Messages in this thread | | | Date | Fri, 11 Sep 2020 15:06:04 +0100 | From | Catalin Marinas <> | Subject | Re: [PATCH V2] arm64/hotplug: Improve memory offline event notifier |
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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
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