Messages in this thread | | | Subject | Re: [PATCH V3 1/3] arm64/mm/hotplug: Register boot memory hot remove notifier earlier | From | Gavin Shan <> | Date | Wed, 23 Sep 2020 16:04:56 +1000 |
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Hi Anshuman,
On 9/21/20 10:05 PM, Anshuman Khandual wrote: > This moves memory notifier registration earlier in the boot process from > device_initcall() to early_initcall() which will help in guarding against > potential early boot memory offline requests. Even though there should not > be any actual offlinig requests till memory block devices are initialized > with memory_dev_init() but then generic init sequence might just change in > future. Hence an early registration for the memory event notifier would be > helpful. While here, just skip the registration if CONFIG_MEMORY_HOTREMOVE > is not enabled and also call out when memory notifier registration fails. > > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Will Deacon <will@kernel.com> > Cc: Mark Rutland <mark.rutland@arm.com> > Cc: Marc Zyngier <maz@kernel.org> > Cc: Steve Capper <steve.capper@arm.com> > Cc: Mark Brown <broonie@kernel.org> > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-kernel@vger.kernel.org > Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> > --- > arch/arm64/mm/mmu.c | 14 ++++++++++++-- > 1 file changed, 12 insertions(+), 2 deletions(-) >
With the following nit-picky comments resolved:
Reviewed-by: Gavin Shan <gshan@redhat.com>
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > index 75df62fea1b6..df3b7415b128 100644 > --- a/arch/arm64/mm/mmu.c > +++ b/arch/arm64/mm/mmu.c > @@ -1499,7 +1499,17 @@ static struct notifier_block prevent_bootmem_remove_nb = { > > static int __init prevent_bootmem_remove_init(void) > { > - return register_memory_notifier(&prevent_bootmem_remove_nb); > + int ret = 0; > + > + if (!IS_ENABLED(CONFIG_MEMORY_HOTREMOVE)) > + return ret; > + > + ret = register_memory_notifier(&prevent_bootmem_remove_nb); > + if (!ret) > + return ret; > + > + pr_err("Notifier registration failed - boot memory can be removed\n"); > + return ret; > }
It might be cleaner if the duplicated return statements can be avoided. Besides, it's always nice to print the errno even though zero is always returned from register_memory_notifier(). So I guess you probably need something like below:
ret = register_memory_notifier(&prevent_bootmem_remove_nb); if (ret) pr_err("%s: Error %d registering notifier\n", __func__, ret)
return ret;
register_memory_notifier # 0 is returned on !CONFIG_MEMORY_HOTPLUG_SPARSE blocking_notifier_chain_register notifier_chain_register # 0 is always returned > -device_initcall(prevent_bootmem_remove_init); > +early_initcall(prevent_bootmem_remove_init); > #endif >
Cheers, Gavin
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