On Mon, Feb 20, 2023 at 01:09:44PM -0800, Roman Gushchin wrote: > On Mon, Feb 20, 2023 at 11:16:38PM +0800, Yue Zhao wrote: > > The knob for cgroup v2 memory controller: memory.oom.group > > will be read and written simultaneously by user space > > programs, thus we'd better change memcg->oom_group access > > with atomic operations to avoid concurrency problems. > > > > Signed-off-by: Yue Zhao <findns94@xxxxxxxxx> > > Hi Yue! > > I'm curious, have any seen any real issues which your patch is solving? > Can you, please, provide a bit more details. > IMHO such details are not needed. oom_group is being accessed concurrently and one of them can be a write access. At least READ_ONCE/WRITE_ONCE is needed here. Most probably syzbot didn't catch this race because it does not know about the memory.oom.group interface.