linux-kernel - Re: BUG: Bad page state in process systemd-udevd (was: [PATCH v9 bpf-next 1/9] x86/Kconfig: select HAVE_ARCH_HUGE_VMALLOC with HAVE_ARCH_HUGE

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Date:   Mon, 28 Mar 2022 06:37:32 +0000
From:   Song Liu <songliubraving@...com>
To:     Paul Menzel <pmenzel@...gen.mpg.de>,
        "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
CC:     Song Liu <song@...nel.org>, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Kernel Team <Kernel-team@...com>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "x86@...nel.org" <x86@...nel.org>,
        "iii@...ux.ibm.com" <iii@...ux.ibm.com>,
        "bpf@...r.kernel.org" <bpf@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Rick P Edgecombe <rick.p.edgecombe@...el.com>,
        "regressions@...ts.linux.dev" <regressions@...ts.linux.dev>
Subject: Re: BUG: Bad page state in process systemd-udevd (was: [PATCH v9
 bpf-next 1/9] x86/Kconfig: select HAVE_ARCH_HUGE_VMALLOC with
 HAVE_ARCH_HUGE_VMAP)

Thanks Paul for highlighting the issue. 

+ Rick, who highlighted some potential issues with this. (also attached
the stack trace). 

> On Mar 27, 2022, at 3:36 AM, Paul Menzel <pmenzel@...gen.mpg.de> wrote:
> 
> Dear Song,
> 
> 
> Am 26.03.22 um 19:46 schrieb Paul Menzel:
>> #regzbot introduced: fac54e2bfb5be2b0bbf115fe80d45f59fd773048
>> #regzbot title: BUG: Bad page state in process systemd-udevd
> 
>> Am 04.02.22 um 19:57 schrieb Song Liu:
>>> From: Song Liu <songliubraving@...com>
>>> 
>>> This enables module_alloc() to allocate huge page for 2MB+ requests.
>>> To check the difference of this change, we need enable config
>>> CONFIG_PTDUMP_DEBUGFS, and call module_alloc(2MB). Before the change,
>>> /sys/kernel/debug/page_tables/kernel shows pte for this map. With the
>>> change, /sys/kernel/debug/page_tables/ show pmd for thie map.
>>> 
>>> Signed-off-by: Song Liu <songliubraving@...com>
>>> ---
>>>   arch/x86/Kconfig | 1 +
>>>   1 file changed, 1 insertion(+)
>>> 
>>> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
>>> index 6fddb63271d9..e0e0d00cf103 100644
>>> --- a/arch/x86/Kconfig
>>> +++ b/arch/x86/Kconfig
>>> @@ -159,6 +159,7 @@ config X86
>>>       select HAVE_ALIGNED_STRUCT_PAGE        if SLUB
>>>       select HAVE_ARCH_AUDITSYSCALL
>>>       select HAVE_ARCH_HUGE_VMAP        if X86_64 || X86_PAE
>>> +    select HAVE_ARCH_HUGE_VMALLOC        if HAVE_ARCH_HUGE_VMAP
>>>       select HAVE_ARCH_JUMP_LABEL
>>>       select HAVE_ARCH_JUMP_LABEL_RELATIVE
>>>       select HAVE_ARCH_KASAN            if X86_64
>> Testing Linus’ current master branch, Linux logs critical messages like below:
>>     BUG: Bad page state in process systemd-udevd  pfn:102e03
>> I bisected to your commit fac54e2bfb5 (x86/Kconfig: select HAVE_ARCH_HUGE_VMALLOC with HAVE_ARCH_HUGE_VMAP).
> 
> Sorry, I forget to mention, that this is a 32-bit (i686) userspace, but a 64-bit Linux kernel, so it might be the same issue as mentioned in commit eed1fcee556f (x86: Disable HAVE_ARCH_HUGE_VMALLOC on 32-bit x86), but didn’t fix the issue for 64-bit Linux kernel and 32-bit userspace.

I will look more into this tomorrow. To clarify, what is the 32-bit user 
space that triggers this? Is it systemd-udevd? Is the systemd also i686?

Thanks,
Song

View attachment "linux-5.18-vmap-bad-page-state.txt" of type "text/plain" (275537 bytes)