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oomd: only check prefix_uid when uid != 0

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If the cgroup is owned by root there is no need to get prefix_uid. Only
check prefix_uid when uid != 0, and then set MANAGED_OOM_PREFERENCE_NONE
and return early if uid != prefix_uid.
This commit is contained in:
Nick Rosbrook 2022-11-28 11:13:08 -05:00
parent cb8d22fa84
commit 66bc4f6fb1
1 changed files with 27 additions and 21 deletions
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48
src/oom/oomd-util.c
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@ -145,7 +145,7 @@ bool oomd_swap_free_below(const OomdSystemContext *ctx, int threshold_permyriad)
}
int oomd_fetch_cgroup_oom_preference(OomdCGroupContext *ctx, const char *prefix) {
uid_t uid, prefix_uid;
uid_t uid;
int r;
assert(ctx);
@ -160,28 +160,34 @@ int oomd_fetch_cgroup_oom_preference(OomdCGroupContext *ctx, const char *prefix)
if (r < 0)
return log_debug_errno(r, "Failed to get owner/group from %s: %m", ctx->path);
r = cg_get_owner(SYSTEMD_CGROUP_CONTROLLER, prefix, &prefix_uid);
if (r < 0)
return log_debug_errno(r, "Failed to get owner/group from %s: %m", ctx->path);
if (uid != 0) {
uid_t prefix_uid;
if (uid == prefix_uid || uid == 0) {
/* Ignore most errors when reading the xattr since it is usually unset and cgroup xattrs are only used
* as an optional feature of systemd-oomd (and the system might not even support them). */
r = cg_get_xattr_bool(SYSTEMD_CGROUP_CONTROLLER, ctx->path, "user.oomd_avoid");
if (r == -ENOMEM)
return log_oom_debug();
if (r < 0 && !ERRNO_IS_XATTR_ABSENT(r))
log_debug_errno(r, "Failed to get xattr user.oomd_avoid, ignoring: %m");
ctx->preference = r > 0 ? MANAGED_OOM_PREFERENCE_AVOID : ctx->preference;
r = cg_get_owner(SYSTEMD_CGROUP_CONTROLLER, prefix, &prefix_uid);
if (r < 0)
return log_debug_errno(r, "Failed to get owner/group from %s: %m", prefix);
r = cg_get_xattr_bool(SYSTEMD_CGROUP_CONTROLLER, ctx->path, "user.oomd_omit");
if (r == -ENOMEM)
return log_oom_debug();
if (r < 0 && !ERRNO_IS_XATTR_ABSENT(r))
log_debug_errno(r, "Failed to get xattr user.oomd_omit, ignoring: %m");
ctx->preference = r > 0 ? MANAGED_OOM_PREFERENCE_OMIT : ctx->preference;
} else
ctx->preference = MANAGED_OOM_PREFERENCE_NONE;
if (uid != prefix_uid) {
ctx->preference = MANAGED_OOM_PREFERENCE_NONE;
return 0;
}
}
/* Ignore most errors when reading the xattr since it is usually unset and cgroup xattrs are only used
* as an optional feature of systemd-oomd (and the system might not even support them). */
r = cg_get_xattr_bool(SYSTEMD_CGROUP_CONTROLLER, ctx->path, "user.oomd_avoid");
if (r == -ENOMEM)
return log_oom_debug();
if (r < 0 && !ERRNO_IS_XATTR_ABSENT(r))
log_debug_errno(r, "Failed to get xattr user.oomd_avoid, ignoring: %m");
ctx->preference = r > 0 ? MANAGED_OOM_PREFERENCE_AVOID : ctx->preference;
r = cg_get_xattr_bool(SYSTEMD_CGROUP_CONTROLLER, ctx->path, "user.oomd_omit");
if (r == -ENOMEM)
return log_oom_debug();
if (r < 0 && !ERRNO_IS_XATTR_ABSENT(r))
log_debug_errno(r, "Failed to get xattr user.oomd_omit, ignoring: %m");
ctx->preference = r > 0 ? MANAGED_OOM_PREFERENCE_OMIT : ctx->preference;
return 0;
}