On 12/21/20 10:47 AM, John Garry wrote: > Yes, I agree, and I'm not sure what I wrote to give that impression. > > About "root partition", above, I'm just saying that / is mounted on a > sda partition: > > root@ubuntu:/home/john# mount | grep sda > /dev/sda2 on / type ext4 (rw,relatime,errors=remount-ro,stripe=32) > /dev/sda1 on /boot/efi type vfat > (rw,relatime,fmask=0077,dmask=0077,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro) Hi John, Thanks for the clarification. I want to take back my suggestion about adding rcu_read_lock() / rcu_read_unlock() in blk_mq_tagset_busy_iter() since it is not allowed to sleep inside an RCU read-side critical section, since blk_mq_tagset_busy_iter() is used in request timeout handling and since there may be blk_mq_ops.timeout implementations that sleep. Ming's suggestion to serialize blk_mq_tagset_busy_iter() and blk_mq_free_rqs() looks interesting to me. Thanks, Bart.
