We're seeing a hang when freezing a container with an nfs bind mount while running iozone. Two iozone processes were hung with this stack trace. [<ffffffff81821b15>] schedule+0x35/0x80 [<ffffffff81821dbe>] schedule_preempt_disabled+0xe/0x10 [<ffffffff818239f9>] __mutex_lock_slowpath+0xb9/0x130 [<ffffffff81823a8f>] mutex_lock+0x1f/0x30 [<ffffffff8121d00b>] do_unlinkat+0x12b/0x2d0 [<ffffffff8121dc16>] SyS_unlink+0x16/0x20 [<ffffffff81825bf2>] entry_SYSCALL_64_fastpath+0x16/0x71 This seems to be due to another iozone thread frozen during unlink with this stack trace: [<ffffffff810e9cfa>] __refrigerator+0x7a/0x140 [<ffffffffc08e80b8>] nfs4_handle_exception+0x118/0x130 [nfsv4] [<ffffffffc08e9efd>] nfs4_proc_remove+0x7d/0xf0 [nfsv4] [<ffffffffc088a329>] nfs_unlink+0x149/0x350 [nfs] [<ffffffff81219bd1>] vfs_unlink+0xf1/0x1a0 [<ffffffff8121d159>] do_unlinkat+0x279/0x2d0 [<ffffffff8121dc16>] SyS_unlink+0x16/0x20 [<ffffffff81825bf2>] entry_SYSCALL_64_fastpath+0x16/0x71 Since nfs is allowing the thread to be frozen with the inode locked it's preventing other threads trying to lock the same inode from freezing. It seems like a bad idea for nfs to be doing this. Can nfs do something different here to prevent this? Maybe use a non-freezable sleep and let the operation complete, or else abort the operation and return ERESTARTSYS? Thanks, Seth -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
