On Tue, May 23, 2023 at 04:02:13PM +0200, Thomas Gleixner wrote: > vmap blocks which have active mappings cannot be purged. Allocations which > have been freed are accounted for in vmap_block::dirty_min/max, so that > they can be detected in _vm_unmap_aliases() as potentially stale TLBs. > > If there are several invocations of _vm_unmap_aliases() then each of them > will flush the dirty range. That's pointless and just increases the > probability of full TLB flushes. > > Avoid that by resetting the flush range after accounting for it. That's > safe versus other invocations of _vm_unmap_aliases() because this is all > serialized with vmap_purge_lock. Just nitpicking, but isn't vb->lock the actually relevant lock here? vmap_purge_lock is only taken after the loop.
