On Thu, Aug 01, 2019 at 11:04:14AM -0700, Masoud Sharbiani wrote: > Hey folks, > I’ve come across an issue that affects most of 4.19, 4.20 and 5.2 linux-stable kernels that has only been fixed in 5.3-rc1. > It was introduced by > > 29ef680 memcg, oom: move out_of_memory back to the charge path > > The gist of it is that if you have a memory control group for a process that repeatedly maps all of the pages of a file with repeated calls to: > > mmap(NULL, pages * PAGE_SIZE, PROT_WRITE|PROT_READ, MAP_FILE|MAP_PRIVATE, fd, 0) > > The memory cg eventually runs out of memory, as it should. However, > prior to the 29ef680 commit, it would kill the running process with > OOM; After that commit ( and until 5.3-rc1; Haven’t pinpointed the > exact commit in between 5.2.0 and 5.3-rc1) the offending process goes > into %100 CPU usage, and doesn’t die (prior behavior) or fail the mmap > call (which is what happens if one runs the test program with a low > ulimit -v value). > > Any ideas on how to chase this down further? Finding the exact patch that fixes this would be great, as then I can add it to the 4.19 and 5.2 stable kernels (4.20 is long end-of-life, no idea why you are messing with that one...) thanks, greg k-h
