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Message-ID: <2febff4d-26ba-4809-a124-7add25ab3d35@samsung.com>
Date: Wed, 31 Jan 2024 16:17:20 +0100
From: Marek Szyprowski <m.szyprowski@...sung.com>
To: Christophe Leroy <christophe.leroy@...roup.eu>, Chen-Yu Tsai
<wenst@...omium.org>, Luis Chamberlain <mcgrof@...nel.org>
Cc: Michael Ellerman <mpe@...erman.id.au>, Nicholas Piggin
<npiggin@...il.com>, Arnd Bergmann <arnd@...db.de>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
"linux-modules@...r.kernel.org" <linux-modules@...r.kernel.org>
Subject: Re: [PATCH 1/3] init: Declare rodata_enabled and mark_rodata_ro()
at all time
Hi Christophe,
On 31.01.2024 12:58, Christophe Leroy wrote:
> Le 30/01/2024 à 18:48, Marek Szyprowski a écrit :
>> [Vous ne recevez pas souvent de courriers de m.szyprowski@...sung.com. Découvrez pourquoi ceci est important à https://aka.ms/LearnAboutSenderIdentification ]
>>
>> On 30.01.2024 12:03, Christophe Leroy wrote:
>>> Le 30/01/2024 à 10:16, Chen-Yu Tsai a écrit :
>>>> [Vous ne recevez pas souvent de courriers de wenst@...omium.org. D?couvrez pourquoi ceci est important ? https://aka.ms/LearnAboutSenderIdentification ]
>>>>
>>>> On Mon, Jan 29, 2024 at 12:09:50PM -0800, Luis Chamberlain wrote:
>>>>> On Thu, Dec 21, 2023 at 10:02:46AM +0100, Christophe Leroy wrote:
>>>>>> Declaring rodata_enabled and mark_rodata_ro() at all time
>>>>>> helps removing related #ifdefery in C files.
>>>>>>
>>>>>> Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
>>>>> Very nice cleanup, thanks!, applied and pushed
>>>>>
>>>>> Luis
>>>> On next-20240130, which has your modules-next branch, and thus this
>>>> series and the other "module: Use set_memory_rox()" series applied,
>>>> my kernel crashes in some very weird way. Reverting your branch
>>>> makes the crash go away.
>>>>
>>>> I thought I'd report it right away. Maybe you folks would know what's
>>>> happening here? This is on arm64.
>>> That's strange, it seems to bug in module_bug_finalize() which is
>>> _before_ calls to module_enable_ro() and such.
>>>
>>> Can you try to revert the 6 patches one by one to see which one
>>> introduces the problem ?
>>>
>>> In reality, only patch 677bfb9db8a3 really change things. Other ones are
>>> more on less only cleanup.
>> I've also run into this issue with today's (20240130) linux-next on my
>> test farm. The issue is not fully reproducible, so it was a bit hard to
>> bisect it automatically. I've spent some time on manual testing and it
>> looks that reverting the following 2 commits on top of linux-next fixes
>> the problem:
>>
>> 65929884f868 ("modules: Remove #ifdef CONFIG_STRICT_MODULE_RWX around
>> rodata_enabled")
>> 677bfb9db8a3 ("module: Don't ignore errors from set_memory_XX()")
>>
>> This in fact means that commit 677bfb9db8a3 is responsible for this
>> regression, as 65929884f868 has to be reverted only because the latter
>> depends on it. Let me know what I can do to help debugging this issue.
>>
> Thanks for the bisect. I suspect you hit one of the errors and something
> goes wrong in the error path.
>
> To confirm this assumption, could you try with the following change on
> top of everything ?
Yes, this is the problem. I've added printing a mod->name to the log.
Here is a log from kernel build from next-20240130 (sometimes it even
boots to shell):
# dmesg | grep module_set_memory
[ 8.061525] module_set_memory(6, 0000000000000000, 0) name ipv6
returned -22
[ 8.067543] WARNING: CPU: 3 PID: 1 at kernel/module/strict_rwx.c:22
module_set_memory+0x9c/0xb8
[ 8.097821] pc : module_set_memory+0x9c/0xb8
[ 8.102068] lr : module_set_memory+0x9c/0xb8
[ 8.183101] module_set_memory+0x9c/0xb8
[ 8.472862] module_set_memory(6, 0000000000000000, 0) name x_tables
returned -22
[ 8.479215] WARNING: CPU: 2 PID: 1 at kernel/module/strict_rwx.c:22
module_set_memory+0x9c/0xb8
[ 8.510978] pc : module_set_memory+0x9c/0xb8
[ 8.515225] lr : module_set_memory+0x9c/0xb8
[ 8.596259] module_set_memory+0x9c/0xb8
[ 10.529879] module_set_memory(6, 0000000000000000, 0) name dm_mod
returned -22
[ 10.536087] WARNING: CPU: 3 PID: 127 at kernel/module/strict_rwx.c:22
module_set_memory+0x9c/0xb8
[ 10.568254] pc : module_set_memory+0x9c/0xb8
[ 10.572501] lr : module_set_memory+0x9c/0xb8
[ 10.653535] module_set_memory+0x9c/0xb8
[ 10.853177] module_set_memory(6, 0000000000000000, 0) name fuse
returned -22
[ 10.859196] WARNING: CPU: 5 PID: 130 at kernel/module/strict_rwx.c:22
module_set_memory+0x9c/0xb8
[ 10.891382] pc : module_set_memory+0x9c/0xb8
[ 10.895629] lr : module_set_memory+0x9c/0xb8
[ 10.976663] module_set_memory+0x9c/0xb8
> diff --git a/kernel/module/strict_rwx.c b/kernel/module/strict_rwx.c
> index a14df9655dbe..fdf8484154dd 100644
> --- a/kernel/module/strict_rwx.c
> +++ b/kernel/module/strict_rwx.c
> @@ -15,9 +15,12 @@ static int module_set_memory(const struct module
> *mod, enum mod_mem_type type,
> int (*set_memory)(unsigned long start, int num_pages))
> {
> const struct module_memory *mod_mem = &mod->mem[type];
> + int err;
>
> set_vm_flush_reset_perms(mod_mem->base);
> - return set_memory((unsigned long)mod_mem->base, mod_mem->size >>
> PAGE_SHIFT);
> + err = set_memory((unsigned long)mod_mem->base, mod_mem->size >>
> PAGE_SHIFT);
> + WARN(err, "module_set_memory(%d, %px, %x) returned %d\n", type,
> mod_mem->base, mod_mem->size, err);
> + return err;
> }
>
> /*
>
>
> Thanks for your help
> Christophe
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
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