diff options
author | Vlastimil Babka <vbabka@suse.cz> | 2020-12-14 19:13:30 -0800 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-12-15 12:13:46 -0800 |
commit | 04013513cc84c401c7de9023ff3eda7863fc4add (patch) | |
tree | e5bfc849020ba667fd4595aa431fa2c97d90afb2 /include | |
parent | b8ca396f984295ba09f25f6982f9abd0bb7f5a29 (diff) |
mm, page_alloc: do not rely on the order of page_poison and init_on_alloc/free parameters
Patch series "cleanup page poisoning", v3.
I have identified a number of issues and opportunities for cleanup with
CONFIG_PAGE_POISON and friends:
- interaction with init_on_alloc and init_on_free parameters depends on
the order of parameters (Patch 1)
- the boot time enabling uses static key, but inefficienty (Patch 2)
- sanity checking is incompatible with hibernation (Patch 3)
- CONFIG_PAGE_POISONING_NO_SANITY can be removed now that we have
init_on_free (Patch 4)
- CONFIG_PAGE_POISONING_ZERO can be most likely removed now that we
have init_on_free (Patch 5)
This patch (of 5):
Enabling page_poison=1 together with init_on_alloc=1 or init_on_free=1
produces a warning in dmesg that page_poison takes precedence. However,
as these warnings are printed in early_param handlers for
init_on_alloc/free, they are not printed if page_poison is enabled later
on the command line (handlers are called in the order of their
parameters), or when init_on_alloc/free is always enabled by the
respective config option - before the page_poison early param handler is
called, it is not considered to be enabled. This is inconsistent.
We can remove the dependency on order by making the init_on_* parameters
only set a boolean variable, and postponing the evaluation after all early
params have been processed. Introduce a new
init_mem_debugging_and_hardening() function for that, and move the related
debug_pagealloc processing there as well.
As a result init_mem_debugging_and_hardening() knows always accurately if
init_on_* and/or page_poison options were enabled. Thus we can also
optimize want_init_on_alloc() and want_init_on_free(). We don't need to
check page_poisoning_enabled() there, we can instead not enable the
init_on_* static keys at all, if page poisoning is enabled. This results
in a simpler and more effective code.
Link: https://lkml.kernel.org/r/20201113104033.22907-1-vbabka@suse.cz
Link: https://lkml.kernel.org/r/20201113104033.22907-2-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mateusz Nosek <mateusznosek0@gmail.com>
Cc: Laura Abbott <labbott@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r-- | include/linux/mm.h | 20 |
1 files changed, 3 insertions, 17 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h index 5ec79757eeae..591c784277ea 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2872,6 +2872,7 @@ extern int apply_to_existing_page_range(struct mm_struct *mm, unsigned long address, unsigned long size, pte_fn_t fn, void *data); +extern void init_mem_debugging_and_hardening(void); #ifdef CONFIG_PAGE_POISONING extern bool page_poisoning_enabled(void); extern void kernel_poison_pages(struct page *page, int numpages, int enable); @@ -2881,35 +2882,20 @@ static inline void kernel_poison_pages(struct page *page, int numpages, int enable) { } #endif -#ifdef CONFIG_INIT_ON_ALLOC_DEFAULT_ON -DECLARE_STATIC_KEY_TRUE(init_on_alloc); -#else DECLARE_STATIC_KEY_FALSE(init_on_alloc); -#endif static inline bool want_init_on_alloc(gfp_t flags) { - if (static_branch_unlikely(&init_on_alloc) && - !page_poisoning_enabled()) + if (static_branch_unlikely(&init_on_alloc)) return true; return flags & __GFP_ZERO; } -#ifdef CONFIG_INIT_ON_FREE_DEFAULT_ON -DECLARE_STATIC_KEY_TRUE(init_on_free); -#else DECLARE_STATIC_KEY_FALSE(init_on_free); -#endif static inline bool want_init_on_free(void) { - return static_branch_unlikely(&init_on_free) && - !page_poisoning_enabled(); + return static_branch_unlikely(&init_on_free); } -#ifdef CONFIG_DEBUG_PAGEALLOC -extern void init_debug_pagealloc(void); -#else -static inline void init_debug_pagealloc(void) {} -#endif extern bool _debug_pagealloc_enabled_early; DECLARE_STATIC_KEY_FALSE(_debug_pagealloc_enabled); |