Remove -i flag

Kernel 5.9 changed how oom_score_adj works, and
I don't think this feature is worth having kernel
version detection to make it work on older & newer
kernels. Just drop it.

Fixes #234

MANPAGE.md

@@ -71,7 +71,7 @@ Send SIGKILL if at or below KILL_SIZE (default SIZE/2), otherwise SIGTERM.
 removed in earlyoom v1.2, ignored for compatibility
 
 #### -i
-user-space oom killer should ignore positive oom_score_adj values
+removed in earlyoom v1.7, ignored for compatibility
 
 #### -d
 enable debugging messages

README.md

@@ -272,6 +272,8 @@ Changelog
 ---------
 * vNEXT
   * Add `-g` flag to kill whole process group ([#247](https://github.com/rfjakob/earlyoom/pull/247))
+  * Remove `-i` flag (ignored for compatibility), it does
+    not work properly on Linux kernels 5.9+ ([#234](https://github.com/rfjakob/earlyoom/issues/234))
 
 * v1.6.2, 2020-10-14
   * Double-check memory situation before killing victim ([commit](https://github.com/rfjakob/earlyoom/commit/e34e0fcec5d9f60eb19a48a3ec2bab175818fdd8))

kill.c

@@ -171,17 +171,6 @@ procinfo_t find_largest_process(const poll_loop_args_t* args)
             }
             cur.badness = res;
         }
-        if (args->ignore_oom_score_adj) {
-            int oom_score_adj = 0;
-            int res = get_oom_score_adj(cur.pid, &oom_score_adj);
-            if (res < 0) {
-                debug(" error reading oom_score_adj: %s\n", strerror(-res));
-                continue;
-            }
-            if (oom_score_adj > 0) {
-                cur.badness -= oom_score_adj;
-            }
-        }
 
         if ((args->prefer_regex || args->avoid_regex)) {
             int res = get_comm(cur.pid, cur.name, sizeof(cur.name));

kill.h

@@ -14,8 +14,6 @@ typedef struct {
     double mem_kill_percent;
     double swap_term_percent;
     double swap_kill_percent;
-    /* ignore /proc/PID/oom_score_adj? */
-    bool ignore_oom_score_adj;
     /* send d-bus notifications? */
     bool notify;
     /* kill all processes within a process group */

main.c

@@ -166,8 +166,7 @@ int main(int argc, char* argv[])
             fprintf(stderr, "Option -k is ignored since earlyoom v1.2\n");
             break;
         case 'i':
-            args.ignore_oom_score_adj = 1;
-            fprintf(stderr, "Ignoring positive oom_score_adj values (-i)\n");
+            fprintf(stderr, "Option -i is ignored since earlyoom v1.7\n");
             break;
         case 'n':
             args.notify = true;

testsuite_cli_test.go

@@ -4,8 +4,6 @@ import (
 	"fmt"
 	"io/ioutil"
 	"math"
-	"os/exec"
-	"regexp"
 	"strconv"
 	"strings"
 	"testing"
@@ -105,7 +103,7 @@ func TestCli(t *testing.T) {
 		// Test --avoid and --prefer
 		{args: []string{"--avoid", "MyProcess1"}, code: -1, stderrContains: "Will avoid killing", stdoutContains: memReport},
 		{args: []string{"--prefer", "MyProcess2"}, code: -1, stderrContains: "Preferring to kill", stdoutContains: memReport},
-		{args: []string{"-i"}, code: -1, stderrContains: "Ignoring positive oom_score_adj values"},
+		{args: []string{"-i"}, code: -1, stderrContains: "Option -i is ignored"},
 		// Extra arguments should error out
 		{args: []string{"xyz"}, code: 13, stderrContains: "extra argument not understood", stdoutEmpty: true},
 		{args: []string{"-i", "1"}, code: 13, stderrContains: "extra argument not understood", stdoutEmpty: true},
@@ -216,47 +214,3 @@ func TestRss(t *testing.T) {
 	}
 	t.Logf("earlyoom RSS: %d kiB", res.rss)
 }
-
-// TestI tests that `earlyoom -i` works as expected
-func TestI(t *testing.T) {
-	cmd := exec.Command("sleep", "60")
-	err := cmd.Start()
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer cmd.Process.Kill()
-	path := fmt.Sprintf("/proc/%d/oom_score_adj", cmd.Process.Pid)
-	err = ioutil.WriteFile(path, []byte("1000"), 0600)
-	if err != nil {
-		t.Fatal(err)
-	}
-	res := runEarlyoom(t, "-d")
-	// We should see a line like this:
-	//   pid 2308155: badness 1000 vm_rss     708 uid 1026 "sleep" <--- new victim
-	// Or, for some reason, this:
-	//   pid  6950: badness 999 vm_rss     772 uid 1026 "sleep" <--- new victim
-	matched := false
-	for _, b := range []int{1000, 999} {
-		pattern := fmt.Sprintf(`pid\s+%d: badness %d`, cmd.Process.Pid, b)
-		matched, err = regexp.MatchString(pattern, res.stdout)
-		if err != nil {
-			t.Fatal(err)
-		}
-		if matched {
-			break
-		}
-	}
-	if !matched {
-		t.Error("did not see badness 1000 or 999 in output")
-		t.Log(res.stdout)
-	}
-	res = runEarlyoom(t, "-d", "-i")
-	pattern := fmt.Sprintf(`pid\s+%d: badness %d`, cmd.Process.Pid, 1000)
-	matched, err = regexp.MatchString(pattern, res.stdout)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if matched {
-		t.Error("saw badness 1000, but should not have")
-	}
-}