On Wed, May 01, 2013 at 08:57:38AM -0700, David Rientjes wrote: > On Wed, 1 May 2013, Shawn Bohrer wrote: > > > I've got two compute clusters with around 350 machines each which are > > running kernels based off of 3.1.9 (Yes I realize this is ancient by > > todays standards). xfs_info output of one of those filesystems? What platform are you running (32 or 64 bit)? > > All of the machines run a 'find' command once an > > hour on one of the mounted XFS filesystems. Occasionally these find > > commands get stuck requiring a reboot of the system. I took a peek > > today and see this with perf: > > > > 72.22% find [kernel.kallsyms] [k] _raw_spin_lock > > | > > --- _raw_spin_lock > > | > > |--98.84%-- vm_map_ram > > | _xfs_buf_map_pages > > | xfs_buf_get > > | xfs_buf_read > > | xfs_trans_read_buf > > | xfs_da_do_buf > > | xfs_da_read_buf > > | xfs_dir2_block_getdents > > | xfs_readdir > > | xfs_file_readdir > > | vfs_readdir > > | sys_getdents > > | system_call_fastpath > > | __getdents64 > > | > > |--1.12%-- _xfs_buf_map_pages > > | xfs_buf_get > > | xfs_buf_read > > | xfs_trans_read_buf > > | xfs_da_do_buf > > | xfs_da_read_buf > > | xfs_dir2_block_getdents > > | xfs_readdir > > | xfs_file_readdir > > | vfs_readdir > > | sys_getdents > > | system_call_fastpath > > | __getdents64 > > --0.04%-- [...] > > > > Looking at the code my best guess is that we are spinning on > > vmap_area_lock, but I could be wrong. This is the only process > > spinning on the machine so I'm assuming either another process has > > blocked while holding the lock, or perhaps this find process has tried > > to acquire the vmap_area_lock twice? > > > > Significant spinlock contention doesn't necessarily mean that there's a > deadlock, but it also doesn't mean the opposite. Depending on your > definition of "occassionally", would it be possible to run with > CONFIG_PROVE_LOCKING and CONFIG_LOCKDEP to see if it uncovers any real > deadlock potential? It sure will. We've been reporting that vm_map_ram is doing GFP_KERNEL allocations from GFP_NOFS context for years, and have reported plenty of lockdep dumps as a result of it. But that's not the problem that is occurring above - lockstat is probably a good thing to look at here to determine exactly what locks are being contended on.... Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx -- 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>