Hi Andrew, Rafael, this has been originally discussed here [1] and previously posted here [2]. I have updated patches according to feedback from Oleg.
The first and third patch are regression fixes and they are a stable material IMO. The second and fourth patch are simple cleanups. The 1st patch is fixing a regression introduced in 3.3 since when OOM killer is not able to kill any frozen task and live lock as a result. The fix gets us back to the 3.2. As it turned out during the discussion [3] this was still not 100% sufficient and that's why we need the 3rd patch. I was thinking about the proper 1st vs. 3rd patch ordering because the 1st patch basically opens a race window considerably reduced by the later patch. This path is hard to do completely race free without a complete synchronization of OOM path (including the allocator) and freezer which is not worth the trouble. Original patch from Cong Wang has covered this by checking cgroup_freezing(current) in __refrigarator path [4]. But this approach still suffers from OOM vs. PM freezer interaction (OOM killer would still live lock waiting for a PM frozen task this time). So I think the most straight forward way is to address only OOM vs. frozen task interaction in the first patch, mark it for stable 3.3+ and leave the race to a separate follow up patch which is applicable to stable 3.2+ (before a3201227f803 made it inefficient). Switching 1st and 3rd patches would make some sense as well but then it might end up even more confusing because we would be fixing a non-existent issue in upstream first... Cong Wang (2): freezer: Do not freeze tasks killed by OOM killer freezer: remove obsolete comments in __thaw_task() Michal Hocko (2): OOM, PM: OOM killed task shouldn't escape PM suspend PM: convert do_each_thread to for_each_process_thread And diffstat says: include/linux/oom.h | 3 +++ kernel/freezer.c | 9 +++------ kernel/power/process.c | 47 ++++++++++++++++++++++++++++++++++++++--------- mm/oom_kill.c | 17 +++++++++++++++++ mm/page_alloc.c | 8 ++++++++ 5 files changed, 69 insertions(+), 15 deletions(-) --- [1] http://marc.info/?l=linux-kernel&m=140986986423092 [2] http://marc.info/?l=linux-mm&m=141277728508500&w=2 [3] http://marc.info/?l=linux-kernel&m=141074263721166 [4] http://marc.info/?l=linux-kernel&m=140986986423092 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/