linux-kernel - RE: [REGRESSION] x86/efi: Make efi_enter/leave_mm() use the use_/unuse_temporary

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Message-ID: <SJ1PR11MB61297D70878E228810F735A9B9832@SJ1PR11MB6129.namprd11.prod.outlook.com>
Date: Wed, 30 Apr 2025 08:47:43 +0000
From: "Borah, Chaitanya Kumar" <chaitanya.kumar.borah@...el.com>
To: Peter Zijlstra <peterz@...radead.org>, Jani Nikula
	<jani.nikula@...ux.intel.com>
CC: "luto@...nel.org" <luto@...nel.org>, "intel-gfx@...ts.freedesktop.org"
	<intel-gfx@...ts.freedesktop.org>, "intel-xe@...ts.freedesktop.org"
	<intel-xe@...ts.freedesktop.org>, "Kurmi, Suresh Kumar"
	<suresh.kumar.kurmi@...el.com>, "Saarinen, Jani" <jani.saarinen@...el.com>,
	"De Marchi, Lucas" <lucas.demarchi@...el.com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...nel.org>,
	"hughd@...gle.com" <hughd@...gle.com>
Subject: RE: [REGRESSION] x86/efi: Make efi_enter/leave_mm() use the
 use_/unuse_temporary_mm() machinery (linux-next)



> -----Original Message-----
> From: Peter Zijlstra <peterz@...radead.org>
> Sent: Tuesday, April 29, 2025 11:59 PM
> To: Jani Nikula <jani.nikula@...ux.intel.com>
> Cc: Borah, Chaitanya Kumar <chaitanya.kumar.borah@...el.com>;
> luto@...nel.org; intel-gfx@...ts.freedesktop.org; intel-
> xe@...ts.freedesktop.org; Kurmi, Suresh Kumar
> <suresh.kumar.kurmi@...el.com>; Saarinen, Jani <jani.saarinen@...el.com>;
> De Marchi, Lucas <lucas.demarchi@...el.com>; linux-kernel@...r.kernel.org;
> Ingo Molnar <mingo@...nel.org>
> Subject: Re: [REGRESSION] x86/efi: Make efi_enter/leave_mm() use the
> use_/unuse_temporary_mm() machinery (linux-next)
> 
> On Tue, Apr 29, 2025 at 12:01:22PM +0300, Jani Nikula wrote:
> > On Thu, 24 Apr 2025, "Borah, Chaitanya Kumar"
> <chaitanya.kumar.borah@...el.com> wrote:
> > > +Andy, Ingo
> > >
> > > Friendly reminder.
> > > Issue is still seen on latest linux-next runs.
> > >
> > > https://intel-gfx-ci.01.org/tree/linux-next/next-20250424/bat-rpls-4
> > > /boot0.txt
> > >
> > > Regards
> > >
> > > Chaitanya
> >
> > Andy, Ingo -
> >
> > Commit e7021e2fe0b4 ("x86/efi: Make efi_enter/leave_mm() use the
> > use_/unuse_temporary_mm() machinery") on linux-next regresses as
> > reported by Chaitanya
> >
> > Please look into it.
> 
> Does your kernel include the below?

This change has not yet landed in linux-next. However, making local change on top of next-20250429 seems to help us.

Important to note that we don't CONFIG_DEBUG_VM=y as mentioned by Hugh.

Any idea when this lands in linux-next?

Regards

Chaitanya

> 
> ---
> commit aef1d0209ddf127a8069aca5fa3a062be4136b76
> Author: Peter Zijlstra <peterz@...radead.org>
> Date:   Fri Apr 18 11:50:34 2025 +0200
> 
>     x86/mm: Fix {,un}use_temporary_mm() IRQ state
> 
>     As the function switch_mm_irqs_off() implies, it ought to be called with
>     IRQs *off*. Commit 58f8ffa91766 ("x86/mm: Allow temporary MMs when
> IRQs
>     are on") caused this to not be the case for EFI.
> 
>     Ensure IRQs are off where it matters.
> 
>     Fixes: 58f8ffa91766 ("x86/mm: Allow temporary MMs when IRQs are on")
>     Reported-by: Borislav Petkov (AMD) <bp@...en8.de>
>     Tested-by: Borislav Petkov (AMD) <bp@...en8.de>
>     Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
>     Signed-off-by: Ingo Molnar <mingo@...nel.org>
>     Cc: H. Peter Anvin <hpa@...or.com>
>     Cc: Andrew Morton <akpm@...ux-foundation.org>
>     Cc: Andy Lutomirski <luto@...nel.org>
>     Cc: Linus Torvalds <torvalds@...ux-foundation.org>
>     Cc: Rik van Riel <riel@...riel.com>
>     Link:
> https://lore.kernel.org/r/20250418095034.GR38216@noisy.programming.kick
> s-ass.net
> 
> diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index
> 79c124f6f3f2..39761c7765bd 100644
> --- a/arch/x86/mm/tlb.c
> +++ b/arch/x86/mm/tlb.c
> @@ -986,6 +986,7 @@ struct mm_struct *use_temporary_mm(struct
> mm_struct *temp_mm)
>  	struct mm_struct *prev_mm;
> 
>  	lockdep_assert_preemption_disabled();
> +	guard(irqsave)();
> 
>  	/*
>  	 * Make sure not to be in TLB lazy mode, as otherwise we'll end up
> @@ -1018,6 +1019,7 @@ struct mm_struct *use_temporary_mm(struct
> mm_struct *temp_mm)  void unuse_temporary_mm(struct mm_struct
> *prev_mm)  {
>  	lockdep_assert_preemption_disabled();
> +	guard(irqsave)();
> 
>  	/* Clear the cpumask, to indicate no TLB flushing is needed anywhere
> */
>  	cpumask_clear_cpu(smp_processor_id(),
> mm_cpumask(this_cpu_read(cpu_tlbstate.loaded_mm)));