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authorSteven Rostedt <rostedt@goodmis.org>2012-07-30 14:42:48 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-07-30 17:25:21 -0700
commitfd4b616b0fbb77e3f349e7d60914f2b7c7e39f9c (patch)
treea0cc595c7680bd08467fb803738d534cfa8f150e /kernel/sysctl.c
parentc1d7e01d7877a397655277a920aeaa3830ed9461 (diff)
downloadlwn-fd4b616b0fbb77e3f349e7d60914f2b7c7e39f9c.tar.gz
lwn-fd4b616b0fbb77e3f349e7d60914f2b7c7e39f9c.zip
sysctl: suppress kmemleak messages
register_sysctl_table() is a strange function, as it makes internal allocations (a header) to register a sysctl_table. This header is a handle to the table that is created, and can be used to unregister the table. But if the table is permanent and never unregistered, the header acts the same as a static variable. Unfortunately, this allocation of memory that is never expected to be freed fools kmemleak in thinking that we have leaked memory. For those sysctl tables that are never unregistered, and have no pointer referencing them, kmemleak will think that these are memory leaks: unreferenced object 0xffff880079fb9d40 (size 192): comm "swapper/0", pid 0, jiffies 4294667316 (age 12614.152s) 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 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<ffffffff8146b590>] kmemleak_alloc+0x73/0x98 [<ffffffff8110a935>] kmemleak_alloc_recursive.constprop.42+0x16/0x18 [<ffffffff8110b852>] __kmalloc+0x107/0x153 [<ffffffff8116fa72>] kzalloc.constprop.8+0xe/0x10 [<ffffffff811703c9>] __register_sysctl_paths+0xe1/0x160 [<ffffffff81170463>] register_sysctl_paths+0x1b/0x1d [<ffffffff8117047d>] register_sysctl_table+0x18/0x1a [<ffffffff81afb0a1>] sysctl_init+0x10/0x14 [<ffffffff81b05a6f>] proc_sys_init+0x2f/0x31 [<ffffffff81b0584c>] proc_root_init+0xa5/0xa7 [<ffffffff81ae5b7e>] start_kernel+0x3d0/0x40a [<ffffffff81ae52a7>] x86_64_start_reservations+0xae/0xb2 [<ffffffff81ae53ad>] x86_64_start_kernel+0x102/0x111 [<ffffffffffffffff>] 0xffffffffffffffff The sysctl_base_table used by sysctl itself is one such instance that registers the table to never be unregistered. Use kmemleak_not_leak() to suppress the kmemleak false positive. Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/sysctl.c')
-rw-r--r--kernel/sysctl.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index b46f496405e4..97186b99b0e4 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -30,6 +30,7 @@
#include <linux/security.h>
#include <linux/ctype.h>
#include <linux/kmemcheck.h>
+#include <linux/kmemleak.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kernel.h>
@@ -1556,7 +1557,10 @@ static struct ctl_table dev_table[] = {
int __init sysctl_init(void)
{
- register_sysctl_table(sysctl_base_table);
+ struct ctl_table_header *hdr;
+
+ hdr = register_sysctl_table(sysctl_base_table);
+ kmemleak_not_leak(hdr);
return 0;
}