mm: make minimum slab alignment a runtime property

PATCH In review Peter Collingbourne 6 participants 7 messages Apr 22, 2022 – Apr 26, 2022

Subsystems (4)

Memory management arm64 Slab allocator Printk

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Peter Collingbourne

author

2022-04-22 20:18 UTC #0 lore raw

PATCH v3 1/1 mm: make minimum slab alignment a runtime property

When CONFIG_KASAN_HW_TAGS is enabled we currently increase the minimum slab alignment to 16. This happens even if MTE is not supported in hardware or disabled via kasan=off, which creates an unnecessary memory overhead in those cases. Eliminate this overhead by making the minimum slab alignment a runtime property and only aligning to 16 if KASAN is enabled at runtime.

On a DragonBoard 845c (non-MTE hardware) with a kernel built with CONFIG_KASAN_HW_TAGS, waiting for quiescence after a full Android boot I see the following Slab measurements in /proc/meminfo (median of 3 reboots):

Before: 169020 kB
After:  167304 kB

Link https://linux-review.googlesource.com/id/I752e725179b43b144153f4b6f584ceb646473ead

Signed-off-by Peter Collingbourne <[email protected]>

Reviewed-by Andrey Konovalov <[email protected]>

---
v3:
- go back to ARCH_SLAB_MINALIGN
- revert changes to fs/binfmt_flat.c
- update arch_slab_minalign() comment to say that it must be a power of two

v2:
- use max instead of max_t in flat_stack_align()

 arch/arm64/include/asm/cache.h | 17 ++++++++++++-----
 include/linux/slab.h           | 12 ++++++++++++
 mm/slab.c                      |  7 +++----
 mm/slab_common.c               |  3 +--
 mm/slob.c                      |  6 +++---
 5 files changed, 31 insertions(+), 14 deletions(-)

arch/arm64/include/asm/cache.h +12 -5

index a074459f8f2f..22b22dc1b1b5 100644
@@ -6,6 +6,7 @@
 #define __ASM_CACHE_H
 
 #include <asm/cputype.h>
+#include <asm/mte-def.h>
 
 #define CTR_L1IP_SHIFT		14
 #define CTR_L1IP_MASK		3

@@ -49,16 +50,22 @@
  */
 #define ARCH_DMA_MINALIGN	(128)
 
+#ifndef __ASSEMBLY__
+
+#include <linux/bitops.h>
+#include <linux/kasan-enabled.h>
+
 #ifdef CONFIG_KASAN_SW_TAGS
 #define ARCH_SLAB_MINALIGN	(1ULL << KASAN_SHADOW_SCALE_SHIFT)
 #elif defined(CONFIG_KASAN_HW_TAGS)
-#define ARCH_SLAB_MINALIGN	MTE_GRANULE_SIZE
+static inline size_t arch_slab_minalign(void)
+{
+	return kasan_hw_tags_enabled() ? MTE_GRANULE_SIZE :
+					 __alignof__(unsigned long long);
+}
+#define arch_slab_minalign() arch_slab_minalign()
 #endif
 
-#ifndef __ASSEMBLY__
-
-#include <linux/bitops.h>
-
 #define ICACHEF_ALIASING	0
 #define ICACHEF_VPIPT		1
 extern unsigned long __icache_flags;

include/linux/slab.h +12 -0

index 373b3ef99f4e..2c7190db4cc0 100644
@@ -209,6 +209,18 @@ void kmem_dump_obj(void *object);
 #define ARCH_SLAB_MINALIGN __alignof__(unsigned long long)
 #endif
 
+/*
+ * Arches can define this function if they want to decide the minimum slab
+ * alignment at runtime. The value returned by the function must be a power
+ * of two and >= ARCH_SLAB_MINALIGN.
+ */
+#ifndef arch_slab_minalign
+static inline size_t arch_slab_minalign(void)
+{
+	return ARCH_SLAB_MINALIGN;
+}
+#endif
+
 /*
  * kmalloc and friends return ARCH_KMALLOC_MINALIGN aligned
  * pointers. kmem_cache_alloc and friends return ARCH_SLAB_MINALIGN

mm/slab.c +3 -4

index 0edb474edef1..97b756976c8b 100644
@@ -3009,10 +3009,9 @@ static void *cache_alloc_debugcheck_after(struct kmem_cache *cachep,
 	objp += obj_offset(cachep);
 	if (cachep->ctor && cachep->flags & SLAB_POISON)
 		cachep->ctor(objp);
-	if (ARCH_SLAB_MINALIGN &&
-	    ((unsigned long)objp & (ARCH_SLAB_MINALIGN-1))) {
-		pr_err("0x%px: not aligned to ARCH_SLAB_MINALIGN=%d\n",
-		       objp, (int)ARCH_SLAB_MINALIGN);
+	if ((unsigned long)objp & (arch_slab_minalign() - 1)) {
+		pr_err("0x%px: not aligned to arch_slab_minalign()=%d\n", objp,
+		       (int)arch_slab_minalign());
 	}
 	return objp;
 }

mm/slab_common.c +1 -2

index 2b3206a2c3b5..33cc49810a54 100644
@@ -154,8 +154,7 @@ static unsigned int calculate_alignment(slab_flags_t flags,
 		align = max(align, ralign);
 	}
 
-	if (align < ARCH_SLAB_MINALIGN)
-		align = ARCH_SLAB_MINALIGN;
+	align = max_t(size_t, align, arch_slab_minalign());
 
 	return ALIGN(align, sizeof(void *));
 }

mm/slob.c +3 -3

index 40ea6e2d4ccd..3bd2669bd690 100644
@@ -478,7 +478,7 @@ static __always_inline void *
 __do_kmalloc_node(size_t size, gfp_t gfp, int node, unsigned long caller)
 {
 	unsigned int *m;
-	int minalign = max_t(size_t, ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);
+	int minalign = max_t(size_t, ARCH_KMALLOC_MINALIGN, arch_slab_minalign());
 	void *ret;
 
 	gfp &= gfp_allowed_mask;

@@ -555,7 +555,7 @@ void kfree(const void *block)
 
 	sp = virt_to_folio(block);
 	if (folio_test_slab(sp)) {
-		int align = max_t(size_t, ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);
+		int align = max_t(size_t, ARCH_KMALLOC_MINALIGN, arch_slab_minalign());
 		unsigned int *m = (unsigned int *)(block - align);
 		slob_free(m, *m + align);
 	} else {

@@ -584,7 +584,7 @@ size_t __ksize(const void *block)
 	if (unlikely(!folio_test_slab(folio)))
 		return folio_size(folio);
 
-	align = max_t(size_t, ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);
+	align = max_t(size_t, ARCH_KMALLOC_MINALIGN, arch_slab_minalign());
 	m = (unsigned int *)(block - align);
 	return SLOB_UNITS(*m) * SLOB_UNIT;
 }

Signature · 1 line

2.36.0.rc2.479.g8af0fa9b8e-goog

Hyeonggon Yoo

Reviewed-by Tested-by on v3 1/1

2022-04-24 10:46 UTC #1 lore raw

Quoted 163 lines · Peter Collingbourne

Before: 169020 kB
After:  167304 kB

Link https://linux-review.googlesource.com/id/I752e725179b43b144153f4b6f584ceb646473ead

Signed-off-by Peter Collingbourne <[email protected]>

Reviewed-by Andrey Konovalov <[email protected]>

---
v3:
- go back to ARCH_SLAB_MINALIGN
- revert changes to fs/binfmt_flat.c
- update arch_slab_minalign() comment to say that it must be a power of two

v2:
- use max instead of max_t in flat_stack_align()

 arch/arm64/include/asm/cache.h | 17 ++++++++++++-----
 include/linux/slab.h           | 12 ++++++++++++
 mm/slab.c                      |  7 +++----
 mm/slab_common.c               |  3 +--
 mm/slob.c                      |  6 +++---
 5 files changed, 31 insertions(+), 14 deletions(-)

arch/arm64/include/asm/cache.h +12 -5

index a074459f8f2f..22b22dc1b1b5 100644
@@ -6,6 +6,7 @@
 #define __ASM_CACHE_H
 
 #include <asm/cputype.h>
+#include <asm/mte-def.h>
 
 #define CTR_L1IP_SHIFT		14
 #define CTR_L1IP_MASK		3

@@ -49,16 +50,22 @@
  */
 #define ARCH_DMA_MINALIGN	(128)
 
+#ifndef __ASSEMBLY__
+
+#include <linux/bitops.h>
+#include <linux/kasan-enabled.h>
+
 #ifdef CONFIG_KASAN_SW_TAGS
 #define ARCH_SLAB_MINALIGN	(1ULL << KASAN_SHADOW_SCALE_SHIFT)
 #elif defined(CONFIG_KASAN_HW_TAGS)
-#define ARCH_SLAB_MINALIGN	MTE_GRANULE_SIZE
+static inline size_t arch_slab_minalign(void)
+{
+	return kasan_hw_tags_enabled() ? MTE_GRANULE_SIZE :
+					 __alignof__(unsigned long long);
+}
+#define arch_slab_minalign() arch_slab_minalign()
 #endif
 
-#ifndef __ASSEMBLY__
-
-#include <linux/bitops.h>
-
 #define ICACHEF_ALIASING	0
 #define ICACHEF_VPIPT		1
 extern unsigned long __icache_flags;

include/linux/slab.h +12 -0

index 373b3ef99f4e..2c7190db4cc0 100644
@@ -209,6 +209,18 @@ void kmem_dump_obj(void *object);
 #define ARCH_SLAB_MINALIGN __alignof__(unsigned long long)
 #endif
 
+/*
+ * Arches can define this function if they want to decide the minimum slab
+ * alignment at runtime. The value returned by the function must be a power
+ * of two and >= ARCH_SLAB_MINALIGN.
+ */
+#ifndef arch_slab_minalign
+static inline size_t arch_slab_minalign(void)
+{
+	return ARCH_SLAB_MINALIGN;
+}
+#endif
+
 /*
  * kmalloc and friends return ARCH_KMALLOC_MINALIGN aligned
  * pointers. kmem_cache_alloc and friends return ARCH_SLAB_MINALIGN

mm/slab.c +3 -4

index 0edb474edef1..97b756976c8b 100644
@@ -3009,10 +3009,9 @@ static void *cache_alloc_debugcheck_after(struct kmem_cache *cachep,
 	objp += obj_offset(cachep);
 	if (cachep->ctor && cachep->flags & SLAB_POISON)
 		cachep->ctor(objp);
-	if (ARCH_SLAB_MINALIGN &&
-	    ((unsigned long)objp & (ARCH_SLAB_MINALIGN-1))) {
-		pr_err("0x%px: not aligned to ARCH_SLAB_MINALIGN=%d\n",
-		       objp, (int)ARCH_SLAB_MINALIGN);
+	if ((unsigned long)objp & (arch_slab_minalign() - 1)) {
+		pr_err("0x%px: not aligned to arch_slab_minalign()=%d\n", objp,
+		       (int)arch_slab_minalign());
 	}
 	return objp;
 }

mm/slab_common.c +1 -2

index 2b3206a2c3b5..33cc49810a54 100644
@@ -154,8 +154,7 @@ static unsigned int calculate_alignment(slab_flags_t flags,
 		align = max(align, ralign);
 	}
 
-	if (align < ARCH_SLAB_MINALIGN)
-		align = ARCH_SLAB_MINALIGN;
+	align = max_t(size_t, align, arch_slab_minalign());
 
 	return ALIGN(align, sizeof(void *));
 }

mm/slob.c +3 -3

index 40ea6e2d4ccd..3bd2669bd690 100644
@@ -478,7 +478,7 @@ static __always_inline void *
 __do_kmalloc_node(size_t size, gfp_t gfp, int node, unsigned long caller)
 {
 	unsigned int *m;
-	int minalign = max_t(size_t, ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);
+	int minalign = max_t(size_t, ARCH_KMALLOC_MINALIGN, arch_slab_minalign());
 	void *ret;
 
 	gfp &= gfp_allowed_mask;

@@ -555,7 +555,7 @@ void kfree(const void *block)
 
 	sp = virt_to_folio(block);
 	if (folio_test_slab(sp)) {
-		int align = max_t(size_t, ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);
+		int align = max_t(size_t, ARCH_KMALLOC_MINALIGN, arch_slab_minalign());
 		unsigned int *m = (unsigned int *)(block - align);
 		slob_free(m, *m + align);
 	} else {

@@ -584,7 +584,7 @@ size_t __ksize(const void *block)
 	if (unlikely(!folio_test_slab(folio)))
 		return folio_size(folio);
 
-	align = max_t(size_t, ARCH_KMALLOC_MINALIGN, ARCH_SLAB_MINALIGN);
+	align = max_t(size_t, ARCH_KMALLOC_MINALIGN, arch_slab_minalign());
 	m = (unsigned int *)(block - align);
 	return SLOB_UNITS(*m) * SLOB_UNIT;
 }

Signature · 1 line

2.36.0.rc2.479.g8af0fa9b8e-goog

Looks good to me.

Reviewed-by Hyeonggon Yoo <[email protected]>

And work properly on my arm64 machine (no MTE support)

Tested-by Hyeonggon Yoo <[email protected]>

Thanks!

Signature · 2 lines

Thanks,
Hyeonggon

David Rientjes

reviewer Acked-by on v3 1/1

2022-04-24 19:15 UTC #2 lore raw

In reply to Peter Collingbourne

Quoted 12 lines · Peter Collingbourne

When CONFIG_KASAN_HW_TAGS is enabled we currently increase the minimum slab alignment to 16. This happens even if MTE is not supported in hardware or disabled via kasan=off, which creates an unnecessary memory overhead in those cases. Eliminate this overhead by making the minimum slab alignment a runtime property and only aligning to 16 if KASAN is enabled at runtime.
On a DragonBoard 845c (non-MTE hardware) with a kernel built with CONFIG_KASAN_HW_TAGS, waiting for quiescence after a full Android boot I see the following Slab measurements in /proc/meminfo (median of 3 reboots):

Quoted 6 lines

Before: 169020 kB
After:  167304 kB
Link https://linux-review.googlesource.com/id/I752e725179b43b144153f4b6f584ceb646473ead
Signed-off-by Peter Collingbourne <[email protected]>
Reviewed-by Andrey Konovalov <[email protected]>

Acked-by David Rientjes <[email protected]>

The command line options are described by Documentation/dev-tools/kasan.rst but it doesn't look like a update is necessary. I think the assumption today is that if we're using kasan=off then we aren't doing the alignment.

I do wonder why kasan=off is not at least mentioned in Documentation/admin-guide/kernel-parameters.txt and perhaps for all other kasan options point the reader to Documentation/dev-tools/kasan.rst.

kernel test robot

build bot

2022-04-25 05:13 UTC #3 lore raw

In reply to Peter Collingbourne

Thank you for the patch! Yet something to improve:

Hi Peter,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on hnaz-mm/master]

url:    https://github.com/intel-lab-lkp/linux/commits/Peter-Collingbourne/mm-make-minimum-slab-alignment-a-runtime-property/20220423-042024
base:   https://github.com/hnaz/linux-mm master
config: arm64-buildonly-randconfig-r002-20220425 (https://download.01.org/0day-ci/archive/20220425/[email protected]/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 1cddcfdc3c683b393df1a5c9063252eb60e52818)

reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross
# install arm64 cross compiling tool for clang build
# apt-get install binutils-aarch64-linux-gnu
# https://github.com/intel-lab-lkp/linux/commit/3aef97055dd4a480e05dff758164f153aaddbb49
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Peter-Collingbourne/mm-make-minimum-slab-alignment-a-runtime-property/20220423-042024 git checkout 3aef97055dd4a480e05dff758164f153aaddbb49
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm64 prepare

If you fix the issue, kindly add following tag as appropriate

Reported-by kernel test robot <[email protected]>

All errors (new ones prefixed by >>):

In file included from kernel/bounds.c:10:
In file included from include/linux/page-flags.h:10:
In file included from include/linux/bug.h:5:
In file included from arch/arm64/include/asm/bug.h:26:
In file included from include/asm-generic/bug.h:22:
In file included from include/linux/printk.h:9:
In file included from include/linux/cache.h:6:
In file included from arch/arm64/include/asm/cache.h:56:
In file included from include/linux/kasan-enabled.h:5:
In file included from include/linux/static_key.h:1:

>> include/linux/jump_label.h:285:2: error: call to undeclared function 'WARN'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
           STATIC_KEY_CHECK_USE(key);
           ^
   include/linux/jump_label.h:81:35: note: expanded from macro 'STATIC_KEY_CHECK_USE'
   #define STATIC_KEY_CHECK_USE(key) WARN(!static_key_initialized,               \
                                     ^
   include/linux/jump_label.h:291:2: error: call to undeclared function 'WARN'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
           STATIC_KEY_CHECK_USE(key);
           ^
   include/linux/jump_label.h:81:35: note: expanded from macro 'STATIC_KEY_CHECK_USE'
   #define STATIC_KEY_CHECK_USE(key) WARN(!static_key_initialized,               \
                                     ^
   include/linux/jump_label.h:313:2: error: call to undeclared function 'WARN'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
           STATIC_KEY_CHECK_USE(key);
           ^
   include/linux/jump_label.h:81:35: note: expanded from macro 'STATIC_KEY_CHECK_USE'
   #define STATIC_KEY_CHECK_USE(key) WARN(!static_key_initialized,               \
                                     ^
>> include/linux/jump_label.h:316:3: error: call to undeclared function 'WARN_ON_ONCE'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
                   WARN_ON_ONCE(atomic_read(&key->enabled) != 1);
                   ^
   include/linux/jump_label.h:324:2: error: call to undeclared function 'WARN'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
           STATIC_KEY_CHECK_USE(key);
           ^
   include/linux/jump_label.h:81:35: note: expanded from macro 'STATIC_KEY_CHECK_USE'
   #define STATIC_KEY_CHECK_USE(key) WARN(!static_key_initialized,               \
                                     ^
   include/linux/jump_label.h:327:3: error: call to undeclared function 'WARN_ON_ONCE'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
                   WARN_ON_ONCE(atomic_read(&key->enabled) != 0);
                   ^

6 errors generated.
make[2]: *** [scripts/Makefile.build:122: kernel/bounds.s] Error 1 make[2]: Target '__build' not remade because of errors. make[1]: *** [Makefile:1283: prepare0] Error 2
make[1]: Target 'prepare' not remade because of errors.
make: *** [Makefile:226: __sub-make] Error 2
make: Target 'prepare' not remade because of errors.

vim +/WARN +285 include/linux/jump_label.h

bf5438fca2950b Jason Baron     2010-09-17  282  
c5905afb0ee655 Ingo Molnar     2012-02-24  283  static inline void static_key_slow_inc(struct static_key *key)
d430d3d7e646eb Jason Baron     2011-03-16  284  {
5cdda5117e125e Borislav Petkov 2017-10-18 @285  	STATIC_KEY_CHECK_USE(key);
d430d3d7e646eb Jason Baron     2011-03-16  286  	atomic_inc(&key->enabled);
d430d3d7e646eb Jason Baron     2011-03-16  287  }
bf5438fca2950b Jason Baron     2010-09-17  288  
c5905afb0ee655 Ingo Molnar     2012-02-24  289  static inline void static_key_slow_dec(struct static_key *key)
bf5438fca2950b Jason Baron     2010-09-17  290  {
5cdda5117e125e Borislav Petkov 2017-10-18  291  	STATIC_KEY_CHECK_USE(key);
d430d3d7e646eb Jason Baron     2011-03-16  292  	atomic_dec(&key->enabled);
bf5438fca2950b Jason Baron     2010-09-17  293  }
bf5438fca2950b Jason Baron     2010-09-17  294  
ce48c146495a1a Peter Zijlstra  2018-01-22  295  #define static_key_slow_inc_cpuslocked(key) static_key_slow_inc(key)
ce48c146495a1a Peter Zijlstra  2018-01-22  296  #define static_key_slow_dec_cpuslocked(key) static_key_slow_dec(key)
ce48c146495a1a Peter Zijlstra  2018-01-22  297  
4c3ef6d79328c0 Jason Baron     2010-09-17  298  static inline int jump_label_text_reserved(void *start, void *end)
4c3ef6d79328c0 Jason Baron     2010-09-17  299  {
4c3ef6d79328c0 Jason Baron     2010-09-17  300  	return 0;
4c3ef6d79328c0 Jason Baron     2010-09-17  301  }
4c3ef6d79328c0 Jason Baron     2010-09-17  302  
91bad2f8d30574 Jason Baron     2010-10-01  303  static inline void jump_label_lock(void) {}
91bad2f8d30574 Jason Baron     2010-10-01  304  static inline void jump_label_unlock(void) {}
91bad2f8d30574 Jason Baron     2010-10-01  305  
d430d3d7e646eb Jason Baron     2011-03-16  306  static inline int jump_label_apply_nops(struct module *mod)
d430d3d7e646eb Jason Baron     2011-03-16  307  {
d430d3d7e646eb Jason Baron     2011-03-16  308  	return 0;
d430d3d7e646eb Jason Baron     2011-03-16  309  }
b202952075f626 Gleb Natapov    2011-11-27  310  
e33886b38cc82a Peter Zijlstra  2015-07-24  311  static inline void static_key_enable(struct static_key *key)
e33886b38cc82a Peter Zijlstra  2015-07-24  312  {
5cdda5117e125e Borislav Petkov 2017-10-18  313  	STATIC_KEY_CHECK_USE(key);
e33886b38cc82a Peter Zijlstra  2015-07-24  314  
1dbb6704de91b1 Paolo Bonzini   2017-08-01  315  	if (atomic_read(&key->enabled) != 0) {
1dbb6704de91b1 Paolo Bonzini   2017-08-01 @316  		WARN_ON_ONCE(atomic_read(&key->enabled) != 1);
1dbb6704de91b1 Paolo Bonzini   2017-08-01  317  		return;
1dbb6704de91b1 Paolo Bonzini   2017-08-01  318  	}
1dbb6704de91b1 Paolo Bonzini   2017-08-01  319  	atomic_set(&key->enabled, 1);
e33886b38cc82a Peter Zijlstra  2015-07-24  320  }
e33886b38cc82a Peter Zijlstra  2015-07-24  321

Signature · 2 lines

0-DAY CI Kernel Test Service
https://01.org/lkp

Vlastimil Babka

2022-04-26 15:12 UTC #4 lore raw

Quoted 28 lines · kernel test robot

Hi Peter,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on hnaz-mm/master]
url:    https://github.com/intel-lab-lkp/linux/commits/Peter-Collingbourne/mm-make-minimum-slab-alignment-a-runtime-property/20220423-042024
base:   https://github.com/hnaz/linux-mm master
config: arm64-buildonly-randconfig-r002-20220425 (https://download.01.org/0day-ci/archive/20220425/202204251346.WbwgrNZw-lkp(a)intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 1cddcfdc3c683b393df1a5c9063252eb60e52818)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross
# install arm64 cross compiling tool for clang build
# apt-get install binutils-aarch64-linux-gnu
# https://github.com/intel-lab-lkp/linux/commit/3aef97055dd4a480e05dff758164f153aaddbb49
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Peter-Collingbourne/mm-make-minimum-slab-alignment-a-runtime-property/20220423-042024 git checkout 3aef97055dd4a480e05dff758164f153aaddbb49
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm64 prepare
If you fix the issue, kindly add following tag as appropriate
Reported-by kernel test robot <[email protected]>
All errors (new ones prefixed by >>):

Quoted 10 lines

In file included from kernel/bounds.c:10:
In file included from include/linux/page-flags.h:10:
In file included from include/linux/bug.h:5:
In file included from arch/arm64/include/asm/bug.h:26:
In file included from include/asm-generic/bug.h:22:
In file included from include/linux/printk.h:9:
In file included from include/linux/cache.h:6:
In file included from arch/arm64/include/asm/cache.h:56:
In file included from include/linux/kasan-enabled.h:5:
In file included from include/linux/static_key.h:1:

Hmm looks like a circular include, cache.h is too "low-level" in the hierarchy to bring in kasan->static_key->jump_label.h definitions? jump_label.h does include bug.h, but we have it above already and have already passed #define _LINUX_BUG_H.

So, a different kind of header with arm64-specific variant?

Quoted 82 lines

Quoted 1 line

Quoted 1 line
include/linux/jump_label.h:285:2: error: call to undeclared function 'WARN'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]

           STATIC_KEY_CHECK_USE(key);
           ^
   include/linux/jump_label.h:81:35: note: expanded from macro 'STATIC_KEY_CHECK_USE'
   #define STATIC_KEY_CHECK_USE(key) WARN(!static_key_initialized,               \
                                     ^
   include/linux/jump_label.h:291:2: error: call to undeclared function 'WARN'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
           STATIC_KEY_CHECK_USE(key);
           ^
   include/linux/jump_label.h:81:35: note: expanded from macro 'STATIC_KEY_CHECK_USE'
   #define STATIC_KEY_CHECK_USE(key) WARN(!static_key_initialized,               \
                                     ^
   include/linux/jump_label.h:313:2: error: call to undeclared function 'WARN'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
           STATIC_KEY_CHECK_USE(key);
           ^
   include/linux/jump_label.h:81:35: note: expanded from macro 'STATIC_KEY_CHECK_USE'
   #define STATIC_KEY_CHECK_USE(key) WARN(!static_key_initialized,               \
                                     ^

Quoted 1 line

Quoted 1 line
include/linux/jump_label.h:316:3: error: call to undeclared function 'WARN_ON_ONCE'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]

                   WARN_ON_ONCE(atomic_read(&key->enabled) != 1);
                   ^
   include/linux/jump_label.h:324:2: error: call to undeclared function 'WARN'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
           STATIC_KEY_CHECK_USE(key);
           ^
   include/linux/jump_label.h:81:35: note: expanded from macro 'STATIC_KEY_CHECK_USE'
   #define STATIC_KEY_CHECK_USE(key) WARN(!static_key_initialized,               \
                                     ^
   include/linux/jump_label.h:327:3: error: call to undeclared function 'WARN_ON_ONCE'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
                   WARN_ON_ONCE(atomic_read(&key->enabled) != 0);
                   ^

vim +/WARN +285 include/linux/jump_label.h

bf5438fca2950b Jason Baron     2010-09-17  282  
c5905afb0ee655 Ingo Molnar     2012-02-24  283  static inline void static_key_slow_inc(struct static_key *key)
d430d3d7e646eb Jason Baron     2011-03-16  284  {
5cdda5117e125e Borislav Petkov 2017-10-18 @285  	STATIC_KEY_CHECK_USE(key);
d430d3d7e646eb Jason Baron     2011-03-16  286  	atomic_inc(&key->enabled);
d430d3d7e646eb Jason Baron     2011-03-16  287  }
bf5438fca2950b Jason Baron     2010-09-17  288  
c5905afb0ee655 Ingo Molnar     2012-02-24  289  static inline void static_key_slow_dec(struct static_key *key)
bf5438fca2950b Jason Baron     2010-09-17  290  {
5cdda5117e125e Borislav Petkov 2017-10-18  291  	STATIC_KEY_CHECK_USE(key);
d430d3d7e646eb Jason Baron     2011-03-16  292  	atomic_dec(&key->enabled);
bf5438fca2950b Jason Baron     2010-09-17  293  }
bf5438fca2950b Jason Baron     2010-09-17  294  
ce48c146495a1a Peter Zijlstra  2018-01-22  295  #define static_key_slow_inc_cpuslocked(key) static_key_slow_inc(key)
ce48c146495a1a Peter Zijlstra  2018-01-22  296  #define static_key_slow_dec_cpuslocked(key) static_key_slow_dec(key)
ce48c146495a1a Peter Zijlstra  2018-01-22  297  
4c3ef6d79328c0 Jason Baron     2010-09-17  298  static inline int jump_label_text_reserved(void *start, void *end)
4c3ef6d79328c0 Jason Baron     2010-09-17  299  {
4c3ef6d79328c0 Jason Baron     2010-09-17  300  	return 0;
4c3ef6d79328c0 Jason Baron     2010-09-17  301  }
4c3ef6d79328c0 Jason Baron     2010-09-17  302  
91bad2f8d30574 Jason Baron     2010-10-01  303  static inline void jump_label_lock(void) {}
91bad2f8d30574 Jason Baron     2010-10-01  304  static inline void jump_label_unlock(void) {}
91bad2f8d30574 Jason Baron     2010-10-01  305  
d430d3d7e646eb Jason Baron     2011-03-16  306  static inline int jump_label_apply_nops(struct module *mod)
d430d3d7e646eb Jason Baron     2011-03-16  307  {
d430d3d7e646eb Jason Baron     2011-03-16  308  	return 0;
d430d3d7e646eb Jason Baron     2011-03-16  309  }
b202952075f626 Gleb Natapov    2011-11-27  310  
e33886b38cc82a Peter Zijlstra  2015-07-24  311  static inline void static_key_enable(struct static_key *key)
e33886b38cc82a Peter Zijlstra  2015-07-24  312  {
5cdda5117e125e Borislav Petkov 2017-10-18  313  	STATIC_KEY_CHECK_USE(key);
e33886b38cc82a Peter Zijlstra  2015-07-24  314  
1dbb6704de91b1 Paolo Bonzini   2017-08-01  315  	if (atomic_read(&key->enabled) != 0) {
1dbb6704de91b1 Paolo Bonzini   2017-08-01 @316  		WARN_ON_ONCE(atomic_read(&key->enabled) != 1);
1dbb6704de91b1 Paolo Bonzini   2017-08-01  317  		return;
1dbb6704de91b1 Paolo Bonzini   2017-08-01  318  	}
1dbb6704de91b1 Paolo Bonzini   2017-08-01  319  	atomic_set(&key->enabled, 1);
e33886b38cc82a Peter Zijlstra  2015-07-24  320  }
e33886b38cc82a Peter Zijlstra  2015-07-24  321

Peter Collingbourne

author

2022-04-26 18:15 UTC #5 lore raw

Quoted 41 lines · Vlastimil Babka

Quoted 28 lines · kernel test robot
Hi Peter,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on hnaz-mm/master]
url:    https://github.com/intel-lab-lkp/linux/commits/Peter-Collingbourne/mm-make-minimum-slab-alignment-a-runtime-property/20220423-042024
base:   https://github.com/hnaz/linux-mm master
config: arm64-buildonly-randconfig-r002-20220425 (https://download.01.org/0day-ci/archive/20220425/202204251346.WbwgrNZw-lkp(a)intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 1cddcfdc3c683b393df1a5c9063252eb60e52818)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross
# install arm64 cross compiling tool for clang build
# apt-get install binutils-aarch64-linux-gnu
# https://github.com/intel-lab-lkp/linux/commit/3aef97055dd4a480e05dff758164f153aaddbb49
git remote add linux-review https://github.com/intel-lab-lkp/linux
git fetch --no-tags linux-review Peter-Collingbourne/mm-make-minimum-slab-alignment-a-runtime-property/20220423-042024 git checkout 3aef97055dd4a480e05dff758164f153aaddbb49
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm64 prepare
If you fix the issue, kindly add following tag as appropriate
Reported-by kernel test robot <[email protected]>
All errors (new ones prefixed by >>):
Quoted 10 lines
In file included from kernel/bounds.c:10:
In file included from include/linux/page-flags.h:10:
In file included from include/linux/bug.h:5:
In file included from arch/arm64/include/asm/bug.h:26:
In file included from include/asm-generic/bug.h:22:
In file included from include/linux/printk.h:9:
In file included from include/linux/cache.h:6:
In file included from arch/arm64/include/asm/cache.h:56:
In file included from include/linux/kasan-enabled.h:5:
In file included from include/linux/static_key.h:1:

Quoted 6 lines

Hmm looks like a circular include, cache.h is too "low-level" in the hierarchy to bring in kasan->static_key->jump_label.h definitions? jump_label.h does include bug.h, but we have it above already and have already passed #define _LINUX_BUG_H.
So, a different kind of header with arm64-specific variant?

The fix that I'm pursuing starts with:

include/linux/printk.h +0 -1

index 1522df223c0f..8e8d74edf121 100644
@@ -6,7 +6,6 @@
 #include <linux/init.h>
 #include <linux/kern_levels.h>
 #include <linux/linkage.h>
-#include <linux/cache.h>
 #include <linux/ratelimit_types.h>
 #include <linux/once_lite.h>

and fixing the fallout from code that was including printk.h and depending on something from cache.h. So far I haven't found much, only 3 fixups required for an arm64 defconfig kernel but I'm trying some more configs as well.

Peter

Catalin Marinas

maintainer Reviewed-by on v3 1/1

2022-04-25 15:56 UTC #6 lore raw

In reply to Peter Collingbourne

Quoted 12 lines · Peter Collingbourne

When CONFIG_KASAN_HW_TAGS is enabled we currently increase the minimum slab alignment to 16. This happens even if MTE is not supported in hardware or disabled via kasan=off, which creates an unnecessary memory overhead in those cases. Eliminate this overhead by making the minimum slab alignment a runtime property and only aligning to 16 if KASAN is enabled at runtime.
On a DragonBoard 845c (non-MTE hardware) with a kernel built with CONFIG_KASAN_HW_TAGS, waiting for quiescence after a full Android boot I see the following Slab measurements in /proc/meminfo (median of 3 reboots):

Quoted 6 lines

Before: 169020 kB
After:  167304 kB
Link https://linux-review.googlesource.com/id/I752e725179b43b144153f4b6f584ceb646473ead
Signed-off-by Peter Collingbourne <[email protected]>
Reviewed-by Andrey Konovalov <[email protected]>

Reviewed-by Catalin Marinas <[email protected]>