commit c3108416e75607f338c2e4b90020d5e899195c3e
author Martin Liu <liumartin@google.com> Thu Sep 03 22:12:14 2020 +0800
committer Martin Liu <liumartin@google.com> Fri Sep 04 00:03:49 2020 +0800
tree 7e5b7fffef4807bbdd71b1669eb1df4e1ca76c49
parent 1f72f5fa4bee58c27fe413898e17d98e7ee61eb1

lmkd: avoid division by zero because of file_base_lru

It seems we have chance that file_base_lru is zero.
Avoid it by adding 1.

Bug: 167660459
Test: boot
Signed-off-by: Martin Liu <liumartin@google.com>
Change-Id: If19dbbaafe6cd28a9d5b7f8a002f3cd33daab5e7

lmkd.cpp

diff --git a/lmkd.cpp b/lmkd.cpp
index a4367c3..22711e9 100644
--- a/lmkd.cpp
+++ b/lmkd.cpp
@@ -2422,7 +2422,8 @@
     if (since_thrashing_reset_ms > THRASHING_RESET_INTERVAL_MS) {
         long windows_passed;
         /* Calculate prev_thrash_growth if we crossed THRASHING_RESET_INTERVAL_MS */
-        prev_thrash_growth = (vs.field.workingset_refault - init_ws_refault) * 100 / base_file_lru;
+        prev_thrash_growth = (vs.field.workingset_refault - init_ws_refault) * 100
+                            / (base_file_lru + 1);
         windows_passed = (since_thrashing_reset_ms / THRASHING_RESET_INTERVAL_MS);
         /*
          * Decay prev_thrashing unless over-the-limit thrashing was registered in the window we
@@ -2440,7 +2441,7 @@
         thrashing_limit = thrashing_limit_pct;
     } else {
         /* Calculate what % of the file-backed pagecache refaulted so far */
-        thrashing = (vs.field.workingset_refault - init_ws_refault) * 100 / base_file_lru;
+        thrashing = (vs.field.workingset_refault - init_ws_refault) * 100 / (base_file_lru + 1);
     }
     /* Add previous cycle's decayed thrashing amount */
     thrashing += prev_thrash_growth;