diff --git a/src/ngx_http_lua_uthread.c b/src/ngx_http_lua_uthread.c
index 2208b2a819..e660abac6b 100644
--- a/src/ngx_http_lua_uthread.c
+++ b/src/ngx_http_lua_uthread.c
@@ -25,6 +25,49 @@
 static int ngx_http_lua_uthread_spawn(lua_State *L);
 static int ngx_http_lua_uthread_wait(lua_State *L);
 static int ngx_http_lua_uthread_kill(lua_State *L);
+static void ngx_http_lua_uthread_cleanup_descendants(ngx_http_lua_ctx_t *ctx,
+    ngx_http_lua_co_ctx_t *parent);
+
+
+static void
+ngx_http_lua_uthread_cleanup_descendants(ngx_http_lua_ctx_t *ctx,
+    ngx_http_lua_co_ctx_t *parent)
+{
+    ngx_uint_t                       i;
+    ngx_list_part_t                 *part;
+    ngx_http_lua_co_ctx_t           *coctx, *cur;
+
+    if (ctx->user_co_ctx == NULL) {
+        return;
+    }
+
+    part = &ctx->user_co_ctx->part;
+    coctx = part->elts;
+
+    for (i = 0; /* void */; i++) {
+
+        if (i >= part->nelts) {
+            if (part->next == NULL) {
+                break;
+            }
+
+            part = part->next;
+            coctx = part->elts;
+            i = 0;
+        }
+
+        if (&coctx[i] == parent || coctx[i].is_uthread) {
+            continue;
+        }
+
+        for (cur = coctx[i].parent_co_ctx; cur; cur = cur->parent_co_ctx) {
+            if (cur == parent) {
+                ngx_http_lua_cleanup_pending_operation(&coctx[i]);
+                break;
+            }
+        }
+    }
+}
 
 
 void
@@ -264,6 +307,7 @@ ngx_http_lua_uthread_kill(lua_State *L)
 
     default:
         ngx_http_lua_cleanup_pending_operation(sub_coctx);
+        ngx_http_lua_uthread_cleanup_descendants(ctx, sub_coctx);
         ngx_http_lua_del_thread(r, L, ctx, sub_coctx);
         ctx->uthreads--;
 
diff --git a/t/127-uthread-kill.t b/t/127-uthread-kill.t
index c397d433b4..b6f7e664fe 100644
--- a/t/127-uthread-kill.t
+++ b/t/127-uthread-kill.t
@@ -617,3 +617,122 @@ GET /t
 ok_count=10
 --- no_error_log
 [error]
+
+
+
+=== TEST 11: kill uthread with child coroutine pending cosocket read after GC
+--- config
+    lua_socket_log_errors off;
+
+    location = /slow-body {
+        content_by_lua_block {
+            local body = string.rep("x", 8192)
+
+            ngx.header["Content-Type"] = "text/plain"
+            ngx.header["Content-Length"] = #body
+
+            ngx.print(body:sub(1, 64))
+            ngx.flush(true)
+            ngx.sleep(0.2)
+            ngx.print(body:sub(65))
+        }
+    }
+
+    location = /t {
+        access_by_lua_block {
+            local port = tonumber(ngx.var.server_port)
+            local pinned_sockets = {}
+            local slow_read_pending = false
+
+            local function read_content_length(sock)
+                local line, err = sock:receive("*l")
+                if not line then
+                    return nil, err
+                end
+
+                local content_length
+                while true do
+                    line, err = sock:receive("*l")
+                    if not line then
+                        return nil, err
+                    end
+
+                    if line == "" then
+                        return content_length
+                    end
+
+                    local name, value = line:match("^([^:]+):%s*(.*)$")
+                    if name and name:lower() == "content-length" then
+                        content_length = tonumber(value)
+                    end
+                end
+            end
+
+            local fast = ngx.thread.spawn(function()
+                for _ = 1, 1000 do
+                    if slow_read_pending then
+                        break
+                    end
+                    ngx.sleep(0.001)
+                end
+
+                return "ok"
+            end)
+
+            local slow = ngx.thread.spawn(function()
+                local child = coroutine.create(function()
+                    local sock = ngx.socket.tcp()
+                    pinned_sockets[#pinned_sockets + 1] = sock
+
+                    sock:settimeout(10000)
+                    local ok, err = sock:connect("127.0.0.1", port)
+                    if not ok then
+                        return nil, err
+                    end
+
+                    ok, err = sock:send("GET /slow-body HTTP/1.1\r\nHost: localhost\r\n\r\n")
+                    if not ok then
+                        return nil, err
+                    end
+
+                    local content_length
+                    content_length, err = read_content_length(sock)
+                    if not content_length then
+                        return nil, err
+                    end
+
+                    slow_read_pending = true
+                    return sock:receive(content_length)
+                end)
+
+                local ok, body, err = coroutine.resume(child)
+                if not ok then
+                    return nil, body
+                end
+
+                return body, err
+            end)
+
+            ngx.thread.wait(fast, slow)
+            ngx.thread.kill(fast)
+            ngx.thread.kill(slow)
+
+            fast = nil
+            slow = nil
+            collectgarbage("collect")
+            collectgarbage("collect")
+
+            ngx.sleep(0.3)
+
+            ngx.say("survived pinned=", #pinned_sockets)
+        }
+
+        content_by_lua_block {
+        }
+    }
+--- request
+GET /t
+--- response_body
+survived pinned=1
+--- no_error_log
+[alert]