[PATCH v5 1/2] printk: stop including cache.h from printk.h

[PATCH v5 1/2] printk: stop including cache.h from printk.h

[Peter Collingbourne]

An inclusion of cache.h in printk.h was added in 2014 in
commit c28aa1f0a847 ("printk/cache: mark printk_once test variable
__read_mostly") in order to bring in the definition of __read_mostly. The
usage of __read_mostly was later removed in commit 3ec25826ae33 ("printk:
Tie printk_once / printk_deferred_once into .data.once for reset")
which made the inclusion of cache.h unnecessary, so remove it.

We have a small amount of code that depended on the inclusion of cache.h
from printk.h; fix that code to include the appropriate header.

This fixes a circular inclusion on arm64 (linux/printk.h -> linux/cache.h
-> asm/cache.h -> linux/kasan-enabled.h -> linux/static_key.h ->
linux/jump_label.h -> linux/bug.h -> asm/bug.h -> linux/printk.h) that
would otherwise be introduced by the next patch.

Build tested using {allyesconfig,defconfig} x {arm64,x86_64}.

Link: https://linux-review.googlesource.com/id/I8fd51f72c9ef1f2d6afd3b2cbc875aa4792c1fba
Signed-off-by: Peter Collingbourne <pcc@google.com>
---
v5:
- fixes for arm randconfig and (tentatively) csky

 arch/arm64/include/asm/mte-kasan.h | 1 +
 arch/arm64/include/asm/percpu.h    | 1 +
 arch/csky/include/asm/processor.h  | 2 +-
 drivers/firmware/smccc/kvm_guest.c | 1 +
 include/linux/printk.h             | 1 -
 kernel/bpf/bpf_lru_list.h          | 1 +
 6 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/mte-kasan.h b/arch/arm64/include/asm/mte-kasan.h
index a857bcacf0fe..9f79425fc65a 100644
--- a/arch/arm64/include/asm/mte-kasan.h
+++ b/arch/arm64/include/asm/mte-kasan.h
@@ -6,6 +6,7 @@
 #define __ASM_MTE_KASAN_H
 
 #include <asm/compiler.h>
+#include <asm/cputype.h>
 #include <asm/mte-def.h>
 
 #ifndef __ASSEMBLY__
diff --git a/arch/arm64/include/asm/percpu.h b/arch/arm64/include/asm/percpu.h
index 8f1661603b78..b9ba19dbdb69 100644
--- a/arch/arm64/include/asm/percpu.h
+++ b/arch/arm64/include/asm/percpu.h
@@ -10,6 +10,7 @@
 #include <asm/alternative.h>
 #include <asm/cmpxchg.h>
 #include <asm/stack_pointer.h>
+#include <asm/sysreg.h>
 
 static inline void set_my_cpu_offset(unsigned long off)
 {
diff --git a/arch/csky/include/asm/processor.h b/arch/csky/include/asm/processor.h
index 688c7548b559..9638206bc44f 100644
--- a/arch/csky/include/asm/processor.h
+++ b/arch/csky/include/asm/processor.h
@@ -4,9 +4,9 @@
 #define __ASM_CSKY_PROCESSOR_H
 
 #include <linux/bitops.h>
+#include <linux/cache.h>
 #include <asm/ptrace.h>
 #include <asm/current.h>
-#include <asm/cache.h>
 #include <abi/reg_ops.h>
 #include <abi/regdef.h>
 #include <abi/switch_context.h>
diff --git a/drivers/firmware/smccc/kvm_guest.c b/drivers/firmware/smccc/kvm_guest.c
index 2d3e866decaa..89a68e7eeaa6 100644
--- a/drivers/firmware/smccc/kvm_guest.c
+++ b/drivers/firmware/smccc/kvm_guest.c
@@ -4,6 +4,7 @@
 
 #include <linux/arm-smccc.h>
 #include <linux/bitmap.h>
+#include <linux/cache.h>
 #include <linux/kernel.h>
 #include <linux/string.h>
 
diff --git a/include/linux/printk.h b/include/linux/printk.h
index 1522df223c0f..8e8d74edf121 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -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>
 
diff --git a/kernel/bpf/bpf_lru_list.h b/kernel/bpf/bpf_lru_list.h
index 6b12f06ee18c..4ea227c9c1ad 100644
--- a/kernel/bpf/bpf_lru_list.h
+++ b/kernel/bpf/bpf_lru_list.h
@@ -4,6 +4,7 @@
 #ifndef __BPF_LRU_LIST_H_
 #define __BPF_LRU_LIST_H_
 
+#include <linux/cache.h>
 #include <linux/list.h>
 #include <linux/spinlock_types.h>
 
-- 
2.36.0.464.gb9c8b46e94-goog

[PATCH v5 2/2] mm: make minimum slab alignment a runtime property

[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):

Before: 169020 kB
After:  167304 kB

Link: https://linux-review.googlesource.com/id/I752e725179b43b144153f4b6f584ceb646473ead
Signed-off-by: Peter Collingbourne <pcc@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
---
v4:
- add a dependent patch to fix the build with CONFIG_JUMP_LABEL disabled

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(-)

diff --git a/arch/arm64/include/asm/cache.h b/arch/arm64/include/asm/cache.h
index a074459f8f2f..22b22dc1b1b5 100644
--- a/arch/arm64/include/asm/cache.h
+++ b/arch/arm64/include/asm/cache.h
@@ -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;
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 373b3ef99f4e..2c7190db4cc0 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -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
diff --git a/mm/slab.c b/mm/slab.c
index 0edb474edef1..97b756976c8b 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -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;
 }
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 2b3206a2c3b5..33cc49810a54 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -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 *));
 }
diff --git a/mm/slob.c b/mm/slob.c
index 40ea6e2d4ccd..3bd2669bd690 100644
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -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;
 }
-- 
2.36.0.464.gb9c8b46e94-goog

Re: [PATCH v5 2/2] mm: make minimum slab alignment a runtime property

[Andrew Morton]

On Wed, 27 Apr 2022 12:58:20 -0700 Peter Collingbourne <pcc@google.com> wrote:

> 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):
> 
> ...
>
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -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());

printf/printk know about size_t.  Use %zu, no cast needed.  But...

>  	}
>  	return objp;
>  }
> diff --git a/mm/slab_common.c b/mm/slab_common.c
> index 2b3206a2c3b5..33cc49810a54 100644
> --- a/mm/slab_common.c
> +++ b/mm/slab_common.c
> @@ -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());

max_t/min_t are nature's way of telling us "you screwed up the types".

So what type _is_ slab alignment?  size_t seems sensible, but the code
prefers unsigned int.  So how about we stick with that?


This compiles.  Still some max_t's in slob.c because I was too lazy to
go fix the type of ARCH_KMALLOC_MINALIGN.

Shrug, I don't know if we can be bothered.   You decide :)


 arch/arm64/include/asm/cache.h |    2 +-
 include/linux/slab.h           |    2 +-
 mm/slab.c                      |    4 ++--
 mm/slab_common.c               |    2 +-
 mm/slob.c                      |   16 +++++++++++-----
 5 files changed, 16 insertions(+), 10 deletions(-)

--- a/arch/arm64/include/asm/cache.h~mm-make-minimum-slab-alignment-a-runtime-property-fix
+++ a/arch/arm64/include/asm/cache.h
@@ -58,7 +58,7 @@
 #ifdef CONFIG_KASAN_SW_TAGS
 #define ARCH_SLAB_MINALIGN	(1ULL << KASAN_SHADOW_SCALE_SHIFT)
 #elif defined(CONFIG_KASAN_HW_TAGS)
-static inline size_t arch_slab_minalign(void)
+static inline unsigned int arch_slab_minalign(void)
 {
 	return kasan_hw_tags_enabled() ? MTE_GRANULE_SIZE :
 					 __alignof__(unsigned long long);
--- a/include/linux/slab.h~mm-make-minimum-slab-alignment-a-runtime-property-fix
+++ a/include/linux/slab.h
@@ -215,7 +215,7 @@ void kmem_dump_obj(void *object);
  * of two and >= ARCH_SLAB_MINALIGN.
  */
 #ifndef arch_slab_minalign
-static inline size_t arch_slab_minalign(void)
+static inline unsigned int arch_slab_minalign(void)
 {
 	return ARCH_SLAB_MINALIGN;
 }
--- a/mm/slab.c~mm-make-minimum-slab-alignment-a-runtime-property-fix
+++ a/mm/slab.c
@@ -3010,8 +3010,8 @@ static void *cache_alloc_debugcheck_afte
 	if (cachep->ctor && cachep->flags & SLAB_POISON)
 		cachep->ctor(objp);
 	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());
+		pr_err("0x%px: not aligned to arch_slab_minalign()=%u\n", objp,
+		       arch_slab_minalign());
 	}
 	return objp;
 }
--- a/mm/slab_common.c~mm-make-minimum-slab-alignment-a-runtime-property-fix
+++ a/mm/slab_common.c
@@ -154,7 +154,7 @@ static unsigned int calculate_alignment(
 		align = max(align, ralign);
 	}
 
-	align = max_t(size_t, align, arch_slab_minalign());
+	align = max(align, arch_slab_minalign());
 
 	return ALIGN(align, sizeof(void *));
 }
--- a/mm/slob.c~mm-make-minimum-slab-alignment-a-runtime-property-fix
+++ a/mm/slob.c
@@ -478,9 +478,11 @@ 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());
+	unsigned int minalign;
 	void *ret;
 
+	minalign = max_t(unsigned int, ARCH_KMALLOC_MINALIGN,
+			 arch_slab_minalign());
 	gfp &= gfp_allowed_mask;
 
 	might_alloc(gfp);
@@ -493,7 +495,7 @@ __do_kmalloc_node(size_t size, gfp_t gfp
 		 * kmalloc()'d objects.
 		 */
 		if (is_power_of_2(size))
-			align = max(minalign, (int) size);
+			align = max_t(unsigned int, minalign, size);
 
 		if (!size)
 			return ZERO_SIZE_PTR;
@@ -555,8 +557,11 @@ 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());
+		unsigned int align = max_t(unsigned int,
+					   ARCH_KMALLOC_MINALIGN,
+					   arch_slab_minalign());
 		unsigned int *m = (unsigned int *)(block - align);
+
 		slob_free(m, *m + align);
 	} else {
 		unsigned int order = folio_order(sp);
@@ -573,7 +578,7 @@ EXPORT_SYMBOL(kfree);
 size_t __ksize(const void *block)
 {
 	struct folio *folio;
-	int align;
+	unsigned int align;
 	unsigned int *m;
 
 	BUG_ON(!block);
@@ -584,7 +589,8 @@ 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(unsigned int, ARCH_KMALLOC_MINALIGN,
+		      arch_slab_minalign());
 	m = (unsigned int *)(block - align);
 	return SLOB_UNITS(*m) * SLOB_UNIT;
 }
_

Re: [PATCH v5 2/2] mm: make minimum slab alignment a runtime property

[Peter Collingbourne]

On Wed, Apr 27, 2022 at 1:27 PM Andrew Morton <akpm@linux-foundation.org> wrote:
>
> On Wed, 27 Apr 2022 12:58:20 -0700 Peter Collingbourne <pcc@google.com> wrote:
>
> > 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):
> >
> > ...
> >
> > --- a/mm/slab.c
> > +++ b/mm/slab.c
> > @@ -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());
>
> printf/printk know about size_t.  Use %zu, no cast needed.  But...
>
> >       }
> >       return objp;
> >  }
> > diff --git a/mm/slab_common.c b/mm/slab_common.c
> > index 2b3206a2c3b5..33cc49810a54 100644
> > --- a/mm/slab_common.c
> > +++ b/mm/slab_common.c
> > @@ -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());
>
> max_t/min_t are nature's way of telling us "you screwed up the types".
>
> So what type _is_ slab alignment?  size_t seems sensible, but the code
> prefers unsigned int.  So how about we stick with that?
>
>
> This compiles.  Still some max_t's in slob.c because I was too lazy to
> go fix the type of ARCH_KMALLOC_MINALIGN.
>
> Shrug, I don't know if we can be bothered.   You decide :)

Hi Andrew,

No strong opinions here. I'm happy with the fixup that you added to
your tree on top of my patch.

Peter

Re: [PATCH v5 2/2] mm: make minimum slab alignment a runtime property

[Vlastimil Babka]

On 4/27/22 21:58, Peter Collingbourne wrote:
> 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 <pcc@google.com>
> Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
> Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
> Tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
> Acked-by: David Rientjes <rientjes@google.com>
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>

Acked-by: Vlastimil Babka <vbabka@suse.cz>
Andrew's fixup LGTM too.

Re: [PATCH v5 1/2] printk: stop including cache.h from printk.h

[Guenter Roeck]

On Wed, Apr 27, 2022 at 12:58:19PM -0700, Peter Collingbourne wrote:
> An inclusion of cache.h in printk.h was added in 2014 in
> commit c28aa1f0a847 ("printk/cache: mark printk_once test variable
> __read_mostly") in order to bring in the definition of __read_mostly. The
> usage of __read_mostly was later removed in commit 3ec25826ae33 ("printk:
> Tie printk_once / printk_deferred_once into .data.once for reset")
> which made the inclusion of cache.h unnecessary, so remove it.
> 
> We have a small amount of code that depended on the inclusion of cache.h
> from printk.h; fix that code to include the appropriate header.
> 
> This fixes a circular inclusion on arm64 (linux/printk.h -> linux/cache.h
> -> asm/cache.h -> linux/kasan-enabled.h -> linux/static_key.h ->
> linux/jump_label.h -> linux/bug.h -> asm/bug.h -> linux/printk.h) that
> would otherwise be introduced by the next patch.
> 
> Build tested using {allyesconfig,defconfig} x {arm64,x86_64}.

But not powerpc:corenet64_smp_defconfig, where it results in lots of
build errors such as

powerpc64-linux-ld: fs/freevxfs/vxfs_fshead.o:(.bss+0x0):
	multiple definition of `____cacheline_aligned';
	fs/freevxfs/vxfs_bmap.o:(.bss+0x0): first defined here

Reverting this patch fixes the problem.

Guenter

---
# bad: [18ecd30af1a8402c162cca1bd58771c0e5be7815] Add linux-next specific files for 20220520
# good: [42226c989789d8da4af1de0c31070c96726d990c] Linux 5.18-rc7
git bisect start 'HEAD' 'v5.18-rc7'
# good: [f9b63740b666dd9887eb0282d21b5f65bb0cadd0] Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/cryptodev-2.6.git
git bisect good f9b63740b666dd9887eb0282d21b5f65bb0cadd0
# good: [1f5eb3e76303572f0318e8c50da51c516580aa03] Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git
git bisect good 1f5eb3e76303572f0318e8c50da51c516580aa03
# good: [4c1d9cc0363691893ef94fa0d798faca013e27d3] Merge branch 'staging-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
git bisect good 4c1d9cc0363691893ef94fa0d798faca013e27d3
# good: [a3204ed0fc565fc76901c67dfc8e04c91a5c8ea4] Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock.git
git bisect good a3204ed0fc565fc76901c67dfc8e04c91a5c8ea4
# bad: [ca228447682904bc749c0702695681543b5dc709] Merge branch 'mm-nonmm-unstable' into mm-everything
git bisect bad ca228447682904bc749c0702695681543b5dc709
# bad: [c0eeeb02d9df878c71a457008900b650d94bd0d9] selftests/uffd: enable uffd-wp for shmem/hugetlbfs
git bisect bad c0eeeb02d9df878c71a457008900b650d94bd0d9
# good: [0a7a0f6f7f3679c906fc55e3805c1d5e2c566f55] hugetlb: fix wrong use of nr_online_nodes
git bisect good 0a7a0f6f7f3679c906fc55e3805c1d5e2c566f55
# good: [c9fe66560bf2dc7d109754414e309888cb8c9ba9] mm/mprotect: do not flush when not required architecturally
git bisect good c9fe66560bf2dc7d109754414e309888cb8c9ba9
# bad: [97d482f4592fde2322c319f07bc54f3a0d37861c] mm/damon/sysfs: reuse damon_set_regions() for regions setting
git bisect bad 97d482f4592fde2322c319f07bc54f3a0d37861c
# good: [54205e9c5425049aef1bc7a812f890f00b5f79c7] mm: rmap: move the cache flushing to the correct place for hugetlb PMD sharing
git bisect good 54205e9c5425049aef1bc7a812f890f00b5f79c7
# bad: [9994715333515e82865e533250e488496b9742f4] selftest/vm: test that mremap fails on non-existent vma
git bisect bad 9994715333515e82865e533250e488496b9742f4
# bad: [d949a8155d139aa890795b802004a196b7f00598] mm: make minimum slab alignment a runtime property
git bisect bad d949a8155d139aa890795b802004a196b7f00598
# bad: [534aa1dc975ac883ad89110534585a96630802a0] printk: stop including cache.h from printk.h
git bisect bad 534aa1dc975ac883ad89110534585a96630802a0
# good: [dfc7ab57560da385f705b28e2bf50e3b90444a6b] mm: rmap: use flush_cache_range() to flush cache for hugetlb pages
git bisect good dfc7ab57560da385f705b28e2bf50e3b90444a6b
# first bad commit: [534aa1dc975ac883ad89110534585a96630802a0] printk: stop including cache.h from printk.h

Re: [PATCH v5 1/2] printk: stop including cache.h from printk.h

[Michael Ellerman]

Guenter Roeck <linux@roeck-us.net> writes:
> On Wed, Apr 27, 2022 at 12:58:19PM -0700, Peter Collingbourne wrote:
>> An inclusion of cache.h in printk.h was added in 2014 in
>> commit c28aa1f0a847 ("printk/cache: mark printk_once test variable
>> __read_mostly") in order to bring in the definition of __read_mostly. The
>> usage of __read_mostly was later removed in commit 3ec25826ae33 ("printk:
>> Tie printk_once / printk_deferred_once into .data.once for reset")
>> which made the inclusion of cache.h unnecessary, so remove it.
>> 
>> We have a small amount of code that depended on the inclusion of cache.h
>> from printk.h; fix that code to include the appropriate header.
>> 
>> This fixes a circular inclusion on arm64 (linux/printk.h -> linux/cache.h
>> -> asm/cache.h -> linux/kasan-enabled.h -> linux/static_key.h ->
>> linux/jump_label.h -> linux/bug.h -> asm/bug.h -> linux/printk.h) that
>> would otherwise be introduced by the next patch.
>> 
>> Build tested using {allyesconfig,defconfig} x {arm64,x86_64}.
>
> But not powerpc:corenet64_smp_defconfig, where it results in lots of
> build errors such as
>
> powerpc64-linux-ld: fs/freevxfs/vxfs_fshead.o:(.bss+0x0):
> 	multiple definition of `____cacheline_aligned';
> 	fs/freevxfs/vxfs_bmap.o:(.bss+0x0): first defined here

I sent a patch to fix it, and will merge the fix via my tree:

http://patchwork.ozlabs.org/project/linuxppc-dev/patch/20220527112035.2842155-1-mpe@ellerman.id.au/

cheers