On 29.08.20 17:26, Alan Stern wrote: > On Sat, Aug 29, 2020 at 09:24:30AM +0200, Martin Kepplinger wrote: >> On 27.08.20 22:29, Alan Stern wrote: >>> Instead, look at sd_resume(). That routine calls __scsi_execute() >>> indirectly through sd_start_stop_device(), and the only reason it does >>> this is because the sdkp->device->manage_start_stop flag is set. You >>> ought to be able to clear this flag in sysfs, by writing to >>> /sys/block/sda/device/scsi_disk/*/manage_start_stop. If you do this >>> before allowing the card reader to go into runtime suspend, does it then >>> resume okay? >> >> manage_start_stop in sysfs is 0 here. > > Hmmm. I'm wondering about something you wrote back in June > (https://marc.info/?l=linux-scsi&m=159345778431615&w=2): > > blk_queue_enter() always - especially when sd is runtime > suspended and I try to mount as above - sets success to be true > for me, so never continues down to bkl_pm_request_resume(). All > I see is "PM: Removing info for No Bus:sda1". > > blk_queue_enter() would always set success to be true because pm > (derived from the BLK_MQ_REQ_PREEMPT flag) is true. But why was the > BLK_MQ_REQ_PREEMPT flag set? In other words, where was > blk_queue_enter() called from? > > Can you get a stack trace (i.e., call dump_stack()) at exactly this > point, that is, when pm is true and q->rpm_status is RPM_SUSPENDED? Or > do you already know the answer? > > I reverted any scsi/block out-of-tree fixes for this. when I try to mount, pm is TRUE (BLK_MQ_REQ_PREEMT set) and that's the first stack trace I get in this condition, inside of blk_queue_enter(): There is more, but I don't know if that's interesting. [ 38.642202] CPU: 2 PID: 1522 Comm: mount Not tainted 5.8.0-1-librem5 #487 [ 38.642207] Hardware name: Purism Librem 5r3 (DT) [ 38.642213] Call trace: [ 38.642233] dump_backtrace+0x0/0x210 [ 38.642242] show_stack+0x20/0x30 [ 38.642252] dump_stack+0xc8/0x128 [ 38.642262] blk_queue_enter+0x1b8/0x2d8 [ 38.642271] blk_mq_alloc_request+0x54/0xb0 [ 38.642277] blk_get_request+0x34/0x78 [ 38.642286] __scsi_execute+0x60/0x1c8 [ 38.642291] scsi_test_unit_ready+0x88/0x118 [ 38.642298] sd_check_events+0x110/0x158 [ 38.642306] disk_check_events+0x68/0x188 [ 38.642312] disk_clear_events+0x84/0x198 [ 38.642320] check_disk_change+0x38/0x90 [ 38.642325] sd_open+0x60/0x148 [ 38.642330] __blkdev_get+0xcc/0x4c8 [ 38.642335] __blkdev_get+0x278/0x4c8 [ 38.642339] blkdev_get+0x128/0x1a8 [ 38.642345] blkdev_open+0x98/0xb0 [ 38.642354] do_dentry_open+0x130/0x3c8 [ 38.642359] vfs_open+0x34/0x40 [ 38.642366] path_openat+0xa30/0xe40 [ 38.642372] do_filp_open+0x84/0x100 [ 38.642377] do_sys_openat2+0x1f4/0x2b0 [ 38.642382] do_sys_open+0x60/0xa8 (...) and of course it doesn't work and /dev/sda1 disappears, see the initial discussion that led to your fix.
