blob: 1eb45ff1028f5ab32391d7d6340554fb797d0687 [file] [log] [blame]
From e352ba4598aa735efd06d448bb90617a5e2ce951 Mon Sep 17 00:00:00 2001
From: Steven Price <steven.price@arm.com>
Date: Mon, 6 Apr 2020 20:08:43 -0700
Subject: [PATCH] include/linux/swapops.h: correct guards for non_swap_entry()
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commit 3f3673d7d324d872d9d8ddb73b3e5e47fbf12e0d upstream.
If CONFIG_DEVICE_PRIVATE is defined, but neither CONFIG_MEMORY_FAILURE nor
CONFIG_MIGRATION, then non_swap_entry() will return 0, meaning that the
condition (non_swap_entry(entry) && is_device_private_entry(entry)) in
zap_pte_range() will never be true even if the entry is a device private
one.
Equally any other code depending on non_swap_entry() will not function as
expected.
I originally spotted this just by looking at the code, I haven't actually
observed any problems.
Looking a bit more closely it appears that actually this situation
(currently at least) cannot occur:
DEVICE_PRIVATE depends on ZONE_DEVICE
ZONE_DEVICE depends on MEMORY_HOTREMOVE
MEMORY_HOTREMOVE depends on MIGRATION
Fixes: 5042db43cc26 ("mm/ZONE_DEVICE: new type of ZONE_DEVICE for unaddressable memory")
Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Link: http://lkml.kernel.org/r/20200305130550.22693-1-steven.price@arm.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/include/linux/swapops.h b/include/linux/swapops.h
index 4d961668e5fc..8ca162c7c4c4 100644
--- a/include/linux/swapops.h
+++ b/include/linux/swapops.h
@@ -363,7 +363,8 @@ static inline void num_poisoned_pages_inc(void)
}
#endif
-#if defined(CONFIG_MEMORY_FAILURE) || defined(CONFIG_MIGRATION)
+#if defined(CONFIG_MEMORY_FAILURE) || defined(CONFIG_MIGRATION) || \
+ defined(CONFIG_DEVICE_PRIVATE)
static inline int non_swap_entry(swp_entry_t entry)
{
return swp_type(entry) >= MAX_SWAPFILES;
--
2.7.4