On Tue, 23 Oct 2012, Ming Lei wrote: > With the problem of non-SMP-safe bitfields access, the power.lock should > be held, but that is not enough to prevent children from being probed or > disconnected. Looks another lock is still needed. I think a global lock > is OK in the infrequent path. Agreed. > Got it, thanks for your detailed explanation. > > Looks the problem is worse than above, not only bitfields are affected, the > adjacent fields might be involved too, see: > > http://lwn.net/Articles/478657/ Linus made it clear (in various emails at the time) that the kernel requires the compiler not to do the sort of things discussed in that article. But even the restrictions he wanted would not prevent adjacent bitfields from interfering with each other. Alan Stern -- 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>