On Sun, Jun 29, 2014 at 09:32:22PM +0200, Christoph Hellwig wrote: > On Sun, Jun 29, 2014 at 11:26:37AM +0300, Michael S. Tsirkin wrote: > > On Fri, Jun 27, 2014 at 07:57:38AM -0400, Josh Boyer wrote: > > > Hi All, > > > > > > We've had a report[1] of the virt_blk driver causing a lot of spew > > > because it's calling a sleeping function from an invalid context. The > > > backtrace is below. This is with kernel v3.16-rc2-69-gd91d66e88ea9. > > > > Hi Jens, pls see below - it looks like the call to blk_mq_end_io > > from IRQ context is causing the issue. > > IIUC you switched virtio to this from __blk_end_request_all in > > > > commit 1cf7e9c68fe84248174e998922b39e508375e7c1 > > virtio_blk: blk-mq support > > > > Is this always safe? > > I note that at least one other driver is doing this: > > drivers/block/mtip32xx/mtip32xx.c > > Just like __blk_end_request_all blk_mq_end_io is supposed to be called > from irq context. The problem is that the MD bio end_io handler is calling > a sleeping function. Not sure if that's a bug in MD though given the > kernfs symbols in the all trace and the recent churn in that area. My understanding is this: bitmap_endwrite -> calls sysfs_notify_dirent_safe under spinlock -> calls kernfs_notify which takes a mutex. So I am guessing it is this commit: commit d911d98748018f7c8facc035ba39c30f5cce6f9c Author: Tejun Heo <tj@xxxxxxxxxx> Date: Wed Apr 9 11:07:31 2014 -0400 kernfs: make kernfs_notify() trigger inotify events too Tejun, what do you think? Josh, Brian, could you try reverting that commit to see if it helps? -- MST _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization