linux-kernel - Re: [PATCH-next v3] lib: parser: optimize match

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Message-ID: <Y8n1rOLdMGDfOgpe@slm.duckdns.org>
Date:   Thu, 19 Jan 2023 16:00:12 -1000
From:   Tejun Heo <tj@...nel.org>
To:     Li Lingfeng <lilingfeng3@...wei.com>
Cc:     linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
        axboe@...nel.dk, akpm@...ux-foundation.org, jack@...e.cz,
        bingjingc@...ology.com, ebiggers@...gle.com,
        james.smart@...adcom.com, houtao1@...wei.com, yi.zhang@...wei.com,
        yangerkun@...wei.com, yukuai3@...wei.com
Subject: Re: [PATCH-next v3] lib: parser: optimize match_NUMER apis to use
 local array

On Fri, Jan 20, 2023 at 10:13:04AM +0800, Li Lingfeng wrote:
> Memory will be allocated to store substring_t in match_strdup(), which means
> the caller of match_strdup() may need to be scheduled out to wait for reclaiming
> memory.
> 
> Using local array to store substring_t to remove the restriction.
> 
> Link: https://lore.kernel.org/all/20221104023938.2346986-5-yukuai1@huaweicloud.com/
> Signed-off-by: Li Lingfeng <lilingfeng3@...wei.com>

 Acked-by: Tejun Heo <tj@...nel.org>

This fixes a sleep-while-atomic splat in blk-iocost, so it'd be a good idea to add:

 Fixes: 2c0647988433 ("blk-iocost: don't release 'ioc->lock' while updating params").

The mm tree likely is the best fit but given the splat the block tree can
work too. Andrew, Jens, what do you think?

Thanks.

-- 
tejun