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authorSteven Price <steven.price@arm.com>2020-04-06 20:08:43 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-04-07 10:43:41 -0700
commit3f3673d7d324d872d9d8ddb73b3e5e47fbf12e0d (patch)
treea47842c1923bef662142c16fdf2446af46f3bd10
parente4a9bc58969abc695a6ebb06d801a99c1bafc001 (diff)
downloadlinux-3f3673d7d324d872d9d8ddb73b3e5e47fbf12e0d.tar.bz2
include/linux/swapops.h: correct guards for non_swap_entry()
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>
-rw-r--r--include/linux/swapops.h3
1 files changed, 2 insertions, 1 deletions
diff --git a/include/linux/swapops.h b/include/linux/swapops.h
index 9a6f06de183b..d9b7c9132c2f 100644
--- a/include/linux/swapops.h
+++ b/include/linux/swapops.h
@@ -350,7 +350,8 @@ 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;