Messages in this thread | | | Date | Sat, 24 Feb 2007 22:10:57 +0000 (GMT) | From | Hugh Dickins <> | Subject | Re: PREEMPT_RCU breaks anon_vma locking ? |
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On Fri, 23 Feb 2007, Paul E. McKenney wrote: > > This look like a valid fix to me, at least as long as the lock is never > dropped in the meantime (e.g., to do I/O). If the lock -is- dropped in > the meantime, then presumably whatever is done to keep the page from > vanishing should allow an rcu_read_unlock() to be placed after each > spin_unlock(&...->lock) and an rcu_read_lock() to be placed before each > spin_lock(&...->lock).
Thankfully no complications of that kind, page_lock_anon_vma is static to mm/rmap.c, and only used to hold the spin lock while examining page tables of the vmas in the list, never a need to drop that lock at all. (Until the day when someone reports such a long list that we start to worry about the latency.)
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