Commit 44405099 authored by Long Li's avatar Long Li Committed by Linus Torvalds
Browse files

mm, slab: check GFP_SLAB_BUG_MASK before alloc_pages in kmalloc_order 



kmalloc cannot allocate memory from HIGHMEM.  Allocating large amounts of
memory currently bypasses the check and will simply leak the memory when
page_address() returns NULL.  To fix this, factor the GFP_SLAB_BUG_MASK
check out of slab & slub, and call it from kmalloc_order() as well.  In
order to make the code clear, the warning message is put in one place.

Signed-off-by: default avatarLong Li <lonuxli.64@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: default avatarPekka Enberg <penberg@kernel.org>
Acked-by: default avatarDavid Rientjes <rientjes@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Link: http://lkml.kernel.org/r/20200704035027.GA62481@lilong


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent dabc3e29

mm/slab.c

+3 −7
Original line number Diff line number Diff line
@@ -2589,13 +2589,9 @@ static struct page *cache_grow_begin(struct kmem_cache *cachep, 
	 * Be lazy and only check for valid flags here,  keeping it out of the

	 * critical path in kmem_cache_alloc().

	 */

	if (unlikely(flags & GFP_SLAB_BUG_MASK)) {

		gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK;

		flags &= ~GFP_SLAB_BUG_MASK;

		pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n",

				invalid_mask, &invalid_mask, flags, &flags);

		dump_stack();

	}

	if (unlikely(flags & GFP_SLAB_BUG_MASK))

		flags = kmalloc_fix_flags(flags);



	WARN_ON_ONCE(cachep->ctor && (flags & __GFP_ZERO));

	local_flags = flags & (GFP_CONSTRAINT_MASK|GFP_RECLAIM_MASK);

mm/slab.h

+1 −0
Original line number Diff line number Diff line
@@ -152,6 +152,7 @@ void create_kmalloc_caches(slab_flags_t); 
struct kmem_cache *kmalloc_slab(size_t, gfp_t);

#endif



gfp_t kmalloc_fix_flags(gfp_t flags);



/* Functions provided by the slab allocators */

int __kmem_cache_create(struct kmem_cache *, slab_flags_t flags);

mm/slab_common.c

+17 −0
Original line number Diff line number Diff line
@@ -26,6 +26,8 @@ 
#define CREATE_TRACE_POINTS

#include <trace/events/kmem.h>



#include "internal.h"



#include "slab.h"



enum slab_state slab_state;
@@ -1332,6 +1334,18 @@ void __init create_kmalloc_caches(slab_flags_t flags) 
}

#endif /* !CONFIG_SLOB */



gfp_t kmalloc_fix_flags(gfp_t flags)

{

	gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK;



	flags &= ~GFP_SLAB_BUG_MASK;

	pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n",

			invalid_mask, &invalid_mask, flags, &flags);

	dump_stack();



	return flags;

}



/*

 * To avoid unnecessary overhead, we pass through large allocation requests

 * directly to the page allocator. We use __GFP_COMP, because we will need to
@@ -1342,6 +1356,9 @@ void *kmalloc_order(size_t size, gfp_t flags, unsigned int order) 
	void *ret = NULL;

	struct page *page;



	if (unlikely(flags & GFP_SLAB_BUG_MASK))

		flags = kmalloc_fix_flags(flags);



	flags |= __GFP_COMP;

	page = alloc_pages(flags, order);

	if (likely(page)) {

mm/slub.c

+2 −7
Original line number Diff line number Diff line
@@ -1745,13 +1745,8 @@ out: 


static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)

{

	if (unlikely(flags & GFP_SLAB_BUG_MASK)) {

		gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK;

		flags &= ~GFP_SLAB_BUG_MASK;

		pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n",

				invalid_mask, &invalid_mask, flags, &flags);

		dump_stack();

	}

	if (unlikely(flags & GFP_SLAB_BUG_MASK))

		flags = kmalloc_fix_flags(flags);



	return allocate_slab(s,

		flags & (GFP_RECLAIM_MASK | GFP_CONSTRAINT_MASK), node);

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