Date:   Wed, 15 Feb 2023 21:17:24 -0800
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Subject: [PATCH v3 09/35] mm: introduce CONFIG_PER_VMA_LOCK
From:   Suren Baghdasaryan <surenb@google.com>
To:     akpm@linux-foundation.org
Cc:     michel@lespinasse.org, jglisse@google.com, mhocko@suse.com,
        vbabka@suse.cz, hannes@cmpxchg.org, mgorman@techsingularity.net,
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        michalechner92@googlemail.com, linux-mm@kvack.org,
        linux-arm-kernel@lists.infradead.org,
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        Suren Baghdasaryan <surenb@google.com>
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This configuration variable will be used to build the support for VMA
locking during page fault handling.

This is enabled 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 | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/mm/Kconfig b/mm/Kconfig
index ca98b2072df5..2e4a7e61768a 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -1211,6 +1211,18 @@ 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
+	def_bool 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
-- 
2.39.1