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[Trusty,SRU] Fix kmalloc slab creation sequence

Message ID 1437398210-15107-2-git-send-email-gavin.guo@canonical.com
State New
Headers show

Commit Message

Gavin Guo July 20, 2015, 1:16 p.m. UTC 
From: Christoph Lameter <cl@linux.com>

BugLink: http://bugs.launchpad.net/bugs/1475204

This patch restores the slab creation sequence that was broken by commit
4066c33d0308f8 and also reverts the portions that introduced the
KMALLOC_LOOP_XXX macros. Those can never really work since the slab creation
is much more complex than just going from a minimum to a maximum number.

The latest upstream kernel boots cleanly on my machine with a 64 bit x86
configuration under KVM using either SLAB or SLUB.

Fixes: 4066c33d0308f8 ("support the slub_debug boot option")
Reported-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(backported from commit a9730fca9946f3697410479e0ef1bd759ba00a77)
Signed-off-by: Gavin Guo <gavin.guo@canonical.com>

Conflicts:
	mm/slab_common.c
---
 include/linux/slab.h | 22 ----------------------
 mm/slab_common.c     | 33 +++++++++++++++++----------------
 2 files changed, 17 insertions(+), 38 deletions(-)
diff mbox

Patch

diff --git a/include/linux/slab.h b/include/linux/slab.h
index 52b0e65..1e2f4fe 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -152,30 +152,8 @@  size_t ksize(const void *);
 #define ARCH_KMALLOC_MINALIGN ARCH_DMA_MINALIGN
 #define KMALLOC_MIN_SIZE ARCH_DMA_MINALIGN
 #define KMALLOC_SHIFT_LOW ilog2(ARCH_DMA_MINALIGN)
-/*
- * The KMALLOC_LOOP_LOW is the definition for the for loop index start number
- * to create the kmalloc_caches object in create_kmalloc_caches(). The first
- * and the second are 96 and 192. You can see that in the kmalloc_index(), if
- * the KMALLOC_MIN_SIZE <= 32, then return 1 (96). If KMALLOC_MIN_SIZE <= 64,
- * then return 2 (192). If the KMALLOC_MIN_SIZE is bigger than 64, we don't
- * need to initialize 96 and 192. Go directly to start the KMALLOC_SHIFT_LOW.
- */
-#if KMALLOC_MIN_SIZE <= 32
-#define KMALLOC_LOOP_LOW 1
-#elif KMALLOC_MIN_SIZE <= 64
-#define KMALLOC_LOOP_LOW 2
-#else
-#define KMALLOC_LOOP_LOW KMALLOC_SHIFT_LOW
-#endif
-
 #else
 #define ARCH_KMALLOC_MINALIGN __alignof__(unsigned long long)
-/*
- * The KMALLOC_MIN_SIZE of slub/slab/slob is 2^3/2^5/2^3. So, even slab is used.
- * The KMALLOC_MIN_SIZE <= 32. The kmalloc-96 and kmalloc-192 should also be
- * initialized.
- */
-#define KMALLOC_LOOP_LOW 1
 #endif
 
 #ifdef CONFIG_SLOB
diff --git a/mm/slab_common.c b/mm/slab_common.c
index d339b9f..88a0ebb 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -422,6 +422,12 @@  static struct {
 	{"kmalloc-67108864", 67108864}
 };
 
+static void new_kmalloc_cache(int idx, unsigned long flags)
+{
+	kmalloc_caches[idx] = create_kmalloc_cache(kmalloc_info[idx].name,
+					kmalloc_info[idx].size, flags);
+}
+
 /*
  * Create the kmalloc array. Some of the regular kmalloc arrays
  * may already have been created because they were needed to
@@ -472,25 +478,20 @@  void __init create_kmalloc_caches(unsigned long flags)
 		for (i = 128 + 8; i <= 192; i += 8)
 			size_index[size_index_elem(i)] = 8;
 	}
-	for (i = KMALLOC_LOOP_LOW; i <= KMALLOC_SHIFT_HIGH; i++) {
-		if (!kmalloc_caches[i]) {
-			kmalloc_caches[i] = create_kmalloc_cache(
-						kmalloc_info[i].name,
-						kmalloc_info[i].size,
-						flags);
-		}
+
+	for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) {
+		if (!kmalloc_caches[i])
+			new_kmalloc_cache(i, flags);
 
 		/*
-		 * "i == 2" is the "kmalloc-192" case which is the last special
-		 * case for initialization and it's the point to jump to
-		 * allocate the minimize size of the object. In slab allocator,
-		 * the KMALLOC_SHIFT_LOW = 5. So, it needs to skip 2^3 and 2^4
-		 * and go straight to allocate 2^5. If the ARCH_DMA_MINALIGN is
-		 * defined, it may be larger than 2^5 and here is also the
-		 * trick to skip the empty gap.
+		 * Caches that are not of the two-to-the-power-of size.
+		 * These have to be created immediately after the
+		 * earlier power of two caches
 		 */
-		if (i == 2)
-			i = (KMALLOC_SHIFT_LOW - 1);
+		if (KMALLOC_MIN_SIZE <= 32 && !kmalloc_caches[1] && i == 6)
+			new_kmalloc_cache(1, flags);
+		if (KMALLOC_MIN_SIZE <= 64 && !kmalloc_caches[2] && i == 7)
+			new_kmalloc_cache(2, flags);
 	}
 
 	/* Kmalloc array is now usable */