Forking new thread because my comment is not related to this patch's purpose but found a thing during reading this patch. On Tue, Apr 26, 2016 at 04:04:30PM +0200, Michal Hocko wrote: > From: Michal Hocko <mhocko@xxxxxxxx> > > Tetsuo has properly noted that mmput slow path might get blocked waiting > for another party (e.g. exit_aio waits for an IO). If that happens the > oom_reaper would be put out of the way and will not be able to process > next oom victim. We should strive for making this context as reliable > and independent on other subsystems as much as possible. > > Introduce mmput_async which will perform the slow path from an async > (WQ) context. This will delay the operation but that shouldn't be a > problem because the oom_reaper has reclaimed the victim's address space > for most cases as much as possible and the remaining context shouldn't > bind too much memory anymore. The only exception is when mmap_sem > trylock has failed which shouldn't happen too often. > > The issue is only theoretical but not impossible. The mmput_async is used for only OOM reaper which is enabled on CONFIG_MMU. So until someone who want to use mmput_async in !CONFIG_MMU come out, we could save sizeof(struct work_struct) per mm in !CONFIG_MMU. -- 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>