slab,slub: don't enable interrupts during early boot
As explained by Benjamin Herrenschmidt:
Oh and btw, your patch alone doesn't fix powerpc, because it's missing
a whole bunch of GFP_KERNEL's in the arch code... You would have to
grep the entire kernel for things that check slab_is_available() and
even then you'll be missing some.
For example, slab_is_available() didn't always exist, and so in the
early days on powerpc, we used a mem_init_done global that is set form
mem_init() (not perfect but works in practice). And we still have code
using that to do the test.
Therefore, mask out __GFP_WAIT, __GFP_IO, and __GFP_FS in the slab allocators
in early boot code to avoid enabling interrupts.
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 0bbc15f..3760e7c 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -85,6 +85,9 @@
__GFP_NOWARN|__GFP_REPEAT|__GFP_NOFAIL|\
__GFP_NORETRY|__GFP_NOMEMALLOC)
+/* Control slab gfp mask during early boot */
+#define SLAB_GFP_BOOT_MASK __GFP_BITS_MASK & ~(__GFP_WAIT|__GFP_IO|__GFP_FS)
+
/* Control allocation constraints */
#define GFP_CONSTRAINT_MASK (__GFP_HARDWALL|__GFP_THISNODE)
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 4880306..219b8fb 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -319,4 +319,6 @@
return kmalloc_node(size, flags | __GFP_ZERO, node);
}
+void __init kmem_cache_init_late(void);
+
#endif /* _LINUX_SLAB_H */
diff --git a/include/linux/slob_def.h b/include/linux/slob_def.h
index 0ec00b3..bb5368d 100644
--- a/include/linux/slob_def.h
+++ b/include/linux/slob_def.h
@@ -34,4 +34,9 @@
return kmalloc(size, flags);
}
+static inline void kmem_cache_init_late(void)
+{
+ /* Nothing to do */
+}
+
#endif /* __LINUX_SLOB_DEF_H */
diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index be5d40c..4dcbc2c 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -302,4 +302,6 @@
}
#endif
+void __init kmem_cache_init_late(void);
+
#endif /* _LINUX_SLUB_DEF_H */
diff --git a/init/main.c b/init/main.c
index b3e8f14..f6204f7 100644
--- a/init/main.c
+++ b/init/main.c
@@ -640,6 +640,7 @@
"enabled early\n");
early_boot_irqs_on();
local_irq_enable();
+ kmem_cache_init_late();
/*
* HACK ALERT! This is early. We're enabling the console before
diff --git a/mm/slab.c b/mm/slab.c
index cd76964..453efcb 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -304,6 +304,12 @@
};
/*
+ * The slab allocator is initialized with interrupts disabled. Therefore, make
+ * sure early boot allocations don't accidentally enable interrupts.
+ */
+static gfp_t slab_gfp_mask __read_mostly = SLAB_GFP_BOOT_MASK;
+
+/*
* Need this for bootstrapping a per node allocator.
*/
#define NUM_INIT_LISTS (3 * MAX_NUMNODES)
@@ -1654,6 +1660,14 @@
*/
}
+void __init kmem_cache_init_late(void)
+{
+ /*
+ * Interrupts are enabled now so all GFP allocations are safe.
+ */
+ slab_gfp_mask = __GFP_BITS_MASK;
+}
+
static int __init cpucache_init(void)
{
int cpu;
@@ -3354,6 +3368,8 @@
unsigned long save_flags;
void *ptr;
+ flags &= slab_gfp_mask;
+
lockdep_trace_alloc(flags);
if (slab_should_failslab(cachep, flags))
@@ -3434,6 +3450,8 @@
unsigned long save_flags;
void *objp;
+ flags &= slab_gfp_mask;
+
lockdep_trace_alloc(flags);
if (slab_should_failslab(cachep, flags))
diff --git a/mm/slub.c b/mm/slub.c
index 3964d3c..30354bf 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -178,6 +178,12 @@
SYSFS /* Sysfs up */
} slab_state = DOWN;
+/*
+ * The slab allocator is initialized with interrupts disabled. Therefore, make
+ * sure early boot allocations don't accidentally enable interrupts.
+ */
+static gfp_t slab_gfp_mask __read_mostly = SLAB_GFP_BOOT_MASK;
+
/* A list of all slab caches on the system */
static DECLARE_RWSEM(slub_lock);
static LIST_HEAD(slab_caches);
@@ -1595,6 +1601,8 @@
unsigned long flags;
unsigned int objsize;
+ gfpflags &= slab_gfp_mask;
+
lockdep_trace_alloc(gfpflags);
might_sleep_if(gfpflags & __GFP_WAIT);
@@ -3104,6 +3112,14 @@
nr_cpu_ids, nr_node_ids);
}
+void __init kmem_cache_init_late(void)
+{
+ /*
+ * Interrupts are enabled now so all GFP allocations are safe.
+ */
+ slab_gfp_mask = __GFP_BITS_MASK;
+}
+
/*
* Find a mergeable slab cache
*/