mm, vmalloc: fix vmalloc users tracking properly

Commit 1f5307b1e094 ("mm, vmalloc: properly track vmalloc users") has
pulled asm/pgtable.h include dependency to linux/vmalloc.h and that
turned out to be a bad idea for some architectures. E.g. m68k fails
with

In file included from arch/m68k/include/asm/pgtable_mm.h:145:0,
from arch/m68k/include/asm/pgtable.h:4,
from include/linux/vmalloc.h:9,
from arch/m68k/kernel/module.c:9:
arch/m68k/include/asm/mcf_pgtable.h: In function 'nocache_page':
>> arch/m68k/include/asm/mcf_pgtable.h:339:43: error: 'init_mm' undeclared (first use in this function)
#define pgd_offset_k(address) pgd_offset(&init_mm, address)

as spotted by kernel build bot. nios2 fails for other reason

In file included from include/asm-generic/io.h:767:0,
from arch/nios2/include/asm/io.h:61,
from include/linux/io.h:25,
from arch/nios2/include/asm/pgtable.h:18,
from include/linux/mm.h:70,
from include/linux/pid_namespace.h:6,
from include/linux/ptrace.h:9,
from arch/nios2/include/uapi/asm/elf.h:23,
from arch/nios2/include/asm/elf.h:22,
from include/linux/elf.h:4,
from include/linux/module.h:15,
from init/main.c:16:
include/linux/vmalloc.h: In function '__vmalloc_node_flags':
include/linux/vmalloc.h:99:40: error: 'PAGE_KERNEL' undeclared (first use in this function); did you mean 'GFP_KERNEL'?

which is due to the newly added #include <asm/pgtable.h>, which on nios2
includes <linux/io.h> and thus <asm/io.h> and <asm-generic/io.h> which
again includes <linux/vmalloc.h>.

Tweaking that around just turns out a bigger headache than necessary.
This patch reverts 1f5307b1e094 and reimplements the original fix in a
different way. __vmalloc_node_flags can stay static inline which will
cover vmalloc* functions. We only have one external user
(kvmalloc_node) and we can export __vmalloc_node_flags_caller and
provide the caller directly. This is much simpler and it doesn't really
need any games with header files.

[[e-mail]: coding-style fixes]
[[e-mail]: revert old comment]
Link: http://lkml.kernel.org/r/[e-mail]
Fixes: 1f5307b1e094 ("mm, vmalloc: properly track vmalloc users")
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Michal Hocko <[e-mail]>
Cc: Tobias Klauser <[e-mail]>
Cc: Geert Uytterhoeven <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

include/linux/vmalloc.h

···
 #include <linux/list.h>
 #include <linux/llist.h>
 #include <asm/page.h>		/* pgprot_t */
-#include <asm/pgtable.h>	/* PAGE_KERNEL */
 #include <linux/rbtree.h>
 
 struct vm_area_struct;		/* vma defining user mapping in mm_types.h */
···
 			const void *caller);
 #ifndef CONFIG_MMU
 extern void *__vmalloc_node_flags(unsigned long size, int node, gfp_t flags);
-#else
-extern void *__vmalloc_node(unsigned long size, unsigned long align,
-			    gfp_t gfp_mask, pgprot_t prot,
-			    int node, const void *caller);
-
-/*
- * We really want to have this inlined due to caller tracking. This
- * function is used by the highlevel vmalloc apis and so we want to track
- * their callers and inlining will achieve that.
- */
-static inline void *__vmalloc_node_flags(unsigned long size,
-					int node, gfp_t flags)
+static inline void *__vmalloc_node_flags_caller(unsigned long size, int node,
+						gfp_t flags, void *caller)
 {
-	return __vmalloc_node(size, 1, flags, PAGE_KERNEL,
-					node, __builtin_return_address(0));
+	return __vmalloc_node_flags(size, node, flags);
 }
+#else
+extern void *__vmalloc_node_flags_caller(unsigned long size,
+					 int node, gfp_t flags, void *caller);
 #endif
 
 extern void vfree(const void *addr);

mm/util.c

···
 	if (ret || size <= PAGE_SIZE)
 		return ret;
 
-	return __vmalloc_node_flags(size, node, flags);
+	return __vmalloc_node_flags_caller(size, node, flags,
+			__builtin_return_address(0));
 }
 EXPORT_SYMBOL(kvmalloc_node);
 

mm/vmalloc.c

···
 }
 EXPORT_SYMBOL(vmap);
 
+static void *__vmalloc_node(unsigned long size, unsigned long align,
+			    gfp_t gfp_mask, pgprot_t prot,
+			    int node, const void *caller);
 static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
 				 pgprot_t prot, int node)
 {
···
  *	with mm people.
  *
  */
-void *__vmalloc_node(unsigned long size, unsigned long align,
+static void *__vmalloc_node(unsigned long size, unsigned long align,
 			    gfp_t gfp_mask, pgprot_t prot,
 			    int node, const void *caller)
 {
···
 				__builtin_return_address(0));
 }
 EXPORT_SYMBOL(__vmalloc);
+
+static inline void *__vmalloc_node_flags(unsigned long size,
+					int node, gfp_t flags)
+{
+	return __vmalloc_node(size, 1, flags, PAGE_KERNEL,
+					node, __builtin_return_address(0));
+}
+
+
+void *__vmalloc_node_flags_caller(unsigned long size, int node, gfp_t flags,
+				  void *caller)
+{
+	return __vmalloc_node(size, 1, flags, PAGE_KERNEL, node, caller);
+}
 
 /**
  *	vmalloc  -  allocate virtually contiguous memory