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). 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? -- 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>