Hey. I think I've noticed that much earlier already, then when a "btrfs send | btrfs receive" pipe received SIGSTOP, ... it seems that when such pipe is running while the computer is suspended... it crashes for no good reason: root@heisenberg:/mnt/snapshots/root# btrfs send 2020-04-04_1 | btrfs receive /data/e/1/snapshots/_external-fs/heisenberg.scientia.net/root/ ; echo $? At subvol 2020-04-04_1 At subvol 2020-04-04_1 ERROR: crc32 mismatch in command 1 It even seems that it somehow prevented the suspend to fully finish, at least on my system: While e.g. the screen was shut off and external USB devices, too, the fan of the CPU continued to run and the LEDs didn't get the typical I'm-suspended flashing pattern. Powering on didn't work either immediately... only after several minutes and closing/opening the lid again the system came back (then with the btrfs send|receive pipe died as above). In he kernel log I found this: Apr 4 05:45:23 heisenberg kernel: [ 9177.331422] PM: suspend entry (deep) Apr 4 05:45:29 heisenberg kernel: [ 9183.131964] Filesystems sync: 5.800 seconds Apr 4 05:45:49 heisenberg kernel: [ 9183.139754] (NULL device *): firmware: direct-loading firmware regulatory.db.p7s Apr 4 05:45:49 heisenberg kernel: [ 9183.139918] (NULL device *): firmware: direct-loading firmware regulatory.db Apr 4 05:45:49 heisenberg kernel: [ 9183.139961] (NULL device *): firmware: direct-loading firmware i915/kbl_dmc_ver1_04.bin Apr 4 05:45:49 heisenberg kernel: [ 9183.140861] (NULL device *): firmware: direct-loading firmware iwlwifi-8265-36.ucode Apr 4 05:45:49 heisenberg kernel: [ 9183.140872] Freezing user space processes ... Apr 4 05:45:49 heisenberg kernel: [ 9203.141630] Freezing of tasks failed after 20.001 seconds (1 tasks refusing to freeze, wq_busy=0): Apr 4 05:45:49 heisenberg kernel: [ 9203.141643] btrfs R running task 0 1973346 3197 0x00004004 Apr 4 05:45:49 heisenberg kernel: [ 9203.141646] Call Trace: Apr 4 05:45:49 heisenberg kernel: [ 9203.141651] ? mutex_lock+0x1f/0x30 Apr 4 05:45:49 heisenberg kernel: [ 9203.141654] ? _cond_resched+0x15/0x30 Apr 4 05:45:49 heisenberg kernel: [ 9203.141655] ? mutex_lock+0xe/0x30 Apr 4 05:45:49 heisenberg kernel: [ 9203.141657] ? _cond_resched+0x15/0x30 Apr 4 05:45:49 heisenberg kernel: [ 9203.141658] ? mutex_lock+0xe/0x30 Apr 4 05:45:49 heisenberg kernel: [ 9203.141661] ? do_splice+0xfa/0x660 Apr 4 05:45:49 heisenberg kernel: [ 9203.141663] ? __x64_sys_splice+0xf2/0x120 Apr 4 05:45:49 heisenberg kernel: [ 9203.141666] ? do_syscall_64+0x52/0x180 Apr 4 05:45:49 heisenberg kernel: [ 9203.141667] ? entry_SYSCALL_64_after_hwframe+0x44/0xa9 Apr 4 05:45:49 heisenberg kernel: [ 9203.141671] OOM killer enabled. Apr 4 05:45:49 heisenberg kernel: [ 9203.141671] Restarting tasks ... done. Apr 4 05:45:49 heisenberg kernel: [ 9203.176215] PM: suspend exit Apr 4 05:45:49 heisenberg kernel: [ 9203.176287] PM: suspend entry (s2idle) Apr 4 05:47:22 heisenberg kernel: [ 9203.887154] Filesystems sync: 0.710 seconds Apr 4 05:47:22 heisenberg kernel: [ 9203.887958] Freezing user space processes ... (elapsed 0.004 seconds) done. Apr 4 05:47:22 heisenberg kernel: [ 9203.892873] OOM killer disabled. Apr 4 05:47:22 heisenberg kernel: [ 9203.892878] Freezing remaining freezable tasks ... (elapsed 0.001 seconds) done. Apr 4 05:47:22 heisenberg kernel: [ 9203.894509] printk: Suspending console(s) (use no_console_suspend to debug) Apr 4 05:47:22 heisenberg kernel: [ 9203.895621] wlan0: deauthenticating from 34:31:c4:42:e5:41 by local choice (Reason: 3=DEAUTH_LEAVING) Apr 4 05:47:22 heisenberg kernel: [ 9203.916926] sd 3:0:0:0: [sdb] Synchronizing SCSI cache Apr 4 05:47:22 heisenberg kernel: [ 9203.925902] e1000e: EEE TX LPI TIMER: 00000011 Apr 4 05:47:22 heisenberg kernel: [ 9203.926011] sd 2:0:0:0: [sda] Synchronizing SCSI cache Apr 4 05:47:22 heisenberg kernel: [ 9203.929166] sd 2:0:0:0: [sda] Stopping disk Apr 4 05:47:22 heisenberg kernel: [ 9206.449932] ACPI: EC: interrupt blocked Apr 4 05:47:22 heisenberg kernel: [ 9294.842883] ACPI: EC: interrupt unblocked Apr 4 05:47:22 heisenberg kernel: [ 9295.406845] sd 2:0:0:0: [sda] Starting disk Apr 4 05:47:22 heisenberg kernel: [ 9296.052818] ata3: SATA link up 6.0 Gbps (SStatus 133 SControl 300) Apr 4 05:47:22 heisenberg kernel: [ 9296.054817] ata3.00: ACPI cmd f5/00:00:00:00:00:a0 (SECURITY FREEZE LOCK) filtered out Apr 4 05:47:22 heisenberg kernel: [ 9296.054818] ata3.00: ACPI cmd b1/c1:00:00:00:00:a0 (DEVICE CONFIGURATION OVERLAY) filtered out Apr 4 05:47:22 heisenberg kernel: [ 9296.054887] ata3.00: ACPI cmd ef/10:09:00:00:00:b0 (SET FEATURES) succeeded Apr 4 05:47:22 heisenberg kernel: [ 9296.055110] ata3.00: supports DRM functions and may not be fully accessible Apr 4 05:47:22 heisenberg kernel: [ 9296.059963] ata3.00: disabling queued TRIM support Apr 4 05:47:22 heisenberg kernel: [ 9296.065210] ata3.00: ACPI cmd f5/00:00:00:00:00:a0 (SECURITY FREEZE LOCK) filtered out Apr 4 05:47:22 heisenberg kernel: [ 9296.065212] ata3.00: ACPI cmd b1/c1:00:00:00:00:a0 (DEVICE CONFIGURATION OVERLAY) filtered out Apr 4 05:47:22 heisenberg kernel: [ 9296.065233] ata3.00: ACPI cmd ef/10:09:00:00:00:b0 (SET FEATURES) succeeded Apr 4 05:47:22 heisenberg kernel: [ 9296.065455] ata3.00: supports DRM functions and may not be fully accessible Apr 4 05:47:22 heisenberg kernel: [ 9296.070254] ata3.00: disabling queued TRIM support Apr 4 05:47:22 heisenberg kernel: [ 9296.075210] ata3.00: configured for UDMA/133 Apr 4 05:47:22 heisenberg kernel: [ 9296.194394] OOM killer enabled. Apr 4 05:47:22 heisenberg kernel: [ 9296.194395] Restarting tasks ... done. Apr 4 05:47:22 heisenberg kernel: [ 9296.269425] PM: suspend exit Afterwards, the systems root fs (btrfs) was apparently still okay, the attached USB devices came up as well (with an external HDD with a btrfs, that seemed to be okay, too,... just the send|receive to it had died). Cheers, Chris PS: kernel 5.5.13, progs 5.4.1
