On Thu, 7 May 2009, Andrew Morton wrote: > The setting and clearing of that thing looks gruesomely racy.. >
It's not racy currently because zone_scan_lock ensures ZONE_OOM_LOCKED gets test/set and cleared atomically for the entire zonelist (the clear happens for the same zonelist that was test/set). Using it for hibernation in the way I've proposed will open it up to the race I earlier described: when a kthread is in the oom killer and subsequently clears its zonelist of ZONE_OOM_LOCKED (all other tasks are frozen so they can't be in the oom killer). That's perfectly acceptable, however, since the system is by definition already oom if kthreads can't get memory so it will end up killing a user task even though it's stuck in D state and will exit on thaw; we aren't concerned about killing needlessly because the oom killer becomes a no-op when it finds a task that has already been killed but hasn't exited by way of TIF_MEMDIE. -- To unsubscribe from this list: send the line "unsubscribe kernel-testers" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
