[PATCH 0/5] MIPS: LLVMLinux: Patches to enable compilation of a working kernel for MIPS using Clang/LLVM

[PATCH 0/5] MIPS: LLVMLinux: Patches to enable compilation of a working kernel for MIPS using Clang/LLVM

[Daniel Sanders]

When combined with 'MIPS: Changed current_thread_info() to an equivalent ...'
(http://www.linux-mips.org/archives/linux-mips/2015-01/msg00070.html), this
patch series makes it possible to compile a working kernel for MIPS using Clang.

The patches aren't inter-dependent so I'm happy to split this up into individual
submissions if that's preferred.

Daniel Sanders (1):
  LLVMLinux: Correct size_index table before replacing the bootstrap
    kmem_cache_node.

Toma Tabacu (4):
  MIPS: LLVMLinux: Fix a 'cast to type not present in union' error.
  MIPS: LLVMLinux: Fix an 'inline asm input/output type mismatch' error.
  MIPS: LLVMLinux: Silence variable self-assignment warnings.
  MIPS: LLVMLinux: Silence unicode warnings when preprocessing assembly.

 arch/mips/include/asm/asmmacro.h |  8 ++++----
 arch/mips/include/asm/checksum.h |  2 +-
 arch/mips/kernel/branch.c        |  6 ++++--
 arch/mips/math-emu/dp_add.c      |  5 -----
 arch/mips/math-emu/dp_sub.c      |  5 -----
 arch/mips/math-emu/sp_add.c      |  5 -----
 arch/mips/math-emu/sp_sub.c      |  5 -----
 mm/slab.c                        |  1 +
 mm/slab.h                        |  1 +
 mm/slab_common.c                 | 36 +++++++++++++++++++++---------------
 mm/slub.c                        |  1 +
 11 files changed, 33 insertions(+), 42 deletions(-)

Signed-off-by: Toma Tabacu <toma.tabacu@imgtec.com>
Signed-off-by: Daniel Sanders <daniel.sanders@imgtec.com>
Cc: "Steven J. Hill" <Steven.Hill@imgtec.com>
Cc: Andreas Herrmann <andreas.herrmann@caviumnetworks.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Daney <david.daney@cavium.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Jim Quinlan <jim2101024@gmail.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Cc: Manuel Lauss <manuel.lauss@gmail.com>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Cc: Paul Bolle <pebolle@tiscali.nl>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: linux-mm@kvack.org

-- 
2.1.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[PATCH 1/5] LLVMLinux: Correct size_index table before replacing the bootstrap kmem_cache_node.

[Daniel Sanders]

This patch moves the initialization of the size_index table slightly
earlier so that the first few kmem_cache_node's can be safely allocated
when KMALLOC_MIN_SIZE is large.

There are currently two ways to generate indices into kmalloc_caches
(via kmalloc_index() and via the size_index table in slab_common.c)
and on some arches (possibly only MIPS) they potentially disagree with
each other until create_kmalloc_caches() has been called. It seems
that the intention is that the size_index table is a fast equivalent
to kmalloc_index() and that create_kmalloc_caches() patches the table
to return the correct value for the cases where kmalloc_index()'s
if-statements apply.

The failing sequence was:
* kmalloc_caches contains NULL elements
* kmem_cache_init initialises the element that 'struct
  kmem_cache_node' will be allocated to. For 32-bit Mips, this is a
  56-byte struct and kmalloc_index returns KMALLOC_SHIFT_LOW (7).
* init_list is called which calls kmalloc_node to allocate a 'struct
  kmem_cache_node'.
* kmalloc_slab selects the kmem_caches element using
  size_index[size_index_elem(size)]. For MIPS, size is 56, and the
  expression returns 6.
* This element of kmalloc_caches is NULL and allocation fails.
* If it had not already failed, it would have called
  create_kmalloc_caches() at this point which would have changed
  size_index[size_index_elem(size)] to 7.

Signed-off-by: Daniel Sanders <daniel.sanders@imgtec.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
---
 mm/slab.c        |  1 +
 mm/slab.h        |  1 +
 mm/slab_common.c | 36 +++++++++++++++++++++---------------
 mm/slub.c        |  1 +
 4 files changed, 24 insertions(+), 15 deletions(-)

diff --git a/mm/slab.c b/mm/slab.c
index 65b5dcb..6c93f28 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1440,6 +1440,7 @@ void __init kmem_cache_init(void)
 	kmalloc_caches[INDEX_NODE] = create_kmalloc_cache("kmalloc-node",
 				kmalloc_size(INDEX_NODE), ARCH_KMALLOC_FLAGS);
 	slab_state = PARTIAL_NODE;
+	correct_kmalloc_cache_index_table();
 
 	slab_early_init = 0;
 
diff --git a/mm/slab.h b/mm/slab.h
index 1cf40054..036c08d 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -71,6 +71,7 @@ unsigned long calculate_alignment(unsigned long flags,
 
 #ifndef CONFIG_SLOB
 /* Kmalloc array related functions */
+void correct_kmalloc_cache_index_table(void);
 void create_kmalloc_caches(unsigned long);
 
 /* Find the kmalloc slab corresponding for a certain size */
diff --git a/mm/slab_common.c b/mm/slab_common.c
index e03dd6f..d2f7379 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -675,25 +675,20 @@ struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
 }
 
 /*
- * Create the kmalloc array. Some of the regular kmalloc arrays
- * may already have been created because they were needed to
- * enable allocations for slab creation.
+ * Patch up the size_index table if we have strange large alignment
+ * requirements for the kmalloc array. This is only the case for
+ * MIPS it seems. The standard arches will not generate any code here.
+ *
+ * Largest permitted alignment is 256 bytes due to the way we
+ * handle the index determination for the smaller caches.
+ *
+ * Make sure that nothing crazy happens if someone starts tinkering
+ * around with ARCH_KMALLOC_MINALIGN
  */
-void __init create_kmalloc_caches(unsigned long flags)
+void __init correct_kmalloc_cache_index_table(void)
 {
 	int i;
 
-	/*
-	 * Patch up the size_index table if we have strange large alignment
-	 * requirements for the kmalloc array. This is only the case for
-	 * MIPS it seems. The standard arches will not generate any code here.
-	 *
-	 * Largest permitted alignment is 256 bytes due to the way we
-	 * handle the index determination for the smaller caches.
-	 *
-	 * Make sure that nothing crazy happens if someone starts tinkering
-	 * around with ARCH_KMALLOC_MINALIGN
-	 */
 	BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
 		(KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1)));
 
@@ -724,6 +719,17 @@ void __init create_kmalloc_caches(unsigned long flags)
 		for (i = 128 + 8; i <= 192; i += 8)
 			size_index[size_index_elem(i)] = 8;
 	}
+}
+
+/*
+ * Create the kmalloc array. Some of the regular kmalloc arrays
+ * may already have been created because they were needed to
+ * enable allocations for slab creation.
+ */
+void __init create_kmalloc_caches(unsigned long flags)
+{
+	int i;
+
 	for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) {
 		if (!kmalloc_caches[i]) {
 			kmalloc_caches[i] = create_kmalloc_cache(NULL,
diff --git a/mm/slub.c b/mm/slub.c
index fe376fe..2217761 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3604,6 +3604,7 @@ void __init kmem_cache_init(void)
 	kmem_cache_node = bootstrap(&boot_kmem_cache_node);
 
 	/* Now we can use the kmem_cache to allocate kmalloc slabs */
+	correct_kmalloc_cache_index_table();
 	create_kmalloc_caches(0);
 
 #ifdef CONFIG_SMP
-- 
2.1.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [PATCH 1/5] LLVMLinux: Correct size_index table before replacing the bootstrap kmem_cache_node.

[Christoph Lameter]

On Tue, 3 Feb 2015, Daniel Sanders wrote:

> +++ b/mm/slab.c
> @@ -1440,6 +1440,7 @@ void __init kmem_cache_init(void)
>  	kmalloc_caches[INDEX_NODE] = create_kmalloc_cache("kmalloc-node",
>  				kmalloc_size(INDEX_NODE), ARCH_KMALLOC_FLAGS);
>  	slab_state = PARTIAL_NODE;
> +	correct_kmalloc_cache_index_table();

Lets call this

	setup_kmalloc_cache_index_table

Please?

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

RE: [PATCH 1/5] LLVMLinux: Correct size_index table before replacing the bootstrap kmem_cache_node.

[Daniel Sanders]

> -----Original Message-----
> From: Christoph Lameter [mailto:cl@linux.com]
> Sent: 03 February 2015 15:15
> To: Daniel Sanders
> Cc: Pekka Enberg; David Rientjes; Joonsoo Kim; Andrew Morton; linux-
> mm@kvack.org; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH 1/5] LLVMLinux: Correct size_index table before
> replacing the bootstrap kmem_cache_node.
> 
> On Tue, 3 Feb 2015, Daniel Sanders wrote:
> 
> > +++ b/mm/slab.c
> > @@ -1440,6 +1440,7 @@ void __init kmem_cache_init(void)
> >  	kmalloc_caches[INDEX_NODE] = create_kmalloc_cache("kmalloc-
> node",
> >  				kmalloc_size(INDEX_NODE),
> ARCH_KMALLOC_FLAGS);
> >  	slab_state = PARTIAL_NODE;
> > +	correct_kmalloc_cache_index_table();
> 
> Lets call this
> 
> 	setup_kmalloc_cache_index_table
> 
> Please?

Sure, I've made the change in my repo. I'll wait a bit before re-sending the patch in case others have feedback too.

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[PATCH v2 1/5] LLVMLinux: Correct size_index table before replacing the bootstrap kmem_cache_node.

[Daniel Sanders]

This patch moves the initialization of the size_index table slightly
earlier so that the first few kmem_cache_node's can be safely allocated
when KMALLOC_MIN_SIZE is large.

There are currently two ways to generate indices into kmalloc_caches
(via kmalloc_index() and via the size_index table in slab_common.c)
and on some arches (possibly only MIPS) they potentially disagree with
each other until create_kmalloc_caches() has been called. It seems
that the intention is that the size_index table is a fast equivalent
to kmalloc_index() and that create_kmalloc_caches() patches the table
to return the correct value for the cases where kmalloc_index()'s
if-statements apply.

The failing sequence was:
* kmalloc_caches contains NULL elements
* kmem_cache_init initialises the element that 'struct
  kmem_cache_node' will be allocated to. For 32-bit Mips, this is a
  56-byte struct and kmalloc_index returns KMALLOC_SHIFT_LOW (7).
* init_list is called which calls kmalloc_node to allocate a 'struct
  kmem_cache_node'.
* kmalloc_slab selects the kmem_caches element using
  size_index[size_index_elem(size)]. For MIPS, size is 56, and the
  expression returns 6.
* This element of kmalloc_caches is NULL and allocation fails.
* If it had not already failed, it would have called
  create_kmalloc_caches() at this point which would have changed
  size_index[size_index_elem(size)] to 7.

Signed-off-by: Daniel Sanders <daniel.sanders@imgtec.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
---

Renamed correct_kmalloc_cache_index_table() to setup_kmalloc_cache_index_table()
as requested.

 mm/slab.c        |  1 +
 mm/slab.h        |  1 +
 mm/slab_common.c | 36 +++++++++++++++++++++---------------
 mm/slub.c        |  1 +
 4 files changed, 24 insertions(+), 15 deletions(-)

diff --git a/mm/slab.c b/mm/slab.c
index 65b5dcb..d476181 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1440,6 +1440,7 @@ void __init kmem_cache_init(void)
 	kmalloc_caches[INDEX_NODE] = create_kmalloc_cache("kmalloc-node",
 				kmalloc_size(INDEX_NODE), ARCH_KMALLOC_FLAGS);
 	slab_state = PARTIAL_NODE;
+	setup_kmalloc_cache_index_table();
 
 	slab_early_init = 0;
 
diff --git a/mm/slab.h b/mm/slab.h
index 1cf40054..6121dcc 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -71,6 +71,7 @@ unsigned long calculate_alignment(unsigned long flags,
 
 #ifndef CONFIG_SLOB
 /* Kmalloc array related functions */
+void setup_kmalloc_cache_index_table(void);
 void create_kmalloc_caches(unsigned long);
 
 /* Find the kmalloc slab corresponding for a certain size */
diff --git a/mm/slab_common.c b/mm/slab_common.c
index e03dd6f..fb45b5a 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -675,25 +675,20 @@ struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
 }
 
 /*
- * Create the kmalloc array. Some of the regular kmalloc arrays
- * may already have been created because they were needed to
- * enable allocations for slab creation.
+ * Patch up the size_index table if we have strange large alignment
+ * requirements for the kmalloc array. This is only the case for
+ * MIPS it seems. The standard arches will not generate any code here.
+ *
+ * Largest permitted alignment is 256 bytes due to the way we
+ * handle the index determination for the smaller caches.
+ *
+ * Make sure that nothing crazy happens if someone starts tinkering
+ * around with ARCH_KMALLOC_MINALIGN
  */
-void __init create_kmalloc_caches(unsigned long flags)
+void __init setup_kmalloc_cache_index_table(void)
 {
 	int i;
 
-	/*
-	 * Patch up the size_index table if we have strange large alignment
-	 * requirements for the kmalloc array. This is only the case for
-	 * MIPS it seems. The standard arches will not generate any code here.
-	 *
-	 * Largest permitted alignment is 256 bytes due to the way we
-	 * handle the index determination for the smaller caches.
-	 *
-	 * Make sure that nothing crazy happens if someone starts tinkering
-	 * around with ARCH_KMALLOC_MINALIGN
-	 */
 	BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
 		(KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1)));
 
@@ -724,6 +719,17 @@ void __init create_kmalloc_caches(unsigned long flags)
 		for (i = 128 + 8; i <= 192; i += 8)
 			size_index[size_index_elem(i)] = 8;
 	}
+}
+
+/*
+ * Create the kmalloc array. Some of the regular kmalloc arrays
+ * may already have been created because they were needed to
+ * enable allocations for slab creation.
+ */
+void __init create_kmalloc_caches(unsigned long flags)
+{
+	int i;
+
 	for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) {
 		if (!kmalloc_caches[i]) {
 			kmalloc_caches[i] = create_kmalloc_cache(NULL,
diff --git a/mm/slub.c b/mm/slub.c
index fe376fe..11abd57 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3604,6 +3604,7 @@ void __init kmem_cache_init(void)
 	kmem_cache_node = bootstrap(&boot_kmem_cache_node);
 
 	/* Now we can use the kmem_cache to allocate kmalloc slabs */
+	setup_kmalloc_cache_index_table();
 	create_kmalloc_caches(0);
 
 #ifdef CONFIG_SMP
-- 
2.1.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[PATCH v3 1/5] slab: Correct size_index table before replacing the bootstrap kmem_cache_node.

[Daniel Sanders]

This patch moves the initialization of the size_index table slightly
earlier so that the first few kmem_cache_node's can be safely allocated
when KMALLOC_MIN_SIZE is large.

There are currently two ways to generate indices into kmalloc_caches
(via kmalloc_index() and via the size_index table in slab_common.c)
and on some arches (possibly only MIPS) they potentially disagree with
each other until create_kmalloc_caches() has been called. It seems
that the intention is that the size_index table is a fast equivalent
to kmalloc_index() and that create_kmalloc_caches() patches the table
to return the correct value for the cases where kmalloc_index()'s
if-statements apply.

The failing sequence was:
* kmalloc_caches contains NULL elements
* kmem_cache_init initialises the element that 'struct
  kmem_cache_node' will be allocated to. For 32-bit Mips, this is a
  56-byte struct and kmalloc_index returns KMALLOC_SHIFT_LOW (7).
* init_list is called which calls kmalloc_node to allocate a 'struct
  kmem_cache_node'.
* kmalloc_slab selects the kmem_caches element using
  size_index[size_index_elem(size)]. For MIPS, size is 56, and the
  expression returns 6.
* This element of kmalloc_caches is NULL and allocation fails.
* If it had not already failed, it would have called
  create_kmalloc_caches() at this point which would have changed
  size_index[size_index_elem(size)] to 7.

Signed-off-by: Daniel Sanders <daniel.sanders@imgtec.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
---

Renamed correct_kmalloc_cache_index_table() to setup_kmalloc_cache_index_table()
as requested.

I don't believe the bug to be LLVM specific but GCC doesn't normally encounter
the problem. I haven't been able to identify exactly what GCC is doing better
(probably inlining) but it seems that GCC is managing to optimize to the point
that it eliminates the problematic allocations. This theory is supported by the
fact that GCC can be made to fail in the same way by changing inline, __inline,
__inline__, and __always_inline in include/linux/compiler-gcc.h such that they
don't actually inline things.

 mm/slab.c        |  1 +
 mm/slab.h        |  1 +
 mm/slab_common.c | 36 +++++++++++++++++++++---------------
 mm/slub.c        |  1 +
 4 files changed, 24 insertions(+), 15 deletions(-)

diff --git a/mm/slab.c b/mm/slab.c
index 65b5dcb..d476181 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1440,6 +1440,7 @@ void __init kmem_cache_init(void)
 	kmalloc_caches[INDEX_NODE] = create_kmalloc_cache("kmalloc-node",
 				kmalloc_size(INDEX_NODE), ARCH_KMALLOC_FLAGS);
 	slab_state = PARTIAL_NODE;
+	setup_kmalloc_cache_index_table();
 
 	slab_early_init = 0;
 
diff --git a/mm/slab.h b/mm/slab.h
index 1cf40054..6121dcc 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -71,6 +71,7 @@ unsigned long calculate_alignment(unsigned long flags,
 
 #ifndef CONFIG_SLOB
 /* Kmalloc array related functions */
+void setup_kmalloc_cache_index_table(void);
 void create_kmalloc_caches(unsigned long);
 
 /* Find the kmalloc slab corresponding for a certain size */
diff --git a/mm/slab_common.c b/mm/slab_common.c
index e03dd6f..fb45b5a 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -675,25 +675,20 @@ struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
 }
 
 /*
- * Create the kmalloc array. Some of the regular kmalloc arrays
- * may already have been created because they were needed to
- * enable allocations for slab creation.
+ * Patch up the size_index table if we have strange large alignment
+ * requirements for the kmalloc array. This is only the case for
+ * MIPS it seems. The standard arches will not generate any code here.
+ *
+ * Largest permitted alignment is 256 bytes due to the way we
+ * handle the index determination for the smaller caches.
+ *
+ * Make sure that nothing crazy happens if someone starts tinkering
+ * around with ARCH_KMALLOC_MINALIGN
  */
-void __init create_kmalloc_caches(unsigned long flags)
+void __init setup_kmalloc_cache_index_table(void)
 {
 	int i;
 
-	/*
-	 * Patch up the size_index table if we have strange large alignment
-	 * requirements for the kmalloc array. This is only the case for
-	 * MIPS it seems. The standard arches will not generate any code here.
-	 *
-	 * Largest permitted alignment is 256 bytes due to the way we
-	 * handle the index determination for the smaller caches.
-	 *
-	 * Make sure that nothing crazy happens if someone starts tinkering
-	 * around with ARCH_KMALLOC_MINALIGN
-	 */
 	BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
 		(KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1)));
 
@@ -724,6 +719,17 @@ void __init create_kmalloc_caches(unsigned long flags)
 		for (i = 128 + 8; i <= 192; i += 8)
 			size_index[size_index_elem(i)] = 8;
 	}
+}
+
+/*
+ * Create the kmalloc array. Some of the regular kmalloc arrays
+ * may already have been created because they were needed to
+ * enable allocations for slab creation.
+ */
+void __init create_kmalloc_caches(unsigned long flags)
+{
+	int i;
+
 	for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) {
 		if (!kmalloc_caches[i]) {
 			kmalloc_caches[i] = create_kmalloc_cache(NULL,
diff --git a/mm/slub.c b/mm/slub.c
index fe376fe..11abd57 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3604,6 +3604,7 @@ void __init kmem_cache_init(void)
 	kmem_cache_node = bootstrap(&boot_kmem_cache_node);
 
 	/* Now we can use the kmem_cache to allocate kmalloc slabs */
+	setup_kmalloc_cache_index_table();
 	create_kmalloc_caches(0);
 
 #ifdef CONFIG_SMP
-- 
2.1.4

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [PATCH v3 1/5] slab: Correct size_index table before replacing the bootstrap kmem_cache_node.

[Pekka Enberg]

On 02/04/2015 11:06 PM, Daniel Sanders wrote:
> This patch moves the initialization of the size_index table slightly
> earlier so that the first few kmem_cache_node's can be safely allocated
> when KMALLOC_MIN_SIZE is large.
>
> There are currently two ways to generate indices into kmalloc_caches
> (via kmalloc_index() and via the size_index table in slab_common.c)
> and on some arches (possibly only MIPS) they potentially disagree with
> each other until create_kmalloc_caches() has been called. It seems
> that the intention is that the size_index table is a fast equivalent
> to kmalloc_index() and that create_kmalloc_caches() patches the table
> to return the correct value for the cases where kmalloc_index()'s
> if-statements apply.
>
> The failing sequence was:
> * kmalloc_caches contains NULL elements
> * kmem_cache_init initialises the element that 'struct
>    kmem_cache_node' will be allocated to. For 32-bit Mips, this is a
>    56-byte struct and kmalloc_index returns KMALLOC_SHIFT_LOW (7).
> * init_list is called which calls kmalloc_node to allocate a 'struct
>    kmem_cache_node'.
> * kmalloc_slab selects the kmem_caches element using
>    size_index[size_index_elem(size)]. For MIPS, size is 56, and the
>    expression returns 6.
> * This element of kmalloc_caches is NULL and allocation fails.
> * If it had not already failed, it would have called
>    create_kmalloc_caches() at this point which would have changed
>    size_index[size_index_elem(size)] to 7.
>
> Signed-off-by: Daniel Sanders <daniel.sanders@imgtec.com>
> Cc: Christoph Lameter <cl@linux.com>
> Cc: Pekka Enberg <penberg@kernel.org>
> Cc: David Rientjes <rientjes@google.com>
> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: linux-mm@kvack.org
> Cc: linux-kernel@vger.kernel.org

Acked-by: Pekka Enberg <penberg@kernel.org>

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [PATCH 1/5] LLVMLinux: Correct size_index table before replacing the bootstrap kmem_cache_node.

[Pekka Enberg]

On 2/3/15 3:37 PM, Daniel Sanders wrote:
> This patch moves the initialization of the size_index table slightly
> earlier so that the first few kmem_cache_node's can be safely allocated
> when KMALLOC_MIN_SIZE is large.

The patch looks OK to me but how is this related to LLVM?

- Pekka

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

RE: [PATCH 1/5] LLVMLinux: Correct size_index table before replacing the bootstrap kmem_cache_node.

[Daniel Sanders]

> -----Original Message-----
> From: Pekka Enberg [mailto:penberg@iki.fi]
> Sent: 04 February 2015 19:33
> To: Daniel Sanders
> Cc: Christoph Lameter; Pekka Enberg; David Rientjes; Joonsoo Kim; Andrew
> Morton; linux-mm@kvack.org; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH 1/5] LLVMLinux: Correct size_index table before
> replacing the bootstrap kmem_cache_node.
> 
> On 2/3/15 3:37 PM, Daniel Sanders wrote:
> > This patch moves the initialization of the size_index table slightly
> > earlier so that the first few kmem_cache_node's can be safely allocated
> > when KMALLOC_MIN_SIZE is large.
> 
> The patch looks OK to me but how is this related to LLVM?
>
> - Pekka

I don't believe the bug to be LLVM specific but GCC doesn't normally encounter the problem. I haven't been able to identify exactly what GCC is doing better (probably inlining) but it seems that GCC is managing to optimize  to the point that it eliminates the problematic allocations. This theory is supported by the fact that GCC can be made to fail in the same way by changing inline, __inline, __inline__, and __always_inline in include/linux/compiler-gcc.h such that they don't actually inline things.

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [PATCH 1/5] LLVMLinux: Correct size_index table before replacing the bootstrap kmem_cache_node.

[Pekka Enberg]

On Wed, Feb 4, 2015 at 10:38 PM, Daniel Sanders
<Daniel.Sanders@imgtec.com> wrote:
> I don't believe the bug to be LLVM specific but GCC doesn't normally encounter the problem. I haven't been able to identify exactly what GCC is doing better (probably inlining) but it seems that GCC is managing to optimize  to the point that it eliminates the problematic allocations. This theory is supported by the fact that GCC can be made to fail in the same way by changing inline, __inline, __inline__, and __always_inline in include/linux/compiler-gcc.h such that they don't actually inline things.

OK, makes sense. Please include that explanation in the changelog and
drop use proper "slab" prefix instead of the confusing "LLVMLinux"
prefix in the subject line.

- Pekka

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

RE: [PATCH 1/5] LLVMLinux: Correct size_index table before replacing the bootstrap kmem_cache_node.

[Daniel Sanders]

> -----Original Message-----
> From: penberg@gmail.com [mailto:penberg@gmail.com] On Behalf Of
> Pekka Enberg
> Sent: 04 February 2015 20:42
> To: Daniel Sanders
> Cc: Christoph Lameter; David Rientjes; Joonsoo Kim; Andrew Morton; linux-
> mm@kvack.org; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH 1/5] LLVMLinux: Correct size_index table before
> replacing the bootstrap kmem_cache_node.
> 
> On Wed, Feb 4, 2015 at 10:38 PM, Daniel Sanders
> <Daniel.Sanders@imgtec.com> wrote:
> > I don't believe the bug to be LLVM specific but GCC doesn't normally
> encounter the problem. I haven't been able to identify exactly what GCC is
> doing better (probably inlining) but it seems that GCC is managing to
> optimize  to the point that it eliminates the problematic allocations. This
> theory is supported by the fact that GCC can be made to fail in the same way
> by changing inline, __inline, __inline__, and __always_inline in
> include/linux/compiler-gcc.h such that they don't actually inline things.
> 
> OK, makes sense. Please include that explanation in the changelog and
> drop use proper "slab" prefix instead of the confusing "LLVMLinux"
> prefix in the subject line.
> 
> - Pekka

Sure. I've just updated the patch with those changes.