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| author | Kees Cook <keescook@chromium.org> | 2018-08-22 07:53:10 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-08-22 20:52:44 +0300 |
| commit | 8c9a134cae6f8d66f35321b07baa202f75ef2199 (patch) | |
| tree | 904ddde917ef7f993e5e1031a0ddfe03632870f7 | |
| parent | a670468f5e0b5fad4db6e4d195f15915dc2a35c1 (diff) | |
| download | linux-8c9a134cae6f8d66f35321b07baa202f75ef2199.tar.xz | |
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>
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 5 | ||||
| -rw-r--r-- | mm/Kconfig.debug | 6 |
2 files changed, 6 insertions, 5 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index bffb0caa3693..970d837bd57f 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3041,8 +3041,9 @@ on: enable the feature page_poison= [KNL] Boot-time parameter changing the state of - poisoning on the buddy allocator. - off: turn off poisoning + poisoning on the buddy allocator, available with + CONFIG_PAGE_POISONING=y. + off: turn off poisoning (default) on: turn on poisoning panic= [KNL] Kernel behaviour on panic: delay <timeout> 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" |