From: Catalin Marinas <catalin.marinas@arm.com> To: Anshuman Khandual <anshuman.khandual@arm.com> Cc: linux-arm-kernel@lists.infradead.org, Will Deacon <will@kernel.org>, Mark Rutland <mark.rutland@arm.com>, Marc Zyngier <maz@kernel.org>, Steve Capper <steve.capper@arm.com>, Mark Brown <broonie@kernel.org>, linux-kernel@vger.kernel.org Subject: Re: [PATCH V2] arm64/hotplug: Improve memory offline event notifier Date: Fri, 11 Sep 2020 15:06:04 +0100 [thread overview] Message-ID: <20200911140603.GB12835@gaia> (raw) In-Reply-To: <1598241869-28416-1-git-send-email-anshuman.khandual@arm.com> Hi Anshuman, On Mon, Aug 24, 2020 at 09:34:29AM +0530, Anshuman Khandual wrote: > This brings about three different changes to the sole memory event notifier > for arm64 platform and improves it's robustness while also enhancing debug > capabilities during potential memory offlining error conditions. > > This moves the memory notifier registration bit earlier in the boot process > from device_initcall() to setup_arch() which will help in guarding against > potential early boot memory offline requests. > > This enables MEM_OFFLINE memory event handling. It will help intercept any > possible error condition such as if boot memory some how still got offlined > even after an expilicit notifier failure, potentially by a future change in > generic hotplug framework. This would help detect such scenarious and help > debug further. > > It also adds a validation function which scans entire boot memory and makes > sure that early memory sections are online. This check is essential for the > memory notifier to work properly as it cannot prevent boot memory offlining > if they are not online to begin with. But this additional sanity check is > enabled only with DEBUG_VM. Could you please split this in separate patches rather than having a single one doing three somewhat related things? > --- a/arch/arm64/kernel/setup.c > +++ b/arch/arm64/kernel/setup.c > @@ -376,6 +376,14 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p) > "This indicates a broken bootloader or old kernel\n", > boot_args[1], boot_args[2], boot_args[3]); > } > + > + /* > + * Register the memory notifier which will prevent boot > + * memory offlining requests - early enough. But there > + * should not be any actual offlinig request till memory > + * block devices are initialized with memory_dev_init(). > + */ > + memory_hotremove_notifier(); Why can this not be an early_initcall()? As you said, memory_dev_init() is called much later, after the SMP was initialised. You could even combine this with validate_bootmem_online_state() in a single early_initcall() which, after checking, registers the notifier. -- Catalin
WARNING: multiple messages have this Message-ID (diff)
From: Catalin Marinas <catalin.marinas@arm.com> To: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Mark Rutland <mark.rutland@arm.com>, Steve Capper <steve.capper@arm.com>, Marc Zyngier <maz@kernel.org>, linux-kernel@vger.kernel.org, Mark Brown <broonie@kernel.org>, Will Deacon <will@kernel.org>, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH V2] arm64/hotplug: Improve memory offline event notifier Date: Fri, 11 Sep 2020 15:06:04 +0100 [thread overview] Message-ID: <20200911140603.GB12835@gaia> (raw) In-Reply-To: <1598241869-28416-1-git-send-email-anshuman.khandual@arm.com> Hi Anshuman, On Mon, Aug 24, 2020 at 09:34:29AM +0530, Anshuman Khandual wrote: > This brings about three different changes to the sole memory event notifier > for arm64 platform and improves it's robustness while also enhancing debug > capabilities during potential memory offlining error conditions. > > This moves the memory notifier registration bit earlier in the boot process > from device_initcall() to setup_arch() which will help in guarding against > potential early boot memory offline requests. > > This enables MEM_OFFLINE memory event handling. It will help intercept any > possible error condition such as if boot memory some how still got offlined > even after an expilicit notifier failure, potentially by a future change in > generic hotplug framework. This would help detect such scenarious and help > debug further. > > It also adds a validation function which scans entire boot memory and makes > sure that early memory sections are online. This check is essential for the > memory notifier to work properly as it cannot prevent boot memory offlining > if they are not online to begin with. But this additional sanity check is > enabled only with DEBUG_VM. Could you please split this in separate patches rather than having a single one doing three somewhat related things? > --- a/arch/arm64/kernel/setup.c > +++ b/arch/arm64/kernel/setup.c > @@ -376,6 +376,14 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p) > "This indicates a broken bootloader or old kernel\n", > boot_args[1], boot_args[2], boot_args[3]); > } > + > + /* > + * Register the memory notifier which will prevent boot > + * memory offlining requests - early enough. But there > + * should not be any actual offlinig request till memory > + * block devices are initialized with memory_dev_init(). > + */ > + memory_hotremove_notifier(); Why can this not be an early_initcall()? As you said, memory_dev_init() is called much later, after the SMP was initialised. You could even combine this with validate_bootmem_online_state() in a single early_initcall() which, after checking, registers the notifier. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-09-11 15:28 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-08-24 4:04 [PATCH V2] arm64/hotplug: Improve memory offline event notifier Anshuman Khandual 2020-08-24 4:04 ` Anshuman Khandual 2020-08-24 4:09 ` Anshuman Khandual 2020-08-24 4:09 ` Anshuman Khandual 2020-09-08 9:23 ` Anshuman Khandual 2020-09-08 9:23 ` Anshuman Khandual 2020-09-11 14:06 ` Catalin Marinas [this message] 2020-09-11 14:06 ` Catalin Marinas 2020-09-14 4:05 ` Anshuman Khandual 2020-09-14 4:05 ` Anshuman Khandual
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