Re: [PATCH V2 1/2] arm64/mm: Fix pfn_valid() for ZONE_DEVICE based memory
From: Will Deacon <will@kernel.org>
Date: 2021-02-11 12:25:58
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linux-mm, lkml
On Thu, Feb 11, 2021 at 05:40:35PM +0530, Anshuman Khandual wrote:
On 2/11/21 5:23 PM, Will Deacon wrote:quoted
On Fri, Feb 05, 2021 at 06:55:53PM +0000, Will Deacon wrote:quoted
On Wed, Feb 03, 2021 at 09:20:39AM +0530, Anshuman Khandual wrote:quoted
On 2/2/21 6:26 PM, David Hildenbrand wrote:quoted
On 02.02.21 13:51, Will Deacon wrote:quoted
On Tue, Feb 02, 2021 at 01:39:29PM +0100, David Hildenbrand wrote:quoted
As I expressed already, long term we should really get rid of the arm64 variant and rather special-case the generic one. Then we won't go out of sync - just as it happened with ZONE_DEVICE handling here.Why does this have to be long term? This ZONE_DEVICE stuff could be the carrot on the stick :)Yes, I suggested to do it now, but Anshuman convinced me that doing a simple fix upfront might be cleaner --- for example when it comes to backporting :)Right. The current pfn_valid() breaks for ZONE_DEVICE memory and this fixes the problem in the present context which can be easily backported if required. Changing or rather overhauling the generic code with new configs as proposed earlier (which I am planning to work on subsequently) would definitely be an improvement for the current pfn_valid() situation in terms of maintainability but then it should not stop us from fixing the problem now.Alright, I've mulled this over a bit. I don't agree that this patch helps with maintainability (quite the opposite, in fact), but perfection is the enemy of the good so I'll queue the series for 5.12. However, I'll revert the changes at the first sign of a problem, so please do work towards a generic solution which can replace this in the medium term.... and dropped. These patches appear to be responsible for a boot regression reported by CKI:Ahh, boot regression ? These patches only change the behaviour for non boot memory only.
Sure, but this thing is horribly fragile, which is why I was nervous about touching it in the first place ;)
Will look into the logs and see if there is something pointing to the problem.
We don't have a log yet, but I've asked whether earlycon works on the problematic machine (the failure seems to be specific to a certain TX2). Either way, this is too late for 5.12 now. Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel