[PATCH v3 0/7] Fix potential kernel panic when increase hardware queue

From: Weiping Zhang <zhangweiping@didiglobal.com>
To: <axboe@kernel.dk>, <bvanassche@acm.org>
Cc: <linux-block@vger.kernel.org>
Subject: [PATCH v3 0/7] Fix potential kernel panic when increase hardware queue
Date: Tue, 7 Apr 2020 03:35:59 +0800	[thread overview]
Message-ID: <cover.1586199103.git.zhangweiping@didiglobal.com> (raw)

Hi,

This series do some improvement base on V2, and also fix two memleaks.
And V2 import a regression for blktest/block/test/029, this test case
will increase and decrease hardware queue count quickly.

Memleak 1:

__blk_mq_alloc_rq_maps
	__blk_mq_alloc_rq_map

if fail
	blk_mq_free_rq_map

Actually, __blk_mq_alloc_rq_map alloc both map and request, here
also need free request.

Memleak 2:
When driver decrease hardware queue, set->nr_hw_queues will be changed
firstly in blk_mq_realloc_tag_set_tags or __blk_mq_update_nr_hw_queues,
then blk_mq_realloc_hw_ctxs and blk_mq_map_swqueue, even
blk_mq_free_tag_set have no chance to free these hardware queue resource,
because they iterate hardware queue by
for (i = 0; i < set->nr_hw_queues; i++).

Patch1~3: rename some function name, no function change.
Patch4: fix first memleak.
Patch5: fix prev_nr_hw_queues issue, need be saved before change.
Patch6: alloc map and request to fix potential kernel panic.

Changes since V2:
 * rename some functions name and fix memleak when free map and requests
 * Not free new allocated map and request, they will be relased when tagset gone

Changes since V1:
 * Add fix for potential kernel panic when increase hardware queue

Weiping Zhang (7):
  block: rename __blk_mq_alloc_rq_map
  block: rename __blk_mq_alloc_rq_maps
  block: rename blk_mq_alloc_rq_maps
  block: free both map and request
  block: save previous hardware queue count before udpate
  block: refactor __blk_mq_alloc_rq_map_and_requests
  block: alloc map and request for new hardware queue

 block/blk-mq.c         | 49 ++++++++++++++++++++++++++++++------------
 include/linux/blk-mq.h |  1 +
 2 files changed, 36 insertions(+), 14 deletions(-)

-- 
2.18.1