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| author |   Joerg Roedel <jroedel@suse.de> | 2020-08-14 17:19:47 +0200 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2020-08-15 13:56:16 +0200 |
| commit | 7a27ef5e83089090f3a4073a9157c862ef00acfc (patch) | |
| tree | 42c076fe753ccd98691928377b000ac5e980b4b7 /arch/x86/mm/init_64.c | |
| parent | x86/mm/64: Do not sync vmalloc/ioremap mappings (diff) | |
| download | linux-dev-7a27ef5e83089090f3a4073a9157c862ef00acfc.tar.xz linux-dev-7a27ef5e83089090f3a4073a9157c862ef00acfc.zip | |
x86/mm/64: Update comment in preallocate_vmalloc_pages()
The comment explaining why 4-level systems only need to allocate on
the P4D level caused some confustion. Update it to better explain why
on 4-level systems the allocation on PUD level is necessary.
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200814151947.26229-3-joro@8bytes.org
Diffstat (limited to 'arch/x86/mm/init_64.c')
| -rw-r--r-- | arch/x86/mm/init_64.c | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index 777d83546764..b5a3fa4033d3 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -1252,14 +1252,19 @@ static void __init preallocate_vmalloc_pages(void) if (!p4d) goto failed; - /* - * With 5-level paging the P4D level is not folded. So the PGDs - * are now populated and there is no need to walk down to the - * PUD level. - */ if (pgtable_l5_enabled()) continue; + /* + * The goal here is to allocate all possibly required + * hardware page tables pointed to by the top hardware + * level. + * + * On 4-level systems, the P4D layer is folded away and + * the above code does no preallocation. Below, go down + * to the pud _software_ level to ensure the second + * hardware level is allocated on 4-level systems too. + */ lvl = "pud"; pud = pud_alloc(&init_mm, p4d, addr); if (!pud) |