEM)
+					- zone_page_state(zone, NR_SWAPCACHE);
 		} else if (zone_idx < classzone_idx) {
 			if (zone_watermark_ok(zone, 0, 0, classzone_idx, 0)) {
 				if (!use_cma_pages) {

include/linux/mmzone.h

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 7aa1662..53b654f 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -151,6 +151,7 @@
 #endif
 	NR_ANON_TRANSPARENT_HUGEPAGES,
 	NR_FREE_CMA_PAGES,
+	NR_SWAPCACHE,
 	NR_VM_ZONE_STAT_ITEMS };
 
 /*

mm/swap_state.c

diff --git a/mm/swap_state.c b/mm/swap_state.c
index cd5c321..d3f58d3 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -97,6 +97,7 @@
 	if (likely(!error)) {
 		address_space->nrpages++;
 		__inc_zone_page_state(page, NR_FILE_PAGES);
+		__inc_zone_page_state(page, NR_SWAPCACHE);
 		INC_CACHE_INFO(add_total);
 	}
 	spin_unlock_irq(&address_space->tree_lock);
@@ -149,6 +150,7 @@
 	ClearPageSwapCache(page);
 	address_space->nrpages--;
 	__dec_zone_page_state(page, NR_FILE_PAGES);
+	__dec_zone_page_state(page, NR_SWAPCACHE);
 	INC_CACHE_INFO(del_total);
 }
 

mm/vmstat.c

diff --git a/mm/vmstat.c b/mm/vmstat.c
index 213f9b7..a68bfb7 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -726,6 +726,7 @@
 #endif
 	"nr_anon_transparent_hugepages",
 	"nr_free_cma",
+	"nr_swapcache",
 	"nr_dirty_threshold",
 	"nr_dirty_background_threshold",