On 09/29/2016 01:27 PM, Paul E. McKenney wrote: > On Thu, Sep 29, 2016 at 10:11:09AM +0300, Nikolay Borisov wrote: [SNIP] >> What in particular should I be looking for in ftrace? tracing the stacks >> on the stuck cpu? > > To start with, how about the sequence of functions that the stuck > CPU is executing? Unfortunately I do not know how to reproduce the issue, but it is being reproduced byt our production load - which is creating backups in this case. They are created by rsyncing files to a loop-back attached files wihch are then unmounted and unmapped.From this crash it is evident that the hang occurs while a volume is being unmounted. But the callstack is in my hang report, no? I have the crashdump with me so if you are interested in anything in particular I can go look for it. I believe an inode eviction was requested, since destroy_inode, which utilizes ext4_i_callback is called in the eviction + some errors paths. And this eviction is executed on this particular CPU. What in particular are you looking for? Unfortunately it's impossible for me to run: trace-cmd record -p function_graph -F <command that causes the issue> [SNIP] -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>