mm/vmalloc: prevent flushing dirty space over and over

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.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Baoquan He <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Reviewed-by: Lorenzo Stoakes <[email protected]>
Cc: Uladzislau Rezki (Sony) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

0 files changed, 0 insertions, 0 deletions