(resend to all) On Thu, Sep 13, 2018 at 9:44 AM, Nikolay Borisov <nbori...@suse.com> wrote: > > > On 13.09.2018 18:30, Chris Murphy wrote: >> This is the 2nd or 3rd thread containing hanging btrfs send, with >> kernel 4.18.x. The subject of one is "btrfs send hung in pipe_wait" >> and the other I can't find at the moment. In that case though the hang >> is reproducible in 4.14.x and weirdly it only happens when a snapshot >> contains (perhaps many) reflinks. Scrub and check lowmem find nothing >> wrong. >> >> I have snapshots with a few reflinks (cp --reflink and also >> deduplication), and I see maybe 15-30 second hangs where nothing is >> apparently happening (in top or iotop), but I'm also not seeing any >> blocked tasks or high CPU usage. Perhaps in my case it's just >> recovering quickly. >> >> Are there any kernel config options in "# Debug Lockups and Hangs" >> that might hint at what's going on? Some of these are enabled in >> Fedora debug kernels, which are built practically daily, e.g. right >> now the latest in the build system is 4.19.0-0.rc3.git2.1 - which >> translates to git 54eda9df17f3. > > If it's a lock-related problem then you need Lock Debugging => Lock > debugging: prove locking correctness
OK looks like that's under a different section as CONFIG_PROVE_LOCKING which is enabled on Fedora debug kernels. # Debug Lockups and Hangs CONFIG_LOCKUP_DETECTOR=y CONFIG_SOFTLOCKUP_DETECTOR=y # CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC is not set CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE=0 CONFIG_HARDLOCKUP_DETECTOR_PERF=y CONFIG_HARDLOCKUP_CHECK_TIMESTAMP=y CONFIG_HARDLOCKUP_DETECTOR=y # CONFIG_BOOTPARAM_HARDLOCKUP_PANIC is not set CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE=0 # Lock Debugging (spinlocks, mutexes, etc...) CONFIG_LOCK_DEBUGGING_SUPPORT=y CONFIG_PROVE_LOCKING=y CONFIG_LOCK_STAT=y CONFIG_DEBUG_SPINLOCK=y CONFIG_DEBUG_LOCK_ALLOC=y CONFIG_LOCKDEP=y # CONFIG_DEBUG_LOCKDEP is not set # CONFIG_DEBUG_LOCKING_API_SELFTESTS is not set CONFIG_LOCK_TORTURE_TEST=m -- Chris Murphy
