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Message-ID: <be5982f8-3928-455e-969c-1e4c419d80a2@pavinjoseph.com>
Date: Fri, 29 Mar 2024 14:26:07 +0530
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Subject: Re: [PATCH v4] x86/mm/ident_map: On UV systems, use gbpages only
 where full GB page should be mapped.
To: Ingo Molnar <mingo@kernel.org>
Cc: Steve Wahl <steve.wahl@hpe.com>, Dave Hansen
 <dave.hansen@linux.intel.com>, Andy Lutomirski <luto@kernel.org>,
 Peter Zijlstra <peterz@infradead.org>, Thomas Gleixner <tglx@linutronix.de>,
 Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
 x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
 linux-kernel@vger.kernel.org,
 Linux regressions mailing list <regressions@lists.linux.dev>,
 stable@vger.kernel.org, Eric Hagberg <ehagberg@gmail.com>,
 Simon Horman <horms@verge.net.au>, Eric Biederman <ebiederm@xmission.com>,
 Dave Young <dyoung@redhat.com>, Sarah Brofeldt <srhb@dbc.dk>,
 Russ Anderson <rja@hpe.com>, Dimitri Sivanich <sivanich@hpe.com>,
 Hou Wenlong <houwenlong.hwl@antgroup.com>,
 Andrew Morton <akpm@linux-foundation.org>, Baoquan He <bhe@redhat.com>,
 Yuntao Wang <ytcoode@gmail.com>, Bjorn Helgaas <bhelgaas@google.com>
References: <20240328160614.1838496-1-steve.wahl@hpe.com>
 <ZgZqhWoRZoq5tJoU@gmail.com>
 <47302624-6466-41a7-85db-f6872d58a4d2@pavinjoseph.com>
 <ZgZ4qlbncvxhboQ0@gmail.com>
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From: Pavin Joseph <me@pavinjoseph.com>
In-Reply-To: <ZgZ4qlbncvxhboQ0@gmail.com>
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On 3/29/24 13:45, Ingo Molnar wrote:
> Just to clarify, we have the following 3 upstream (and soon to be upstream) versions:
> 
>   v1: pre-d794734c9bbf kernels
>   v2: d794734c9bbf x86/mm/ident_map: Use gbpages only where full GB page should be mapped.
>   v3: c567f2948f57 Revert "x86/mm/ident_map: Use gbpages only where full GB page should be mapped."
> 
> Where v1 and v3 ought to be the same in behavior.
> 
> So how does the failure matrix look like on your systems? Is my
> understanding accurate:
> 
> 
>             regular boot  | regular kexec | nogbpages boot | nogbpages kexec boot
>   ------------------------|---------------------------------------------------
>   v1:       OK            | OK            | OK             | FAIL
>   v2:       OK            | FAIL          | FAIL           | FAIL

Slight correction:

    regular boot  | regular kexec | nogbpages boot | nogbpages kexec boot
-----------------|---------------|----------------|------------------
v1:       OK     | OK            | OK             | FAIL
v2:       OK     | FAIL          | OK             | FAIL

Pavin.