Re: [PATCH v13 06/14] mm: HUGE_VMAP arch support cleanup

Le 28/04/2021 à 10:32, Christophe Leroy a écrit :

Le 17/03/2021 à 07:23, Nicholas Piggin a écrit :

quoted

This changes the awkward approach where architectures provide init
functions to determine which levels they can provide large mappings for,
to one where the arch is queried for each call.

This removes code and indirection, and allows constant-folding of dead
code for unsupported levels.

This also adds a prot argument to the arch query. This is unused
currently but could help with some architectures (e.g., some powerpc
processors can't map uncacheable memory with large pages).

Cc: linuxppc-dev@lists.ozlabs.org
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Thomas Gleixner <redacted>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: x86@kernel.org
Cc: "H. Peter Anvin" <hpa@zytor.com>
Reviewed-by: Ding Tianhong <redacted>
Acked-by: Catalin Marinas <catalin.marinas@arm.com> [arm64]
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
  arch/arm64/include/asm/vmalloc.h         |  8 ++
  arch/arm64/mm/mmu.c                      | 10 +--
  arch/powerpc/include/asm/vmalloc.h       |  8 ++
  arch/powerpc/mm/book3s64/radix_pgtable.c |  8 +-
  arch/x86/include/asm/vmalloc.h           |  7 ++
  arch/x86/mm/ioremap.c                    | 12 +--
  include/linux/io.h                       |  9 ---
  include/linux/vmalloc.h                  |  6 ++
  init/main.c                              |  1 -
  mm/debug_vm_pgtable.c                    |  4 +-
  mm/ioremap.c                             | 94 ++++++++++--------------
  11 files changed, 87 insertions(+), 80 deletions(-)

quoted

diff --git a/mm/ioremap.c b/mm/ioremap.c
index 3f4d36f9745a..3264d0203785 100644
--- a/mm/ioremap.c
+++ b/mm/ioremap.c

@@ -16,49 +16,16 @@

  #include "pgalloc-track.h"
  #ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
-static int __read_mostly ioremap_p4d_capable;
-static int __read_mostly ioremap_pud_capable;
-static int __read_mostly ioremap_pmd_capable;
-static int __read_mostly ioremap_huge_disabled;
+static bool __ro_after_init iomap_max_page_shift = PAGE_SHIFT;

Must be an int, not a bool.

And the initial value seems wrong. Should be P4D_SHIFT ?

quoted

  static int __init set_nohugeiomap(char *str)
  {
-    ioremap_huge_disabled = 1;
+    iomap_max_page_shift = P4D_SHIFT;

And PAGE_SHIFT here when NO hugeiomap ?

quoted

      return 0;
  }
  early_param("nohugeiomap", set_nohugeiomap);

Christophe

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