On Wed, 2011-04-27 at 17:32 -0700, john stultz wrote: > On Wed, 2011-04-27 at 16:51 -0700, David Rientjes wrote: > > On Tue, 26 Apr 2011, john stultz wrote: > > > In the meantime, I'll put some effort into trying to protect unlocked > > > current->comm acccess using get_task_comm() where possible. Won't happen > > > in a day, and help would be appreciated. > > > > > > > We need to stop protecting ->comm with ->alloc_lock since it is used for > > other members of task_struct that may or may not be held in a function > > that wants to read ->comm. We should probably introduce a seqlock. > > Agreed. My initial approach is to consolidate accesses to use > get_task_comm(), with special case to skip the locking if tsk==current, > as well as a lock free __get_task_comm() for cases where its not current > being accessed and the task locking is already done. > > Once that's all done, the next step is to switch to a seqlock (or > possibly RCU if Dave is still playing with that idea), internally in the > get_task_comm implementation and then yank the special __get_task_comm. So thinking further, this can be simplified by adding the seqlock first, and then retaining the task_locking only in the set_task_comm path until all comm accessors are converted to using get_task_comm. I'll be sending out some initial patches for review shortly. thanks -john -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>