As long as we hold the vnode interlock there is no chance for this vnode
to gain new references.
Fixes false alarms observed by Thor Lancelot Simon and reported on tech-kern.
Ok: David Holland <dholland@netbsd.org>
if the vnode we want to clean is a layered vnode and the caller already
locked its lower vnode.
Change getnewvnode() to always allocate a fresh vnode and add a helper
thread (vdrain) to keep the number of allocated vnodes within desiredvnodes.
Rename getcleanvnode() to cleanvnode() and let it take a vnode from the
lists, clean and free it.
Reviewed by: David Holland <dholland@netbsd.org>
Should fix:
PR #19110 (nullfs mounts over NFS cause lock manager problems)
PR #34102 (ffs panic in NetBSD 3.0_STABLE)
PR #45115 (lock error panic when build.sh*3 and daily script is running)
PR #45355 (Reader/writer lock error: rw_vector_enter: locking against myself)
- Reorganize locking in UVM and provide extra serialisation for pmap(9).
New lock order: [vmpage-owner-lock] -> pmap-lock.
- Simplify locking in some pmap(9) modules by removing P->V locking.
- Use lock object on vmobjlock (and thus vnode_t::v_interlock) to share
the locks amongst UVM objects where necessary (tmpfs, layerfs, unionfs).
- Rewrite and optimise x86 TLB shootdown code, make it simpler and cleaner.
Add TLBSTATS option for x86 to collect statistics about TLB shootdowns.
- Unify /dev/mem et al in MI code and provide required locking (removes
kernel-lock on some ports). Also, avoid cache-aliasing issues.
Thanks to Andrew Doran and Joerg Sonnenberger, as their initial patches
formed the core changes of this branch.
hannken