On Fri, Jun 26 2015 at  3:47am -0400,
Geert Uytterhoeven [off-list ref] wrote:

On Fri, Jun 26, 2015 at 2:13 AM, Linux Kernel Mailing List
[off-list ref] wrote:

quoted

Gitweb:     http://git.kernel.org/linus/;a=commit;h=66a636356647a9be8885c2ce2948de126577698a
Commit:     66a636356647a9be8885c2ce2948de126577698a
Parent:     40775257b97e27305cf5c2425be7acaa6edee4ea
Refname:    refs/heads/master
Author:     Joe Thornber [off-list ref]
AuthorDate: Fri May 15 15:33:34 2015 +0100
Committer:  Mike Snitzer [off-list ref]
CommitDate: Thu Jun 11 17:12:59 2015 -0400

    dm cache: add stochastic-multi-queue (smq) policy

quoted

diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index edcf4ab..b597273 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig

@@ -304,6 +304,18 @@ config DM_CACHE_MQ
          This is meant to be a general purpose policy.  It prioritises
          reads over writes.

+config DM_CACHE_SMQ
+       tristate "Stochastic MQ Cache Policy (EXPERIMENTAL)"
+       depends on DM_CACHE
+       default y

A feature cannot be "EXPERIMENTAL", and be enabled by default.
Please drop (at least) one of them.

Thanks for your concern, but: no.

If you look closer the entirety of DM cache is marked EXPERIMENTAL:

config DM_CACHE
       tristate "Cache target (EXPERIMENTAL)"
...
config DM_CACHE_MQ
       tristate "MQ Cache Policy (EXPERIMENTAL)"
...
config DM_CACHE_SMQ
       tristate "Stochastic MQ Cache Policy (EXPERIMENTAL)"
...
config DM_CACHE_CLEANER
       tristate "Cleaner Cache Policy (EXPERIMENTAL)"