Commit 04013513 authored by Vlastimil Babka's avatar Vlastimil Babka Committed by Linus Torvalds

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.czSigned-off-by: default avatarVlastimil Babka <vbabka@suse.cz>
Reviewed-by: default avatarDavid Hildenbrand <david@redhat.com>
Reviewed-by: default avatarMike 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b8ca396f
...@@ -2872,6 +2872,7 @@ extern int apply_to_existing_page_range(struct mm_struct *mm, ...@@ -2872,6 +2872,7 @@ extern int apply_to_existing_page_range(struct mm_struct *mm,
unsigned long address, unsigned long size, unsigned long address, unsigned long size,
pte_fn_t fn, void *data); pte_fn_t fn, void *data);
extern void init_mem_debugging_and_hardening(void);
#ifdef CONFIG_PAGE_POISONING #ifdef CONFIG_PAGE_POISONING
extern bool page_poisoning_enabled(void); extern bool page_poisoning_enabled(void);
extern void kernel_poison_pages(struct page *page, int numpages, int enable); 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, ...@@ -2881,35 +2882,20 @@ static inline void kernel_poison_pages(struct page *page, int numpages,
int enable) { } int enable) { }
#endif #endif
#ifdef CONFIG_INIT_ON_ALLOC_DEFAULT_ON
DECLARE_STATIC_KEY_TRUE(init_on_alloc);
#else
DECLARE_STATIC_KEY_FALSE(init_on_alloc); DECLARE_STATIC_KEY_FALSE(init_on_alloc);
#endif
static inline bool want_init_on_alloc(gfp_t flags) static inline bool want_init_on_alloc(gfp_t flags)
{ {
if (static_branch_unlikely(&init_on_alloc) && if (static_branch_unlikely(&init_on_alloc))
!page_poisoning_enabled())
return true; return true;
return flags & __GFP_ZERO; 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); DECLARE_STATIC_KEY_FALSE(init_on_free);
#endif
static inline bool want_init_on_free(void) static inline bool want_init_on_free(void)
{ {
return static_branch_unlikely(&init_on_free) && return static_branch_unlikely(&init_on_free);
!page_poisoning_enabled();
} }
#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; extern bool _debug_pagealloc_enabled_early;
DECLARE_STATIC_KEY_FALSE(_debug_pagealloc_enabled); DECLARE_STATIC_KEY_FALSE(_debug_pagealloc_enabled);
......
...@@ -824,7 +824,7 @@ static void __init mm_init(void) ...@@ -824,7 +824,7 @@ static void __init mm_init(void)
* bigger than MAX_ORDER unless SPARSEMEM. * bigger than MAX_ORDER unless SPARSEMEM.
*/ */
page_ext_init_flatmem(); page_ext_init_flatmem();
init_debug_pagealloc(); init_mem_debugging_and_hardening();
report_meminit(); report_meminit();
mem_init(); mem_init();
/* page_owner must be initialized after buddy is ready */ /* page_owner must be initialized after buddy is ready */
......
...@@ -167,53 +167,26 @@ unsigned long totalcma_pages __read_mostly; ...@@ -167,53 +167,26 @@ unsigned long totalcma_pages __read_mostly;
int percpu_pagelist_fraction; int percpu_pagelist_fraction;
gfp_t gfp_allowed_mask __read_mostly = GFP_BOOT_MASK; 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); DEFINE_STATIC_KEY_FALSE(init_on_alloc);
#endif
EXPORT_SYMBOL(init_on_alloc); 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); DEFINE_STATIC_KEY_FALSE(init_on_free);
#endif
EXPORT_SYMBOL(init_on_free); 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) static int __init early_init_on_alloc(char *buf)
{ {
int ret;
bool bool_result;
ret = kstrtobool(buf, &bool_result); return kstrtobool(buf, &_init_on_alloc_enabled_early);
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;
} }
early_param("init_on_alloc", early_init_on_alloc); 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) static int __init early_init_on_free(char *buf)
{ {
int ret; return kstrtobool(buf, &_init_on_free_enabled_early);
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;
} }
early_param("init_on_free", early_init_on_free); early_param("init_on_free", early_init_on_free);
...@@ -730,19 +703,6 @@ static int __init early_debug_pagealloc(char *buf) ...@@ -730,19 +703,6 @@ static int __init early_debug_pagealloc(char *buf)
} }
early_param("debug_pagealloc", early_debug_pagealloc); 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) static int __init debug_guardpage_minorder_setup(char *buf)
{ {
unsigned long res; unsigned long res;
...@@ -794,6 +754,42 @@ static inline void clear_page_guard(struct zone *zone, struct page *page, ...@@ -794,6 +754,42 @@ static inline void clear_page_guard(struct zone *zone, struct page *page,
unsigned int order, int migratetype) {} unsigned int order, int migratetype) {}
#endif #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) static inline void set_buddy_order(struct page *page, unsigned int order)
{ {
set_page_private(page, order); set_page_private(page, order);
......
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