linux-kernel - Re: [PATCH v3 1/2] x86/mm: Handle alloc failure in phys_*

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Message-ID: <cce191c5-1467-44a5-8f8f-56dde0e05fb2@neon.tech>
Date: Fri, 13 Jun 2025 21:17:33 +0100
From: Em Sharnoff <sharnoff@...n.tech>
To: Dave Hansen <dave.hansen@...el.com>, linux-kernel@...r.kernel.org,
 x86@...nel.org, linux-mm@...ck.org
Cc: Ingo Molnar <mingo@...nel.org>, "H. Peter Anvin" <hpa@...or.com>,
 Andy Lutomirski <luto@...nel.org>, Peter Zijlstra <peterz@...radead.org>,
 Thomas Gleixner <tglx@...utronix.de>, Borislav Petkov <bp@...en8.de>,
 "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>,
 Oleg Vasilev <oleg@...n.tech>, Arthur Petukhovsky <arthur@...n.tech>,
 Stefan Radig <stefan@...n.tech>, Misha Sakhnov <misha@...n.tech>
Subject: Re: [PATCH v3 1/2] x86/mm: Handle alloc failure in phys_*_init()

On 6/11/25 20:36, Dave Hansen wrote:
> On 6/11/25 12:26, Em Sharnoff wrote:
> > 2. Change the phys_*_init() functions to return int, and directly update
> >    max_pfn_mapped from within them. They already call update_page_count(),
> >    maybe this is similar?
> 
> That seems like the most straightforward. Each time they update a
> mapping, they call a helper which bumps up 'max_pfn_mapped'.

Update on this -- turns out I was wrong again. 'paddr_last' is also used to
update 'pfn_mapped', which is more complex. Hopefully still within reason.

I've posted a new patch set, patch 1/4 adopts the "call a helper" route.
Design-wise, it's less clean than I'd like, but let me know what you think.
https://lore.kernel.org/all/7d0d307d-71eb-4913-8023-bccc7a8a4a3d@neon.tech/

Em