linux-kernel - Re: kmemleaks on ac3b43283923 ("module: replace module_layout with module

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Message-ID: <ZCcwkCBgyxOgROVu@bombadil.infradead.org>
Date:   Fri, 31 Mar 2023 12:12:16 -0700
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     jim.cromie@...il.com
Cc:     linux-modules@...r.kernel.org, song@...nel.org,
        LKML <linux-kernel@...r.kernel.org>,
        Jason Baron <jbaron@...mai.com>,
        Greg KH <gregkh@...uxfoundation.org>
Subject: Re: kmemleaks on ac3b43283923 ("module: replace module_layout with
 module_memory")

On Fri, Mar 31, 2023 at 11:08:23AM -0600, jim.cromie@...il.com wrote:
> :#> uptime
>  09:45:32 up 1 day, 23:07,  0 users,  load average: 0.07, 0.04, 0.01
> :#> uname -a
> Linux (none) 6.3.0-rc1-f2-00001-gac3b43283923 #359 SMP PREEMPT_DYNAMIC
> Wed Mar 29 09:33:11 MDT 2023 x86_64 x86_64 x86_64 GNU/Linux
> 
> the leaks I sent previously might be from/on a different commit,
> heres the relevant one
> 
> fwiw, the config is unremarkable.  it started with
> CONFIG_BUILD_SALT="5.16.8-200.fc35.x86_64"
> then `make localmodconfig` to drop anything I dont have hw for
> then `virtme-configkernel --update` to pick up the 9p,etc config options
> And some extra DEBUG_* options
> If you'd like to see runs with others, or see the config itself, please ask.

If you wanna see things explode

echo 0 > /proc/sys/vm/oom_dump_tasks
./stress-ng --module 20 --module-name xfs

This assumes xfs is not already loaded, and has all dependencies already
loaded. What would test the load_module() path.

If you wanna see if the test is earlier, you can try a module which
is already loaded on your system.

> :#> uname -a
> Linux (none) 6.3.0-rc1-f2-00001-gac3b43283923 #359 SMP PREEMPT_DYNAMIC
> Wed Mar 29 09:33:11 MDT 2023 x86_64 x86_64 x86_64 GNU/Linux
> :#> ./grok_kmemleak -n
> not: bless( {
>   'backtraces' => {
>     '[<0000000058fb276d>] __kmalloc_node_track_caller+0x4a/0x140
>     [<00000000a2f80203>] memdup_user+0x26/0x90
>     [<00000000f7cd3624>] strndup_user+0x3f/0x60
>     [<0000000098fd26c5>] load_module+0x188b/0x20e0

Can you do:

gdb vmlinux
l *(load_module+0x188b)

And provide the output?

> }, 'LeakSet' )
> mods: bless( {
>   'backtraces' => {
>     '[<0000000058fb276d>] __kmalloc_node_track_caller+0x4a/0x140
>     [<00000000ab7b01fd>] kstrdup+0x32/0x60
>     [<000000005ed25b98>] kobject_set_name_vargs+0x1c/0x90
>     [<0000000090fe19ca>] kobject_init_and_add+0x4d/0x90
>     [<0000000045666935>] mod_sysfs_setup+0xa9/0x6e0

Ok that is a specific enough hint. I'll take a review of this sysfs
path see what changed that could break.

>     [<00000000d6f7187b>] load_module+0x1de3/0x20e0
>     [<0000000074361279>] __do_sys_finit_module+0x93/0xf0
>     [<000000004caeb948>] do_syscall_64+0x34/0x80
>     [<000000009f5d036c>] entry_SYSCALL_64_after_hwframe+0x46/0xb0' => 16
>   },

  Luis