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Subject: Re: [PATCH V9 1/4] perf/core: Add PERF_SAMPLE_DATA_PAGE_SIZE
From:   "Liang, Kan" <kan.liang@linux.intel.com>
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Will Deacon <will@kernel.org>,
        Michael Ellerman <mpe@ellerman.id.au>, mingo@redhat.com,
        acme@kernel.org, linux-kernel@vger.kernel.org,
        mark.rutland@arm.com, alexander.shishkin@linux.intel.com,
        jolsa@redhat.com, eranian@google.com, ak@linux.intel.com,
        dave.hansen@intel.com, kirill.shutemov@linux.intel.com,
        benh@kernel.crashing.org, paulus@samba.org,
        David Miller <davem@davemloft.net>
References: <20201001135749.2804-1-kan.liang@linux.intel.com>
 <20201001135749.2804-2-kan.liang@linux.intel.com>
 <20201009090927.GQ2611@hirez.programming.kicks-ass.net>
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 <8e88ba79-7c40-ea32-a7ed-bdc4fc04b2af@linux.intel.com>
Message-ID: <b971a36d-5cd7-a40e-fb37-38ab196450ec@linux.intel.com>
Date:   Tue, 10 Nov 2020 10:20:24 -0500
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On 11/4/2020 12:11 PM, Liang, Kan wrote:
> 
> 
> On 10/13/2020 12:34 PM, Peter Zijlstra wrote:
>> Subject: perf,mm: Handle non-page-table-aligned hugetlbfs
>> From: Peter Zijlstra<peterz@infradead.org>
>> Date: Fri, 9 Oct 2020 11:09:27 +0200
>>
>> A limited nunmber of architectures support hugetlbfs sizes that do not
>> align with the page-tables (ARM64, Power, Sparc64). Add support for
>> this to the generic perf_get_page_size() implementation, and also
>> allow an architecture to override this implementation.
>>
>> This latter is only needed when it uses non-page-table aligned huge
>> pages in its kernel map.
>>
>> Signed-off-by: Peter Zijlstra (Intel)<peterz@infradead.org>
>> ---
>>   kernel/events/core.c |   39 +++++++++++++++++++++++++++++++++------
>>   1 file changed, 33 insertions(+), 6 deletions(-)
>>
>> --- a/kernel/events/core.c
>> +++ b/kernel/events/core.c
>> @@ -6996,10 +6996,18 @@ static u64 perf_virt_to_phys(u64 virt)
>>   #ifdef CONFIG_MMU
>>   /*
>> - * Return the MMU page size of a given virtual address
>> + * Return the MMU page size of a given virtual address.
>> + *
>> + * This generic implementation handles page-table aligned huge pages, 
>> as well
>> + * as non-page-table aligned hugetlbfs compound pages.
>> + *
>> + * If an architecture supports and uses non-page-table aligned pages 
>> in their
>> + * kernel mapping it will need to provide it's own implementation of 
>> this
>> + * function.
>>    */
>> -static u64 __perf_get_page_size(struct mm_struct *mm, unsigned long 
>> addr)
>> +__weak u64 arch_perf_get_page_size(struct mm_struct *mm, unsigned 
>> long addr)
>>   {
>> +    struct page *page;
>>       pgd_t *pgd;
>>       p4d_t *p4d;
>>       pud_t *pud;
>> @@ -7021,15 +7029,27 @@ static u64 __perf_get_page_size(struct m
>>       if (!pud_present(*pud))
>>           return 0;
>> -    if (pud_leaf(*pud))
>> +    if (pud_leaf(*pud)) {
>> +#ifdef pud_page
>> +        page = pud_page(*pud);
>> +        if (PageHuge(page))
>> +            return page_size(compound_head(page));
>> +#endif
>>           return 1ULL << PUD_SHIFT;
>> +    }
>>       pmd = pmd_offset(pud, addr);
>>       if (!pmd_present(*pmd))
>>           return 0;
>> -    if (pmd_leaf(*pmd))
>> +    if (pmd_leaf(*pmd)) {
>> +#ifdef pmd_page
>> +        page = pmd_page(*pmd);
>> +        if (PageHuge(page))
>> +            return page_size(compound_head(page));
>> +#endif
>>           return 1ULL << PMD_SHIFT;
>> +    }
>>       pte = pte_offset_map(pmd, addr);
>>       if (!pte_present(*pte)) {
>> @@ -7037,13 +7057,20 @@ static u64 __perf_get_page_size(struct m
>>           return 0;
>>       }
>> +    page = pte_page(*pte);
>> +    if (PageHuge(page)) {
>> +        u64 size = page_size(compound_head(page));
>> +        pte_unmap(pte);
>> +        return size;
>> +    }
>> +
> 
> The PageHuge() check for PTE crashes my machine when I did page size 
> test. (Sorry, I didn't find the issue earlier. I just found some time to 
> re-run the page size test.)
> 
> It seems we don't need the check for PTE here. The size should be always 
> PAGE_SIZE, no? After I remove the check, everything looks good.
> 

Hi Peter,

Any comments for this issue?

As my understanding, we don't need the PageHuge() check for PTE page 
here. However, I don't expect that the page fault crashes here. Because 
perf already check the pte_present(*pte) before invoking PageHuge().

I'm not sure if it's triggered by other potential issues, so I'm asking 
here rather than submiting a patch to simply remove the PageHuge() check.

Thanks,
Kan
> 
> [  167.383120] BUG: unable to handle page fault for address: 
> fffffca803fb8000
> [  167.383121] #PF: supervisor read access in kernel mode
> [  167.383121] #PF: error_code(0x0000) - not-present page
> [  167.383121] PGD 4adfc8067 P4D 4adfc8067 PUD 4adfc7067 PMD 0
> [  167.383122] Oops: 0000 [#1] SMP NOPTI
> [  167.383122] CPU: 0 PID: 2461 Comm: perf Not tainted 
> 5.10.0-rc1_page_size+ #54
> [  167.383123] Hardware name: Intel Corporation Ice Lake Client 
> Platform/IceLake U DDR4 SODIMM PD RVP TLC, BIOS 
> ICLSFWR1.R00.3162.A00.1904162000 04/16/2019
> [  167.383123] traps: PANIC: double fault, error_code: 0x0
> [  167.383123] double fault: 0000 [#2] SMP NOPTI
> [  167.383123] CPU: 0 PID: 2461 Comm: perf Not tainted 
> 5.10.0-rc1_page_size+ #54
> [  167.383124] Hardware name: Intel Corporation Ice Lake Client 
> Platform/IceLake U DDR4 SODIMM PD RVP TLC, BIOS 
> ICLSFWR1.R00.3162.A00.1904162000 04/16/2019
> [  167.383124] RIP: 0010:__sprint_symbol+0xb/0x100
> [  167.383124] Code: 85 e4 75 b9 48 85 c0 75 bc 49 89 d8 4c 89 e1 4c 89 
> fa 4c 89 f6 4c 89 ef e8 42 70 04 00 eb a6 0f 1f 44 00 00 55 48 89 e5 41 
> 57 <41> 56 49 89 f6 41 55 41 89 cd 48 8d 4d b8 41 54 49 89 fc 53 48 63
> [  167.383125] RSP: 0018:fffffe000000b000 EFLAGS: 00010046
> [  167.383125] RAX: 0000000000000053 RBX: 00000000ffff0a00 RCX: 
> 0000000000000001
> [  167.383125] RDX: 0000000000000000 RSI: ffffffff9f8a6176 RDI: 
> fffffe000000b029
> [  167.383126] RBP: fffffe000000b008 R08: ffffffffa0bf8661 R09: 
> 0000000000000001
> [  167.383126] R10: 000000000000000f R11: ffff9e641dc189c8 R12: 
> ffff9e641dc189c9
> [  167.383126] R13: ffff9e641dc1a7e0 R14: ffff0a00ffffff05 R15: 
> fffffe000000b029
> [  167.383126] FS:  0000000000000000(0000) GS:ffff9e641dc00000(0000) 
> knlGS:0000000000000000
> [  167.383127] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [  167.383127] CR2: fffffe000000aff8 CR3: 000000014a0ba004 CR4: 
> 0000000000770ef0
> [  167.383127] PKRU: 55555554
> [  167.383127] Call Trace:
> [  167.383127]  <NMI>
> [  167.383128]  sprint_symbol+0x15/0x20
> [  167.383128]  symbol_string+0x49/0x90
> [  167.383128]  pointer+0x118/0x3e0
> [  167.383128]  vsnprintf+0x1ec/0x4e0
> [  167.383128]  vscnprintf+0xd/0x30
> [  167.383129]  printk_safe_log_store+0x65/0xe0
> [  167.383129]  vprintk_func+0x8d/0x100
> [  167.383129]  printk+0x58/0x6f
> [  167.383129]  ? PageHuge+0x6/0x40
> [  167.383129]  show_ip+0x2c/0x3d
> [  167.383130]  show_iret_regs+0x17/0x40
> [  167.383130]  __show_regs+0x27/0x40
> [  167.383130]  ? dump_stack_print_info+0x9e/0xb0
> [  167.383130]  show_regs+0x3b/0x50
> [  167.383130]  __die_body+0x20/0x70
> [  167.383131]  __die+0x2b/0x33
> [  167.383131]  no_context+0x152/0x350
> [  167.383131]  __bad_area_nosemaphore+0x50/0x160
> [  167.383131]  bad_area_nosemaphore+0x16/0x20
> [  167.383131]  do_kern_addr_fault+0x62/0x70
> [  167.383132]  exc_page_fault+0xcd/0x150
> [  167.383132]  asm_exc_page_fault+0x1e/0x30
> [  167.383132] RIP: 0010:PageHuge+0x6/0x40
> [  167.383132] Code: c8 48 89 0e 48 39 47 08 48 0f 46 47 08 48 89 02 c3 
> 0f 1f 00 55 be 00 04 00 00 48 89 e5 e8 72 90 2a 00 5d c3 0f 1f 44 00 00 
> 55 <48> 8b 07 48 89 e5 a9 00 00 01 00 75 09 48 8b 47 08 83 e0 01 74 17
> [  167.383133] RSP: 0018:fffffe000000b5c0 EFLAGS: 00010086
> [  167.383133] RAX: 00000000fee0017b RBX: fffffca803fb8000 RCX: 
> 0000000000000000
> [  167.383133] RDX: 7fffffff011ffe84 RSI: ffff9e635b614fe8 RDI: 
> fffffca803fb8000
> [  167.383134] RBP: fffffe000000b5d8 R08: 000fffffc0000000 R09: 
> 000000000000000d
> [  167.383134] R10: 0000000000000001 R11: 00000000000011da R12: 
> 000000000048c14f
> [  167.383134] R13: fffffe000000b8c0 R14: ffff9e60955aa800 R15: 
> ffffffffff5fd340
> [  167.383134]  ? arch_perf_get_page_size+0x2e4/0x330
> [  167.383135]  perf_get_page_size.part.0+0x3c/0x50
> [  167.383135]  perf_prepare_sample+0x1cc/0x740
> [  167.383135]  perf_event_output_forward+0x30/0x90
> [  167.383135]  ? sched_clock+0x9/0x10
> [  167.383135]  ? __perf_event_account_interrupt+0xcc/0xe0
> [  167.383136]  __perf_event_overflow+0x57/0xf0
> [  167.383136]  perf_event_overflow+0x14/0x20
> [  167.383136]  __intel_pmu_pebs_event+0x2a8/0x3a0
> [  167.383136]  ? get_data_src.isra.0+0xc0/0xc0
> [  167.383136]  ? perf_event_stop+0xa0/0xa0
> [  167.383137]  ? native_apic_mem_write+0x2/0x10
> [  167.383137]  ? native_apic_mem_write+0x2/0x10
> [  167.383137]  intel_pmu_drain_pebs_icl+0x1bf/0x1f0
> [  167.383137]  ? get_data_src.isra.0+0xc0/0xc0
> [  167.383137]  handle_pmi_common+0xb6/0x2a0
> [  167.383138]  intel_pmu_handle_irq+0xca/0x170
> [  167.383138]  perf_event_nmi_handler+0x2d/0x50
> [  167.383138]  nmi_handle+0x5d/0x100
> [  167.383138]  default_do_nmi+0x45/0x110
> [  167.383138]  exc_nmi+0x15a/0x1a0
> [  167.383139]  end_repeat_nmi+0x16/0x55
> [  167.383139] RIP: 0010:perf_iterate_ctx+0x0/0x170
> [  167.383139] Code: b0 95 01 41 89 c5 72 d9 48 c7 c7 40 a0 fb a0 e8 16 
> 47 b8 00 b8 f4 ff ff ff e9 cb fe ff ff 66 90 66 2e 0f 1f 84 00 00 00 00 
> 00 <55> 48 89 e5 41 57 41 56 41 55 41 54 4c 8d 67 60 53 48 83 ec 08 48
> [  167.383140] RSP: 0018:ffffb51d01907ca8 EFLAGS: 00000246
> [  167.383140] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 
> 0000000000000001
> [  167.383140] RDX: 0000000000000000 RSI: ffffffff9f815460 RDI: 
> ffff9e60c5423500
> [  167.383140] RBP: ffffb51d01907d08 R08: 00000026f8cdcae0 R09: 
> 0000000000000021
> [  167.383141] R10: 0000000000000000 R11: ffff9e641dc11ec8 R12: 
> 0000000000000000
> [  167.383141] R13: ffff9e641dc33300 R14: ffff9e60aaf69e00 R15: 
> ffff9e60c5423500
> [  167.383141]  ? perf_event_stop+0xa0/0xa0
> [  167.383141]  ? perf_swevent_init+0x190/0x190
> [  167.383142]  ? perf_swevent_init+0x190/0x190
> [  167.383142]  </NMI>
> [  167.383142]  ? perf_event_exec+0x1ca/0x210
> [  167.383142]  begin_new_exec+0x5ba/0x980
> [  167.383142]  load_elf_binary+0x6ae/0x17a0
> [  167.383143]  ? __kernel_read+0x1a0/0x2d0
> [  167.383143]  ? __kernel_read+0x1a0/0x2d0
> [  167.383143]  bprm_execve+0x2f6/0x660
> [  167.383143]  do_execveat_common.isra.0+0x189/0x1c0
> [  167.383143]  __x64_sys_execve+0x37/0x50
> [  167.383144]  do_syscall_64+0x38/0x90
> [  167.383144]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> [  167.383144] RIP: 0033:0x7f2c347dae97
> [  167.383144] Code: Unable to access opcode bytes at RIP 0x7f2c347dae6d.
> [  167.383144] RSP: 002b:00007ffe73f584a8 EFLAGS: 00000202 ORIG_RAX: 
> 000000000000003b
> [  167.383145] RAX: ffffffffffffffda RBX: 00005625a990cd70 RCX: 
> 00007f2c347dae97
> [  167.383145] RDX: 00005625a990caf0 RSI: 00005625a990cd70 RDI: 
> 00007ffe73f6069f
> [  167.383145] RBP: 00007ffe73f58540 R08: 00007ffe73f584a0 R09: 
> 00007f2c368502b0
> [  167.383146] R10: 0000000000000016 R11: 0000000000000202 R12: 
> 00005625a990caf0
> [  167.383146] R13: 00005625a8c06870 R14: 0000000000000000 R15: 
> 00007ffe73f6069f
> [  167.383146] Modules linked in: snd_hda_codec_hdmi 
> snd_hda_codec_realtek snd_hda_codec_generic ledtrig_audio 
> nf_conntrack_netlink nfnetlink xfrm_user xfrm_algo xt_addrtype 
> br_netfilter xt_CHECKSUM iptable_mangle xt_MASQUERADE iptable_nat nf_nat 
> xt_conntrack nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 libcrc32c 
> ipt_REJECT nf_reject_ipv4 xt_tcpudp bridge stp llc ebtable_filter 
> ebtables ip6table_filter ip6_tables iptable_filter overlay bnep 
> hid_sensor_magn_3d hid_sensor_gyro_3d hid_sensor_als hid_sensor_accel_3d 
> hid_sensor_rotation hid_sensor_incl_3d hid_sensor_trigger 
> industrialio_triggered_buffer kfifo_buf hid_sensor_iio_common 
> industrialio hid_sensor_custom hid_sensor_hub intel_ishtp_hid 
> binfmt_misc spi_pxa2xx_platform dw_dmac dw_dmac_core 8250_dw mei_hdcp 
> i2c_designware_platform i2c_designware_core intel_rapl_msr wmi_bmof 
> intl_wmi_thunderbolt x86_pkg_temp_thermal snd_hda_intel intel_powerclamp 
> coretemp snd_intel_dspcfg nls_iso8859_1 snd_hda_codec kvm_intel 
> snd_hda_core snd_hwdep kvm
> [  167.383158]  snd_pcm irqbypass snd_seq_midi crct10dif_pclmul 
> crc32_pclmul ghash_clmulni_intel snd_seq_midi_event snd_rawmidi 
> aesni_intel crypto_simd cryptd snd_seq glue_helper rapl snd_seq_device 
> intel_cstate snd_timer ofpart cmdlinepart intel_spi_pci snd e1000e 
> intel_spi spi_nor soundcore mtd iwlmvm mei_me mei mac80211 libarc4 
> iwlwifi intel_lpss_pci intel_lpss cfg80211 asix usbnet mii joydev btusb 
> btrtl btbcm btintel bluetooth ecdh_generic ecc intel_ish_ipc 
> processor_thermal_device intel_ishtp intel_rapl_common 
> int340x_thermal_zone thunderbolt intel_soc_dts_iosf ucsi_acpi typec_ucsi 
> typec wmi intel_hid int3400_thermal sparse_keymap acpi_pad 
> acpi_thermal_rel acpi_tad sch_fq_codel parport_pc ppdev lp parport 
> ip_tables x_tables hid_generic usbhid hid input_leds serio_raw mac_hid 
> pinctrl_icelake
> [  168.121417] ---[ end trace 7f4c6d2d09e5e90f ]---
> [  168.121417] RIP: 0010:PageHuge+0x6/0x40
> [  168.121417] ode: c8 48 89 0e 48 39 47 08 48 0f 46 47 08 48 89 02 c3 
> 0f 1f 00 55 be 00 04 00 00 48 89 e5 e8 72 90 2a 00 5d c3 0f 1f 44 00 00 
> 55 <48> 8b 07 48 89 e5 a9 00 00 01 00 75 09 48 8b 47 08 83 e0 01 74 17
> [  168.121418] RSP: 0018:fffffe000000b5c0 EFLAGS: 00010086
> [  168.121418] RAX: 00000000fee0017b RBX: fffffca803fb8000 RCX: 
> 0000000000000000
> [  168.121419] RDX: 7fffffff011ffe84 RSI: ffff9e635b614fe8 RDI: 
> fffffca803fb8000
> [  168.121419] RBP: fffffe000000b5d8 R08: 000fffffc0000000 R09: 
> 000000000000000d
> [  168.121419] R10: 0000000000000001 R11: 00000000000011da R12: 
> 000000000048c14f
> [  168.121419] R13: fffffe000000b8c0 R14: ffff9e60955aa800 R15: 
> ffffffffff5fd340
> [  168.121420] FS:  0000000000000000(0000) GS:ffff9e641dc00000(0000) 
> knlGS:0000000000000000
> [  168.121420] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [  168.121420] CR2: 00007f2c347dae6d CR3: 000000014a0ba004 CR4: 
> 0000000000770ef0
> [  168.121420] PKRU: 55555554
> [  168.121421] Kernel panic - not syncing: Fatal exception in interrupt
> [  168.121520] Kernel Offset: 0x1e600000 from 0xffffffff81000000 
> (relocation range: 0xffffffff80000000-0xffffffffbfffffff)