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SubjectRe: Possible memory leaks in proc_sysctl.c
Catalin Marinas <catalin.marinas@arm.com> writes:

> Hi Eric,
>
> Following your commit f728019bb (sysctl: register only tables of sysctl
> files), I get several kmemleak reports. They all seem to be header
> allocations with kzalloc() in __register_sysctl_table() and
> __register_sysctl_paths(). The patch isn't simple to quickly figure out
> what may be wrong.

Due to a change in the data structure places where we register the
sysctl permanently and ignore the result from the register_sysctl_...
family of functions now report this leak.

majianpeng has done a good of getting kmemleak_not_leak annotations into
the net tree, and I have one of his patches pending to put into my
sysctl tree (see below).

I don't know if the issue is serious enough to warrant putting the
changes into 3.4 but the patches are trivial.

The pending patch for kernel/sysctl.c

Eric


From 349f2cf150ba9aabdcc24c174f7dab09d3da4508 Mon Sep 17 00:00:00 2001
From: majianpeng <majianpeng@gmail.com>
Date: Tue, 17 Apr 2012 13:45:52 +0800
Subject: [PATCH] sysctl:Remove memleak reports by kmemeleak_not_leak


Signed-off-by: majianpeng <majianpeng@gmail.com>
---
kernel/sysctl.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 4ab1187..136ac3b 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1551,7 +1551,7 @@ static struct ctl_table dev_table[] = {

int __init sysctl_init(void)
{
- register_sysctl_table(sysctl_base_table);
+ kmemleak_not_leak(register_sysctl_table(sysctl_base_table));
return 0;
}


> Tested on an ARM platform with 3.4-rc3.
>
> unreferenced object 0xbf86c380 (size 128):
> comm "swapper/0", pid 0, jiffies 4294937306 (age 69938.200s)
> hex dump (first 32 bytes):
> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> 00 00 00 00 2c eb 4c 80 00 00 00 00 00 00 00 00 ....,.L.........
> backtrace:
> [<800be064>] create_object+0xe8/0x224
> [<800bb120>] __kmalloc+0x118/0x19c
> [<801116b8>] __register_sysctl_paths+0x128/0x1d0
> [<8048a248>] sysctl_init+0xc/0x18
> [<80483810>] start_kernel+0x310/0x32c
> [<60008044>] 0x60008044
> [<ffffffff>] 0xffffffff
> unreferenced object 0xbf862380 (size 64):
> comm "swapper/0", pid 0, jiffies 4294937306 (age 69938.200s)
> hex dump (first 32 bytes):
> 84 bf 4e 80 00 00 00 00 01 00 00 00 01 00 00 00 ..N.............
> 00 00 00 00 00 00 00 00 28 31 4d 80 28 31 4d 80 ........(1M.(1M.
> backtrace:
> [<800be064>] create_object+0xe8/0x224
> [<800bb120>] __kmalloc+0x118/0x19c
> [<80110f5c>] __register_sysctl_table+0x4c/0x468
> [<801114a4>] register_leaf_sysctl_tables+0x12c/0x200
> [<8011151c>] register_leaf_sysctl_tables+0x1a4/0x200
> [<801116e4>] __register_sysctl_paths+0x154/0x1d0
> [<8048a248>] sysctl_init+0xc/0x18
> [<80483810>] start_kernel+0x310/0x32c
> [<60008044>] 0x60008044
> [<ffffffff>] 0xffffffff
> unreferenced object 0xbf8623c0 (size 64):
> comm "swapper/0", pid 0, jiffies 4294937306 (age 69938.200s)
> hex dump (first 32 bytes):
> a8 bf 4e 80 00 00 00 00 01 00 00 00 01 00 00 00 ..N.............
> 00 00 00 00 00 00 00 00 28 31 4d 80 28 31 4d 80 ........(1M.(1M.
> backtrace:
> [<800be064>] create_object+0xe8/0x224
> [<800bb120>] __kmalloc+0x118/0x19c
> [<80110f5c>] __register_sysctl_table+0x4c/0x468
> [<801114a4>] register_leaf_sysctl_tables+0x12c/0x200
> [<8011151c>] register_leaf_sysctl_tables+0x1a4/0x200
> [<801116e4>] __register_sysctl_paths+0x154/0x1d0
> [<8048a248>] sysctl_init+0xc/0x18
> [<80483810>] start_kernel+0x310/0x32c
> [<60008044>] 0x60008044
> [<ffffffff>] 0xffffffff
> unreferenced object 0xbf973380 (size 64):
> comm "swapper/0", pid 1, jiffies 4294937392 (age 69937.350s)
> hex dump (first 32 bytes):
> c0 06 50 80 00 00 00 00 01 00 00 00 01 00 00 00 ..P.............
> 00 00 00 00 c0 06 50 80 28 31 4d 80 28 31 4d 80 ......P.(1M.(1M.
> backtrace:
> [<800be064>] create_object+0xe8/0x224
> [<800bb120>] __kmalloc+0x118/0x19c
> [<80110f5c>] __register_sysctl_table+0x4c/0x468
> [<80111754>] __register_sysctl_paths+0x1c4/0x1d0
> [<8049aa54>] sysctl_core_init+0x1c/0x38
> [<800086dc>] do_one_initcall+0x34/0x17c
> [<804839a0>] kernel_init+0x174/0x21c
> [<8000f978>] kernel_thread_exit+0x0/0x8
> [<ffffffff>] 0xffffffff
> unreferenced object 0xbfa27280 (size 64):
> comm "swapper/0", pid 1, jiffies 4294937393 (age 69937.340s)
> hex dump (first 32 bytes):
> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> 00 00 00 00 80 33 4e 80 00 00 00 00 00 00 00 00 .....3N.........
> backtrace:
> [<800be064>] create_object+0xe8/0x224
> [<800bb120>] __kmalloc+0x118/0x19c
> [<801116b8>] __register_sysctl_paths+0x128/0x1d0
> [<8049c810>] inet_init+0xa8/0x28c
> [<800086dc>] do_one_initcall+0x34/0x17c
> [<804839a0>] kernel_init+0x174/0x21c
> [<8000f978>] kernel_thread_exit+0x0/0x8
> [<ffffffff>] 0xffffffff
> unreferenced object 0xbfa27100 (size 64):
> comm "swapper/0", pid 1, jiffies 4294937393 (age 69937.340s)
> hex dump (first 32 bytes):
> 18 0d 50 80 00 00 00 00 01 00 00 00 01 00 00 00 ..P.............
> 00 00 00 00 00 00 00 00 28 31 4d 80 28 31 4d 80 ........(1M.(1M.
> backtrace:
> [<800be064>] create_object+0xe8/0x224
> [<800bb120>] __kmalloc+0x118/0x19c
> [<80110f5c>] __register_sysctl_table+0x4c/0x468
> [<801114a4>] register_leaf_sysctl_tables+0x12c/0x200
> [<8011151c>] register_leaf_sysctl_tables+0x1a4/0x200
> [<801116e4>] __register_sysctl_paths+0x154/0x1d0
> [<8049c810>] inet_init+0xa8/0x28c
> [<800086dc>] do_one_initcall+0x34/0x17c
> [<804839a0>] kernel_init+0x174/0x21c
> [<8000f978>] kernel_thread_exit+0x0/0x8
> [<ffffffff>] 0xffffffff
>
>
> Thanks.


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