linux-kernel - Re: [REGRESSION] Platforms supporting SGX fail to kexec due to 96c6b8f212a ("memblock: report failures when memblock_can

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Date: Thu, 1 Feb 2024 10:36:37 -0800
From: Ashok Raj <ashok.raj@...el.com>
To: Linux regressions mailing list <regressions@...ts.linux.dev>
CC: Mike Rapoport <rppt@...nel.org>, Linus Torvalds
	<torvalds@...ux-foundation.org>, LKML Mailing List
	<linux-kernel@...r.kernel.org>, Thomas Gleixner <tglx@...utronix.de>,
	Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...el.com>, "Ingo
 Molnar" <mingo@...nel.org>, Song Shuai <songshuaishuai@...ylab.org>, "Ashok
 Raj" <ashok.raj@...el.com>
Subject: Re: [REGRESSION] Platforms supporting SGX fail to kexec due to
 96c6b8f212a ("memblock: report failures when memblock_can_resize is not
 set")

Hi Mike,

On Thu, Feb 01, 2024 at 11:38:38AM +0100, Linux regression tracking (Thorsten Leemhuis) wrote:
> On 31.12.23 08:26, Mike Rapoport wrote:
> > On Thu, Dec 28, 2023 at 04:33:49PM -0800, Ashok Raj wrote:
> >> 96c6b8f212a ("memblock: report failures when memblock_can_resize is not set")
> >>
> >> Causes kexec failure. Backing out this change, kexec succeeds. Symptom is
> >> it appears to hang, possibly hung at the panic. Although I have the
> >> earlyprintk enabled, I don't see any console messages when new kernel
> >> boots. 
> >>
> >> Also tested turning off CONFIG_X86_SGX, the kernel with this commit
> >> included also kexec's fine.
> >>
> >> Booting from warm/cold reset has no issues. Only kexec to new kernel with
> >> this change included and CONFIG_X86_SGX=y causes the kexec failure.
> > 
> > Can you add memblock=debug to the kernel command line and send logs for
> > normal boot and kexec with CONFIG_X86_SGX=y and e96c6b8f212a reverted?
> 
> Ashok, you afaics never replied. Did you forget about it? Or was the
> issue resolved later or never a regression in the first place? I for now
> assume it's one of the latter and stop tracking this:

Sorry I went AWOL on this.. I did try the newer kernel's (6.8-rc1) and its not
happening any more, and kexec seems to work well. 

On the same problem kernel adding memblock=debug make it dissappear, and
even adding some code to that suspect area changed behavior.

I'm not able to reproduce it again. Sorry for the delay.

Cheers,
Ashok