The patch titled
Subject: mm, page_alloc: do not rely on the order of page_poison and init_on_alloc/free parameters
has been removed from the -mm tree. Its filename was
mm-page_alloc-do-not-rely-on-the-order-of-page_poison-and-init_on_alloc-free-parameters.patch
This patch was dropped because an updated version will be merged
------------------------------------------------------
From: Vlastimil Babka <vbabka@xxxxxxx>
Subject: mm, page_alloc: do not rely on the order of page_poison and init_on_alloc/free parameters
Patch series "cleanup page poisoning", v2.
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/20201103152237.9853-1-vbabka@xxxxxxx
Link: https://lkml.kernel.org/r/20201103152237.9853-2-vbabka@xxxxxxx
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Mateusz Nosek <mateusznosek0@xxxxxxxxx>
Cc: Laura Abbott <labbott@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Len Brown <len.brown@xxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Cc: Pavel Machek <pavel@xxxxxx>
Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
Cc: Akinobu Mita <akinobu.mita@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mm.h | 20 +--------
init/main.c | 2
mm/page_alloc.c | 88 ++++++++++++++++++++-----------------------
3 files changed, 46 insertions(+), 64 deletions(-)
--- a/include/linux/mm.h~mm-page_alloc-do-not-rely-on-the-order-of-page_poison-and-init_on_alloc-free-parameters
+++ a/include/linux/mm.h
@@ -2850,6 +2850,7 @@ extern int apply_to_existing_page_range(
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);
@@ -2859,35 +2860,20 @@ static inline void kernel_poison_pages(s
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);
--- a/init/main.c~mm-page_alloc-do-not-rely-on-the-order-of-page_poison-and-init_on_alloc-free-parameters
+++ a/init/main.c
@@ -815,7 +815,7 @@ 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 */
--- a/mm/page_alloc.c~mm-page_alloc-do-not-rely-on-the-order-of-page_poison-and-init_on_alloc-free-parameters
+++ a/mm/page_alloc.c
@@ -165,53 +165,26 @@ unsigned long totalcma_pages __read_most
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);
@@ -728,19 +701,6 @@ static int __init 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)
{
unsigned long res;
@@ -792,6 +752,42 @@ static inline void clear_page_guard(stru
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);
_
Patches currently in -mm which might be from vbabka@xxxxxxx are
mm-slub-use-kmem_cache_debug_flags-in-deactivate_slab.patch
mm-page_poison-use-static-key-more-efficiently.patch
kernel-power-allow-hibernation-with-page_poison-sanity-checking.patch
mm-page_poison-remove-config_page_poisoning_no_sanity.patch
mm-page_poison-remove-config_page_poisoning_zero.patch
