mm: Extend gfp masking to the page allocator

The page allocator also needs the masking of gfp flags during boot,
so this moves it out of slab/slub and uses it with the page allocator
as well.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/gfp.h

@@ -99,7 +99,7 @@ struct vm_area_struct;
 			__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)
+#define GFP_BOOT_MASK __GFP_BITS_MASK & ~(__GFP_WAIT|__GFP_IO|__GFP_FS)
 
 /* Control allocation constraints */
 #define GFP_CONSTRAINT_MASK (__GFP_HARDWALL|__GFP_THISNODE)
@@ -348,4 +348,11 @@ static inline void oom_killer_enable(void)
 	oom_killer_disabled = false;
 }
 
+extern gfp_t gfp_allowed_mask;
+
+static inline void set_gfp_allowed_mask(gfp_t mask)
+{
+	gfp_allowed_mask = mask;
+}
+
 #endif /* __LINUX_GFP_H */

init/main.c

@@ -642,6 +642,10 @@ asmlinkage void __init start_kernel(void)
 				 "enabled early\n");
 	early_boot_irqs_on();
 	local_irq_enable();
+
+	/* Interrupts are enabled now so all GFP allocations are safe. */
+	set_gfp_allowed_mask(__GFP_BITS_MASK);
+
 	kmem_cache_init_late();
 
 	/*

mm/page_alloc.c

@@ -73,6 +73,7 @@ unsigned long totalram_pages __read_mostly;
 unsigned long totalreserve_pages __read_mostly;
 unsigned long highest_memmap_pfn __read_mostly;
 int percpu_pagelist_fraction;
+gfp_t gfp_allowed_mask __read_mostly = GFP_BOOT_MASK;
 
 #ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
 int pageblock_order __read_mostly;
@@ -1863,6 +1864,8 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
 	struct page *page;
 	int migratetype = allocflags_to_migratetype(gfp_mask);
 
+	gfp_mask &= gfp_allowed_mask;
+
 	lockdep_trace_alloc(gfp_mask);
 
 	might_sleep_if(gfp_mask & __GFP_WAIT);

mm/slab.c

@@ -304,12 +304,6 @@ struct kmem_list3 {
 	int free_touched;		/* updated without locking */
 };
 
-/*
- * 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.
  */
@@ -1559,11 +1553,6 @@ void __init kmem_cache_init_late(void)
 {
 	struct kmem_cache *cachep;
 
-	/*
-	 * Interrupts are enabled now so all GFP allocations are safe.
-	 */
-	slab_gfp_mask = __GFP_BITS_MASK;
-
 	/* 6) resize the head arrays to their final sizes */
 	mutex_lock(&cache_chain_mutex);
 	list_for_each_entry(cachep, &cache_chain, next)
@@ -3307,7 +3296,7 @@ __cache_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid,
 	unsigned long save_flags;
 	void *ptr;
 
-	flags &= slab_gfp_mask;
+	flags &= gfp_allowed_mask;
 
 	lockdep_trace_alloc(flags);
 
@@ -3392,7 +3381,7 @@ __cache_alloc(struct kmem_cache *cachep, gfp_t flags, void *caller)
 	unsigned long save_flags;
 	void *objp;
 
-	flags &= slab_gfp_mask;
+	flags &= gfp_allowed_mask;
 
 	lockdep_trace_alloc(flags);
 

mm/slub.c

@@ -179,12 +179,6 @@ static enum {
 	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);
@@ -1692,7 +1686,7 @@ static __always_inline void *slab_alloc(struct kmem_cache *s,
 	unsigned long flags;
 	unsigned int objsize;
 
-	gfpflags &= slab_gfp_mask;
+	gfpflags &= gfp_allowed_mask;
 
 	lockdep_trace_alloc(gfpflags);
 	might_sleep_if(gfpflags & __GFP_WAIT);
@@ -3220,10 +3214,6 @@ void __init kmem_cache_init(void)
 
 void __init kmem_cache_init_late(void)
 {
-	/*
-	 * Interrupts are enabled now so all GFP allocations are safe.
-	 */
-	slab_gfp_mask = __GFP_BITS_MASK;
 }
 
 /*