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authorCatalin Marinas <catalin.marinas@arm.com>2022-11-04 04:10:34 +0300
committerMarc Zyngier <maz@kernel.org>2022-11-29 12:26:06 +0300
commitb0284cd29a957e62d60c2886fd663be93c56f9c0 (patch)
tree2b17fdf221c44da29cbc1951a9f46be1f1cafa8f /mm/Kconfig
parent30a0b95b1335e12efef89dd78518ed3e4a71a763 (diff)
downloadlinux-b0284cd29a957e62d60c2886fd663be93c56f9c0.tar.xz
mm: Do not enable PG_arch_2 for all 64-bit architectures
Commit 4beba9486abd ("mm: Add PG_arch_2 page flag") introduced a new page flag for all 64-bit architectures. However, even if an architecture is 64-bit, it may still have limited spare bits in the 'flags' member of 'struct page'. This may happen if an architecture enables SPARSEMEM without SPARSEMEM_VMEMMAP as is the case with the newly added loongarch. This architecture port needs 19 more bits for the sparsemem section information and, while it is currently fine with PG_arch_2, adding any more PG_arch_* flags will trigger build-time warnings. Add a new CONFIG_ARCH_USES_PG_ARCH_X option which can be selected by architectures that need more PG_arch_* flags beyond PG_arch_1. Select it on arm64. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> [pcc@google.com: fix build with CONFIG_ARM64_MTE disabled] Signed-off-by: Peter Collingbourne <pcc@google.com> Reported-by: kernel test robot <lkp@intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Steven Price <steven.price@arm.com> Reviewed-by: Steven Price <steven.price@arm.com> Signed-off-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20221104011041.290951-2-pcc@google.com
Diffstat (limited to 'mm/Kconfig')
-rw-r--r--mm/Kconfig8
1 files changed, 8 insertions, 0 deletions
diff --git a/mm/Kconfig b/mm/Kconfig
index 57e1d8c5b505..807bd7192f51 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -1005,6 +1005,14 @@ config ARCH_USES_HIGH_VMA_FLAGS
config ARCH_HAS_PKEYS
bool
+config ARCH_USES_PG_ARCH_X
+ bool
+ help
+ Enable the definition of PG_arch_x page flags with x > 1. Only
+ suitable for 64-bit architectures with CONFIG_FLATMEM or
+ CONFIG_SPARSEMEM_VMEMMAP enabled, otherwise there may not be
+ enough room for additional bits in page->flags.
+
config VM_EVENT_COUNTERS
default y
bool "Enable VM event counters for /proc/vmstat" if EXPERT