On Tue, May 14, 2019 at 12:13:52AM +0200, Mark Kettenis wrote:
> This changes uvm_unmap_detach() to get rid of the "easy" entries first
> before grabbing the kernel lock. Probably doesn't help much with the
> lock contention, but it avoids a locking problem that happens with
> pools that use kernel_map() to allocate the kva for their pages.
>
> ok?
>
Reads ok to me, ok mlarkin
>
> Index: uvm/uvm_map.c
> ===
> RCS file: /cvs/src/sys/uvm/uvm_map.c,v
> retrieving revision 1.243
> diff -u -p -r1.243 uvm_map.c
> --- uvm/uvm_map.c 23 Apr 2019 13:35:12 - 1.243
> +++ uvm/uvm_map.c 13 May 2019 22:09:26 -
> @@ -1538,8 +1538,18 @@ uvm_mapent_tryjoin(struct vm_map *map, s
> void
> uvm_unmap_detach(struct uvm_map_deadq *deadq, int flags)
> {
> - struct vm_map_entry *entry;
> + struct vm_map_entry *entry, *tmp;
> int waitok = flags & UVM_PLA_WAITOK;
> +
> + TAILQ_FOREACH_SAFE(entry, deadq, dfree.deadq, tmp) {
> + /* Skip entries for which we have to grab the kernel lock. */
> + if (entry->aref.ar_amap || UVM_ET_ISSUBMAP(entry) ||
> + UVM_ET_ISOBJ(entry))
> + continue;
> +
> + TAILQ_REMOVE(deadq, entry, dfree.deadq);
> + uvm_mapent_free(entry);
> + }
>
> if (TAILQ_EMPTY(deadq))
> return;
>
