On Thu 27-06-24 16:33:00, xiujianfeng wrote: > > > On 2024/6/27 15:13, Michal Hocko wrote: > > On Wed 26-06-24 09:42:32, Xiu Jianfeng wrote: > >> Both the end of memory_stat_format() and memcg_stat_format() will call > >> WARN_ON_ONCE(seq_buf_has_overflowed()). However, memory_stat_format() > >> is the only caller of memcg_stat_format(), when memcg is on the default > >> hierarchy, seq_buf_has_overflowed() will be executed twice, so remove > >> the reduntant one. > > > > Shouldn't we rather remove both? Are they giving us anything useful > > actually? Would a simpl pr_warn be sufficient? Afterall all we care > > about is to learn that we need to grow the buffer size because our stats > > do not fit anymore. It is not really important whether that is an OOM or > > cgroupfs interface path. > > I did a test, when I removed both of them and added a lot of prints in > memcg_stat_format() to make the seq_buf overflow, and then cat > memory.stat in user mode, no OOM occurred, and there were no warning > logs in the kernel. The default buffer size is PAGE_SIZE. -- Michal Hocko SUSE Labs
