fsnotify: Fix fsnotify_mark_connector race

[Joshua R. Poulson]

On Azure we have had sporadic cases of soft lockups in fsnotify that may very well be mitigated by the following fix. The LKML thread is "kernel panics with 4.14.X".

This should be applied to 4.13 and 4.15 versions of the linux-azure kernel, and possibly the 4.15 generic kernel in bionic as well.

-----

fsnotify() acquires a reference to a fsnotify_mark_connector through
the SRCU-protected pointer to_tell->i_fsnotify_marks. However, it
appears that no precautions are taken in fsnotify_put_mark() to
ensure that fsnotify() drops its reference to this
fsnotify_mark_connector before assigning a value to its 'destroy_next'
field. This can result in fsnotify_put_mark() assigning a value
to a connector's 'destroy_next' field right before fsnotify() tries to
traverse the linked list referenced by the connector's 'list' field.
Since these two fields are members of the same union, this behavior
results in a kernel panic.

This issue is resolved by moving the connector's 'destroy_next' field
into the object pointer union. This should work since the object pointer
access is protected by both a spinlock and the value of the 'flags'
field, and the 'flags' field is cleared while holding the spinlock in
fsnotify_put_mark() before 'destroy_next' is updated. It shouldn't be
possible for another thread to accidentally read from the object pointer
after the 'destroy_next' field is updated.

The offending behavior here is extremely unlikely; since
fsnotify_put_mark() removes references to a connector (specifically,
it ensures that the connector is unreachable from the inode it was
formerly attached to) before updating its 'destroy_next' field, a
sizeable chunk of code in fsnotify_put_mark() has to execute in the
short window between when fsnotify() acquires the connector reference
and saves the value of its 'list' field. On the HEAD kernel, I've only
been able to reproduce this by inserting a udelay(1) in fsnotify().
However, I've been able to reproduce this issue without inserting a
udelay(1) anywhere on older unmodified release kernels, so I believe
it's worth fixing at HEAD.

References: https://bugzilla.kernel.org/show_bug.cgi?id=199437
Fixes: 08991e83b7286635167bab40927665a90fb00d81
CC: <email address hidden>
Signed-off-by: Robert Kolchmeyer <email address hidden>
Signed-off-by: Jan Kara <email address hidden>

[Brad Figg (brad-figg)]

This bug is awaiting verification that the kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-bionic' to 'verification-done-bionic'. If the problem still exists, change the tag 'verification-needed-bionic' to 'verification-failed-bionic'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux-azure - 4.15.0-1012.12

---------------
linux-azure (4.15.0-1012.12) bionic; urgency=medium

  * linux-image-4.15.0-20-generic install after upgrade from xenial breaks
    (LP: #1767133)
    - Packaging: Add versioned dependency for linux-base

  [ Ubuntu: 4.15.0-22.24 ]

  * CVE-2018-3639 (powerpc)
    - powerpc/64s: Add support for a store forwarding barrier at kernel entry/exit
    - stf-barrier: set eieio instruction bit 6 for future optimisations
  * CVE-2018-3639 (x86)
    - x86/nospec: Simplify alternative_msr_write()
    - x86/bugs: Concentrate bug detection into a separate function
    - x86/bugs: Concentrate bug reporting into a separate function
    - x86/bugs: Read SPEC_CTRL MSR during boot and re-use reserved bits
    - x86/bugs, KVM: Support the combination of guest and host IBRS
    - x86/bugs: Expose /sys/../spec_store_bypass
    - x86/cpufeatures: Add X86_FEATURE_RDS
    - x86/bugs: Provide boot parameters for the spec_store_bypass_disable
      mitigation
    - x86/bugs/intel: Set proper CPU features and setup RDS
    - x86/bugs: Whitelist allowed SPEC_CTRL MSR values
    - x86/bugs/AMD: Add support to disable RDS on Fam[15,16,17]h if requested
    - x86/KVM/VMX: Expose SPEC_CTRL Bit(2) to the guest
    - x86/speculation: Create spec-ctrl.h to avoid include hell
    - prctl: Add speculation control prctls
    - x86/process: Allow runtime control of Speculative Store Bypass
    - x86/speculation: Add prctl for Speculative Store Bypass mitigation
    - nospec: Allow getting/setting on non-current task
    - proc: Provide details on speculation flaw mitigations
    - seccomp: Enable speculation flaw mitigations
    - x86/bugs: Make boot modes __ro_after_init
    - prctl: Add force disable speculation
    - seccomp: Use PR_SPEC_FORCE_DISABLE
    - seccomp: Add filter flag to opt-out of SSB mitigation
    - seccomp: Move speculation migitation control to arch code
    - x86/speculation: Make "seccomp" the default mode for Speculative Store
      Bypass
    - x86/bugs: Rename _RDS to _SSBD
    - proc: Use underscores for SSBD in 'status'
    - Documentation/spec_ctrl: Do some minor cleanups
    - x86/bugs: Fix __ssb_select_mitigation() return type
    - x86/bugs: Make cpu_show_common() static
  * LSM Stacking prctl values should be redefined as to not collide with
    upstream prctls (LP: #1769263) // CVE-2018-3639
    - SAUCE: LSM stacking: adjust prctl values

  [ Ubuntu: 4.15.0-21.22 ]

  * linux: 4.15.0-21.22 -proposed tracker (LP: #1767397)
  * initramfs-tools exception during pm.DoInstall with do-release-upgrade from
    16.04 to 18.04 (LP: #1766727)
    - Add linux-image-* Breaks on s390-tools (<< 2.3.0-0ubuntu3)
  * linux-image-4.15.0-20-generic install after upgrade from xenial breaks
    (LP: #1767133)
    - Packaging: Depends on linux-base that provides the necessary tools
  * linux-image packages need to Breaks flash-kernel << 3.90ubuntu2
    (LP: #1766629)
    - linux-image-* breaks on flash-kernel (<< 3.90ubuntu2)

linux-azure (4.15.0-1011.11) bionic; urgency=medium

  * linux-azure: 4.15.0-1011.11 -proposed tracker (LP: #1770294)

  * fsnotify: Fix fsnotify_mark_connector ra...

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux-azure - 4.13.0-1018.21

---------------
linux-azure (4.13.0-1018.21) xenial; urgency=medium

  [ Ubuntu: 4.13.0-43.48 ]

  * CVE-2018-3639 (powerpc)
    - SAUCE: rfi-flush: update H_CPU_* macro names to upstream
    - SAUCE: rfi-flush: update plpar_get_cpu_characteristics() signature to
      upstream
    - SAUCE: update pseries_setup_rfi_flush() capitalization to upstream
    - powerpc/pseries: Support firmware disable of RFI flush
    - powerpc/powernv: Support firmware disable of RFI flush
    - powerpc/64s: Allow control of RFI flush via debugfs
    - powerpc/rfi-flush: Move the logic to avoid a redo into the debugfs code
    - powerpc/rfi-flush: Always enable fallback flush on pseries
    - powerpc/rfi-flush: Differentiate enabled and patched flush types
    - powerpc/pseries: Add new H_GET_CPU_CHARACTERISTICS flags
    - powerpc: Add security feature flags for Spectre/Meltdown
    - powerpc/powernv: Set or clear security feature flags
    - powerpc/pseries: Set or clear security feature flags
    - powerpc/powernv: Use the security flags in pnv_setup_rfi_flush()
    - powerpc/pseries: Use the security flags in pseries_setup_rfi_flush()
    - powerpc/pseries: Fix clearing of security feature flags
    - powerpc: Move default security feature flags
    - powerpc/pseries: Restore default security feature flags on setup
    - powerpc/64s: Add support for a store forwarding barrier at kernel entry/exit
  * CVE-2018-3639 (x86)
    - SAUCE: Add X86_FEATURE_ARCH_CAPABILITIES
    - SAUCE: x86: Add alternative_msr_write
    - x86/nospec: Simplify alternative_msr_write()
    - x86/pti: Do not enable PTI on CPUs which are not vulnerable to Meltdown
    - x86/bugs: Concentrate bug detection into a separate function
    - x86/bugs: Concentrate bug reporting into a separate function
    - x86/msr: Add definitions for new speculation control MSRs
    - x86/bugs: Read SPEC_CTRL MSR during boot and re-use reserved bits
    - x86/bugs, KVM: Support the combination of guest and host IBRS
    - x86/bugs: Expose /sys/../spec_store_bypass
    - x86/cpufeatures: Add X86_FEATURE_RDS
    - x86/bugs: Provide boot parameters for the spec_store_bypass_disable
      mitigation
    - x86/bugs/intel: Set proper CPU features and setup RDS
    - x86/bugs: Whitelist allowed SPEC_CTRL MSR values
    - x86/bugs/AMD: Add support to disable RDS on Fam[15,16,17]h if requested
    - x86/KVM/VMX: Expose SPEC_CTRL Bit(2) to the guest
    - x86/speculation: Create spec-ctrl.h to avoid include hell
    - prctl: Add speculation control prctls
    - x86/process: Allow runtime control of Speculative Store Bypass
    - x86/speculation: Add prctl for Speculative Store Bypass mitigation
    - nospec: Allow getting/setting on non-current task
    - proc: Provide details on speculation flaw mitigations
    - seccomp: Enable speculation flaw mitigations
    - SAUCE: x86/bugs: Honour SPEC_CTRL default
    - x86/bugs: Make boot modes __ro_after_init
    - prctl: Add force disable speculation
    - seccomp: Use PR_SPEC_FORCE_DISABLE
    - seccomp: Add filter flag to opt-out of SSB mitigation
    - seccomp: Move speculation migitation control to arch cod...

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is missing log files that will aid in diagnosing the problem. While running an Ubuntu kernel (not a mainline or third-party kernel) please enter the following command in a terminal window:

apport-collect 1765564

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

[Oded David (dudidu)]

Hi,

Can you please approve the issue got fixed in kernel version 4.13.0-1018-azure

[Joshua R. Poulson (jrp)]

We have let affected customers know that this kernel is available and are awaiting their feedback on whether fixing this particular race condition also addressed the issues they are experiencing.

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux-azure - 4.15.0-1012.12

---------------
linux-azure (4.15.0-1012.12) bionic; urgency=medium

  * linux-image-4.15.0-20-generic install after upgrade from xenial breaks
    (LP: #1767133)
    - Packaging: Add versioned dependency for linux-base

  [ Ubuntu: 4.15.0-22.24 ]

  * CVE-2018-3639 (powerpc)
    - powerpc/64s: Add support for a store forwarding barrier at kernel entry/exit
    - stf-barrier: set eieio instruction bit 6 for future optimisations
  * CVE-2018-3639 (x86)
    - x86/nospec: Simplify alternative_msr_write()
    - x86/bugs: Concentrate bug detection into a separate function
    - x86/bugs: Concentrate bug reporting into a separate function
    - x86/bugs: Read SPEC_CTRL MSR during boot and re-use reserved bits
    - x86/bugs, KVM: Support the combination of guest and host IBRS
    - x86/bugs: Expose /sys/../spec_store_bypass
    - x86/cpufeatures: Add X86_FEATURE_RDS
    - x86/bugs: Provide boot parameters for the spec_store_bypass_disable
      mitigation
    - x86/bugs/intel: Set proper CPU features and setup RDS
    - x86/bugs: Whitelist allowed SPEC_CTRL MSR values
    - x86/bugs/AMD: Add support to disable RDS on Fam[15,16,17]h if requested
    - x86/KVM/VMX: Expose SPEC_CTRL Bit(2) to the guest
    - x86/speculation: Create spec-ctrl.h to avoid include hell
    - prctl: Add speculation control prctls
    - x86/process: Allow runtime control of Speculative Store Bypass
    - x86/speculation: Add prctl for Speculative Store Bypass mitigation
    - nospec: Allow getting/setting on non-current task
    - proc: Provide details on speculation flaw mitigations
    - seccomp: Enable speculation flaw mitigations
    - x86/bugs: Make boot modes __ro_after_init
    - prctl: Add force disable speculation
    - seccomp: Use PR_SPEC_FORCE_DISABLE
    - seccomp: Add filter flag to opt-out of SSB mitigation
    - seccomp: Move speculation migitation control to arch code
    - x86/speculation: Make "seccomp" the default mode for Speculative Store
      Bypass
    - x86/bugs: Rename _RDS to _SSBD
    - proc: Use underscores for SSBD in 'status'
    - Documentation/spec_ctrl: Do some minor cleanups
    - x86/bugs: Fix __ssb_select_mitigation() return type
    - x86/bugs: Make cpu_show_common() static
  * LSM Stacking prctl values should be redefined as to not collide with
    upstream prctls (LP: #1769263) // CVE-2018-3639
    - SAUCE: LSM stacking: adjust prctl values

  [ Ubuntu: 4.15.0-21.22 ]

  * linux: 4.15.0-21.22 -proposed tracker (LP: #1767397)
  * initramfs-tools exception during pm.DoInstall with do-release-upgrade from
    16.04 to 18.04 (LP: #1766727)
    - Add linux-image-* Breaks on s390-tools (<< 2.3.0-0ubuntu3)
  * linux-image-4.15.0-20-generic install after upgrade from xenial breaks
    (LP: #1767133)
    - Packaging: Depends on linux-base that provides the necessary tools
  * linux-image packages need to Breaks flash-kernel << 3.90ubuntu2
    (LP: #1766629)
    - linux-image-* breaks on flash-kernel (<< 3.90ubuntu2)

linux-azure (4.15.0-1011.11) bionic; urgency=medium

  * linux-azure: 4.15.0-1011.11 -proposed tracker (LP: #1770294)

  * fsnotify: Fix fsnotify_mark_connector ra...

[Brad Figg (brad-figg)]

This bug is awaiting verification that the kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-artful' to 'verification-done-artful'. If the problem still exists, change the tag 'verification-needed-artful' to 'verification-failed-artful'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Stefan Bader (smb)]

Any progress on the verification for this?

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 4.15.0-23.25

---------------
linux (4.15.0-23.25) bionic; urgency=medium

  * linux: 4.15.0-23.25 -proposed tracker (LP: #1772927)

  * arm64 SDEI support needs trampoline code for KPTI (LP: #1768630)
    - arm64: mmu: add the entry trampolines start/end section markers into
      sections.h
    - arm64: sdei: Add trampoline code for remapping the kernel

  * Some PCIe errors not surfaced through rasdaemon (LP: #1769730)
    - ACPI: APEI: handle PCIe AER errors in separate function
    - ACPI: APEI: call into AER handling regardless of severity

  * qla2xxx: Fix page fault at kmem_cache_alloc_node() (LP: #1770003)
    - scsi: qla2xxx: Fix session cleanup for N2N
    - scsi: qla2xxx: Remove unused argument from qlt_schedule_sess_for_deletion()
    - scsi: qla2xxx: Serialize session deletion by using work_lock
    - scsi: qla2xxx: Serialize session free in qlt_free_session_done
    - scsi: qla2xxx: Don't call dma_free_coherent with IRQ disabled.
    - scsi: qla2xxx: Fix warning in qla2x00_async_iocb_timeout()
    - scsi: qla2xxx: Prevent relogin trigger from sending too many commands
    - scsi: qla2xxx: Fix double free bug after firmware timeout
    - scsi: qla2xxx: Fixup locking for session deletion

  * Several hisi_sas bug fixes (LP: #1768974)
    - scsi: hisi_sas: dt-bindings: add an property of signal attenuation
    - scsi: hisi_sas: support the property of signal attenuation for v2 hw
    - scsi: hisi_sas: fix the issue of link rate inconsistency
    - scsi: hisi_sas: fix the issue of setting linkrate register
    - scsi: hisi_sas: increase timer expire of internal abort task
    - scsi: hisi_sas: remove unused variable hisi_sas_devices.running_req
    - scsi: hisi_sas: fix return value of hisi_sas_task_prep()
    - scsi: hisi_sas: Code cleanup and minor bug fixes

  * [bionic] machine stuck and bonding not working well when nvmet_rdma module
    is loaded (LP: #1764982)
    - nvmet-rdma: Don't flush system_wq by default during remove_one
    - nvme-rdma: Don't flush delete_wq by default during remove_one

  * Warnings/hang during error handling of SATA disks on SAS controller
    (LP: #1768971)
    - scsi: libsas: defer ata device eh commands to libata

  * Hotplugging a SATA disk into a SAS controller may cause crash (LP: #1768948)
    - ata: do not schedule hot plug if it is a sas host

  * ISST-LTE:pKVM:Ubuntu1804: rcu_sched self-detected stall on CPU follow by CPU
    ATTEMPT TO RE-ENTER FIRMWARE! (LP: #1767927)
    - powerpc/powernv: Handle unknown OPAL errors in opal_nvram_write()
    - powerpc/64s: return more carefully from sreset NMI
    - powerpc/64s: sreset panic if there is no debugger or crash dump handlers

  * fsnotify: Fix fsnotify_mark_connector race (LP: #1765564)
    - fsnotify: Fix fsnotify_mark_connector race

  * Hang on network interface removal in Xen virtual machine (LP: #1771620)
    - xen-netfront: Fix hang on device removal

  * HiSilicon HNS NIC names are truncated in /proc/interrupts (LP: #1765977)
    - net: hns: Avoid action name truncation

  * Ubuntu 18.04 kernel crashed while in degraded mode (LP: #1770849)
    - SAUCE: powerpc/perf: Fix memory allocation for...

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 4.13.0-45.50

---------------
linux (4.13.0-45.50) artful; urgency=medium

  * linux: 4.13.0-45.50 -proposed tracker (LP: #1774124)

  * CVE-2018-3639 (x86)
    - SAUCE: Set generic SSBD feature for Intel cpus

linux (4.13.0-44.49) artful; urgency=medium

  * linux: 4.13.0-44.49 -proposed tracker (LP: #1772951)

  * CVE-2018-3639 (x86)
    - x86/cpu: Make alternative_msr_write work for 32-bit code
    - x86/cpu/AMD: Fix erratum 1076 (CPB bit)
    - x86/bugs: Fix the parameters alignment and missing void
    - KVM: SVM: Move spec control call after restore of GS
    - x86/speculation: Use synthetic bits for IBRS/IBPB/STIBP
    - x86/cpufeatures: Disentangle MSR_SPEC_CTRL enumeration from IBRS
    - x86/cpufeatures: Disentangle SSBD enumeration
    - x86/cpufeatures: Add FEATURE_ZEN
    - x86/speculation: Handle HT correctly on AMD
    - x86/bugs, KVM: Extend speculation control for VIRT_SPEC_CTRL
    - x86/speculation: Add virtualized speculative store bypass disable support
    - x86/speculation: Rework speculative_store_bypass_update()
    - x86/bugs: Unify x86_spec_ctrl_{set_guest,restore_host}
    - x86/bugs: Expose x86_spec_ctrl_base directly
    - x86/bugs: Remove x86_spec_ctrl_set()
    - x86/bugs: Rework spec_ctrl base and mask logic
    - x86/speculation, KVM: Implement support for VIRT_SPEC_CTRL/LS_CFG
    - KVM: SVM: Implement VIRT_SPEC_CTRL support for SSBD
    - x86/bugs: Rename SSBD_NO to SSB_NO
    - KVM: VMX: Expose SSBD properly to guests.

  * [Ubuntu 16.04] kernel: fix rwlock implementation (LP: #1761674)
    - SAUCE: (no-up) s390: fix rwlock implementation

  * CVE-2018-7492
    - rds: Fix NULL pointer dereference in __rds_rdma_map

  * CVE-2018-8781
    - drm: udl: Properly check framebuffer mmap offsets

  * fsnotify: Fix fsnotify_mark_connector race (LP: #1765564)
    - fsnotify: Fix fsnotify_mark_connector race

  * Kernel panic on boot (m1.small in cn-north-1) (LP: #1771679)
    - x86/xen: Reset VCPU0 info pointer after shared_info remap

  * Suspend to idle: Open lid didn't resume (LP: #1771542)
    - ACPI / PM: Do not reconfigure GPEs for suspend-to-idle

  * CVE-2018-1092
    - ext4: fail ext4_iget for root directory if unallocated

  * [SRU][Artful] using vfio-pci on a combination of cn8xxx and some PCI devices
    results in a kernel panic. (LP: #1770254)
    - PCI: Avoid bus reset if bridge itself is broken
    - PCI: Mark Cavium CN8xxx to avoid bus reset
    - PCI: Avoid slot reset if bridge itself is broken

  * Battery drains when laptop is off (shutdown) (LP: #1745646)
    - PCI / PM: Check device_may_wakeup() in pci_enable_wake()

  * perf record crash: refcount_inc assertion failed (LP: #1769027)
    - perf cgroup: Fix refcount usage
    - perf xyarray: Fix wrong processing when closing evsel fd

  * Dell Latitude 5490/5590 BIOS update 1.1.9 causes black screen at boot
    (LP: #1764194)
    - drm/i915/bios: filter out invalid DDC pins from VBT child devices

  * Fix an issue that some PCI devices get incorrectly suspended (LP: #1764684)
    - PCI / PM: Always check PME wakeup capability for runtime wakeup support

  * [SRU][Bionic/Artful] fix false positives in W...

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 4.15.0-23.25

---------------
linux (4.15.0-23.25) bionic; urgency=medium

  * linux: 4.15.0-23.25 -proposed tracker (LP: #1772927)

  * arm64 SDEI support needs trampoline code for KPTI (LP: #1768630)
    - arm64: mmu: add the entry trampolines start/end section markers into
      sections.h
    - arm64: sdei: Add trampoline code for remapping the kernel

  * Some PCIe errors not surfaced through rasdaemon (LP: #1769730)
    - ACPI: APEI: handle PCIe AER errors in separate function
    - ACPI: APEI: call into AER handling regardless of severity

  * qla2xxx: Fix page fault at kmem_cache_alloc_node() (LP: #1770003)
    - scsi: qla2xxx: Fix session cleanup for N2N
    - scsi: qla2xxx: Remove unused argument from qlt_schedule_sess_for_deletion()
    - scsi: qla2xxx: Serialize session deletion by using work_lock
    - scsi: qla2xxx: Serialize session free in qlt_free_session_done
    - scsi: qla2xxx: Don't call dma_free_coherent with IRQ disabled.
    - scsi: qla2xxx: Fix warning in qla2x00_async_iocb_timeout()
    - scsi: qla2xxx: Prevent relogin trigger from sending too many commands
    - scsi: qla2xxx: Fix double free bug after firmware timeout
    - scsi: qla2xxx: Fixup locking for session deletion

  * Several hisi_sas bug fixes (LP: #1768974)
    - scsi: hisi_sas: dt-bindings: add an property of signal attenuation
    - scsi: hisi_sas: support the property of signal attenuation for v2 hw
    - scsi: hisi_sas: fix the issue of link rate inconsistency
    - scsi: hisi_sas: fix the issue of setting linkrate register
    - scsi: hisi_sas: increase timer expire of internal abort task
    - scsi: hisi_sas: remove unused variable hisi_sas_devices.running_req
    - scsi: hisi_sas: fix return value of hisi_sas_task_prep()
    - scsi: hisi_sas: Code cleanup and minor bug fixes

  * [bionic] machine stuck and bonding not working well when nvmet_rdma module
    is loaded (LP: #1764982)
    - nvmet-rdma: Don't flush system_wq by default during remove_one
    - nvme-rdma: Don't flush delete_wq by default during remove_one

  * Warnings/hang during error handling of SATA disks on SAS controller
    (LP: #1768971)
    - scsi: libsas: defer ata device eh commands to libata

  * Hotplugging a SATA disk into a SAS controller may cause crash (LP: #1768948)
    - ata: do not schedule hot plug if it is a sas host

  * ISST-LTE:pKVM:Ubuntu1804: rcu_sched self-detected stall on CPU follow by CPU
    ATTEMPT TO RE-ENTER FIRMWARE! (LP: #1767927)
    - powerpc/powernv: Handle unknown OPAL errors in opal_nvram_write()
    - powerpc/64s: return more carefully from sreset NMI
    - powerpc/64s: sreset panic if there is no debugger or crash dump handlers

  * fsnotify: Fix fsnotify_mark_connector race (LP: #1765564)
    - fsnotify: Fix fsnotify_mark_connector race

  * Hang on network interface removal in Xen virtual machine (LP: #1771620)
    - xen-netfront: Fix hang on device removal

  * HiSilicon HNS NIC names are truncated in /proc/interrupts (LP: #1765977)
    - net: hns: Avoid action name truncation

  * Ubuntu 18.04 kernel crashed while in degraded mode (LP: #1770849)
    - SAUCE: powerpc/perf: Fix memory allocation for...

[Andy Whitcroft (apw)]

This bug was erroneously marked for verification in bionic; verification is not required and verification-needed-bionic is being removed.