warning from change_protection in 6.1 rc1
Michael Ellerman
mpe at ellerman.id.au
Thu Oct 20 19:41:23 AEDT 2022
"Nicholas Piggin" <npiggin at gmail.com> writes:
> On Wed Oct 19, 2022 at 8:21 PM AEST, Dan Horák wrote:
>> Hi,
>>
>> in my first boot with the 6.1 rc1 kernel I have received a couple of
>> warnings from change_protection on Talos II P9 system, see the details
>> below. Nothing like that was noticed in 6.0 or earlier.
>
> Thanks for the report. This is a false positive in a warning I added
> because page_savedwrite overloads the _PAGE_PRIVILEGED bit. The warning
> should be harmless and the code will do the right thing (and it will
> flush). I think this should do it as a minimal fix.
>
> I don't really like that we use that bit for this, I think it should not
> cause a hardware access issue like with KUAP because there are no RWX
> permissions, but having something like pte_user suddenly return false on
> these seems a bit fragile. I'd rather use another bit for this,
> something like _PAGE_SAO. But that shouldn't be done for this release...
There is an RFC to remove the savedwrite stuff entirely:
https://lore.kernel.org/all/20220926152618.194810-1-david@redhat.com/
cheers
> diff --git a/arch/powerpc/include/asm/book3s/64/tlbflush.h b/arch/powerpc/include/asm/book3s/64/tlbflush.h
> index 67655cd60545..4b9eab0995ec 100644
> --- a/arch/powerpc/include/asm/book3s/64/tlbflush.h
> +++ b/arch/powerpc/include/asm/book3s/64/tlbflush.h
> @@ -178,9 +178,19 @@ static inline bool __pte_flags_need_flush(unsigned long oldval,
>
> /*
> * We do not expect kernel mappings or non-PTEs or not-present PTEs.
> + * pte_savedwrite does use _PAGE_PRIVILEGED for user mappings, so
> + * have to filter that out.
> */
> - VM_WARN_ON_ONCE(oldval & _PAGE_PRIVILEGED);
> - VM_WARN_ON_ONCE(newval & _PAGE_PRIVILEGED);
> + if (!IS_ENABLED(CONFIG_NUMA_BALANCING) ||
> + ((oldval & (_PAGE_PRESENT | _PAGE_PTE | _PAGE_RWX)) !=
> + (_PAGE_PRESENT | _PAGE_PTE)))
> + VM_WARN_ON_ONCE(oldval & _PAGE_PRIVILEGED);
> +
> + if (!IS_ENABLED(CONFIG_NUMA_BALANCING) ||
> + ((newval & (_PAGE_PRESENT | _PAGE_PTE | _PAGE_RWX)) !=
> + (_PAGE_PRESENT | _PAGE_PTE)))
> + VM_WARN_ON_ONCE(newval & _PAGE_PRIVILEGED);
> +
> VM_WARN_ON_ONCE(!(oldval & _PAGE_PTE));
> VM_WARN_ON_ONCE(!(newval & _PAGE_PTE));
> VM_WARN_ON_ONCE(!(oldval & _PAGE_PRESENT));
>>
>>
>> Thanks,
>>
>> Dan
>>
>> [ 79.229100] ------------[ cut here ]------------
>> [ 79.229109] WARNING: CPU: 61 PID: 2987 at arch/powerpc/include/asm/book3s/64/tlbflush.h:183 change_protection+0xfd0/0x1610
>> [ 79.229125] Modules linked in: nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_objref nf_conntrack_tftp nft_ct kvm_hv kvm nfsv3 nfs_acl rpcsec_gss_krb5 auth_rpcgss nfsv4 dns_resolver nfs lockd grace sunrpc fscache netfs nf_tables ebtable_nat ebtable_broute ip6table_nat ip6table_mangle ip6table_raw ip6table_security iptable_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 iptable_mangle iptable_raw iptable_security bridge stp llc ip_set nfnetlink rfkill ebtable_filter ebtables ip6table_filter iptable_filter binfmt_misc dm_crypt xfs snd_hda_codec_realtek snd_hda_codec_generic ledtrig_audio snd_hda_codec_hdmi ftdi_sio onboard_usb_hub snd_hda_intel snd_intel_dspcfg snd_hda_codec snd_hda_core snd_hwdep snd_seq snd_seq_device snd_pcm snd_timer ses enclosure ofpart snd soundcore scsi_transport_sas at24 ipmi_powernv ipmi_devintf powernv_flash regmap_i2c opal_prd crct10dif_vpmsum i2c_opal ipmi_msghandler mtd rtc_opal amdgpu raid1 drm_ttm_helper ttm mfd_core gpu_sc
>> hed vmx_crypto
>> [ 79.229258] crc32c_vpmsum drm_buddy nvme drm_display_helper nvme_core tg3 nvme_common aacraid cec ip6_tables ip_tables i2c_dev fuse
>> [ 79.229283] CPU: 61 PID: 2987 Comm: lightdm-gtk-gre Not tainted 6.1.0-0.rc1.15.fc38.ppc64le #1
>> [ 79.229289] Hardware name: T2P9D01 REV 1.00 POWER9 0x4e1202 opal:skiboot-bc106a0 PowerNV
>> [ 79.229291] NIP: c000000000495aa0 LR: c000000000495608 CTR: 0000000000000000
>> [ 79.229295] REGS: c00020001766f690 TRAP: 0700 Not tainted (6.1.0-0.rc1.15.fc38.ppc64le)
>> [ 79.229299] MSR: 9000000000029033 <SF,HV,EE,ME,IR,DR,RI,LE> CR: 44242420 XER: 00000156
>> [ 79.229316] CFAR: c00000000049562c IRQMASK: 0
>> GPR00: c000000000495608 c00020001766f930 c000000001dd7100 c00020001e4e3700
>> GPR04: 0000000154440000 c00020004eac3920 84030a73002000c0 88030a73002000c0
>> GPR08: 0000000000000040 0000000000000001 0000000000000040 0000000000000009
>> GPR12: c00020001795f708 c0002007be1a9700 c0002000554b0000 0000000154440000
>> GPR16: c01fffffffff9f40 fffffffffffffe7f c000000002acdbb8 c000000002a3aef0
>> GPR20: c00020001766fac8 ff7fffffffffefbf 0801000000000080 c00c00080013ab28
>> GPR24: 0000000000000004 c00c00080013ab00 0000000154600000 00000001549b0000
>> GPR28: 88030a73002000c0 c000200054354510 000000000000000d c00020004eac3920
>> [ 79.229377] NIP [c000000000495aa0] change_protection+0xfd0/0x1610
>> [ 79.229384] LR [c000000000495608] change_protection+0xb38/0x1610
>> [ 79.229390] Call Trace:
>> [ 79.229392] [c00020001766f930] [c000000000495608] change_protection+0xb38/0x1610 (unreliable)
>> [ 79.229401] [c00020001766faa0] [c0000000004eda5c] change_prot_numa+0x7c/0x120
>> [ 79.229408] [c00020001766fb70] [c0000000001ad5dc] task_numa_work+0x2cc/0x500
>> [ 79.229414] [c00020001766fc70] [c000000000185bb4] task_work_run+0xf4/0x180
>> [ 79.229421] [c00020001766fcc0] [c0000000000218c4] do_notify_resume+0x434/0x470
>> [ 79.229429] [c00020001766fd80] [c00000000002c29c] interrupt_exit_user_prepare_main+0x1dc/0x2c0
>> [ 79.229437] [c00020001766fde0] [c00000000002c618] interrupt_exit_user_prepare+0x58/0xb0
>> [ 79.229444] [c00020001766fe10] [c00000000000c8f4] interrupt_return_srr_user+0x8/0x138
>> [ 79.229452] --- interrupt: 900 at 0x7fffa62b7cfc
>> [ 79.229458] NIP: 00007fffa62b7cfc LR: 00007fffa62b7c48 CTR: 0000000000000639
>> [ 79.229461] REGS: c00020001766fe80 TRAP: 0900 Not tainted (6.1.0-0.rc1.15.fc38.ppc64le)
>> [ 79.229464] MSR: 900000000280f033 <SF,HV,VEC,VSX,EE,PR,FP,ME,IR,DR,RI,LE> CR: 88444424 XER: 00000156
>> [ 79.229484] CFAR: 0000000000000000 IRQMASK: 0
>> GPR00: 00007fffa62b7c28 00007fffc324a3e0 00007fffa63f7a00 00007ffe53000000
>> GPR04: 00007ffe532d7800 00007fff594d9610 00007fff594d8e90 00000000000000b8
>> GPR08: 00007ffe532d7d20 00007fff594d7d30 00000000000000b9 0000000000000000
>> GPR12: 00007fffa611bfd0 00007fffa6e58d00 0000000000000008 00007fffa5d97480
>> GPR16: 0000000154958000 000000000000000b 0000000000000020 0001000000000000
>> GPR20: 000000000000027f 0000000154907000 00000001543e9100 0000000000000000
>> GPR24: 0000000000000004 00000000000004b0 0000000000000780 0000000000001e00
>> GPR28: 000000000000032c 0000000000001e00 00007fff594d7810 00000001548d71a0
>> [ 79.229545] NIP [00007fffa62b7cfc] 0x7fffa62b7cfc
>> [ 79.229548] LR [00007fffa62b7c48] 0x7fffa62b7c48
>> [ 79.229551] --- interrupt: 900
>> [ 79.229553] Instruction dump:
>> [ 79.229555] 0fe00000 60000000 60000000 60420000 0fe00000 60000000 60000000 60420000
>> [ 79.229568] 0fe00000 60000000 60000000 60420000 <0fe00000> 60000000 60000000 60420000
>> [ 79.229580] ---[ end trace 0000000000000000 ]---
>> [ 245.260381] ------------[ cut here ]------------
>> [ 245.260388] WARNING: CPU: 4 PID: 4468 at arch/powerpc/include/asm/book3s/64/tlbflush.h:182 change_protection+0xfc0/0x1610
>> [ 245.260405] Modules linked in: nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_objref nf_conntrack_tftp nft_ct kvm_hv kvm nfsv3 nfs_acl rpcsec_gss_krb5 auth_rpcgss nfsv4 dns_resolver nfs lockd grace sunrpc fscache netfs nf_tables ebtable_nat ebtable_broute ip6table_nat ip6table_mangle ip6table_raw ip6table_security iptable_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 iptable_mangle iptable_raw iptable_security bridge stp llc ip_set nfnetlink rfkill ebtable_filter ebtables ip6table_filter iptable_filter binfmt_misc dm_crypt xfs snd_hda_codec_realtek snd_hda_codec_generic ledtrig_audio snd_hda_codec_hdmi ftdi_sio onboard_usb_hub snd_hda_intel snd_intel_dspcfg snd_hda_codec snd_hda_core snd_hwdep snd_seq snd_seq_device snd_pcm snd_timer ses enclosure ofpart snd soundcore scsi_transport_sas at24 ipmi_powernv ipmi_devintf powernv_flash regmap_i2c opal_prd crct10dif_vpmsum i2c_opal ipmi_msghandler mtd rtc_opal amdgpu raid1 drm_ttm_helper ttm mfd_core gpu_sc
>> hed vmx_crypto
>> [ 245.260542] crc32c_vpmsum drm_buddy nvme drm_display_helper nvme_core tg3 nvme_common aacraid cec ip6_tables ip_tables i2c_dev fuse
>> [ 245.260565] CPU: 4 PID: 4468 Comm: WebExtensions Tainted: G W ------- --- 6.1.0-0.rc1.15.fc38.ppc64le #1
>> [ 245.260571] Hardware name: T2P9D01 REV 1.00 POWER9 0x4e1202 opal:skiboot-bc106a0 PowerNV
>> [ 245.260574] NIP: c000000000495a90 LR: c000000000495608 CTR: 0000000000000000
>> [ 245.260578] REGS: c000000039adf3e0 TRAP: 0700 Tainted: G W ------- --- (6.1.0-0.rc1.15.fc38.ppc64le)
>> [ 245.260582] MSR: 9000000000029033 <SF,HV,EE,ME,IR,DR,RI,LE> CR: 48422244 XER: 0000007d
>> [ 245.260600] CFAR: c000000000495624 IRQMASK: 0
>> GPR00: c000000000495608 c000000039adf680 c000000001dd7100 c00000002c576900
>> GPR04: 00002ce2ebc90000 c000000091a2e148 8803c8a6000000c0 8603c8a6000000c0
>> GPR08: 0000000000000040 0000000000000001 0000000000000040 0000000000000009
>> GPR12: 0000000000000005 c0000007bfdeba00 c00000007195b9d8 00002ce2ebc90000
>> GPR16: c01fffffffff9f40 fffffffffffffe7f c000000002acdbb8 c000000002a3aef0
>> GPR20: c000000039adf938 ff7fffffffffefbf 0401000000000080 c00c0000002468a8
>> GPR24: 0000000000000000 c00c000000246880 00002ce2ebca0000 00002ce2ebca0000
>> GPR28: 8603c8a6000000c0 c000000091a18af0 0000000000000000 c000000091a2e148
>> [ 245.260660] NIP [c000000000495a90] change_protection+0xfc0/0x1610
>> [ 245.260666] LR [c000000000495608] change_protection+0xb38/0x1610
>> [ 245.260673] Call Trace:
>> [ 245.260675] [c000000039adf680] [c000000000495608] change_protection+0xb38/0x1610 (unreliable)
>> [ 245.260684] [c000000039adf7f0] [c000000000496214] mprotect_fixup+0x134/0x3a0
>> [ 245.260691] [c000000039adf8d0] [c0000000004967c0] do_mprotect_pkey+0x340/0x580
>> [ 245.260699] [c000000039adfa20] [c000000000496a30] sys_mprotect+0x30/0x40
>> [ 245.260706] [c000000039adfa40] [c00000000002d308] system_call_exception+0x178/0x320
>> [ 245.260715] [c000000039adfe10] [c00000000000c170] system_call_vectored_common+0xf0/0x280
>> [ 245.260725] --- interrupt: 3000 at 0x7fff90f5d698
>> [ 245.260731] NIP: 00007fff90f5d698 LR: 0000000000000000 CTR: 0000000000000000
>> [ 245.260734] REGS: c000000039adfe80 TRAP: 3000 Tainted: G W ------- --- (6.1.0-0.rc1.15.fc38.ppc64le)
>> [ 245.260737] MSR: 900000000280f033 <SF,HV,VEC,VSX,EE,PR,FP,ME,IR,DR,RI,LE> CR: 44244448 XER: 00000000
>> [ 245.260758] IRQMASK: 0
>> GPR00: 000000000000007d 00007fffc4e69ec0 00007fff91066e00 00002ce2ebc90000
>> GPR04: 0000000000010000 0000000000000003 0000000000000000 0000000000000018
>> GPR08: 000000000000057b 0000000000000000 0000000000000000 0000000000000000
>> GPR12: 0000000000000000 00007fff9187c300 0000000000000000 0000000000000000
>> GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
>> GPR20: 0000000155b45178 0000000156140ec8 0000000155c1e300 0000000000000000
>> GPR24: 0000000000000000 00007fffc4e6a080 00007fffc4e6a220 00007fffc4e69fc8
>> GPR28: 00002ce2ebc90000 0000000000000004 000000000001ffb7 0000000000100000
>> [ 245.260815] NIP [00007fff90f5d698] 0x7fff90f5d698
>> [ 245.260818] LR [0000000000000000] 0x0
>> [ 245.260821] --- interrupt: 3000
>> [ 245.260823] Instruction dump:
>> [ 245.260826] 3b180001 61290008 b1340020 4bfffc54 0fe00000 60000000 60000000 60420000
>> [ 245.260838] 0fe00000 60000000 60000000 60420000 <0fe00000> 60000000 60000000 60420000
>> [ 245.260850] ---[ end trace 0000000000000000 ]---
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