* Re: Bug with report THP eligibility for each vma
[not found] <CALouPAi8KEuPw_Ly5W=MkYi8Yw3J6vr8mVezYaxxVyKCxH1x_g@mail.gmail.com>
@ 2018-12-24 7:49 ` Michal Hocko
2018-12-24 11:35 ` William Kucharski
2018-12-24 12:12 ` Mike Rapoport
0 siblings, 2 replies; 5+ messages in thread
From: Michal Hocko @ 2018-12-24 7:49 UTC (permalink / raw)
To: Paul Oppenheimer, Andrew Morton
Cc: Vlastimil Babka, David Rientjes, Jan Kara, Mike Rapoport, linux-mm, LKML
[Cc-ing mailing list and people involved in the original patch]
On Fri 21-12-18 13:42:24, Paul Oppenheimer wrote:
> Hello! I've never reported a kernel bug before, and since its on the
> "next" tree I was told to email the author of the relevant commit.
> Please redirect me to the correct place if I've made a mistake.
>
> When opening firefox or chrome, and using it for a good 7 seconds, it
> hangs in "uninterruptible sleep" and I recieve a "BUG" in dmesg. This
> doesn't occur when reverting this commit:
> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=48cf516f8c.
> Ive attached the output of decode_stacktrace.sh and the relevant dmesg
> log to this email.
>
> Thanks
> BUG: unable to handle kernel NULL pointer dereference at 00000000000000e8
Thanks for the bug report! This is offset 232 and that matches
file->f_mapping as per pahole
pahole -C file ./vmlinux | grep f_mapping
struct address_space * f_mapping; /* 232 8 */
I thought that each file really has to have a mapping. But the following
should heal the issue and add an extra care.
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index f64733c23067..fc9d70a9fbd1 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -66,6 +66,8 @@ bool transparent_hugepage_enabled(struct vm_area_struct *vma)
{
if (vma_is_anonymous(vma))
return __transparent_hugepage_enabled(vma);
+ if (!vma->vm_file || !vma->vm_file->f_mapping)
+ return false;
if (shmem_mapping(vma->vm_file->f_mapping) && shmem_huge_enabled(vma))
return __transparent_hugepage_enabled(vma);
Andrew, could you fold it to the original patch please?
Keeping the rest for the reference.
> #PF error: [normal kernel read fault]
> PGD 0 P4D 0
> Oops: 0000 [#1] PREEMPT SMP PTI
> CPU: 7 PID: 2687 Comm: StreamTrans #56 Tainted: G U 4.20.0-rc7-next-20181221-beppy+ #15
> Hardware name: Dell Inc. XPS 13 9360/0TPN17, BIOS 2.10.0 09/27/2018
> RIP: 0010:transparent_hugepage_enabled (??:?)
> Code: 17 fd 00 e9 20 ff ff ff 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 53 48 89 fb 48 83 bf 90 00 00 00 00 74 27 48 8b 87 a0 00 00 00 <48> 8b b8 e8 00 00 00 e8 7a cc fa ff 84 c0 75 04 31 c0 5b c3 48 89
> All code
> ========
> 0: 17 (bad)
> 1: fd std
> 2: 00 e9 add %ch,%cl
> 4: 20 ff and %bh,%bh
> 6: ff (bad)
> 7: ff 0f decl (%rdi)
> 9: 1f (bad)
> a: 84 00 test %al,(%rax)
> c: 00 00 add %al,(%rax)
> e: 00 00 add %al,(%rax)
> 10: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
> 15: 53 push %rbx
> 16: 48 89 fb mov %rdi,%rbx
> 19: 48 83 bf 90 00 00 00 cmpq $0x0,0x90(%rdi)
> 20: 00
> 21: 74 27 je 0x4a
> 23: 48 8b 87 a0 00 00 00 mov 0xa0(%rdi),%rax
> 2a:* 48 8b b8 e8 00 00 00 mov 0xe8(%rax),%rdi <-- trapping instruction
> 31: e8 7a cc fa ff callq 0xfffffffffffaccb0
> 36: 84 c0 test %al,%al
> 38: 75 04 jne 0x3e
> 3a: 31 c0 xor %eax,%eax
> 3c: 5b pop %rbx
> 3d: c3 retq
> 3e: 48 rex.W
> 3f: 89 .byte 0x89
>
> Code starting with the faulting instruction
> ===========================================
> 0: 48 8b b8 e8 00 00 00 mov 0xe8(%rax),%rdi
> 7: e8 7a cc fa ff callq 0xfffffffffffacc86
> c: 84 c0 test %al,%al
> e: 75 04 jne 0x14
> 10: 31 c0 xor %eax,%eax
> 12: 5b pop %rbx
> 13: c3 retq
> 14: 48 rex.W
> 15: 89 .byte 0x89
> RSP: 0018:ffffb79744f17d28 EFLAGS: 00010282
> RAX: 0000000000000000 RBX: ffff8948c17aff00 RCX: 0000000000000000
> RDX: 0000000000000004 RSI: ffffffffab1165ba RDI: ffff8948c17aff00
> RBP: ffff8948c17aff00 R08: 0000000000000007 R09: ffff894927e547b2
> R10: 0000000000000000 R11: ffff894927e549da R12: ffffb79744f17d38
> R13: ffff8948c17aff00 R14: ffff89489bef9400 R15: ffff89488b775a80
> FS: 00007fa54ad43700(0000) GS:ffff8949363c0000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00000000000000e8 CR3: 000000025c0ee003 CR4: 00000000003606e0
> Call Trace:
> show_smap (/home/bep/.opt/kernel/linux-e/fs/proc/task_mmu.c:805)
> seq_read (/home/bep/.opt/kernel/linux-e/fs/seq_file.c:269)
> __vfs_read (/home/bep/.opt/kernel/linux-e/fs/read_write.c:421)
> vfs_read (/home/bep/.opt/kernel/linux-e/fs/read_write.c:452 /home/bep/.opt/kernel/linux-e/fs/read_write.c:437)
> ksys_read (/home/bep/.opt/kernel/linux-e/fs/read_write.c:579)
> do_syscall_64 (/home/bep/.opt/kernel/linux-e/arch/x86/entry/common.c:290)
> entry_SYSCALL_64_after_hwframe (/home/bep/.opt/kernel/linux/arch/x86/entry/entry_64.S:184)
> RIP: 0033:0x7fa585fb3184
> Code: c3 0f 1f 44 00 00 41 54 49 89 d4 55 48 89 f5 53 89 fb 48 83 ec 10 e8 5b fc ff ff 4c 89 e2 48 89 ee 89 df 41 89 c0 31 c0 0f 05 <48> 3d 00 f0 ff ff 77 38 44 89 c7 48 89 44 24 08 e8 97 fc ff ff 48
> All code
> ========
> 0: c3 retq
> 1: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
> 6: 41 54 push %r12
> 8: 49 89 d4 mov %rdx,%r12
> b: 55 push %rbp
> c: 48 89 f5 mov %rsi,%rbp
> f: 53 push %rbx
> 10: 89 fb mov %edi,%ebx
> 12: 48 83 ec 10 sub $0x10,%rsp
> 16: e8 5b fc ff ff callq 0xfffffffffffffc76
> 1b: 4c 89 e2 mov %r12,%rdx
> 1e: 48 89 ee mov %rbp,%rsi
> 21: 89 df mov %ebx,%edi
> 23: 41 89 c0 mov %eax,%r8d
> 26: 31 c0 xor %eax,%eax
> 28: 0f 05 syscall
> 2a:* 48 3d 00 f0 ff ff cmp $0xfffffffffffff000,%rax <-- trapping instruction
> 30: 77 38 ja 0x6a
> 32: 44 89 c7 mov %r8d,%edi
> 35: 48 89 44 24 08 mov %rax,0x8(%rsp)
> 3a: e8 97 fc ff ff callq 0xfffffffffffffcd6
> 3f: 48 rex.W
>
> Code starting with the faulting instruction
> ===========================================
> 0: 48 3d 00 f0 ff ff cmp $0xfffffffffffff000,%rax
> 6: 77 38 ja 0x40
> 8: 44 89 c7 mov %r8d,%edi
> b: 48 89 44 24 08 mov %rax,0x8(%rsp)
> 10: e8 97 fc ff ff callq 0xfffffffffffffcac
> 15: 48 rex.W
> RSP: 002b:00007fa54ad42060 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
> RAX: ffffffffffffffda RBX: 000000000000002c RCX: 00007fa585fb3184
> RDX: 0000000000001fff RSI: 00007fa54ffb2000 RDI: 000000000000002c
> RBP: 00007fa54ffb2000 R08: 0000000000000000 R09: 000000000000001e
> R10: 00007fa585c0dae0 R11: 0000000000000246 R12: 0000000000001fff
> R13: 00007fa54ad42510 R14: 00007fa54ffb2fc5 R15: 00007fa54ad42498
> Modules linked in: thunderbolt sch_cake rfcomm fuse arc4 iwlmvm mac80211 btusb btrtl btbcm btintel bnep bluetooth iwlwifi snd_hda_codec_hdmi ecdh_generic snd_hda_codec_realtek snd_hda_codec_generic snd_hda_intel cfg80211 snd_hda_codec nf_log_ipv6 ip6t_REJECT nf_reject_ipv6 snd_hwdep xt_hl snd_hda_core ip6t_rt nf_log_ipv4 nf_log_common joydev snd_pcm mousedev ipt_REJECT nf_reject_ipv4 hid_multitouch intel_rapl xt_LOG xt_comment nls_iso8859_1 intel_pmc_core nls_cp437 intel_powerclamp xt_limit kvm_intel xt_addrtype xt_tcpudp dell_laptop snd_timer xt_conntrack ledtrig_audio snd dell_wmi nf_conntrack efi_pstore dell_smbios mei_me dcdbas input_leds idma64 mei wmi_bmof intel_wmi_thunderbolt dell_wmi_descriptor efivars rfkill intel_pch_thermal intel_lpss_pci processor_thermal_device i2c_i801 soundcore intel_lpss intel_soc_dts_iosf i2c_hid evdev int3403_thermal int3400_thermal intel_vbtn rtc_cmos int340x_thermal_zone acpi_thermal_rel intel_hid mac_hid nf_defrag_ipv6 nf_defrag_ipv4
> ip6table_filter ip6_tables iptable_filter bpfilter coretemp msr dell_smm_hwmon crypto_user ip_tables x_tables algif_skcipher af_alg rtsx_pci_sdmmc mmc_core crct10dif_pclmul crc32_pclmul xhci_pci ghash_clmulni_intel serio_raw rtsx_pci xhci_hcd i915 kvmgt vfio_mdev mdev vfio_iommu_type1 vfio kvm irqbypass intel_gtt
> CR2: 00000000000000e8
> ---[ end trace 77d24d35c4e5213f ]---
> RIP: 0010:transparent_hugepage_enabled (??:?)
> Code: 17 fd 00 e9 20 ff ff ff 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 53 48 89 fb 48 83 bf 90 00 00 00 00 74 27 48 8b 87 a0 00 00 00 <48> 8b b8 e8 00 00 00 e8 7a cc fa ff 84 c0 75 04 31 c0 5b c3 48 89
> All code
> ========
> 0: 17 (bad)
> 1: fd std
> 2: 00 e9 add %ch,%cl
> 4: 20 ff and %bh,%bh
> 6: ff (bad)
> 7: ff 0f decl (%rdi)
> 9: 1f (bad)
> a: 84 00 test %al,(%rax)
> c: 00 00 add %al,(%rax)
> e: 00 00 add %al,(%rax)
> 10: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
> 15: 53 push %rbx
> 16: 48 89 fb mov %rdi,%rbx
> 19: 48 83 bf 90 00 00 00 cmpq $0x0,0x90(%rdi)
> 20: 00
> 21: 74 27 je 0x4a
> 23: 48 8b 87 a0 00 00 00 mov 0xa0(%rdi),%rax
> 2a:* 48 8b b8 e8 00 00 00 mov 0xe8(%rax),%rdi <-- trapping instruction
> 31: e8 7a cc fa ff callq 0xfffffffffffaccb0
> 36: 84 c0 test %al,%al
> 38: 75 04 jne 0x3e
> 3a: 31 c0 xor %eax,%eax
> 3c: 5b pop %rbx
> 3d: c3 retq
> 3e: 48 rex.W
> 3f: 89 .byte 0x89
>
> Code starting with the faulting instruction
> ===========================================
> 0: 48 8b b8 e8 00 00 00 mov 0xe8(%rax),%rdi
> 7: e8 7a cc fa ff callq 0xfffffffffffacc86
> c: 84 c0 test %al,%al
> e: 75 04 jne 0x14
> 10: 31 c0 xor %eax,%eax
> 12: 5b pop %rbx
> 13: c3 retq
> 14: 48 rex.W
> 15: 89 .byte 0x89
> RSP: 0018:ffffb79744f17d28 EFLAGS: 00010282
> RAX: 0000000000000000 RBX: ffff8948c17aff00 RCX: 0000000000000000
> RDX: 0000000000000004 RSI: ffffffffab1165ba RDI: ffff8948c17aff00
> RBP: ffff8948c17aff00 R08: 0000000000000007 R09: ffff894927e547b2
> R10: 0000000000000000 R11: ffff894927e549da R12: ffffb79744f17d38
> R13: ffff8948c17aff00 R14: ffff89489bef9400 R15: ffff89488b775a80
> FS: 00007fa54ad43700(0000) GS:ffff8949363c0000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> BUG: unable to handle kernel NULL pointer dereference at 00000000000000e8
> #PF error: [normal kernel read fault]
> PGD 0 P4D 0
> Oops: 0000 [#1] PREEMPT SMP PTI
> CPU: 7 PID: 2687 Comm: StreamTrans #56 Tainted: G U 4.20.0-rc7-next-20181221-beppy+ #15
> Hardware name: Dell Inc. XPS 13 9360/0TPN17, BIOS 2.10.0 09/27/2018
> RIP: 0010:transparent_hugepage_enabled+0x1a/0xa0
> Code: 17 fd 00 e9 20 ff ff ff 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 53 48 89 fb 48 83 bf 90 00 00 00 00 74 27 48 8b 87 a0 00 00 00 <48> 8b b8 e8 00 00 00 e8 7a cc fa ff 84 c0 75 04 31 c0 5b c3 48 89
> RSP: 0018:ffffb79744f17d28 EFLAGS: 00010282
> RAX: 0000000000000000 RBX: ffff8948c17aff00 RCX: 0000000000000000
> RDX: 0000000000000004 RSI: ffffffffab1165ba RDI: ffff8948c17aff00
> RBP: ffff8948c17aff00 R08: 0000000000000007 R09: ffff894927e547b2
> R10: 0000000000000000 R11: ffff894927e549da R12: ffffb79744f17d38
> R13: ffff8948c17aff00 R14: ffff89489bef9400 R15: ffff89488b775a80
> FS: 00007fa54ad43700(0000) GS:ffff8949363c0000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00000000000000e8 CR3: 000000025c0ee003 CR4: 00000000003606e0
> Call Trace:
> show_smap+0xd7/0x200
> seq_read+0x2e8/0x410
> __vfs_read+0x36/0x1a0
> vfs_read+0x8a/0x140
> ksys_read+0x52/0xc0
> do_syscall_64+0x48/0xf0
> entry_SYSCALL_64_after_hwframe+0x44/0xa9
> RIP: 0033:0x7fa585fb3184
> Code: c3 0f 1f 44 00 00 41 54 49 89 d4 55 48 89 f5 53 89 fb 48 83 ec 10 e8 5b fc ff ff 4c 89 e2 48 89 ee 89 df 41 89 c0 31 c0 0f 05 <48> 3d 00 f0 ff ff 77 38 44 89 c7 48 89 44 24 08 e8 97 fc ff ff 48
> RSP: 002b:00007fa54ad42060 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
> RAX: ffffffffffffffda RBX: 000000000000002c RCX: 00007fa585fb3184
> RDX: 0000000000001fff RSI: 00007fa54ffb2000 RDI: 000000000000002c
> RBP: 00007fa54ffb2000 R08: 0000000000000000 R09: 000000000000001e
> R10: 00007fa585c0dae0 R11: 0000000000000246 R12: 0000000000001fff
> R13: 00007fa54ad42510 R14: 00007fa54ffb2fc5 R15: 00007fa54ad42498
> Modules linked in: thunderbolt sch_cake rfcomm fuse arc4 iwlmvm mac80211 btusb btrtl btbcm btintel bnep bluetooth iwlwifi snd_hda_codec_hdmi ecdh_generic snd_hda_codec_realtek snd_hda_codec_generic snd_hda_intel cfg80211 snd_hda_codec nf_log_ipv6 ip6t_REJECT nf_reject_ipv6 snd_hwdep xt_hl snd_hda_core ip6t_rt nf_log_ipv4 nf_log_common joydev snd_pcm mousedev ipt_REJECT nf_reject_ipv4 hid_multitouch intel_rapl xt_LOG xt_comment nls_iso8859_1 intel_pmc_core nls_cp437 intel_powerclamp xt_limit kvm_intel xt_addrtype xt_tcpudp dell_laptop snd_timer xt_conntrack ledtrig_audio snd dell_wmi nf_conntrack efi_pstore dell_smbios mei_me dcdbas input_leds idma64 mei wmi_bmof intel_wmi_thunderbolt dell_wmi_descriptor efivars rfkill intel_pch_thermal intel_lpss_pci processor_thermal_device i2c_i801 soundcore intel_lpss intel_soc_dts_iosf i2c_hid evdev int3403_thermal int3400_thermal intel_vbtn rtc_cmos int340x_thermal_zone acpi_thermal_rel intel_hid mac_hid nf_defrag_ipv6 nf_defrag_ipv4
> ip6table_filter ip6_tables iptable_filter bpfilter coretemp msr dell_smm_hwmon crypto_user ip_tables x_tables algif_skcipher af_alg rtsx_pci_sdmmc mmc_core crct10dif_pclmul crc32_pclmul xhci_pci ghash_clmulni_intel serio_raw rtsx_pci xhci_hcd i915 kvmgt vfio_mdev mdev vfio_iommu_type1 vfio kvm irqbypass intel_gtt
> CR2: 00000000000000e8
> ---[ end trace 77d24d35c4e5213f ]---
> RIP: 0010:transparent_hugepage_enabled+0x1a/0xa0
> Code: 17 fd 00 e9 20 ff ff ff 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 53 48 89 fb 48 83 bf 90 00 00 00 00 74 27 48 8b 87 a0 00 00 00 <48> 8b b8 e8 00 00 00 e8 7a cc fa ff 84 c0 75 04 31 c0 5b c3 48 89
> RSP: 0018:ffffb79744f17d28 EFLAGS: 00010282
> RAX: 0000000000000000 RBX: ffff8948c17aff00 RCX: 0000000000000000
> RDX: 0000000000000004 RSI: ffffffffab1165ba RDI: ffff8948c17aff00
> RBP: ffff8948c17aff00 R08: 0000000000000007 R09: ffff894927e547b2
> R10: 0000000000000000 R11: ffff894927e549da R12: ffffb79744f17d38
> R13: ffff8948c17aff00 R14: ffff89489bef9400 R15: ffff89488b775a80
> FS: 00007fa54ad43700(0000) GS:ffff8949363c0000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00000000000000e8 CR3: 000000025c0ee003 CR4: 00000000003606e0
--
Michal Hocko
SUSE Labs
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: Bug with report THP eligibility for each vma
2018-12-24 7:49 ` Bug with report THP eligibility for each vma Michal Hocko
@ 2018-12-24 11:35 ` William Kucharski
2018-12-24 11:35 ` William Kucharski
2018-12-24 12:12 ` Mike Rapoport
1 sibling, 1 reply; 5+ messages in thread
From: William Kucharski @ 2018-12-24 11:35 UTC (permalink / raw)
To: Michal Hocko
Cc: Paul Oppenheimer, Andrew Morton, Vlastimil Babka, David Rientjes,
Jan Kara, Mike Rapoport, linux-mm, LKML
> On Dec 24, 2018, at 12:49 AM, Michal Hocko <mhocko@suse.com> wrote:
>
> [Cc-ing mailing list and people involved in the original patch]
>
> On Fri 21-12-18 13:42:24, Paul Oppenheimer wrote:
>> Hello! I've never reported a kernel bug before, and since its on the
>> "next" tree I was told to email the author of the relevant commit.
>> Please redirect me to the correct place if I've made a mistake.
>>
>> When opening firefox or chrome, and using it for a good 7 seconds, it
>> hangs in "uninterruptible sleep" and I recieve a "BUG" in dmesg. This
>> doesn't occur when reverting this commit:
>> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=48cf516f8c.
>> Ive attached the output of decode_stacktrace.sh and the relevant dmesg
>> log to this email.
>>
>> Thanks
>
>> BUG: unable to handle kernel NULL pointer dereference at 00000000000000e8
>
> Thanks for the bug report! This is offset 232 and that matches
> file->f_mapping as per pahole
> pahole -C file ./vmlinux | grep f_mapping
> struct address_space * f_mapping; /* 232 8 */
>
> I thought that each file really has to have a mapping. But the following
> should heal the issue and add an extra care.
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index f64733c23067..fc9d70a9fbd1 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -66,6 +66,8 @@ bool transparent_hugepage_enabled(struct vm_area_struct *vma)
> {
> if (vma_is_anonymous(vma))
> return __transparent_hugepage_enabled(vma);
> + if (!vma->vm_file || !vma->vm_file->f_mapping)
> + return false;
> if (shmem_mapping(vma->vm_file->f_mapping) && shmem_huge_enabled(vma))
> return __transparent_hugepage_enabled(vma);
From what I see in code in mm/mmap.c, it seems if vma->vm_file is non-zero
vma->vm_file->f_mapping may be assumed to be non-NULL; see unlink_file_vma()
and __vma_link_file() for two examples, which both use the construct:
file = vma->vm_file;
if (file) {
struct address_space *mapping = file->f_mapping;
[ ... ]
[ code that dereferences "mapping" without further checks ]
}
I see nothing wrong with your second check but a few extra instructions
performed, but depending upon how often transparent_hugepage_enabled() is called
there may be at least theoretical performance concerns.
William Kucharski
william.kucharski@oracle.com
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Bug with report THP eligibility for each vma
2018-12-24 11:35 ` William Kucharski
@ 2018-12-24 11:35 ` William Kucharski
0 siblings, 0 replies; 5+ messages in thread
From: William Kucharski @ 2018-12-24 11:35 UTC (permalink / raw)
To: Michal Hocko
Cc: Paul Oppenheimer, Andrew Morton, Vlastimil Babka, David Rientjes,
Jan Kara, Mike Rapoport, linux-mm, LKML
> On Dec 24, 2018, at 12:49 AM, Michal Hocko <mhocko@suse.com> wrote:
>
> [Cc-ing mailing list and people involved in the original patch]
>
> On Fri 21-12-18 13:42:24, Paul Oppenheimer wrote:
>> Hello! I've never reported a kernel bug before, and since its on the
>> "next" tree I was told to email the author of the relevant commit.
>> Please redirect me to the correct place if I've made a mistake.
>>
>> When opening firefox or chrome, and using it for a good 7 seconds, it
>> hangs in "uninterruptible sleep" and I recieve a "BUG" in dmesg. This
>> doesn't occur when reverting this commit:
>> https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=48cf516f8c.
>> Ive attached the output of decode_stacktrace.sh and the relevant dmesg
>> log to this email.
>>
>> Thanks
>
>> BUG: unable to handle kernel NULL pointer dereference at 00000000000000e8
>
> Thanks for the bug report! This is offset 232 and that matches
> file->f_mapping as per pahole
> pahole -C file ./vmlinux | grep f_mapping
> struct address_space * f_mapping; /* 232 8 */
>
> I thought that each file really has to have a mapping. But the following
> should heal the issue and add an extra care.
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index f64733c23067..fc9d70a9fbd1 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -66,6 +66,8 @@ bool transparent_hugepage_enabled(struct vm_area_struct *vma)
> {
> if (vma_is_anonymous(vma))
> return __transparent_hugepage_enabled(vma);
> + if (!vma->vm_file || !vma->vm_file->f_mapping)
> + return false;
> if (shmem_mapping(vma->vm_file->f_mapping) && shmem_huge_enabled(vma))
> return __transparent_hugepage_enabled(vma);
From what I see in code in mm/mmap.c, it seems if vma->vm_file is non-zero
vma->vm_file->f_mapping may be assumed to be non-NULL; see unlink_file_vma()
and __vma_link_file() for two examples, which both use the construct:
file = vma->vm_file;
if (file) {
struct address_space *mapping = file->f_mapping;
[ ... ]
[ code that dereferences "mapping" without further checks ]
}
I see nothing wrong with your second check but a few extra instructions
performed, but depending upon how often transparent_hugepage_enabled() is called
there may be at least theoretical performance concerns.
William Kucharski
william.kucharski@oracle.com
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Bug with report THP eligibility for each vma
2018-12-24 7:49 ` Bug with report THP eligibility for each vma Michal Hocko
2018-12-24 11:35 ` William Kucharski
@ 2018-12-24 12:12 ` Mike Rapoport
2018-12-24 18:51 ` Michal Hocko
1 sibling, 1 reply; 5+ messages in thread
From: Mike Rapoport @ 2018-12-24 12:12 UTC (permalink / raw)
To: Michal Hocko
Cc: Paul Oppenheimer, Andrew Morton, Vlastimil Babka, David Rientjes,
Jan Kara, linux-mm, LKML
On Mon, Dec 24, 2018 at 08:49:16AM +0100, Michal Hocko wrote:
> [Cc-ing mailing list and people involved in the original patch]
>
> On Fri 21-12-18 13:42:24, Paul Oppenheimer wrote:
> > Hello! I've never reported a kernel bug before, and since its on the
> > "next" tree I was told to email the author of the relevant commit.
> > Please redirect me to the correct place if I've made a mistake.
> >
> > When opening firefox or chrome, and using it for a good 7 seconds, it
> > hangs in "uninterruptible sleep" and I recieve a "BUG" in dmesg. This
> > doesn't occur when reverting this commit:
> > https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=48cf516f8c.
> > Ive attached the output of decode_stacktrace.sh and the relevant dmesg
> > log to this email.
> >
> > Thanks
>
> > BUG: unable to handle kernel NULL pointer dereference at 00000000000000e8
>
> Thanks for the bug report! This is offset 232 and that matches
> file->f_mapping as per pahole
> pahole -C file ./vmlinux | grep f_mapping
> struct address_space * f_mapping; /* 232 8 */
>
> I thought that each file really has to have a mapping. But the following
> should heal the issue and add an extra care.
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index f64733c23067..fc9d70a9fbd1 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -66,6 +66,8 @@ bool transparent_hugepage_enabled(struct vm_area_struct *vma)
> {
> if (vma_is_anonymous(vma))
> return __transparent_hugepage_enabled(vma);
> + if (!vma->vm_file || !vma->vm_file->f_mapping)
> + return false;
> if (shmem_mapping(vma->vm_file->f_mapping) && shmem_huge_enabled(vma))
> return __transparent_hugepage_enabled(vma);
We have vma_is_shmem(), it can be used to replace shmem_mapping() without
adding the check for !vma->vm_file
>
> Andrew, could you fold it to the original patch please?
>
> Keeping the rest for the reference.
>
> > #PF error: [normal kernel read fault]
> > PGD 0 P4D 0
> > Oops: 0000 [#1] PREEMPT SMP PTI
> > CPU: 7 PID: 2687 Comm: StreamTrans #56 Tainted: G U 4.20.0-rc7-next-20181221-beppy+ #15
> > Hardware name: Dell Inc. XPS 13 9360/0TPN17, BIOS 2.10.0 09/27/2018
> > RIP: 0010:transparent_hugepage_enabled (??:?)
> > Code: 17 fd 00 e9 20 ff ff ff 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 53 48 89 fb 48 83 bf 90 00 00 00 00 74 27 48 8b 87 a0 00 00 00 <48> 8b b8 e8 00 00 00 e8 7a cc fa ff 84 c0 75 04 31 c0 5b c3 48 89
> > All code
> > ========
> > 0: 17 (bad)
> > 1: fd std
> > 2: 00 e9 add %ch,%cl
> > 4: 20 ff and %bh,%bh
> > 6: ff (bad)
> > 7: ff 0f decl (%rdi)
> > 9: 1f (bad)
> > a: 84 00 test %al,(%rax)
> > c: 00 00 add %al,(%rax)
> > e: 00 00 add %al,(%rax)
> > 10: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
> > 15: 53 push %rbx
> > 16: 48 89 fb mov %rdi,%rbx
> > 19: 48 83 bf 90 00 00 00 cmpq $0x0,0x90(%rdi)
> > 20: 00
> > 21: 74 27 je 0x4a
> > 23: 48 8b 87 a0 00 00 00 mov 0xa0(%rdi),%rax
> > 2a:* 48 8b b8 e8 00 00 00 mov 0xe8(%rax),%rdi <-- trapping instruction
> > 31: e8 7a cc fa ff callq 0xfffffffffffaccb0
> > 36: 84 c0 test %al,%al
> > 38: 75 04 jne 0x3e
> > 3a: 31 c0 xor %eax,%eax
> > 3c: 5b pop %rbx
> > 3d: c3 retq
> > 3e: 48 rex.W
> > 3f: 89 .byte 0x89
> >
> > Code starting with the faulting instruction
> > ===========================================
> > 0: 48 8b b8 e8 00 00 00 mov 0xe8(%rax),%rdi
> > 7: e8 7a cc fa ff callq 0xfffffffffffacc86
> > c: 84 c0 test %al,%al
> > e: 75 04 jne 0x14
> > 10: 31 c0 xor %eax,%eax
> > 12: 5b pop %rbx
> > 13: c3 retq
> > 14: 48 rex.W
> > 15: 89 .byte 0x89
> > RSP: 0018:ffffb79744f17d28 EFLAGS: 00010282
> > RAX: 0000000000000000 RBX: ffff8948c17aff00 RCX: 0000000000000000
> > RDX: 0000000000000004 RSI: ffffffffab1165ba RDI: ffff8948c17aff00
> > RBP: ffff8948c17aff00 R08: 0000000000000007 R09: ffff894927e547b2
> > R10: 0000000000000000 R11: ffff894927e549da R12: ffffb79744f17d38
> > R13: ffff8948c17aff00 R14: ffff89489bef9400 R15: ffff89488b775a80
> > FS: 00007fa54ad43700(0000) GS:ffff8949363c0000(0000) knlGS:0000000000000000
> > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 00000000000000e8 CR3: 000000025c0ee003 CR4: 00000000003606e0
> > Call Trace:
> > show_smap (/home/bep/.opt/kernel/linux-e/fs/proc/task_mmu.c:805)
> > seq_read (/home/bep/.opt/kernel/linux-e/fs/seq_file.c:269)
> > __vfs_read (/home/bep/.opt/kernel/linux-e/fs/read_write.c:421)
> > vfs_read (/home/bep/.opt/kernel/linux-e/fs/read_write.c:452 /home/bep/.opt/kernel/linux-e/fs/read_write.c:437)
> > ksys_read (/home/bep/.opt/kernel/linux-e/fs/read_write.c:579)
> > do_syscall_64 (/home/bep/.opt/kernel/linux-e/arch/x86/entry/common.c:290)
> > entry_SYSCALL_64_after_hwframe (/home/bep/.opt/kernel/linux/arch/x86/entry/entry_64.S:184)
> > RIP: 0033:0x7fa585fb3184
> > Code: c3 0f 1f 44 00 00 41 54 49 89 d4 55 48 89 f5 53 89 fb 48 83 ec 10 e8 5b fc ff ff 4c 89 e2 48 89 ee 89 df 41 89 c0 31 c0 0f 05 <48> 3d 00 f0 ff ff 77 38 44 89 c7 48 89 44 24 08 e8 97 fc ff ff 48
> > All code
> > ========
> > 0: c3 retq
> > 1: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
> > 6: 41 54 push %r12
> > 8: 49 89 d4 mov %rdx,%r12
> > b: 55 push %rbp
> > c: 48 89 f5 mov %rsi,%rbp
> > f: 53 push %rbx
> > 10: 89 fb mov %edi,%ebx
> > 12: 48 83 ec 10 sub $0x10,%rsp
> > 16: e8 5b fc ff ff callq 0xfffffffffffffc76
> > 1b: 4c 89 e2 mov %r12,%rdx
> > 1e: 48 89 ee mov %rbp,%rsi
> > 21: 89 df mov %ebx,%edi
> > 23: 41 89 c0 mov %eax,%r8d
> > 26: 31 c0 xor %eax,%eax
> > 28: 0f 05 syscall
> > 2a:* 48 3d 00 f0 ff ff cmp $0xfffffffffffff000,%rax <-- trapping instruction
> > 30: 77 38 ja 0x6a
> > 32: 44 89 c7 mov %r8d,%edi
> > 35: 48 89 44 24 08 mov %rax,0x8(%rsp)
> > 3a: e8 97 fc ff ff callq 0xfffffffffffffcd6
> > 3f: 48 rex.W
> >
> > Code starting with the faulting instruction
> > ===========================================
> > 0: 48 3d 00 f0 ff ff cmp $0xfffffffffffff000,%rax
> > 6: 77 38 ja 0x40
> > 8: 44 89 c7 mov %r8d,%edi
> > b: 48 89 44 24 08 mov %rax,0x8(%rsp)
> > 10: e8 97 fc ff ff callq 0xfffffffffffffcac
> > 15: 48 rex.W
> > RSP: 002b:00007fa54ad42060 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
> > RAX: ffffffffffffffda RBX: 000000000000002c RCX: 00007fa585fb3184
> > RDX: 0000000000001fff RSI: 00007fa54ffb2000 RDI: 000000000000002c
> > RBP: 00007fa54ffb2000 R08: 0000000000000000 R09: 000000000000001e
> > R10: 00007fa585c0dae0 R11: 0000000000000246 R12: 0000000000001fff
> > R13: 00007fa54ad42510 R14: 00007fa54ffb2fc5 R15: 00007fa54ad42498
> > Modules linked in: thunderbolt sch_cake rfcomm fuse arc4 iwlmvm mac80211 btusb btrtl btbcm btintel bnep bluetooth iwlwifi snd_hda_codec_hdmi ecdh_generic snd_hda_codec_realtek snd_hda_codec_generic snd_hda_intel cfg80211 snd_hda_codec nf_log_ipv6 ip6t_REJECT nf_reject_ipv6 snd_hwdep xt_hl snd_hda_core ip6t_rt nf_log_ipv4 nf_log_common joydev snd_pcm mousedev ipt_REJECT nf_reject_ipv4 hid_multitouch intel_rapl xt_LOG xt_comment nls_iso8859_1 intel_pmc_core nls_cp437 intel_powerclamp xt_limit kvm_intel xt_addrtype xt_tcpudp dell_laptop snd_timer xt_conntrack ledtrig_audio snd dell_wmi nf_conntrack efi_pstore dell_smbios mei_me dcdbas input_leds idma64 mei wmi_bmof intel_wmi_thunderbolt dell_wmi_descriptor efivars rfkill intel_pch_thermal intel_lpss_pci processor_thermal_device i2c_i801 soundcore intel_lpss intel_soc_dts_iosf i2c_hid evdev int3403_thermal int3400_thermal intel_vbtn rtc_cmos int340x_thermal_zone acpi_thermal_rel intel_hid mac_hid nf_defrag_ipv6 nf_defrag_ipv4
> > ip6table_filter ip6_tables iptable_filter bpfilter coretemp msr dell_smm_hwmon crypto_user ip_tables x_tables algif_skcipher af_alg rtsx_pci_sdmmc mmc_core crct10dif_pclmul crc32_pclmul xhci_pci ghash_clmulni_intel serio_raw rtsx_pci xhci_hcd i915 kvmgt vfio_mdev mdev vfio_iommu_type1 vfio kvm irqbypass intel_gtt
> > CR2: 00000000000000e8
> > ---[ end trace 77d24d35c4e5213f ]---
> > RIP: 0010:transparent_hugepage_enabled (??:?)
> > Code: 17 fd 00 e9 20 ff ff ff 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 53 48 89 fb 48 83 bf 90 00 00 00 00 74 27 48 8b 87 a0 00 00 00 <48> 8b b8 e8 00 00 00 e8 7a cc fa ff 84 c0 75 04 31 c0 5b c3 48 89
> > All code
> > ========
> > 0: 17 (bad)
> > 1: fd std
> > 2: 00 e9 add %ch,%cl
> > 4: 20 ff and %bh,%bh
> > 6: ff (bad)
> > 7: ff 0f decl (%rdi)
> > 9: 1f (bad)
> > a: 84 00 test %al,(%rax)
> > c: 00 00 add %al,(%rax)
> > e: 00 00 add %al,(%rax)
> > 10: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
> > 15: 53 push %rbx
> > 16: 48 89 fb mov %rdi,%rbx
> > 19: 48 83 bf 90 00 00 00 cmpq $0x0,0x90(%rdi)
> > 20: 00
> > 21: 74 27 je 0x4a
> > 23: 48 8b 87 a0 00 00 00 mov 0xa0(%rdi),%rax
> > 2a:* 48 8b b8 e8 00 00 00 mov 0xe8(%rax),%rdi <-- trapping instruction
> > 31: e8 7a cc fa ff callq 0xfffffffffffaccb0
> > 36: 84 c0 test %al,%al
> > 38: 75 04 jne 0x3e
> > 3a: 31 c0 xor %eax,%eax
> > 3c: 5b pop %rbx
> > 3d: c3 retq
> > 3e: 48 rex.W
> > 3f: 89 .byte 0x89
> >
> > Code starting with the faulting instruction
> > ===========================================
> > 0: 48 8b b8 e8 00 00 00 mov 0xe8(%rax),%rdi
> > 7: e8 7a cc fa ff callq 0xfffffffffffacc86
> > c: 84 c0 test %al,%al
> > e: 75 04 jne 0x14
> > 10: 31 c0 xor %eax,%eax
> > 12: 5b pop %rbx
> > 13: c3 retq
> > 14: 48 rex.W
> > 15: 89 .byte 0x89
> > RSP: 0018:ffffb79744f17d28 EFLAGS: 00010282
> > RAX: 0000000000000000 RBX: ffff8948c17aff00 RCX: 0000000000000000
> > RDX: 0000000000000004 RSI: ffffffffab1165ba RDI: ffff8948c17aff00
> > RBP: ffff8948c17aff00 R08: 0000000000000007 R09: ffff894927e547b2
> > R10: 0000000000000000 R11: ffff894927e549da R12: ffffb79744f17d38
> > R13: ffff8948c17aff00 R14: ffff89489bef9400 R15: ffff89488b775a80
> > FS: 00007fa54ad43700(0000) GS:ffff8949363c0000(0000) knlGS:0000000000000000
> > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > BUG: unable to handle kernel NULL pointer dereference at 00000000000000e8
> > #PF error: [normal kernel read fault]
> > PGD 0 P4D 0
> > Oops: 0000 [#1] PREEMPT SMP PTI
> > CPU: 7 PID: 2687 Comm: StreamTrans #56 Tainted: G U 4.20.0-rc7-next-20181221-beppy+ #15
> > Hardware name: Dell Inc. XPS 13 9360/0TPN17, BIOS 2.10.0 09/27/2018
> > RIP: 0010:transparent_hugepage_enabled+0x1a/0xa0
> > Code: 17 fd 00 e9 20 ff ff ff 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 53 48 89 fb 48 83 bf 90 00 00 00 00 74 27 48 8b 87 a0 00 00 00 <48> 8b b8 e8 00 00 00 e8 7a cc fa ff 84 c0 75 04 31 c0 5b c3 48 89
> > RSP: 0018:ffffb79744f17d28 EFLAGS: 00010282
> > RAX: 0000000000000000 RBX: ffff8948c17aff00 RCX: 0000000000000000
> > RDX: 0000000000000004 RSI: ffffffffab1165ba RDI: ffff8948c17aff00
> > RBP: ffff8948c17aff00 R08: 0000000000000007 R09: ffff894927e547b2
> > R10: 0000000000000000 R11: ffff894927e549da R12: ffffb79744f17d38
> > R13: ffff8948c17aff00 R14: ffff89489bef9400 R15: ffff89488b775a80
> > FS: 00007fa54ad43700(0000) GS:ffff8949363c0000(0000) knlGS:0000000000000000
> > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 00000000000000e8 CR3: 000000025c0ee003 CR4: 00000000003606e0
> > Call Trace:
> > show_smap+0xd7/0x200
> > seq_read+0x2e8/0x410
> > __vfs_read+0x36/0x1a0
> > vfs_read+0x8a/0x140
> > ksys_read+0x52/0xc0
> > do_syscall_64+0x48/0xf0
> > entry_SYSCALL_64_after_hwframe+0x44/0xa9
> > RIP: 0033:0x7fa585fb3184
> > Code: c3 0f 1f 44 00 00 41 54 49 89 d4 55 48 89 f5 53 89 fb 48 83 ec 10 e8 5b fc ff ff 4c 89 e2 48 89 ee 89 df 41 89 c0 31 c0 0f 05 <48> 3d 00 f0 ff ff 77 38 44 89 c7 48 89 44 24 08 e8 97 fc ff ff 48
> > RSP: 002b:00007fa54ad42060 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
> > RAX: ffffffffffffffda RBX: 000000000000002c RCX: 00007fa585fb3184
> > RDX: 0000000000001fff RSI: 00007fa54ffb2000 RDI: 000000000000002c
> > RBP: 00007fa54ffb2000 R08: 0000000000000000 R09: 000000000000001e
> > R10: 00007fa585c0dae0 R11: 0000000000000246 R12: 0000000000001fff
> > R13: 00007fa54ad42510 R14: 00007fa54ffb2fc5 R15: 00007fa54ad42498
> > Modules linked in: thunderbolt sch_cake rfcomm fuse arc4 iwlmvm mac80211 btusb btrtl btbcm btintel bnep bluetooth iwlwifi snd_hda_codec_hdmi ecdh_generic snd_hda_codec_realtek snd_hda_codec_generic snd_hda_intel cfg80211 snd_hda_codec nf_log_ipv6 ip6t_REJECT nf_reject_ipv6 snd_hwdep xt_hl snd_hda_core ip6t_rt nf_log_ipv4 nf_log_common joydev snd_pcm mousedev ipt_REJECT nf_reject_ipv4 hid_multitouch intel_rapl xt_LOG xt_comment nls_iso8859_1 intel_pmc_core nls_cp437 intel_powerclamp xt_limit kvm_intel xt_addrtype xt_tcpudp dell_laptop snd_timer xt_conntrack ledtrig_audio snd dell_wmi nf_conntrack efi_pstore dell_smbios mei_me dcdbas input_leds idma64 mei wmi_bmof intel_wmi_thunderbolt dell_wmi_descriptor efivars rfkill intel_pch_thermal intel_lpss_pci processor_thermal_device i2c_i801 soundcore intel_lpss intel_soc_dts_iosf i2c_hid evdev int3403_thermal int3400_thermal intel_vbtn rtc_cmos int340x_thermal_zone acpi_thermal_rel intel_hid mac_hid nf_defrag_ipv6 nf_defrag_ipv4
> > ip6table_filter ip6_tables iptable_filter bpfilter coretemp msr dell_smm_hwmon crypto_user ip_tables x_tables algif_skcipher af_alg rtsx_pci_sdmmc mmc_core crct10dif_pclmul crc32_pclmul xhci_pci ghash_clmulni_intel serio_raw rtsx_pci xhci_hcd i915 kvmgt vfio_mdev mdev vfio_iommu_type1 vfio kvm irqbypass intel_gtt
> > CR2: 00000000000000e8
> > ---[ end trace 77d24d35c4e5213f ]---
> > RIP: 0010:transparent_hugepage_enabled+0x1a/0xa0
> > Code: 17 fd 00 e9 20 ff ff ff 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 53 48 89 fb 48 83 bf 90 00 00 00 00 74 27 48 8b 87 a0 00 00 00 <48> 8b b8 e8 00 00 00 e8 7a cc fa ff 84 c0 75 04 31 c0 5b c3 48 89
> > RSP: 0018:ffffb79744f17d28 EFLAGS: 00010282
> > RAX: 0000000000000000 RBX: ffff8948c17aff00 RCX: 0000000000000000
> > RDX: 0000000000000004 RSI: ffffffffab1165ba RDI: ffff8948c17aff00
> > RBP: ffff8948c17aff00 R08: 0000000000000007 R09: ffff894927e547b2
> > R10: 0000000000000000 R11: ffff894927e549da R12: ffffb79744f17d38
> > R13: ffff8948c17aff00 R14: ffff89489bef9400 R15: ffff89488b775a80
> > FS: 00007fa54ad43700(0000) GS:ffff8949363c0000(0000) knlGS:0000000000000000
> > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 00000000000000e8 CR3: 000000025c0ee003 CR4: 00000000003606e0
>
>
> --
> Michal Hocko
> SUSE Labs
>
--
Sincerely yours,
Mike.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: Bug with report THP eligibility for each vma
2018-12-24 12:12 ` Mike Rapoport
@ 2018-12-24 18:51 ` Michal Hocko
0 siblings, 0 replies; 5+ messages in thread
From: Michal Hocko @ 2018-12-24 18:51 UTC (permalink / raw)
To: Mike Rapoport, Andrew Morton
Cc: Paul Oppenheimer, Vlastimil Babka, David Rientjes, Jan Kara,
linux-mm, LKML
On Mon 24-12-18 14:12:51, Mike Rapoport wrote:
> On Mon, Dec 24, 2018 at 08:49:16AM +0100, Michal Hocko wrote:
> > [Cc-ing mailing list and people involved in the original patch]
> >
> > On Fri 21-12-18 13:42:24, Paul Oppenheimer wrote:
> > > Hello! I've never reported a kernel bug before, and since its on the
> > > "next" tree I was told to email the author of the relevant commit.
> > > Please redirect me to the correct place if I've made a mistake.
> > >
> > > When opening firefox or chrome, and using it for a good 7 seconds, it
> > > hangs in "uninterruptible sleep" and I recieve a "BUG" in dmesg. This
> > > doesn't occur when reverting this commit:
> > > https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=48cf516f8c.
> > > Ive attached the output of decode_stacktrace.sh and the relevant dmesg
> > > log to this email.
> > >
> > > Thanks
> >
> > > BUG: unable to handle kernel NULL pointer dereference at 00000000000000e8
> >
> > Thanks for the bug report! This is offset 232 and that matches
> > file->f_mapping as per pahole
> > pahole -C file ./vmlinux | grep f_mapping
> > struct address_space * f_mapping; /* 232 8 */
> >
> > I thought that each file really has to have a mapping. But the following
> > should heal the issue and add an extra care.
> >
> > diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> > index f64733c23067..fc9d70a9fbd1 100644
> > --- a/mm/huge_memory.c
> > +++ b/mm/huge_memory.c
> > @@ -66,6 +66,8 @@ bool transparent_hugepage_enabled(struct vm_area_struct *vma)
> > {
> > if (vma_is_anonymous(vma))
> > return __transparent_hugepage_enabled(vma);
> > + if (!vma->vm_file || !vma->vm_file->f_mapping)
> > + return false;
> > if (shmem_mapping(vma->vm_file->f_mapping) && shmem_huge_enabled(vma))
> > return __transparent_hugepage_enabled(vma);
>
> We have vma_is_shmem(), it can be used to replace shmem_mapping() without
> adding the check for !vma->vm_file
Yes, this looks like a much better choice. Thanks! Andrew, could you
fold this in instead.
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index f64733c23067..e093cf5e4640 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -66,7 +66,7 @@ bool transparent_hugepage_enabled(struct vm_area_struct *vma)
{
if (vma_is_anonymous(vma))
return __transparent_hugepage_enabled(vma);
- if (shmem_mapping(vma->vm_file->f_mapping) && shmem_huge_enabled(vma))
+ if (vma_is_shmem(vma) && shmem_huge_enabled(vma))
return __transparent_hugepage_enabled(vma);
return false;
--
Michal Hocko
SUSE Labs
^ permalink raw reply related [flat|nested] 5+ messages in thread
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2018-12-24 7:49 ` Bug with report THP eligibility for each vma Michal Hocko
2018-12-24 11:35 ` William Kucharski
2018-12-24 11:35 ` William Kucharski
2018-12-24 12:12 ` Mike Rapoport
2018-12-24 18:51 ` Michal Hocko
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