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Date:   Sat, 19 Aug 2023 14:01:38 -0700
From:   "Paul E. McKenney" <paulmck@kernel.org>
To:     Baoquan He <bhe@redhat.com>
Cc:     eric.devolder@oracle.com, linux-kernel@vger.kernel.org,
        linux-next@vger.kernel.org, sfr@canb.auug.org.au,
        tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
        dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com,
        sourabhjain@linux.ibm.com, hbathini@linux.ibm.com
Subject: Re: [BUG resend next-20230818] error: 'prepare_elf_headers' defined
 but not used
Message-ID: <a6f29741-39e2-41fd-a253-1a0477b89a9f@paulmck-laptop>
Reply-To: paulmck@kernel.org
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 <ZOC94WelqfS0vsFK@MiWiFi-R3L-srv>
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On Sat, Aug 19, 2023 at 09:04:33PM +0800, Baoquan He wrote:
> On 08/18/23 at 07:28pm, Paul E. McKenney wrote:
> > Hello!
> > 
> > This morning's rcutorture testing on next-20230818 complained about
> > prepare_elf_headers() being defined but unused on several rcutorture
> > scenarios.  The patch below makes rcutorture happy, but might or might
> > not be a proper fix.
> > 
> > This is a resend adding a few more people on CC, given a possible
> > relationship to 9f1f399ca999 ("x86/crash: add x86 crash hotplug support").
> > 
> > Thoughts?
> > 
> 
> Thanks for reporting this, Paul.
> > 
> > ------------------------------------------------------------------------
> > 
> > diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
> > index 1d0f824559fce..926c39e22387b 100644
> > --- a/arch/x86/kernel/crash.c
> > +++ b/arch/x86/kernel/crash.c
> > @@ -127,7 +127,8 @@ void native_machine_crash_shutdown(struct pt_regs *regs)
> >  	crash_save_cpu(regs, safe_smp_processor_id());
> >  }
> >  
> > -#if defined(CONFIG_KEXEC_FILE) || defined(CONFIG_CRASH_DUMP)
> > +#if (defined(CONFIG_KEXEC_FILE) || defined(CONFIG_CRASH_DUMP)) && defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC)
> 
> Hi Eric,
> 
> Now prepare_elf_headers() is needed for kexec_file_load and crash
> hotplug support of kexec_load, change it like this?
> 
> #if defined(CONFIG_KEXEC_FILE) || defined(CONFIG_CRASH_HOTPLUG)

If you mean the patch below:

Tested-by: Paul E. McKenney <paulmck@kernel.org>

------------------------------------------------------------------------

diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index 1d0f824559fc..c92d88680dbf 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -127,7 +127,7 @@ void native_machine_crash_shutdown(struct pt_regs *regs)
 	crash_save_cpu(regs, safe_smp_processor_id());
 }
 
-#if defined(CONFIG_KEXEC_FILE) || defined(CONFIG_CRASH_DUMP)
+#if defined(CONFIG_KEXEC_FILE) || defined(CONFIG_CRASH_HOTPLUG)
 static int get_nr_ram_ranges_callback(struct resource *res, void *arg)
 {
 	unsigned int *nr_ranges = arg;