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authorKees Cook <keescook@chromium.org>2018-08-21 21:53:10 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-08-22 10:52:44 -0700
commit8c9a134cae6f8d66f35321b07baa202f75ef2199 (patch)
tree904ddde917ef7f993e5e1031a0ddfe03632870f7 /mm
parenta670468f5e0b5fad4db6e4d195f15915dc2a35c1 (diff)
downloadlinux-stericsson-8c9a134cae6f8d66f35321b07baa202f75ef2199.tar.gz
mm: clarify CONFIG_PAGE_POISONING and usage
The Kconfig text for CONFIG_PAGE_POISONING doesn't mention that it has to be enabled explicitly. This updates the documentation for that and adds a note about CONFIG_PAGE_POISONING to the "page_poison" command line docs. While here, change description of CONFIG_PAGE_POISONING_ZERO too, as it's not "random" data, but rather the fixed debugging value that would be used when not zeroing. Additionally removes a stray "bool" in the Kconfig. Link: http://lkml.kernel.org/r/20180725223832.GA43733@beast Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Laura Abbott <labbott@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/Kconfig.debug6
1 files changed, 3 insertions, 3 deletions
diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug
index e5e606ee5f71..9a7b8b049d04 100644
--- a/mm/Kconfig.debug
+++ b/mm/Kconfig.debug
@@ -46,7 +46,8 @@ config PAGE_POISONING
Fill the pages with poison patterns after free_pages() and verify
the patterns before alloc_pages. The filling of the memory helps
reduce the risk of information leaks from freed data. This does
- have a potential performance impact.
+ have a potential performance impact if enabled with the
+ "page_poison=1" kernel boot option.
Note that "poison" here is not the same thing as the "HWPoison"
for CONFIG_MEMORY_FAILURE. This is software poisoning only.
@@ -65,7 +66,7 @@ config PAGE_POISONING_NO_SANITY
say N.
config PAGE_POISONING_ZERO
- bool "Use zero for poisoning instead of random data"
+ bool "Use zero for poisoning instead of debugging value"
depends on PAGE_POISONING
---help---
Instead of using the existing poison value, fill the pages with
@@ -75,7 +76,6 @@ config PAGE_POISONING_ZERO
allocation.
If unsure, say N
- bool
config DEBUG_PAGE_REF
bool "Enable tracepoint to track down page reference manipulation"