path: root/mm/Kconfig.debug
diff options
authorVlastimil Babka <>2020-12-14 19:13:41 -0800
committerLinus Torvalds <>2020-12-15 12:13:46 -0800
commit8f424750baaafcef229791882e879da01c9473b5 (patch)
tree01453fbaf9e238df6de2d898a4490e01ab2d986c /mm/Kconfig.debug
parent03b6c9a3e8805606c0bb4ad41855fac3bf85c3b9 (diff)
mm, page_poison: remove CONFIG_PAGE_POISONING_NO_SANITY
CONFIG_PAGE_POISONING_NO_SANITY skips the check on page alloc whether the poison pattern was corrupted, suggesting a use-after-free. The motivation to introduce it in commit 8823b1dbc05f ("mm/page_poison.c: enable PAGE_POISONING as a separate option") was to simply sanitize freed pages, optimally together with CONFIG_PAGE_POISONING_ZERO. These days we have an init_on_free=1 boot option, which makes this use case of page poisoning redundant. For sanitizing, writing zeroes is sufficient, there is pretty much no benefit from writing the 0xAA poison pattern to freed pages, without checking it back on alloc. Thus, remove this option and suggest init_on_free instead in the main config's help. Link: Signed-off-by: Vlastimil Babka <> Acked-by: David Hildenbrand <> Cc: Mike Rapoport <> Cc: Rafael J. Wysocki <> Cc: Alexander Potapenko <> Cc: Kees Cook <> Cc: Laura Abbott <> Cc: Mateusz Nosek <> Cc: Michal Hocko <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'mm/Kconfig.debug')
1 files changed, 4 insertions, 11 deletions
diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug
index c57786ad5be9..14e29fe5bfa6 100644
--- a/mm/Kconfig.debug
+++ b/mm/Kconfig.debug
@@ -74,18 +74,11 @@ config PAGE_POISONING
Note that "poison" here is not the same thing as the "HWPoison"
for CONFIG_MEMORY_FAILURE. This is software poisoning only.
- If unsure, say N
+ If you are only interested in sanitization of freed pages without
+ checking the poison pattern on alloc, you can boot the kernel with
+ "init_on_free=1" instead of enabling this.
- depends on PAGE_POISONING
- bool "Only poison, don't sanity check"
- help
- Skip the sanity checking on alloc, only fill the pages with
- poison on free. This reduces some of the overhead of the
- poisoning feature.
- If you are only interested in sanitization, say Y. Otherwise
- say N.
+ If unsure, say N
bool "Use zero for poisoning instead of debugging value"