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author | Vlastimil Babka <vbabka@suse.cz> | 2020-12-14 19:13:30 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-12-15 12:13:46 -0800 |
commit | 04013513cc84c401c7de9023ff3eda7863fc4add (patch) | |
tree | e5bfc849020ba667fd4595aa431fa2c97d90afb2 | |
parent | b8ca396f984295ba09f25f6982f9abd0bb7f5a29 (diff) | |
download | linux-stable-04013513cc84c401c7de9023ff3eda7863fc4add.tar.gz linux-stable-04013513cc84c401c7de9023ff3eda7863fc4add.tar.bz2 linux-stable-04013513cc84c401c7de9023ff3eda7863fc4add.zip |
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>
-rw-r--r-- | include/linux/mm.h | 20 | ||||
-rw-r--r-- | init/main.c | 2 | ||||
-rw-r--r-- | mm/page_alloc.c | 88 |
3 files changed, 46 insertions, 64 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); diff --git a/init/main.c b/init/main.c index 404366e1a64d..3024c4db17a9 100644 --- a/init/main.c +++ b/init/main.c @@ -824,7 +824,7 @@ static void __init mm_init(void) * bigger than MAX_ORDER unless SPARSEMEM. */ page_ext_init_flatmem(); - init_debug_pagealloc(); + init_mem_debugging_and_hardening(); report_meminit(); mem_init(); /* page_owner must be initialized after buddy is ready */ diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 521d29718c9e..3fd0c8d5745f 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -167,53 +167,26 @@ unsigned long totalcma_pages __read_mostly; int percpu_pagelist_fraction; gfp_t gfp_allowed_mask __read_mostly = GFP_BOOT_MASK; -#ifdef CONFIG_INIT_ON_ALLOC_DEFAULT_ON -DEFINE_STATIC_KEY_TRUE(init_on_alloc); -#else DEFINE_STATIC_KEY_FALSE(init_on_alloc); -#endif EXPORT_SYMBOL(init_on_alloc); -#ifdef CONFIG_INIT_ON_FREE_DEFAULT_ON -DEFINE_STATIC_KEY_TRUE(init_on_free); -#else DEFINE_STATIC_KEY_FALSE(init_on_free); -#endif EXPORT_SYMBOL(init_on_free); +static bool _init_on_alloc_enabled_early __read_mostly + = IS_ENABLED(CONFIG_INIT_ON_ALLOC_DEFAULT_ON); static int __init early_init_on_alloc(char *buf) { - int ret; - bool bool_result; - ret = kstrtobool(buf, &bool_result); - if (ret) - return ret; - if (bool_result && page_poisoning_enabled()) - pr_info("mem auto-init: CONFIG_PAGE_POISONING is on, will take precedence over init_on_alloc\n"); - if (bool_result) - static_branch_enable(&init_on_alloc); - else - static_branch_disable(&init_on_alloc); - return 0; + return kstrtobool(buf, &_init_on_alloc_enabled_early); } early_param("init_on_alloc", early_init_on_alloc); +static bool _init_on_free_enabled_early __read_mostly + = IS_ENABLED(CONFIG_INIT_ON_FREE_DEFAULT_ON); static int __init early_init_on_free(char *buf) { - int ret; - bool bool_result; - - ret = kstrtobool(buf, &bool_result); - if (ret) - return ret; - if (bool_result && page_poisoning_enabled()) - pr_info("mem auto-init: CONFIG_PAGE_POISONING is on, will take precedence over init_on_free\n"); - if (bool_result) - static_branch_enable(&init_on_free); - else - static_branch_disable(&init_on_free); - return 0; + return kstrtobool(buf, &_init_on_free_enabled_early); } early_param("init_on_free", early_init_on_free); @@ -730,19 +703,6 @@ static int __init early_debug_pagealloc(char *buf) } early_param("debug_pagealloc", early_debug_pagealloc); -void init_debug_pagealloc(void) -{ - if (!debug_pagealloc_enabled()) - return; - - static_branch_enable(&_debug_pagealloc_enabled); - - if (!debug_guardpage_minorder()) - return; - - static_branch_enable(&_debug_guardpage_enabled); -} - static int __init debug_guardpage_minorder_setup(char *buf) { unsigned long res; @@ -794,6 +754,42 @@ static inline void clear_page_guard(struct zone *zone, struct page *page, unsigned int order, int migratetype) {} #endif +/* + * Enable static keys related to various memory debugging and hardening options. + * Some override others, and depend on early params that are evaluated in the + * order of appearance. So we need to first gather the full picture of what was + * enabled, and then make decisions. + */ +void init_mem_debugging_and_hardening(void) +{ + if (_init_on_alloc_enabled_early) { + if (page_poisoning_enabled()) + pr_info("mem auto-init: CONFIG_PAGE_POISONING is on, " + "will take precedence over init_on_alloc\n"); + else + static_branch_enable(&init_on_alloc); + } + if (_init_on_free_enabled_early) { + if (page_poisoning_enabled()) + pr_info("mem auto-init: CONFIG_PAGE_POISONING is on, " + "will take precedence over init_on_free\n"); + else + static_branch_enable(&init_on_free); + } + +#ifdef CONFIG_DEBUG_PAGEALLOC + if (!debug_pagealloc_enabled()) + return; + + static_branch_enable(&_debug_pagealloc_enabled); + + if (!debug_guardpage_minorder()) + return; + + static_branch_enable(&_debug_guardpage_enabled); +#endif +} + static inline void set_buddy_order(struct page *page, unsigned int order) { set_page_private(page, order); |