From 964cf35c88f93b4927dbc4e950dfa4d880c7f9d1 Mon Sep 17 00:00:00 2001
From: Nick Piggin <npiggin@suse.de>
Date: Mon, 15 Jun 2009 13:35:10 +0300
Subject: SLUB: Fix early boot GFP_DMA allocations
Recent change to use slab allocations earlier exposed a bug where
SLUB can call schedule_work and try to call sysfs before it is
safe to do so.
Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Tested-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
---
mm/slub.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)
(limited to 'mm')
diff --git a/mm/slub.c b/mm/slub.c
index 30354bfeb43d..dcbfda0b02ed 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2610,6 +2610,7 @@ static noinline struct kmem_cache *dma_kmalloc_cache(int index, gfp_t flags)
struct kmem_cache *s;
char *text;
size_t realsize;
+ unsigned long slabflags;
s = kmalloc_caches_dma[index];
if (s)
@@ -2631,9 +2632,18 @@ static noinline struct kmem_cache *dma_kmalloc_cache(int index, gfp_t flags)
(unsigned int)realsize);
s = kmalloc(kmem_size, flags & ~SLUB_DMA);
+ /*
+ * Must defer sysfs creation to a workqueue because we don't know
+ * what context we are called from. Before sysfs comes up, we don't
+ * need to do anything because our sysfs initcall will start by
+ * adding all existing slabs to sysfs.
+ */
+ slabflags = SLAB_CACHE_DMA;
+ if (slab_state >= SYSFS)
+ slabflags |= __SYSFS_ADD_DEFERRED;
+
if (!s || !text || !kmem_cache_open(s, flags, text,
- realsize, ARCH_KMALLOC_MINALIGN,
- SLAB_CACHE_DMA|__SYSFS_ADD_DEFERRED, NULL)) {
+ realsize, ARCH_KMALLOC_MINALIGN, slabflags, NULL)) {
kfree(s);
kfree(text);
goto unlock_out;
@@ -2642,7 +2652,8 @@ static noinline struct kmem_cache *dma_kmalloc_cache(int index, gfp_t flags)
list_add(&s->list, &slab_caches);
kmalloc_caches_dma[index] = s;
- schedule_work(&sysfs_add_work);
+ if (slab_state >= SYSFS)
+ schedule_work(&sysfs_add_work);
unlock_out:
up_write(&slub_lock);
--
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