From: Tejun Heo <tj@kernel.org>
To: John Garry <john.g.garry@oracle.com>
Cc: axboe@kernel.dk, linux-block@vger.kernel.org,
cgroups@vger.kernel.org, linux-kernel@vger.kernel.org,
kernel-team@fb.com, newella@fb.com, hch@lst.de
Subject: Re: [PATCH 12/27] blk-iocost: grab ioc->lock for debt handling
Date: Thu, 13 Jun 2024 12:20:24 -1000 [thread overview]
Message-ID: <ZmtwqDsMnTJHQB6o@slm.duckdns.org> (raw)
In-Reply-To: <45603be5-65ae-4d45-bfbe-22c3c1e22280@oracle.com>
Hello,
On Wed, Jun 12, 2024 at 12:33:19PM +0100, John Garry wrote:
...
> This generates the following sparse warnings on mainline today:
>
> CHECK block/blk-iocost.c
> block/blk-iocost.c:685:9: warning: context imbalance in 'iocg_lock' -
> wrong count at exit
> block/blk-iocost.c:696:28: warning: context imbalance in 'iocg_unlock'
> - unexpected unlock
>
> If we try to break iocg_lock() into one version for lock_ioc set and another
> for lock_ioc unset, we can solve the sparse issues for those functions, but
> then we get another sparse issue from the callsites for those functions:
>
> block/blk-iocost.c:2679:17: warning: context imbalance in
> 'ioc_rqos_throttle' - different lock contexts for basic block
>
> I tried to solve with a total ioc_rqos_throttle() re-org and much code
> duplication by calling the different lock and unlock versions from
> effectively 2x separate copies of ioc_rqos_throttle(), as sparse seems
> confused with how we call these functions. It's a total no-go.
>
> Any simpler idea to solve these? Or just something to live with?
I kinda gave up on sparse lock checking as there's not much it can do that
lockdep can't and the annotations are too awkward and inconsistent
throughout the code base. So, my tendency is just to ignore it.
Thanks.
--
tejun
next prev parent reply other threads:[~2024-06-13 22:20 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-01 18:52 [PATCHSET for-5.10/block] blk-iocost: iocost: improve donation, debt and excess handling Tejun Heo
2020-09-01 18:52 ` [PATCH 01/27] blk-iocost: ioc_pd_free() shouldn't assume irq disabled Tejun Heo
2020-09-01 18:52 ` [PATCH 02/27] blk-stat: make q->stats->lock irqsafe Tejun Heo
2020-09-01 18:52 ` [PATCH 03/27] blk-iocost: use local[64]_t for percpu stat Tejun Heo
2020-11-20 21:51 ` Stafford Horne
2020-11-20 22:13 ` Tejun Heo
2020-09-01 18:52 ` [PATCH 04/27] blk-iocost: rename propagate_active_weights() to propagate_weights() Tejun Heo
2020-09-01 18:52 ` [PATCH 05/27] blk-iocost: clamp inuse and skip noops in __propagate_weights() Tejun Heo
2020-09-01 18:52 ` [PATCH 06/27] blk-iocost: move iocg_kick_delay() above iocg_kick_waitq() Tejun Heo
2020-09-01 18:52 ` [PATCH 07/27] blk-iocost: make iocg_kick_waitq() call iocg_kick_delay() after paying debt Tejun Heo
2020-09-01 18:52 ` [PATCH 08/27] blk-iocost: s/HWEIGHT_WHOLE/WEIGHT_ONE/g Tejun Heo
2020-09-01 18:52 ` [PATCH 09/27] blk-iocost: use WEIGHT_ONE based fixed point number for weights Tejun Heo
2020-09-01 18:52 ` [PATCH 10/27] blk-iocost: make ioc_now->now and ioc->period_at 64bit Tejun Heo
2020-09-01 18:52 ` [PATCH 11/27] blk-iocost: streamline vtime margin and timer slack handling Tejun Heo
2020-09-01 18:52 ` [PATCH 12/27] blk-iocost: grab ioc->lock for debt handling Tejun Heo
2024-06-12 11:33 ` John Garry
2024-06-13 22:20 ` Tejun Heo [this message]
2020-09-01 18:52 ` [PATCH 13/27] blk-iocost: add absolute usage stat Tejun Heo
2020-09-01 18:52 ` [PATCH 14/27] blk-iocost: calculate iocg->usages[] from iocg->local_stat.usage_us Tejun Heo
2020-09-01 18:52 ` [PATCH 15/27] blk-iocost: replace iocg->has_surplus with ->surplus_list Tejun Heo
2020-09-01 18:52 ` [PATCH 16/27] blk-iocost: decouple vrate adjustment from surplus transfers Tejun Heo
2020-09-01 18:52 ` [PATCH 17/27] blk-iocost: restructure surplus donation logic Tejun Heo
2020-09-01 18:52 ` [PATCH 18/27] blk-iocost: implement Andy's method for donation weight updates Tejun Heo
2020-09-01 18:52 ` [PATCH 19/27] blk-iocost: revamp donation amount determination Tejun Heo
2020-09-01 18:52 ` [PATCH 20/27] blk-iocost: revamp in-period donation snapbacks Tejun Heo
2020-09-01 18:52 ` [PATCH 21/27] blk-iocost: revamp debt handling Tejun Heo
2020-09-01 18:52 ` [PATCH 22/27] blk-iocost: implement delay adjustment hysteresis Tejun Heo
2020-09-01 18:52 ` [PATCH 23/27] blk-iocost: halve debts if device stays idle Tejun Heo
2020-09-01 18:52 ` [PATCH 24/27] blk-iocost: implement vtime loss compensation Tejun Heo
2020-09-01 18:52 ` [PATCH 25/27] blk-iocost: restore inuse update tracepoints Tejun Heo
2020-09-01 18:52 ` [PATCH 26/27] blk-iocost: add three debug stat - cost.wait, indebt and indelay Tejun Heo
2020-09-01 18:52 ` [PATCH 27/27] blk-iocost: update iocost_monitor.py Tejun Heo
2020-09-01 22:57 ` [PATCHSET for-5.10/block] blk-iocost: iocost: improve donation, debt and excess handling Jens Axboe
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