On Fri, Apr 22, 2022 at 08:57:28AM -0700, David Vernet wrote: > test_memcg_sock() in the cgroup memcg tests, verifies expected memory > accounting for sockets. The test forks a process which functions as a TCP > server, and sends large buffers back and forth between itself (as the TCP > client) and the forked TCP server. While doing so, it verifies that > memory.current and memory.stat.sock look correct. > > There is currently a check in tcp_client() which asserts memory.current >= > memory.stat.sock. This check is racy, as between memory.current and > memory.stat.sock being queried, a packet could come in which causes > mem_cgroup_charge_skmem() to be invoked. This could cause memory.stat.sock > to exceed memory.current. Reversing the order of querying doesn't address > the problem either, as memory may be reclaimed between the two calls. But just curious, does it fix the flakiness (assuming there is no memory pressure)? > Instead, this patch just removes that assertion altogether, and instead > relies on the values_close() check that follows to validate the expected > accounting. Acked-by: Roman Gushchin <roman.gushchin@xxxxxxxxx>
