I don't know exactly when it started since this is not my own computer, it's my wife's and she does not use it really often.
I installed the upstream kernel : # uname -a Linux marine-i5-2500k 4.18.0-041800rc6-generic #201807221830 SMP Sun Jul 22 22:33:11 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux It is now working as expected. ** Changed in: linux (Ubuntu) Status: Incomplete => Confirmed ** Summary changed: - System resume instantly from sleep + System resume instantly from sleep - kernel-fixed-upstream -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1782813 Title: System resume instantly from sleep - kernel-fixed-upstream Status in linux package in Ubuntu: Confirmed Bug description: The computer goes into suspend mode, and then automatically resume. This happen when sleep is intiated automatically due to inactivity, as well as manually. The suspend mode has already worked well on this machine, so I am confident this is not hardware related. ProblemType: Bug DistroRelease: Ubuntu 16.04 Package: linux-image-4.4.0-131-generic 4.4.0-131.157 ProcVersionSignature: Ubuntu 4.4.0-131.157-generic 4.4.134 Uname: Linux 4.4.0-131-generic x86_64 ApportVersion: 2.20.1-0ubuntu2.18 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: marine 2988 F.... pulseaudio CurrentDesktop: Unity Date: Fri Jul 20 19:31:54 2018 HibernationDevice: RESUME=UUID=273fc082-eb27-436c-beb0-0d730da9167d InstallationDate: Installed on 2011-10-18 (2466 days ago) InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111012) IwConfig: lo no wireless extensions. eth0 no wireless extensions. MachineType: Gigabyte Technology Co., Ltd. To be filled by O.E.M. ProcFB: 0 inteldrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.4.0-131-generic root=UUID=b7e421af-7df0-42bb-8a12-eadc92e04f53 ro quiet splash vt.handoff=7 RelatedPackageVersions: linux-restricted-modules-4.4.0-131-generic N/A linux-backports-modules-4.4.0-131-generic N/A linux-firmware 1.157.20 RfKill: SourcePackage: linux UpgradeStatus: Upgraded to xenial on 2016-10-02 (655 days ago) dmi.bios.date: 09/19/2012 dmi.bios.vendor: American Megatrends Inc. dmi.bios.version: F13 dmi.board.asset.tag: To be filled by O.E.M. dmi.board.name: Z77M-D3H dmi.board.vendor: Gigabyte Technology Co., Ltd. dmi.board.version: x.x dmi.chassis.asset.tag: To Be Filled By O.E.M. dmi.chassis.type: 3 dmi.chassis.vendor: Gigabyte Technology Co., Ltd. dmi.chassis.version: To Be Filled By O.E.M. dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrF13:bd09/19/2012:svnGigabyteTechnologyCo.,Ltd.:pnTobefilledbyO.E.M.:pvrTobefilledbyO.E.M.:rvnGigabyteTechnologyCo.,Ltd.:rnZ77M-D3H:rvrx.x:cvnGigabyteTechnologyCo.,Ltd.:ct3:cvrToBeFilledByO.E.M.: dmi.product.name: To be filled by O.E.M. dmi.product.version: To be filled by O.E.M. dmi.sys.vendor: Gigabyte Technology Co., Ltd. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1782813/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp