On Sat 09-07-16 16:49:32, Shayan Pooya wrote: > I came across the following issue in kernel 3.16 (Ubuntu 14.04) which > was then reproduced in kernels 4.4 LTS: > After a couple of of memcg oom-kills in a cgroup, a syscall in > *another* process in the same cgroup hangs indefinitely. > > Reproducing: > > # mkdir -p strace_run > # mkdir /sys/fs/cgroup/memory/1 > # echo 1073741824 > /sys/fs/cgroup/memory/1/memory.limit_in_bytes > # echo 0 > /sys/fs/cgroup/memory/1/memory.swappiness > # for i in $(seq 1000); do ./call-mem-hog > /sys/fs/cgroup/memory/1/cgroup.procs & done > > Where call-mem-hog is: > #!/bin/sh > set -ex > echo $$ > $1 > echo "Adding $$ to $1" > strace -ff -tt ./mem-hog 2> strace_run/$$ > > > Initially I thought it was a userspace bug in dash as it only happened > with /bin/sh (which points to dash) and not with bash. I see the > following hanging processes: > > USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND > root 20999 0.0 0.0 4508 100 pts/6 S 16:28 0:00 > /bin/sh ./call-mem-hog /sys/fs/cgroup/memory/1/cgroup.procs > > However, when using strace, I noticed that sometimes there is actually > a mem-hog process hanging on sbrk syscall (Of course the > memory.oom_control is 0 and this is not expected). > Sending an ABRT signal to the waiting strace process then resulted in > the mem-hog process getting oom-killed by the kernel. Could you post the stack trace of the hung oom victim? Also could you post the full kernel log? -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>