This problem is caused by an upstream memory management feature called watermark boosting. Normally, when a memory allocation fails and falls back to the page allocator, the page allocator will wake up kswapd to free up pages in order to make the memory allocation succeed. kswapd tries to free memory until it reaches a minimum amount of memory for each memory zone called the high watermark.
What watermark boosting does is try to preemptively fire up kswapd to free memory when there hasn't been an allocation failure. It does this by increasing kswapd's high watermark goal and then firing up kswapd. The reason why this causes freezes is because, with the increased high watermark goal, kswapd will steal memory from processes that need it in order to make forward progress. These processes will, in turn, try to allocate memory again, which will cause kswapd to steal necessary pages from those processes again, in a positive feedback loop known as page thrashing. When page thrashing occurs, your system is essentially livelocked until the necessary forward progress can be made to stop processes from trying to continuously allocate memory and trigger kswapd to steal it back. This problem already occurs with kswapd *without* watermark boosting, but it's usually only encountered on machines with a small amount of memory and/or a slow CPU. Watermark boosting just makes the existing problem worse enough to notice on higher spec'd machines. To fix the issue in this bug, watermark boosting can be disabled with the following: # echo 0 > /proc/sys/vm/watermark_boost_factor There's really no harm in doing so, because watermark boosting is an inherently broken feature... -- 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/1861359 Title: swap storms kills interactive use Status in linux package in Ubuntu: Confirmed Bug description: Hello, several times since upgrading to focal from 19.04 I've found my computer entirely unresponsive for periods of twenty or thirty seconds. No mouse movement, no keyboard input, the screen output does not change. My computer was using swap space and despite very slow writeout speeds well below what the NVME drive can handle, the computer was unusable. I've captured some vmstat 1 output and top output that I started collecting during the event. (Normally one very long painful period is followed by several shorter periods of uselessness.) Thanks ProblemType: Bug DistroRelease: Ubuntu 20.04 Package: linux-image-5.4.0-12-generic 5.4.0-12.15 ProcVersionSignature: Ubuntu 5.4.0-12.15-generic 5.4.8 Uname: Linux 5.4.0-12-generic x86_64 NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair ApportVersion: 2.20.11-0ubuntu15 Architecture: amd64 Date: Wed Jan 29 23:44:05 2020 ProcEnviron: TERM=rxvt-unicode-256color PATH=(custom, no user) XDG_RUNTIME_DIR=<set> LANG=en_US.UTF-8 SHELL=/bin/bash SourcePackage: linux-signed-5.4 UpgradeStatus: Upgraded to focal on 2020-01-24 (5 days ago) --- ProblemType: Bug AlsaVersion: Advanced Linux Sound Architecture Driver Version k5.4.0-12-generic. ApportVersion: 2.20.11-0ubuntu16 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: sarnold 2734 F.... pulseaudio /dev/snd/controlC1: sarnold 2734 F.... pulseaudio Card0.Amixer.info: Card hw:0 'PCH'/'HDA Intel PCH at 0x2fe1028000 irq 145' Mixer name : 'Realtek ALC285' Components : 'HDA:10ec0285,17aa225c,00100002 HDA:8086280b,80860101,00100000' Controls : 53 Simple ctrls : 15 Card1.Amixer.info: Card hw:1 'Audio'/'Generic ThinkPad Dock USB Audio at usb-0000:00:14.0-4.2.4, high speed' Mixer name : 'USB Mixer' Components : 'USB17ef:306f' Controls : 9 Simple ctrls : 4 DistroRelease: Ubuntu 20.04 HibernationDevice: RESUME=none IwConfig: Error: [Errno 2] No such file or directory: 'iwconfig': 'iwconfig' MachineType: LENOVO 20KHCTO1WW NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair Package: linux (not installed) ProcEnviron: TERM=rxvt-unicode-256color PATH=(custom, no user) XDG_RUNTIME_DIR=<set> LANG=en_US.UTF-8 SHELL=/bin/bash ProcFB: 0 i915drmfb ProcKernelCmdLine: BOOT_IMAGE=/BOOT/ubuntu@/vmlinuz-5.4.0-12-generic root=ZFS=rpool/ROOT/ubuntu ro root=ZFS=rpool/ROOT/ubuntu quiet splash acpi_osi=! "acpi_osi=Windows 2015" vt.handoff=1 ProcVersionSignature: Ubuntu 5.4.0-12.15-generic 5.4.8 RelatedPackageVersions: linux-restricted-modules-5.4.0-12-generic N/A linux-backports-modules-5.4.0-12-generic N/A linux-firmware 1.185 Tags: focal Uname: Linux 5.4.0-12-generic x86_64 UpgradeStatus: Upgraded to focal on 2020-01-24 (5 days ago) UserGroups: adm cdrom libvirt lpadmin plugdev sambashare sbuild sudo _MarkForUpload: True dmi.bios.date: 11/25/2019 dmi.bios.vendor: LENOVO dmi.bios.version: N23ET69W (1.44 ) dmi.board.asset.tag: Not Available dmi.board.name: 20KHCTO1WW dmi.board.vendor: LENOVO dmi.board.version: SDK0J40709 WIN dmi.chassis.asset.tag: No Asset Information dmi.chassis.type: 10 dmi.chassis.vendor: LENOVO dmi.chassis.version: None dmi.modalias: dmi:bvnLENOVO:bvrN23ET69W(1.44):bd11/25/2019:svnLENOVO:pn20KHCTO1WW:pvrThinkPadX1Carbon6th:rvnLENOVO:rn20KHCTO1WW:rvrSDK0J40709WIN:cvnLENOVO:ct10:cvrNone: dmi.product.family: ThinkPad X1 Carbon 6th dmi.product.name: 20KHCTO1WW dmi.product.sku: LENOVO_MT_20KH_BU_Think_FM_ThinkPad X1 Carbon 6th dmi.product.version: ThinkPad X1 Carbon 6th dmi.sys.vendor: LENOVO --- ProblemType: Bug AlsaVersion: Advanced Linux Sound Architecture Driver Version k5.4.0-12-generic. ApportVersion: 2.20.11-0ubuntu16 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: sarnold 2734 F.... pulseaudio /dev/snd/controlC1: sarnold 2734 F.... pulseaudio Card0.Amixer.info: Card hw:0 'PCH'/'HDA Intel PCH at 0x2fe1028000 irq 145' Mixer name : 'Realtek ALC285' Components : 'HDA:10ec0285,17aa225c,00100002 HDA:8086280b,80860101,00100000' Controls : 53 Simple ctrls : 15 Card1.Amixer.info: Card hw:1 'Audio'/'Generic ThinkPad Dock USB Audio at usb-0000:00:14.0-4.2.4, high speed' Mixer name : 'USB Mixer' Components : 'USB17ef:306f' Controls : 9 Simple ctrls : 4 DistroRelease: Ubuntu 20.04 HibernationDevice: RESUME=none IwConfig: Error: [Errno 2] No such file or directory: 'iwconfig': 'iwconfig' MachineType: LENOVO 20KHCTO1WW NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair Package: linux (not installed) ProcEnviron: TERM=rxvt-unicode-256color PATH=(custom, no user) XDG_RUNTIME_DIR=<set> LANG=en_US.UTF-8 SHELL=/bin/bash ProcFB: 0 i915drmfb ProcKernelCmdLine: BOOT_IMAGE=/BOOT/ubuntu@/vmlinuz-5.4.0-12-generic root=ZFS=rpool/ROOT/ubuntu ro root=ZFS=rpool/ROOT/ubuntu quiet splash acpi_osi=! "acpi_osi=Windows 2015" vt.handoff=1 ProcVersionSignature: Ubuntu 5.4.0-12.15-generic 5.4.8 RelatedPackageVersions: linux-restricted-modules-5.4.0-12-generic N/A linux-backports-modules-5.4.0-12-generic N/A linux-firmware 1.185 Tags: focal Uname: Linux 5.4.0-12-generic x86_64 UpgradeStatus: Upgraded to focal on 2020-01-24 (5 days ago) UserGroups: adm cdrom libvirt lpadmin plugdev sambashare sbuild sudo _MarkForUpload: True dmi.bios.date: 11/25/2019 dmi.bios.vendor: LENOVO dmi.bios.version: N23ET69W (1.44 ) dmi.board.asset.tag: Not Available dmi.board.name: 20KHCTO1WW dmi.board.vendor: LENOVO dmi.board.version: SDK0J40709 WIN dmi.chassis.asset.tag: No Asset Information dmi.chassis.type: 10 dmi.chassis.vendor: LENOVO dmi.chassis.version: None dmi.modalias: dmi:bvnLENOVO:bvrN23ET69W(1.44):bd11/25/2019:svnLENOVO:pn20KHCTO1WW:pvrThinkPadX1Carbon6th:rvnLENOVO:rn20KHCTO1WW:rvrSDK0J40709WIN:cvnLENOVO:ct10:cvrNone: dmi.product.family: ThinkPad X1 Carbon 6th dmi.product.name: 20KHCTO1WW dmi.product.sku: LENOVO_MT_20KH_BU_Think_FM_ThinkPad X1 Carbon 6th dmi.product.version: ThinkPad X1 Carbon 6th dmi.sys.vendor: LENOVO To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1861359/+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
