proc: fix MemAvailable in /proc/meminfo to exclude tmpfs files

The "total_cache" from memory.stat of cgroup includes
the memory used by tmpfs files ("total_shmem"). Considering
it as available memory is wrong because files created
on a tmpfs file system cannot be simply reclaimed.

So the available memory is calculated with the sum of:
 * Memory the kernel knows is free
 * Memory that contained in the kernel active file LRU,
   that can be reclaimed if necessary
 * Memory that is contained in the kernel non-active file
   LRU, that can be reclaimed if necessary

Signed-off-by: Kyeong Yoo <kyeong.yoo@alliedtelesis.co.nz>

diff --git a/src/proc_fuse.c b/src/proc_fuse.c
index 40eb26804253bbd6ede8666f280267cef151fe3d..1d253bbad5f8a7923bf3015144792d0ea8084d7e 100644 (file)
--- a/src/proc_fuse.c
+++ b/src/proc_fuse.c
@@ -1351,7 +1351,7 @@ static int proc_meminfo_read(char *buf, size_t size, off_t offset,
                        snprintf(lbuf, 100, "MemFree:        %8" PRIu64 " kB\n", memlimit - memusage);
                        printme = lbuf;
                } else if (startswith(line, "MemAvailable:")) {
-                       snprintf(lbuf, 100, "MemAvailable:   %8" PRIu64 " kB\n", memlimit - memusage + mstat.total_cache / 1024);
+                       snprintf(lbuf, 100, "MemAvailable:   %8" PRIu64 " kB\n", memlimit - memusage + (mstat.total_active_file + mstat.total_inactive_file) / 1024);
                        printme = lbuf;
                } else if (startswith(line, "SwapTotal:")) {
                        if (wants_swap) {