Martin, On 8/17/17 09:41, Damien Le Moal wrote: > Martin, > > On 8/17/17 09:11, Martin K. Petersen wrote: >> >> Bart, >> >>> For an unknown reason this patch causes the boot process to hang on >>> PowerPC systems: >> >> OK, dropped it from fixes for now. >> >> Thanks! > > It means that commit 70e42fd02c46e2aa9ab07b766d418637e3a51de7 "scsi: > sd_zbc: Write unlock zone from sd_uninit_cmnd()" will need to be > reverted too as it will not solve the potential deadlock anymore. Bart's > patch was needed for it to work. > > So we are back to the initial patch I sent that Chirstoph nacked, that > is, not write locking zones with scsi-mq to avoid deadlocking (blk-mq > does not dispatch write requests in order anyway, so SMR does not work > with mq for now). > > Other solutions would be: > 1) Do not change the zone locking and add a big fat warning for scanned > zoned block devices that things can get nasty > 2) Fail initialization of zoned block devices with scsi-mq (do not > create the block devices) > > (2) may actually be the better solution for now until I get a fix for > blk-mq. > > Thoughts ? > > Best regards. Actually, we can keep that commit as it makes the sq case cleaner anyway. But we need something else to prevent deadlock in the mq case... -- Damien Le Moal, Western Digital
