>>>>> On Fri, 4 Feb 2005 09:44:10 -0800, Jun Sun <jsun@xxxxxxxxxx> said: jsun> It seems to me a naive solution is to introduce a spinlock to jsun> make all three operation automic. you flush tlb first and make jsun> relavent tlb fault handling sync with this spinlock as well. jsun> At in theory it should fix the problem, but the spinlock might jsun> be held for too long this dup_mmap(). Yes, it may be too long. Also dup_mmap might sleep via alloc_pages, cond_resched_lock, etc. therefore the spinlock can not be held entirely. Now I think fixing copy_cow_page() might be a way to go. jsun> BTW, is this problem real or hypothetic? Yes. This is a real problem. Using fork() in multi-thread program should be legal and perhaps only way to call external program (system() will use fork() internally). It will not be a special case. --- Atsushi Nemoto
