add --prefer-only option to only kill processes matching --prefer

While --avoid exists to list processes that should not be killed, it may be desirable to have earlyoom simply ignore any processes that do not match the regex specified in --prefer. It should be noted that the Linux kernel may still opt to kill other processes if earlyoom did not free up enough memory to prevent an oom. Signed-off-by: Murat Boyar <[email protected]> Signed-off-by: Cedric Hombourger <[email protected]>
rfjakob · Mar 11, 2024 · 687e820 · 687e820
1 parent c19f61a
commit 687e820
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Showing 4 changed files with 30 additions and 5 deletions.
diff --git a/kill.c b/kill.c
@@ -309,11 +309,15 @@ bool is_larger(const poll_loop_args_t* args, const procinfo_t* victim, procinfo_
             debug("pid %d: error reading process name: %s\n", cur->pid, strerror(-res));
             return false;
         }
-        if (args->prefer_regex && regexec(args->prefer_regex, cur->name, (size_t)0, NULL, 0) == 0) {
-            if (args->sort_by_rss) {
-                cur->VmRSSkiB += VMRSS_PREFER;
-            } else {
-                cur->badness += BADNESS_PREFER;
+        if (args->prefer_regex) {
+            if (regexec(args->prefer_regex, cur->name, (size_t)0, NULL, 0) == 0) {
+                if (args->sort_by_rss) {
+                    cur->VmRSSkiB += VMRSS_PREFER;
+                } else {
+                    cur->badness += BADNESS_PREFER;
+                }
+            } else if (args->prefer_only) {
+                return false;
             }
         }
         if (args->avoid_regex && regexec(args->avoid_regex, cur->name, (size_t)0, NULL, 0) == 0) {

diff --git a/kill.h b/kill.h
@@ -33,6 +33,8 @@ typedef struct {
     int report_interval_ms;
     /* Flag --dryrun was passed */
     bool dryrun;
+    /* Flag --prefer-only was passed */
+    bool prefer_only;
 } poll_loop_args_t;
 
 void kill_process(const poll_loop_args_t* args, int sig, const procinfo_t* victim);

diff --git a/main.c b/main.c
@@ -43,6 +43,7 @@ enum {
     LONG_OPT_IGNORE_ROOT,
     LONG_OPT_USE_SYSLOG,
     LONG_OPT_SORT_BY_RSS,
+    LONG_OPT_PREFER_ONLY,
 };
 
 static int set_oom_score_adj(int);
@@ -129,6 +130,7 @@ int main(int argc, char* argv[])
     const char* short_opt = "m:s:M:S:kingN:dvr:ph";
     struct option long_opt[] = {
         { "prefer", required_argument, NULL, LONG_OPT_PREFER },
+        { "prefer-only", no_argument, NULL, LONG_OPT_PREFER_ONLY },
         { "avoid", required_argument, NULL, LONG_OPT_AVOID },
         { "ignore", required_argument, NULL, LONG_OPT_IGNORE },
         { "dryrun", no_argument, NULL, LONG_OPT_DRYRUN },
@@ -234,6 +236,10 @@ int main(int argc, char* argv[])
         case LONG_OPT_PREFER:
             prefer_cmds = optarg;
             break;
+        case LONG_OPT_PREFER_ONLY:
+            warn("prefer-only mode enabled, will only kill processes matching --prefer\n");
+            args.prefer_only = 1;
+            break;
         case LONG_OPT_AVOID:
             avoid_cmds = optarg;
             break;
@@ -273,6 +279,7 @@ int main(int argc, char* argv[])
                 "  --ignore-root-user        do not kill processes owned by root\n"
                 "  --sort-by-rss             find process with the largest rss (default oom_score)\n"
                 "  --prefer REGEX            prefer to kill processes matching REGEX\n"
+                "  --prefer-only             only kill processes matched by --prefer\n"
                 "  --avoid REGEX             avoid killing processes matching REGEX\n"
                 "  --ignore REGEX            ignore processes matching REGEX\n"
                 "  --dryrun                  dry run (do not kill any processes)\n"
@@ -324,6 +331,14 @@ int main(int argc, char* argv[])
         }
         fprintf(stderr, "Preferring to kill process names that match regex '%s'\n", prefer_cmds);
     }
+    if (args.prefer_only) {
+        if (!prefer_cmds) {
+            fatal(EINVAL, "prefer-only requires --prefer\n");
+        } else if (avoid_cmds) {
+            avoid_cmds = NULL;
+            warn("prefer-only and --avoid are mutually exclusive, ignoring --avoid\n");
+        }
+    }
     if (avoid_cmds) {
         args.avoid_regex = &_avoid_regex;
         if (regcomp(args.avoid_regex, avoid_cmds, REG_EXTENDED | REG_NOSUB) != 0) {

diff --git a/testsuite_cli_test.go b/testsuite_cli_test.go
@@ -105,6 +105,10 @@ func TestCli(t *testing.T) {
 		// Test --avoid, --prefer, --ignore-root-user and --sort-by-rss
 		{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{"--prefer", "MyProcess1", "--prefer-only", "--avoid", "MyProcess2"}, code: -1, stderrContains: "prefer-only and --avoid are mutually", stdoutContains: memReport},
+		{args: []string{"--prefer", "MyProcess1", "--prefer-only"}, code: -1, stderrContains: "prefer-only mode enabled", stdoutContains: memReport},
+		{args: []string{"--avoid", "MyProcess2", "--prefer-only"}, code: 22, stderrContains: "fatal", stdoutEmpty: true},
+		{args: []string{"--prefer-only"}, code: 22, stderrContains: "fatal", stdoutEmpty: true},
 		{args: []string{"--ignore-root-user"}, code: -1, stderrContains: "Processes owned by root will not be killed", stdoutContains: memReport},
 		{args: []string{"--sort-by-rss"}, code: -1, stderrContains: "Find process with the largest rss", stdoutContains: memReport},
 		{args: []string{"-i"}, code: -1, stderrContains: "Option -i is ignored"},