From: Chris Down <chris@chrisdown.name>
Date: Sun, 15 Feb 2026 17:42:51 +0000 (+0800)
Subject: oomd: Fix Killed signal reason being lost
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=936d864b0baf9d1a48ab9d062d7991c729549f99;p=thirdparty%2Fsystemd.git

oomd: Fix Killed signal reason being lost

Emitting "oom" doesn't mesh with the org.freedesktop.oom1.Manager
Killed() API contract, which defines "memory-used" and "memory-pressure"
as possible reasons. Consumers that key off reason thus will either lose
policy attribution or may reject the unknown value completely.

Plumb the reason through so it is visible to consumers.
---

diff --git a/src/oom/oomd-manager.c b/src/oom/oomd-manager.c
index 1ab7099d2ec..09790b90f57 100644
--- a/src/oom/oomd-manager.c
+++ b/src/oom/oomd-manager.c
@@ -416,7 +416,7 @@ static int monitor_swap_contexts_handler(sd_event_source *s, uint64_t usec, void
                         return 0;
                 }
 
-                r = oomd_cgroup_kill_mark(m, selected);
+                r = oomd_cgroup_kill_mark(m, selected, "memory-used");
                 if (r == -ENOMEM)
                         return log_oom();
                 if (r < 0)
@@ -534,7 +534,7 @@ static int monitor_memory_pressure_contexts_handler(sd_event_source *s, uint64_t
                                 return 0;
                         }
 
-                        r = oomd_cgroup_kill_mark(m, selected);
+                        r = oomd_cgroup_kill_mark(m, selected, "memory-pressure");
                         if (r == -ENOMEM)
                                 return log_oom();
                         if (r < 0)
diff --git a/src/oom/oomd-util.c b/src/oom/oomd-util.c
index 8167e10a8b8..55e17df46f0 100644
--- a/src/oom/oomd-util.c
+++ b/src/oom/oomd-util.c
@@ -27,6 +27,7 @@
 typedef struct OomdKillState {
         Manager *manager;
         OomdCGroupContext *ctx;
+        const char *reason;
         /* This holds sd_varlink references */
         Set *links;
 } OomdKillState;
@@ -245,11 +246,12 @@ int oomd_sort_cgroup_contexts(Hashmap *h, oomd_compare_t compare_func, const cha
         return (int) k;
 }
 
-int oomd_cgroup_kill(Manager *m, OomdCGroupContext *ctx, bool recurse) {
+int oomd_cgroup_kill(Manager *m, OomdCGroupContext *ctx, bool recurse, const char *reason) {
         _cleanup_set_free_ Set *pids_killed = NULL;
         int r;
 
         assert(ctx);
+        assert(!m || reason);
 
         pids_killed = set_new(NULL);
         if (!pids_killed)
@@ -288,7 +290,7 @@ int oomd_cgroup_kill(Manager *m, OomdCGroupContext *ctx, bool recurse) {
                                           "Killed",
                                           "ss",
                                           ctx->path,
-                                          "oom");
+                                          reason);
 
         return !set_isempty(pids_killed);
 }
@@ -334,7 +336,7 @@ static void oomd_kill_state_remove(OomdKillState *ks) {
         if (!set_isempty(ks->links))
                 return;
 
-        r = oomd_cgroup_kill(ks->manager, ks->ctx, /* recurse= */ true);
+        r = oomd_cgroup_kill(ks->manager, ks->ctx, /* recurse= */ true, ks->reason);
         if (r < 0)
                 log_debug_errno(r, "Failed to kill cgroup '%s', ignoring: %m", ks->ctx->path);
         oomd_kill_state_free(ks);
@@ -465,11 +467,12 @@ static int oomd_prekill_hook(Manager *m, OomdKillState *ks) {
         return 0;
 }
 
-int oomd_cgroup_kill_mark(Manager *m, OomdCGroupContext *ctx) {
+int oomd_cgroup_kill_mark(Manager *m, OomdCGroupContext *ctx, const char *reason) {
         int r;
 
         assert(ctx);
         assert(m);
+        assert(reason);
 
         if (m->dry_run) {
                 _cleanup_free_ char *cg_path = NULL;
@@ -489,6 +492,7 @@ int oomd_cgroup_kill_mark(Manager *m, OomdCGroupContext *ctx) {
         *ks = (OomdKillState) {
                 .manager = m,
                 .ctx = oomd_cgroup_context_ref(ctx),
+                .reason = reason,
         };
 
         r = set_ensure_put(&m->kill_states, &oomd_kill_state_hash_ops, ks);
diff --git a/src/oom/oomd-util.h b/src/oom/oomd-util.h
index cf80c6f57b5..d4e1a9207bd 100644
--- a/src/oom/oomd-util.h
+++ b/src/oom/oomd-util.h
@@ -124,8 +124,8 @@ int oomd_sort_cgroup_contexts(Hashmap *h, oomd_compare_t compare_func, const cha
 int oomd_fetch_cgroup_oom_preference(OomdCGroupContext *ctx, const char *prefix);
 
 /* Returns a negative value on error, 0 if no processes were killed, or 1 if processes were killed. */
-int oomd_cgroup_kill(Manager *m, OomdCGroupContext *ctx, bool recurse);
-int oomd_cgroup_kill_mark(Manager *m, OomdCGroupContext *ctx);
+int oomd_cgroup_kill(Manager *m, OomdCGroupContext *ctx, bool recurse, const char *reason);
+int oomd_cgroup_kill_mark(Manager *m, OomdCGroupContext *ctx, const char *reason);
 
 /* The following oomd_kill_by_* functions return 1 if processes were killed, or negative otherwise. */
 /* If `prefix` is supplied, only cgroups whose paths start with `prefix` are eligible candidates. Otherwise,
diff --git a/src/oom/test-oomd-util.c b/src/oom/test-oomd-util.c
index 76ff43cb272..0dada0de6c8 100644
--- a/src/oom/test-oomd-util.c
+++ b/src/oom/test-oomd-util.c
@@ -88,7 +88,11 @@ TEST(oomd_cgroup_kill) {
                 ASSERT_OK(fork_and_sleep(5, &two));
                 ASSERT_OK(cg_attach(subcgroup, two.pid));
 
-                ASSERT_OK_POSITIVE(oomd_cgroup_kill(NULL /* manager */, &(OomdCGroupContext){ .path = subcgroup }, false /* recurse */));
+                ASSERT_OK_POSITIVE(oomd_cgroup_kill(
+                                                   /* m= */ NULL,
+                                                   &(OomdCGroupContext){ .path = subcgroup },
+                                                   /* recurse= */ false,
+                                                   /* reason= */ NULL));
 
                 ASSERT_OK(cg_get_xattr(subcgroup, "user.oomd_ooms", &v, /* ret_size= */ NULL));
                 ASSERT_STREQ(v, i == 0 ? "1" : "2");