linux-kernel - Re: [PATCH v6 03/16] dma-debug: refactor to use physical addresses for page mapping

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Message-ID: <5ffc63e9-19bd-4e12-92fc-57fe12d10f4f@samsung.com>
Date: Fri, 12 Sep 2025 00:23:17 +0200
From: Marek Szyprowski <m.szyprowski@...sung.com>
To: Leon Romanovsky <leon@...nel.org>
Cc: Jason Gunthorpe <jgg@...dia.com>, Abdiel Janulgue
	<abdiel.janulgue@...il.com>, Alexander Potapenko <glider@...gle.com>, Alex
	Gaynor <alex.gaynor@...il.com>, Andrew Morton <akpm@...ux-foundation.org>,
	Christoph Hellwig <hch@....de>, Danilo Krummrich <dakr@...nel.org>, David
	Hildenbrand <david@...hat.com>, iommu@...ts.linux.dev, Jason Wang
	<jasowang@...hat.com>, Jens Axboe <axboe@...nel.dk>, Joerg Roedel
	<joro@...tes.org>, Jonathan Corbet <corbet@....net>, Juergen Gross
	<jgross@...e.com>, kasan-dev@...glegroups.com, Keith Busch
	<kbusch@...nel.org>, linux-block@...r.kernel.org, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	linux-nvme@...ts.infradead.org, linuxppc-dev@...ts.ozlabs.org,
	linux-trace-kernel@...r.kernel.org, Madhavan Srinivasan
	<maddy@...ux.ibm.com>, Masami Hiramatsu <mhiramat@...nel.org>, Michael
	Ellerman <mpe@...erman.id.au>, "Michael S. Tsirkin" <mst@...hat.com>, Miguel
	Ojeda <ojeda@...nel.org>, Robin Murphy <robin.murphy@....com>,
	rust-for-linux@...r.kernel.org, Sagi Grimberg <sagi@...mberg.me>, Stefano
	Stabellini <sstabellini@...nel.org>, Steven Rostedt <rostedt@...dmis.org>,
	virtualization@...ts.linux.dev, Will Deacon <will@...nel.org>,
	xen-devel@...ts.xenproject.org
Subject: Re: [PATCH v6 03/16] dma-debug: refactor to use physical addresses
 for page mapping

On 10.09.2025 07:26, Leon Romanovsky wrote:
> On Tue, Sep 09, 2025 at 10:37:48PM +0300, Leon Romanovsky wrote:
>> On Tue, Sep 09, 2025 at 04:27:31PM +0300, Leon Romanovsky wrote:
>>> From: Leon Romanovsky <leonro@...dia.com>
>> <...>
>>
>>>   include/linux/page-flags.h         |  1 +
>> <...>
>>
>>> --- a/include/linux/page-flags.h
>>> +++ b/include/linux/page-flags.h
>>> @@ -614,6 +614,7 @@ FOLIO_FLAG(dropbehind, FOLIO_HEAD_PAGE)
>>>    * available at this point.
>>>    */
>>>   #define PageHighMem(__p) is_highmem_idx(page_zonenum(__p))
>>> +#define PhysHighMem(__p) (PageHighMem(phys_to_page(__p)))
>> This was a not so great idea to add PhysHighMem() because of "else"
>> below which unfolds to maze of macros and automatically generated
>> functions with "static inline int Page##uname ..." signature.
>>
>>>   #define folio_test_highmem(__f)	is_highmem_idx(folio_zonenum(__f))
>>>   #else
>>>   PAGEFLAG_FALSE(HighMem, highmem)
> After sleeping over it, the following hunk will help:
>
> diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
> index dfbc4ba86bba2..2a1f346178024 100644
> --- a/include/linux/page-flags.h
> +++ b/include/linux/page-flags.h
> @@ -614,11 +614,11 @@ FOLIO_FLAG(dropbehind, FOLIO_HEAD_PAGE)
>    * available at this point.
>    */
>   #define PageHighMem(__p) is_highmem_idx(page_zonenum(__p))
> -#define PhysHighMem(__p) (PageHighMem(phys_to_page(__p)))
>   #define folio_test_highmem(__f)        is_highmem_idx(folio_zonenum(__f))
>   #else
>   PAGEFLAG_FALSE(HighMem, highmem)
>   #endif
> +#define PhysHighMem(__p) (PageHighMem(phys_to_page(__p)))
>
>   /* Does kmap_local_folio() only allow access to one page of the folio? */
>   #ifdef CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP

Okay, I will add this fixup while applying the patches.

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland