Re: [PATCH] mm, vmalloc: fix vmalloc users tracking properly

[Michal Hocko <mhocko@kernel.org>]

Sigh. I've apparently managed to screw up again. This should address the
nommu breakage reported by 0-day.
---
>From 95d49bf93ae4467f3f918520ec03b3596e5b36cc Mon Sep 17 00:00:00 2001
From: Michal Hocko <mhocko@suse.com>
Date: Tue, 9 May 2017 16:27:39 +0200
Subject: [PATCH] mm, vmalloc: fix vmalloc users tracking properly

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.

Fixes: 1f5307b1e094 ("mm, vmalloc: properly track vmalloc users")
Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 include/linux/vmalloc.h | 17 ++++++-----------
 mm/util.c               |  3 ++-
 mm/vmalloc.c            | 18 +++++++++++++++++-
 3 files changed, 25 insertions(+), 13 deletions(-)

diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 0328ce003992..268b3a919a5f 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -6,7 +6,6 @@
 #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 */
@@ -83,22 +82,18 @@ extern void *__vmalloc_node_range(unsigned long size, unsigned long align,
 			const void *caller);
 #ifndef CONFIG_MMU
 extern 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_flags(size, node, 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)
-{
-	return __vmalloc_node(size, 1, flags, PAGE_KERNEL,
-					node, __builtin_return_address(0));
-}
+extern void *__vmalloc_node_flags_caller(unsigned long size,
+					int node, gfp_t flags, void* caller);
 #endif
 
 extern void vfree(const void *addr);
diff --git a/mm/util.c b/mm/util.c
index 718154debc87..464df3489903 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -382,7 +382,8 @@ void *kvmalloc_node(size_t size, gfp_t flags, int node)
 	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);
 
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 1dda6d8a200a..4a1de70e68e1 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1649,6 +1649,9 @@ void *vmap(struct page **pages, unsigned int count,
 }
 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)
 {
@@ -1791,7 +1794,7 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align,
  *	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)
 {
@@ -1806,6 +1809,19 @@ void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
 }
 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
  *	@size:		allocation size
-- 
2.11.0

-- 
Michal Hocko
SUSE Labs