On 11/02/2019 17:36, Marc Gonzalez wrote: > On 08/02/2019 16:49, Bart Van Assche wrote: > >> Does this problem only occur with block devices backed by the UFS driver >> or does this problem also occur with other block drivers? > > Yes, same issue with a USB3 mass storage device: > > usb 2-1: new SuperSpeed Gen 1 USB device number 2 using xhci-hcd > usb 2-1: New USB device found, idVendor=05dc, idProduct=a838, bcdDevice=11.00 > usb 2-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3 > usb 2-1: Product: USB Flash Drive > usb 2-1: Manufacturer: Lexar > usb 2-1: SerialNumber: AAYW2W7I13BAR0JC > usb-storage 2-1:1.0: USB Mass Storage device detected > scsi host0: usb-storage 2-1:1.0 > scsi 0:0:0:0: Direct-Access Lexar USB Flash Drive 1100 PQ: 0 ANSI: 6 > sd 0:0:0:0: [sda] 62517248 512-byte logical blocks: (32.0 GB/29.8 GiB) > sd 0:0:0:0: [sda] Write Protect is off > sd 0:0:0:0: [sda] Mode Sense: 43 00 00 00 > sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA > sda: sda1 > sd 0:0:0:0: [sda] Attached SCSI removable disk > > # dd if=/dev/sda of=/dev/null bs=1M status=progress > 3879731200 bytes (3.9 GB, 3.6 GiB) copied, 56.0097 s, 69.3 MB/s > > So the problem could be in SCSI glue, or block, or mm? Unlikely. Someone else would have been affected... A colleague pointed out that some memory areas are reserved downstream. Perhaps the FW goes haywire once the kernel touches reserved memory? I'm off to test that hypothesis. Regards.