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From: Miles Chen <miles.chen@mediatek.com>
To: <robin.murphy@arm.com>
Cc: <iommu@lists.linux-foundation.org>, <joro@8bytes.org>,
	<linux-kernel@vger.kernel.org>, <miles.chen@mediatek.com>,
	<stable@vger.kernel.org>, <will@kernel.org>,
	<wsd_upstream@mediatek.com>, <yf.wang@mediatek.com>
Subject: Re: [PATCH] iommu/iova: Improve 32-bit free space estimate
Date: Sat, 5 Mar 2022 08:03:37 +0800	[thread overview]
Message-ID: <20220305000337.24995-1-miles.chen@mediatek.com> (raw)
In-Reply-To: <77b0c978-7caa-c333-6015-1d784b5daf3f@arm.com>

Hi Joerg, Robin,

> Applied without stable tag for now. If needed, please consider
> re-sending it for stable when this patch is merged upstream.

> Yeah, having figured out the history, I ended up with the opinion that 
> it was a missed corner-case optimisation opportunity, rather than an 
> actual error with respect to intent or implementation, so I 
> intentionally left that out. Plus figuring out an exact Fixes tag might 
> be tricky - as above I reckon it probably only started to become 
> significant somwehere around 5.11 or so.
> 
> All of these various levels of retry mechanisms are only a best-effort 
> thing, and ultimately if you're making large allocations from a small 
> space there are always going to be *some* circumstances that still 
> manage to defeat them. Over time, we've made them try harder, but that 
> fact that we haven't yet made them try hard enough to work well for a 
> particular use-case does not constitute a bug. However as Joerg says, 
> anyone's welcome to make a case to Greg to backport a mainline commit if 
> it's a low-risk change with significant benefit to real-world stable 
> kernel users.

Got it, thank you. 
We will try to push to the android LTS trees we need.

Thanks,
Miles

> 
> Thanks all!
> 
> Robin.

      reply	other threads:[~2022-03-05  0:03 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <033815732d83ca73b13c11485ac39336f15c3b40.1646318408.git.robin.murphy@arm.com>
2022-03-03 23:36 ` [PATCH] iommu/iova: Improve 32-bit free space estimate Miles Chen
2022-03-04  9:41   ` Joerg Roedel
2022-03-04 11:32     ` Robin Murphy
2022-03-05  0:03       ` Miles Chen [this message]

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