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From:   Oleksandr Natalenko <oleksandr@natalenko.name>
To:     linux-kernel@vger.kernel.org
Cc:     linux-block@vger.kernel.org, Jens Axboe <axboe@kernel.dk>,
        Ming Lei <ming.lei@redhat.com>, Christoph Hellwig <hch@lst.de>,
        Laurence Oberman <loberman@redhat.com>,
        Paolo Valente <paolo.valente@linaro.org>,
        David Jeffery <djeffery@redhat.com>,
        Bart Van Assche <bvanassche@acm.org>
Subject: [PATCH] block: increase BLKCG_MAX_POLS
Date:   Sat, 17 Jul 2021 14:33:28 +0200
Message-Id: <20210717123328.945810-1-oleksandr@natalenko.name>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

After mq-deadline learnt to deal with cgroups, the BLKCG_MAX_POLS value
became too small for all the elevators to be registered properly. The
following issue is seen:

```
calling  bfq_init+0x0/0x8b @ 1
blkcg_policy_register: BLKCG_MAX_POLS too small
initcall bfq_init+0x0/0x8b returned -28 after 507 usecs
```

and BFQ is non-functional.

Increase BLKCG_MAX_POLS to allow space for everyone

Link: https://lore.kernel.org/lkml/8988303.mDXGIdCtx8@natalenko.name/
Signed-off-by: Oleksandr Natalenko <oleksandr@natalenko.name>
---
 include/linux/blkdev.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 3177181c4326..d3afea47ade6 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -57,7 +57,7 @@ struct blk_keyslot_manager;
  * Maximum number of blkcg policies allowed to be registered concurrently.
  * Defined here to simplify include dependency.
  */
-#define BLKCG_MAX_POLS		5
+#define BLKCG_MAX_POLS		6
 
 typedef void (rq_end_io_fn)(struct request *, blk_status_t);
 
-- 
2.32.0