On 10/24, Tejun Heo wrote: > > Hello, > > On Tue, Oct 23, 2012 at 05:51:28PM +0200, Oleg Nesterov wrote: > > Yes, yes. But in this case (I mean, for uprobes) "threadgroup" in the name > > is misleading. It should be called unconditially without any argument. > > > > Please see > > > > [PATCH 1/2] brw_mutex: big read-write mutex > > http://marc.info/?l=linux-kernel&m=135032816223715 > > Ooh... that's something completely different. > > > [PATCH 2/2] uprobes: Use brw_mutex to fix register/unregister vs dup_mmap() race > > http://marc.info/?l=linux-kernel&m=135032817823720 > > > > for details, but in short 2/2 needs this giant lock to block dup_mmap() > > system-wide, while cgroup (currently) only needs threadgroup lock if > > CLONE_THREAD (ignoring do_exit) and per-task. > > > > So please forget, I no longer think it makes sense to use the same > > thing for uprobes and cgroups. > > It is quite tempting to reduce hot path overhead and penalize cgroup > migration ops more tho. Write-locking brw_mutex on migration might > not be too bad. Why did you change your mind? Well, mostly because I do not think 1/2 will be ever applied ;) Since we already have (to my surprise!) percpu_rw_semaphore, I do not think I can add another similar lock. Perhaps uprobes can use percpu_rw_semaphore, but I am not sure... Oleg. _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/containers
