On 11/14/2014 08:32 AM, Mel Gorman wrote:> This is follow up from the "pipe/page fault oddness" thread. Hi Mel, Applying this patch series I've started seeing the following straight away: [ 367.547848] page:ffffea0003fb7db0 count:1007 mapcount:1005 mapping:ffff8800691f2f58 index:0x37 [ 367.551481] flags: 0x5001aa8030202d(locked|referenced|uptodate|lru|writeback|unevictable|mlocked) [ 367.555382] page dumped because: VM_BUG_ON_PAGE(!v9inode->writeback_fid) [ 367.558262] page->mem_cgroup:ffff88006d8a1bd8 [ 367.560403] ------------[ cut here ]------------ [ 367.562343] kernel BUG at fs/9p/vfs_addr.c:190! [ 367.564239] invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC KASAN [ 367.566991] Dumping ftrace buffer: [ 367.568481] (ftrace buffer empty) [ 367.569914] Modules linked in: [ 367.570254] CPU: 3 PID: 8234 Comm: kworker/u52:1 Not tainted 3.18.0-rc4-next-20141114-sasha-00054-ga9ff95e-dirty #1459 [ 367.570254] Workqueue: writeback bdi_writeback_workfn (flush-9p-1) [ 367.570254] task: ffff8801e21d8000 ti: ffff8801e1f34000 task.ti: ffff8801e1f34000 [ 367.570254] RIP: v9fs_vfs_writepage_locked (fs/9p/vfs_addr.c:190 (discriminator 1)) [ 367.570254] RSP: 0018:ffff8801e1f376c8 EFLAGS: 00010286 [ 367.570254] RAX: 0000000000000021 RBX: ffffea0003fb7db0 RCX: 0000000000000000 [ 367.570254] RDX: 0000000000000021 RSI: ffffffff9208b2e6 RDI: ffff8801e21d8d0c [ 367.570254] RBP: ffff8801e1f37728 R08: 0000000000000001 R09: 0000000000000000 [ 367.570254] R10: 0000000000000001 R11: 0000000000000001 R12: ffff8800691f2d48 [ 367.570254] R13: 0000000000001000 R14: ffff8800691f2c30 R15: ffff8800691f2c98 [ 367.570254] FS: 0000000000000000(0000) GS:ffff8801e5c00000(0000) knlGS:0000000000000000 [ 367.570254] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 367.570254] CR2: 0000000000000000 CR3: 00000000ca00c000 CR4: 00000000000006a0 [ 367.570254] DR0: ffffffff81000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 367.570254] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600 [ 367.570254] Stack: [ 367.570254] ffffda003c43b1a1 ffffda003c43b1a1 0000000000000000 0000000000000002 [ 367.570254] 0000000000000002 0000000000037000 ffff8801e1f37758 ffffea0003fb7db0 [ 367.570254] 0000000000000000 ffff8801e1f37a60 ffff8801e1f37a60 ffffea0003fb7db0 [ 367.570254] Call Trace: [ 367.570254] v9fs_vfs_writepage (fs/9p/vfs_addr.c:212) [ 367.570254] __writepage (include/linux/pagemap.h:32 mm/page-writeback.c:2006) [ 367.570254] write_cache_pages (mm/page-writeback.c:1943) [ 367.570254] ? bdi_set_max_ratio (mm/page-writeback.c:2003) [ 367.570254] ? sched_clock_local (kernel/sched/clock.c:202) [ 367.570254] generic_writepages (mm/page-writeback.c:2030) [ 367.570254] do_writepages (mm/page-writeback.c:2047) [ 367.570254] __writeback_single_inode (fs/fs-writeback.c:461 (discriminator 3)) [ 367.570254] writeback_sb_inodes (fs/fs-writeback.c:706) [ 367.570254] __writeback_inodes_wb (fs/fs-writeback.c:749) [ 367.570254] wb_writeback (fs/fs-writeback.c:880) [ 367.570254] ? __lock_is_held (kernel/locking/lockdep.c:3518) [ 367.570254] bdi_writeback_workfn (fs/fs-writeback.c:1015 fs/fs-writeback.c:1060) [ 367.570254] process_one_work (kernel/workqueue.c:2023 include/linux/jump_label.h:114 include/trace/events/workqueue.h:111 kernel/workqueue.c:2028) [ 367.570254] ? process_one_work (kernel/workqueue.c:2020) [ 367.570254] ? get_lock_stats (kernel/locking/lockdep.c:249) [ 367.570254] worker_thread (include/linux/list.h:189 kernel/workqueue.c:2156) [ 367.570254] ? __schedule (./arch/x86/include/asm/bitops.h:311 include/linux/thread_info.h:91 include/linux/sched.h:2939 kernel/sched/core.c:2848) [ 367.570254] ? rescuer_thread (kernel/workqueue.c:2100) [ 367.570254] kthread (kernel/kthread.c:207) [ 367.570254] ? flush_kthread_work (kernel/kthread.c:176) [ 367.570254] ret_from_fork (arch/x86/kernel/entry_64.S:348) [ 367.570254] ? flush_kthread_work (kernel/kthread.c:176) [ 367.570254] Code: 48 83 c4 38 44 89 f0 5b 41 5c 41 5d 41 5e 41 5f 5d c3 66 2e 0f 1f 84 00 00 00 00 00 48 c7 c6 f8 18 37 93 48 89 df e8 e1 8b 93 fe <0f> 0b 48 89 de 48 c7 c7 30 bd 9f 95 48 89 4d b8 e8 10 5f 02 0f All code ======== 0: 48 83 c4 38 add $0x38,%rsp 4: 44 89 f0 mov %r14d,%eax 7: 5b pop %rbx 8: 41 5c pop %r12 a: 41 5d pop %r13 c: 41 5e pop %r14 e: 41 5f pop %r15 10: 5d pop %rbp 11: c3 retq 12: 66 2e 0f 1f 84 00 00 nopw %cs:0x0(%rax,%rax,1) 19: 00 00 00 1c: 48 c7 c6 f8 18 37 93 mov $0xffffffff933718f8,%rsi 23: 48 89 df mov %rbx,%rdi 26: e8 e1 8b 93 fe callq 0xfffffffffe938c0c 2b:* 0f 0b ud2 <-- trapping instruction 2d: 48 89 de mov %rbx,%rsi 30: 48 c7 c7 30 bd 9f 95 mov $0xffffffff959fbd30,%rdi 37: 48 89 4d b8 mov %rcx,-0x48(%rbp) 3b: e8 10 5f 02 0f callq 0xf025f50 ... Code starting with the faulting instruction =========================================== 0: 0f 0b ud2 2: 48 89 de mov %rbx,%rsi 5: 48 c7 c7 30 bd 9f 95 mov $0xffffffff959fbd30,%rdi c: 48 89 4d b8 mov %rcx,-0x48(%rbp) 10: e8 10 5f 02 0f callq 0xf025f25 ... [ 367.570254] RIP v9fs_vfs_writepage_locked (fs/9p/vfs_addr.c:190 (discriminator 1)) [ 367.570254] RSP <ffff8801e1f376c8> (Note that I replaced the BUG_ON with a VM_BUG_ON_PAGE to get some extra information.) Thanks, Sasha -- 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>