oom-score: restore oom score before running exit command

When the exit command is executed, the oom score is restored to its
original value otherwise the command runs with -1000.

Closes: containers/podman#20765

Signed-off-by: Giuseppe Scrivano <[email protected]>

src/conmon.c

@@ -43,7 +43,6 @@ int main(int argc, char *argv[])
 	_cleanup_gerror_ GError *err = NULL;
 	char buf[BUF_SIZE];
 	int num_read;
-	int old_oom_score = 0;
 	_cleanup_close_ int dev_null_r_cleanup = -1;
 	_cleanup_close_ int dev_null_w_cleanup = -1;
 	_cleanup_close_ int dummyfd = -1;
@@ -55,7 +54,7 @@ int main(int argc, char *argv[])
 
 	process_cli();
 
-	attempt_oom_adjust(-1000, &old_oom_score);
+	attempt_oom_adjust(-1000);
 
 	/* ignoring SIGPIPE prevents conmon from being spuriously killed */
 	signal(SIGPIPE, SIG_IGN);
@@ -295,7 +294,7 @@ int main(int argc, char *argv[])
 		}
 
 		// We don't want runc to be unkillable so we reset the oom_score_adj back to 0
-		attempt_oom_adjust(old_oom_score, NULL);
+		reset_oom_adjust();
 		execv(g_ptr_array_index(runtime_argv, 0), (char **)runtime_argv->pdata);
 		exit(127);
 	}

src/ctr_exit.c

@@ -7,6 +7,7 @@
 #include "globals.h"
 #include "ctr_logging.h"
 #include "close_fds.h"
+#include "oom.h"
 
 #include <errno.h>
 #include <glib.h>
@@ -201,6 +202,8 @@ void do_exit_command()
 		sleep(opt_exit_delay);
 	}
 
+	reset_oom_adjust();
+
 	execv(opt_exit_command, args);
 
 	/* Should not happen, but better be safe. */

src/ctr_logging.c

@@ -600,6 +600,8 @@ static void reopen_k8s_file(void)
 		return;
 
 	_cleanup_free_ char *k8s_log_path_tmp = g_strdup_printf("%s.tmp", k8s_log_path);
+	_cleanup_free_ char *k8s_log_path_tmp_old = g_strdup_printf("%s.tmp.old", k8s_log_path);
+	_cleanup_free_ char *k8s_log_path_old = g_strdup_printf("%s.1", k8s_log_path);
 
 	/* Sync the logs to disk */
 	if (!opt_no_sync_log && fsync(k8s_log_fd) < 0) {
@@ -614,6 +616,10 @@ static void reopen_k8s_file(void)
 	if (k8s_log_fd < 0)
 		pexitf("Failed to open log file %s", k8s_log_path);
 
+	unlink(k8s_log_path_tmp_old);
+	link(k8s_log_path, k8s_log_path_tmp_old);
+	rename(k8s_log_path_tmp_old, k8s_log_path_old);
+
 	/* Replace the previous file */
 	if (rename(k8s_log_path_tmp, k8s_log_path) < 0) {
 		pexit("Failed to rename log file");

src/oom.c

@@ -5,7 +5,9 @@
 #include <string.h>
 #include <unistd.h>
 
-void attempt_oom_adjust(int oom_score, int *old_value)
+int old_oom_score = 0;
+
+static void write_oom_adjust(int oom_score, int *old_value)
 {
 #ifdef __linux__
 	char fmt_oom_score[16];
@@ -30,3 +32,13 @@ void attempt_oom_adjust(int oom_score, int *old_value)
 	(void)old_value;
 #endif
 }
+
+void attempt_oom_adjust(int oom_score)
+{
+	write_oom_adjust(oom_score, &old_oom_score);
+}
+
+void reset_oom_adjust()
+{
+	write_oom_adjust(old_oom_score, NULL);
+}

src/oom.h

@@ -1,6 +1,7 @@
 #if !defined(OOM_H)
 #define OOM_H
 
-void attempt_oom_adjust(int oom_score, int *old_value);
+void attempt_oom_adjust(int oom_score);
+void reset_oom_adjust();
 
 #endif // OOM_H