linux-kernel - Re: [PATCH v2] x86/pm: fix false positive kmemleak report in msr_build

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Message-ID: <YmgOP1FFmidS9ecJ@zn.tnic>
Date:   Tue, 26 Apr 2022 17:22:39 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Matthieu Baerts <matthieu.baerts@...sares.net>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Pavel Machek <pavel@....cz>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>, Chen Yu <yu.c.chen@...el.com>,
        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
        Catalin Marinas <catalin.marinas@....com>, linux-mm@...ck.org,
        Mat Martineau <mathew.j.martineau@...ux.intel.com>,
        Ingo Molnar <mingo@...nel.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] x86/pm: fix false positive kmemleak report in
 msr_build_context()

On Sat, Apr 23, 2022 at 08:24:10PM +0200, Matthieu Baerts wrote:
> diff --git a/arch/x86/include/asm/suspend_64.h b/arch/x86/include/asm/suspend_64.h
> index 35bb35d28733..bb7023dbf524 100644
> --- a/arch/x86/include/asm/suspend_64.h
> +++ b/arch/x86/include/asm/suspend_64.h
> @@ -14,9 +14,13 @@
>   * Image of the saved processor state, used by the low level ACPI suspend to
>   * RAM code and by the low level hibernation code.
>   *
> - * If you modify it, fix arch/x86/kernel/acpi/wakeup_64.S and make sure that
> - * __save/__restore_processor_state(), defined in arch/x86/kernel/suspend_64.c,
> - * still work as required.
> + * If you modify it before 'misc_enable', fix arch/x86/kernel/acpi/wakeup_64.S

Why does before misc_enable matter?

arch/x86/kernel/asm-offsets_64.c computes the offsets and there is a
member like saved_context_gdt_desc which will get moved after your
change but that's not a problem because the offset will get recomputed
at build time.

Hm?

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette