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SubjectRe: V3.10-rc1 memory leak
On Wed, May 15, 2013 at 01:57:03AM +0100, Steven Rostedt wrote:
> On Tue, 2013-05-14 at 17:20 -0400, Steven Rostedt wrote:
> > On Tue, 2013-05-14 at 16:10 -0500, Larry Finger wrote:
> > > On 05/14/2013 03:30 PM, Catalin Marinas wrote:
> > > >
> > > > I just got a patch today:
> > > >
> > > > https://lkml.org/lkml/2013/5/10/607
> > > >
> > > > which could be related. If Rusty doesn't push it I'll do. But please let
> > > > me know if it does not solve the problem.
> > >
> > > This patch fixes my problem. Now I can see the next new problem reported by
> > > kmemleak. :)
> > >
> > > Thanks to you and Jianpeng Ma,
> > >
> > > Larry
> > >
> >
> > It goes away on my testing too. So you can add:
> >
> > Tested-by: Steven Rostedt <rostedt@goodmis.org>
> >
>
> But we are not out of the woods yet. I'm also getting these:
>
> unreferenced object 0xffff88007800efc0 (size 32):
> comm "modprobe", pid 1309, jiffies 4294697214 (age 188.356s)
> hex dump (first 32 bytes):
> 00 00 00 00 00 00 00 00 a8 d0 3e a0 ff ff ff ff ..........>.....
> 30 d1 3e a0 ff ff ff ff 00 00 00 00 00 00 00 00 0.>.............
> backtrace:
> [<ffffffff814b535f>] kmemleak_alloc+0x73/0x98
> [<ffffffff8112003c>] kmemleak_alloc_recursive.constprop.42+0x16/0x18
> [<ffffffff81120dfe>] kmem_cache_alloc_trace+0xc0/0x10b
> [<ffffffff810e5478>] jump_label_module_notify+0xce/0x1d5
> [<ffffffff814d221d>] notifier_call_chain+0x37/0x63
> [<ffffffff8105c29c>] __blocking_notifier_call_chain+0x4b/0x60
> [<ffffffff8105c2c5>] blocking_notifier_call_chain+0x14/0x16
> [<ffffffff8108fe83>] load_module+0x1d7f/0x20d3
> [<ffffffff810902b0>] SyS_init_module+0xd9/0xdb
> [<ffffffff814d5754>] tracesys+0xdd/0xe2
> [<ffffffffffffffff>] 0xffffffffffffffff
>
> Where it points to the allocation in jump_label_add_module() where it
> allocates the jlm. And this does get freed in jump_label_del_module().

Indeed, another false positive (I should use modules more often ;).
Here's a patch:

---------------------8<----------------------------------

From 0621c7e1909ea86bf8499a0ffe5ea59d1007ee8c Mon Sep 17 00:00:00 2001
From: Catalin Marinas <catalin.marinas@arm.com>
Date: Wed, 15 May 2013 15:30:46 +0100
Subject: [PATCH] kmemleak: Scan the jump label module section

Objects allocated in jump_label_add_module() are currently reported as
leaks, though the pointers are stored in the module jump label section.
This patch informs kmemleak that this section needs to be scanned.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reported-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/module.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/kernel/module.c b/kernel/module.c
index b049939..ff83711 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2764,6 +2764,13 @@ static void find_module_sections(struct module *mod, struct load_info *info)
mod->jump_entries = section_objs(info, "__jump_table",
sizeof(*mod->jump_entries),
&mod->num_jump_entries);
+ /*
+ * This section contains pointers to objects allocated in
+ * jump_label_add_module() and not scanning it leads to false
+ * positives.
+ */
+ kmemleak_scan_area(mod->jump_entries, sizeof(*mod->jump_entries) *
+ mod->num_jump_entries, GFP_KERNEL);
#endif
#ifdef CONFIG_EVENT_TRACING
mod->trace_events = section_objs(info, "_ftrace_events",

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