+++ Ravineet Singh [13/05/16 16:15 +0200]:
Thanks for the reply,
I indeed had CONFIG_LIVEPATCH configured, after removing it, it is possible
to unload the kpatch module
via kpatch unload .
Also install/uninstall seems to work fine. Also an installed kpatch module
is auto loaded upon boot.
The only issue I see is; while unloading a kpatch module, a dump from the
kernel is generated (se below).
Any ideas?
regards
/Ravineet
[ 29.144476] kpatch: loaded patch module 'kpatch_0001_Test_kpatch'
[ 37.464348] kpatch: unloaded patch module 'kpatch_0001_Test_kpatch'
[ 37.466345] ------------[ cut here ]------------
[ 37.466742] WARNING: CPU: 4 PID: 1878 at kernel/module.c:1107
module_put+0x95/0xa0
Hm, that looks like some sort of module refcount issue (it's WARNing
in module_put). I am however unable to reproduce the problem with the
kpatch.ko core module under 4.6.0-rc4..
Quick questions: What are you patching in kpatch_0001_Test_kpatch, and
how are you loading/unloading the module? Are you able reproduce the
problem consistently (i.e. it happens every time you unload)? Trying
to figure out if this is just a kernel fluke or if the problem is on
our side.
Thanks,
Jessica
[ 37.467373] Modules linked in: kpatch(O) [last unloaded:
kpatch_0001_Test_kpatch]
[ 37.468034] CPU: 4 PID: 1878 Comm: rmmod Tainted: G W O K
4.6-rc4+ #3
[ 37.468625] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
Bochs 01/01/2011
[ 37.469024] 0000000000000000 ffff88007ba03e10 ffffffff81336508
0000000000000000
[ 37.469024] 0000000000000000 ffff88007ba03e50 ffffffff8105ab51
000004537ba03e30
[ 37.469024] ffff88007b7b7f80 ffffffffa0002640 ffffffffa0017420
ffffffffa0017190
[ 37.469024] Call Trace:
[ 37.469024] [<ffffffff81336508>] dump_stack+0x4d/0x65
[ 37.469024] [<ffffffff8105ab51>] __warn+0xd1/0xf0
[ 37.469024] [<ffffffff8105ac3d>] warn_slowpath_null+0x1d/0x20
[ 37.469024] [<ffffffff810cc345>] module_put+0x95/0xa0
[ 37.469024] [<ffffffff810cc3b1>] module_unload_free+0x41/0xc0
[ 37.469024] [<ffffffff810cdeff>] free_module+0x19f/0x2b0
[ 37.469024] [<ffffffff810ce1bc>] SyS_delete_module+0x1ac/0x230
[ 37.469024] [<ffffffff81002af2>] ? syscall_return_slowpath+0x92/0x100
[ 37.469024] [<ffffffff818d649b>] entry_SYSCALL_64_fastpath+0x13/0x8f
[ 37.475283] ---[ end trace 3b7c7357c1bf21ff ]---
On 25 April 2016 at 19:58, Josh Poimboeuf <[email protected]> wrote:
On Fri, Apr 22, 2016 at 04:00:15PM +0200, Ravineet Singh wrote:
> Hi,
> Not sure if this is the correct forum but I'll try anyway.
> I am looking at the possibility to build kpatch-patches on x86 machines
to
> be deployed in a arm v8 environment.
>
> The first step is to verify kpatch on x86_64 and initially I have a
> couple a hinder.
> I might have missed one or several steps but, it seems like the kpatch
> sysfs entry is not created and hence
> listing nor unloading is possible...
>
> I basically follwed the guide on: https://github.com/dynup/kpatch for
> debian 8.
>
> I guess it is obvious to you guys but:
> root@debian64:~/kpatch (master) # strace kpatch list 2>&1 | grep "/sys"
> stat("/sys/kernel/kpatch/patches/*", 0x7ffcb713dff0) = -1 ENOENT (No such
> file or directory)
>
> Could someone point me in the right direction please :)
Hi Ravineet,
Any chance your kernel was compiled with CONFIG_LIVEPATCH? If so, you
built a livepatch module and you'll need to manage the patch using the
/sys/kernel/livepatch directory because the kpatch command-line utility
doesn't know how to interact with livepatch yet.
--
Josh
--
Regards
Ravineet
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