Messages in this thread | | | Subject | Re: [PATCH] mm/thp: Make ARCH_ENABLE_SPLIT_PMD_PTLOCK dependent on PGTABLE_LEVELS > 2 | From | Anshuman Khandual <> | Date | Mon, 10 May 2021 15:46:41 +0530 |
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On 5/10/21 3:40 PM, Oscar Salvador wrote: > On Mon, May 10, 2021 at 03:36:29PM +0530, Anshuman Khandual wrote: >> >> >> On 5/10/21 2:23 PM, Peter Zijlstra wrote: >>> On Mon, May 10, 2021 at 10:05:45AM +0530, Anshuman Khandual wrote: >>>> - select ARCH_ENABLE_SPLIT_PMD_PTLOCK if X86_64 || X86_PAE >>>> + select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE) >>> >>> It's still very early on a Monday, but IIRC this new condition is >>> identical to the pre-existing one. >> >> Did not get it, could you please elaborate ? > > When using x86_PAE, you must have more than two pgtable levels, right? > And not speaking of x86_64.
arch/x86/Kconfig..
config PGTABLE_LEVELS int default 5 if X86_5LEVEL default 4 if X86_64 default 3 if X86_PAE default 2
Both X86_PAE and X86_64 will always have page table levels > 2 ? But regardless, it might be still useful to assert (PGTABLE_LEVELS > 2) before selecting ARCH_ENABLE_SPLIT_PMD_PTLOCK.
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