linux-kernel - Re: [PATCH for-5.16/block] iocost: Fix divide-by-zero on donation from low hweight cgroup

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Date:   Tue, 14 Dec 2021 06:58:20 -0700
From:   Jens Axboe <axboe@...nel.dk>
To:     Tejun Heo <tj@...nel.org>
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-team@...com, cgroups@...r.kernel.org
Subject: Re: [PATCH for-5.16/block] iocost: Fix divide-by-zero on donation from low hweight cgroup

On Mon, 13 Dec 2021 14:14:43 -1000, Tejun Heo wrote:
> The donation calculation logic assumes that the donor has non-zero
> after-donation hweight, so the lowest active hweight a donating cgroup can
> have is 2 so that it can donate 1 while keeping the other 1 for itself.
> Earlier, we only donated from cgroups with sizable surpluses so this
> condition was always true. However, with the precise donation algorithm
> implemented, f1de2439ec43 ("blk-iocost: revamp donation amount
> determination") made the donation amount calculation exact enabling even low
> hweight cgroups to donate.
> 
> [...]

Applied, thanks!

[1/1] iocost: Fix divide-by-zero on donation from low hweight cgroup
      commit: edaa26334c117a584add6053f48d63a988d25a6e

Best regards,
-- 
Jens Axboe