On 2023/3/7 10:48, Matthew Wilcox wrote: > On Tue, Mar 07, 2023 at 10:36:55AM +0800, Haifeng Xu wrote: >> On 2023/3/6 21:49, David Hildenbrand wrote: >>> On 06.03.23 03:49, Haifeng Xu wrote: >>>> mem_cgroup_oom_synchronize() has checked whether current memcg_in_oom is >>>> set or not, so remove the check in handle_mm_fault(). >>> >>> "mem_cgroup_oom_synchronize() will returned immediately if memcg_in_oom is not set, so remove the check from handle_mm_fault()". >>> >>> However, that requires now always an indirect function call -- do we care about dropping that optimization? >>> >>> >> >> If memcg_in_oom is set, we will check it twice, one is from handle_mm_fault(), the other is from mem_cgroup_oom_synchronize(). That seems a bit redundant. >> >> if memcg_in_oom is not set, mem_cgroup_oom_synchronize() returns directly. Though it's an indirect function call, but the time spent can be negligible >> compare to the whole mm user falut preocess. And that won't cause stack overflow error. > > I suggest you measure it. Ok, I'll make a simple test.
