Update: The procs_blocked leak has TWO sources, not just the USB card reader.
Testing with usb-storage.quirks=05e3:0751:i (card reader fully ignored, confirmed "device ignored" in dmesg, no /dev/sdc created) still shows procs_blocked=4. The second source is empty AHCI/SATA ports. This system has an Intel AHCI controller (0000:00:17.0) with 6 ports, 2 occupied (sda, sdb) and 4 empty (ata3-6, all showing "SATA link down"). Adding libata.force=3:disable,4:disable,5:disable,6:disable drops procs_blocked from 4 to 2. Both sources share the same boot-time async scan code path: do_scan_async → async_run_entry_fn → blk_execute_rq → io_schedule_timeout This is not USB-specific — it's a general SCSI async scan accounting bug affecting both USB mass-storage and AHCI during boot. Summary of all test results: No workarounds: procs_blocked=4 :i only (card reader): procs_blocked=4 (AHCI still leaks) libata.force only: procs_blocked=2 :i + libata.force: procs_blocked=2 (same as libata.force alone) Warm reprobe (ftrace): procs_blocked unchanged (boot-specific) -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2146707 Title: Boot-time SCSI async probe leaks nr_iowait (procs_blocked) — USB card reader 05e3:0751 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2146707/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
