linux-kernel - Re: [PATCH 05/11] x86: remove HIGHMEM64G support

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <Z_rDdnlSs0rts3b9@gmail.com>
Date: Sat, 12 Apr 2025 21:48:06 +0200
From: Ingo Molnar <mingo@...nel.org>
To: Mike Rapoport <rppt@...nel.org>
Cc: Dave Hansen <dave.hansen@...el.com>, Arnd Bergmann <arnd@...nel.org>,
	linux-kernel@...r.kernel.org, x86@...nel.org,
	Arnd Bergmann <arnd@...db.de>, Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andy Shevchenko <andy@...nel.org>,
	Matthew Wilcox <willy@...radead.org>,
	Sean Christopherson <seanjc@...gle.com>,
	Davide Ciminaghi <ciminaghi@...dd.com>,
	Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org
Subject: Re: [PATCH 05/11] x86: remove HIGHMEM64G support


* Mike Rapoport <rppt@...nel.org> wrote:

> On Fri, Apr 11, 2025 at 04:44:13PM -0700, Dave Hansen wrote:
> > Has anyone run into any problems on 6.15-rc1 with this stuff?
> > 
> > 0xf75fe000 is the mem_map[] entry for the first page >4GB. It obviously
> > wasn't allocated, thus the oops. Looks like the memblock for the >4GB
> > memory didn't get removed although the pgdats seem correct.
> 
> That's apparently because of 6faea3422e3b ("arch, mm: streamline HIGHMEM
> freeing"). 
> Freeing of high memory was clamped to the end of ZONE_HIGHMEM which is 4G
> and after 6faea3422e3b there's no more clamping, so memblock_free_all()
> tries to free memory >4G as well.
>  
> > I'll dig into it some more. Just wanted to make sure there wasn't a fix
> > out there already.
> 
> This should fix it.
> 
> diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
> index 57120f0749cc..4b24c0ccade4 100644
> --- a/arch/x86/kernel/e820.c
> +++ b/arch/x86/kernel/e820.c
> @@ -1300,6 +1300,8 @@ void __init e820__memblock_setup(void)
>  		memblock_add(entry->addr, entry->size);
>  	}
>  
> +	memblock_remove(PFN_PHYS(max_pfn), -1);
> +
>  	/* Throw away partial pages: */
>  	memblock_trim_memory(PAGE_SIZE);

Mind sending a full patch with changelog, SOB, Ard's Tested-by, Dave's 
Reported-by, etc.?

Thanks,

	Ingo