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SubjectRe: [PATCH] mm, vmalloc: properly track vmalloc users
On Wed 03-05-17 08:52:01, kbuild test robot wrote:
> Hi Michal,
>
> [auto build test ERROR on mmotm/master]
> [also build test ERROR on next-20170502]
> [cannot apply to v4.11]
> [if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
>
> url: https://github.com/0day-ci/linux/commits/Michal-Hocko/mm-vmalloc-properly-track-vmalloc-users/20170503-065022
> base: git://git.cmpxchg.org/linux-mmotm.git master
> config: m68k-m5475evb_defconfig (attached as .config)
> compiler: m68k-linux-gcc (GCC) 4.9.0
> reproduce:
> wget https://raw.githubusercontent.com/01org/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
> chmod +x ~/bin/make.cross
> # save the attached .config to linux build tree
> make.cross ARCH=m68k
>
> All error/warnings (new ones prefixed by >>):
>
> 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:

OK, I was little bit worried to pull pgtable.h include in, but my cross
compile build test battery didn't show any issues. I do not have m68k
there though. So let's just do this differently. The following updated
patch hasn't passed the full build test battery but it should just work.

Thanks for your testing.
---
From 33a6239135cb444654f48d5e942e7f34898e24ea Mon Sep 17 00:00:00 2001
From: Michal Hocko <mhocko@suse.com>
Date: Tue, 2 May 2017 11:18:29 +0200
Subject: [PATCH] mm, vmalloc: properly track vmalloc users

__vmalloc_node_flags used to be static inline but this has changed by
"mm: introduce kv[mz]alloc helpers" because kvmalloc_node needs to use
it as well and the code is outside of the vmalloc proper. I haven't
realized that changing this will lead to a subtle bug though. The
function is responsible to track the caller as well. This caller is
then printed by /proc/vmallocinfo. If __vmalloc_node_flags is not inline
then we would get only direct users of __vmalloc_node_flags as callers
(e.g. v[mz]alloc) which reduces usefulness of this debugging feature
considerably. It simply doesn't help to see that the given range belongs
to vmalloc as a caller:
0xffffc90002c79000-0xffffc90002c7d000 16384 vmalloc+0x16/0x18 pages=3 vmalloc N0=3
0xffffc90002c81000-0xffffc90002c85000 16384 vmalloc+0x16/0x18 pages=3 vmalloc N1=3
0xffffc90002c8d000-0xffffc90002c91000 16384 vmalloc+0x16/0x18 pages=3 vmalloc N1=3
0xffffc90002c95000-0xffffc90002c99000 16384 vmalloc+0x16/0x18 pages=3 vmalloc N1=3

We really want to catch the _caller_ of the vmalloc function. Fix this
issue by making __vmalloc_node_flags static inline again and export
__vmalloc_node_flags_caller for kvmalloc_node().

Signed-off-by: Michal Hocko <mhocko@suse.com>
---
include/linux/vmalloc.h | 16 +++++++++++++++-
mm/util.c | 3 ++-
mm/vmalloc.c | 8 +++++++-
3 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 46991ad3ddd5..4a0fabeb1e92 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -80,7 +80,21 @@ extern void *__vmalloc_node_range(unsigned long size, unsigned long align,
unsigned long start, unsigned long end, gfp_t gfp_mask,
pgprot_t prot, unsigned long vm_flags, int node,
const void *caller);
-extern void *__vmalloc_node_flags(unsigned long size, int node, gfp_t flags);
+#ifndef CONFIG_MMU
+extern void *__vmalloc_node_flags_caller(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
+/*
+ * 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.
+ */
+extern void *__vmalloc_node_flags_caller(unsigned long size,
+ int node, gfp_t flags, void* caller);
+#endif

extern void vfree(const void *addr);
extern void vfree_atomic(const void *addr);
diff --git a/mm/util.c b/mm/util.c
index 3022051da938..c35e5870921d 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -380,7 +380,8 @@ 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 65912eb93a2c..1a97d4a31406 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1809,13 +1809,19 @@ void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
}
EXPORT_SYMBOL(__vmalloc);

-void *__vmalloc_node_flags(unsigned long size,
+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

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