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Date:   Mon,  9 Jan 2023 12:53:03 -0800
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Subject: [PATCH 08/41] mm: introduce CONFIG_PER_VMA_LOCK
From:   Suren Baghdasaryan <surenb@google.com>
To:     akpm@linux-foundation.org
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This configuration variable will be used to build the support for VMA
locking during page fault handling.

This is enabled by default on supported architectures with SMP and MMU
set.

The architecture support is needed since the page fault handler is called
from the architecture's page faulting code which needs modifications to
handle faults under VMA lock.

Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
 mm/Kconfig | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/mm/Kconfig b/mm/Kconfig
index ff7b209dec05..0aeca3794972 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -1183,6 +1183,19 @@ config LRU_GEN_STATS
 	  This option has a per-memcg and per-node memory overhead.
 # }
 
+config ARCH_SUPPORTS_PER_VMA_LOCK
+       def_bool n
+
+config PER_VMA_LOCK
+	bool "Per-vma locking support"
+	default y
+	depends on ARCH_SUPPORTS_PER_VMA_LOCK && MMU && SMP
+	help
+	  Allow per-vma locking during page fault handling.
+
+	  This feature allows locking each virtual memory area separately when
+	  handling page faults instead of taking mmap_lock.
+
 source "mm/damon/Kconfig"
 
 endmenu
-- 
2.39.0