Hi all, While fuzzing with trinity inside a KVM tools guest running the latest -next kernel, I've stumbled on the following spew: [12191.987737] BUG: unable to handle kernel paging request at ffff88035615eca8 [12191.988865] IP: page_get_anon_vma (./arch/x86/include/asm/atomic.h:27 ./arch/x86/include/asm/atomic.h:197 include/linux/atomic.h:17 mm/rmap.c:417) [12191.990071] PGD 2ed4b067 PUD 9753bd067 PMD 97530c067 PTE 800000035615e060 [12191.991578] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC [12191.991578] Dumping ftrace buffer: [12191.991578] (ftrace buffer empty) [12191.991578] Modules linked in: [12191.991578] CPU: 5 PID: 3079 Comm: khugepaged Not tainted 3.17.0-rc3-next-20140903-sasha-00034-g33e7ae9 #1108 [12191.991578] task: ffff8802729f3000 ti: ffff880272b0c000 task.ti: ffff880272b0c000 [12191.991578] RIP: page_get_anon_vma (./arch/x86/include/asm/atomic.h:27 ./arch/x86/include/asm/atomic.h:197 include/linux/atomic.h:17 mm/rmap.c:417) [12191.991578] RSP: 0018:ffff880272b0f7b8 EFLAGS: 00010246 [12191.991578] RAX: 0000000000000000 RBX: ffff88035615ec00 RCX: 0000000000000001 [12191.991578] RDX: ffff88035615ec01 RSI: ffffffffa72e2182 RDI: ffffffffa71ebfd4 [12191.991578] RBP: ffff880272b0f7d8 R08: 0000000000000001 R09: 0000000000000000 [12191.991578] R10: 0000000000000000 R11: 0000000000000000 R12: ffffea000a72aa40 [12191.991578] R13: ffff880272b0f8f8 R14: ffffea000a72aa40 R15: 000000000029cc00 [12191.991578] FS: 0000000000000000(0000) GS:ffff8804c9e00000(0000) knlGS:0000000000000000 [12192.020146] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [12192.020146] CR2: ffff88035615eca8 CR3: 000000002c032000 CR4: 00000000000006a0 [12192.020146] Stack: [12192.020146] ffffffffa72e2135 ffff880272b0f8f8 ffffea000a72aa60 ffffea000d2b7780 [12192.020146] ffff880272b0f888 ffffffffa730d27a ffff880272b0f7f8 000000008b880a00 [12192.020146] ffff8804c5e00340 ffff8802729f3000 0000000100000000 0000000000000000 [12192.020146] Call Trace: [12192.020146] ? page_get_anon_vma (mm/rmap.c:405) [12192.020146] migrate_pages (mm/migrate.c:853 mm/migrate.c:941 mm/migrate.c:1122) [12192.020146] ? __reset_isolation_suitable (mm/compaction.c:947) [12192.020146] ? isolate_freepages_block (mm/compaction.c:918) [12192.020146] compact_zone (mm/compaction.c:1209) [12192.020146] compact_zone_order (mm/compaction.c:1258) [12192.020146] try_to_compact_pages (mm/compaction.c:1323) [12192.020146] __alloc_pages_direct_compact (mm/page_alloc.c:2313) [12192.020146] __alloc_pages_slowpath (mm/page_alloc.c:2760) [12192.020146] __alloc_pages_nodemask (mm/page_alloc.c:2838) [12192.020146] ? collapse_huge_page.isra.31 (mm/huge_memory.c:766 mm/huge_memory.c:2336 mm/huge_memory.c:2435) [12192.020146] collapse_huge_page.isra.31 (mm/huge_memory.c:2336 mm/huge_memory.c:2435) [12192.020146] ? debug_smp_processor_id (lib/smp_processor_id.c:57) [12192.020146] ? put_lock_stats.isra.12 (./arch/x86/include/asm/preempt.h:98 kernel/locking/lockdep.c:254) [12192.020146] ? khugepaged_scan_mm_slot (include/linux/spinlock.h:349 mm/huge_memory.c:2604 mm/huge_memory.c:2700) [12192.020146] ? preempt_count_sub (kernel/sched/core.c:2626) [12192.020146] khugepaged_scan_mm_slot (mm/huge_memory.c:2704) [12192.020146] khugepaged (include/linux/spinlock.h:349 mm/huge_memory.c:2784 mm/huge_memory.c:2817) [12192.020146] ? bit_waitqueue (kernel/sched/wait.c:291) [12192.020146] ? khugepaged_scan_mm_slot (mm/huge_memory.c:2810) [12192.020146] kthread (kernel/kthread.c:210) [12192.020146] ? kthread_create_on_node (kernel/kthread.c:176) [12192.020146] ret_from_fork (arch/x86/kernel/entry_64.S:348) [12192.020146] ? kthread_create_on_node (kernel/kthread.c:176) [12192.020146] Code: ee ff 0f 1f 00 49 8b 54 24 08 48 89 d0 83 e0 03 48 83 f8 01 0f 85 cb 00 00 00 41 8b 44 24 18 85 c0 0f 88 be 00 00 00 48 8d 5a ff <8b> 8b a8 00 00 00 85 c9 0f 84 ac 00 00 00 8d 71 01 89 c8 48 8d All code ======== 0: ee out %al,(%dx) 1: ff 0f decl (%rdi) 3: 1f (bad) 4: 00 49 8b add %cl,-0x75(%rcx) 7: 54 push %rsp 8: 24 08 and $0x8,%al a: 48 89 d0 mov %rdx,%rax d: 83 e0 03 and $0x3,%eax 10: 48 83 f8 01 cmp $0x1,%rax 14: 0f 85 cb 00 00 00 jne 0xe5 1a: 41 8b 44 24 18 mov 0x18(%r12),%eax 1f: 85 c0 test %eax,%eax 21: 0f 88 be 00 00 00 js 0xe5 27: 48 8d 5a ff lea -0x1(%rdx),%rbx 2b:* 8b 8b a8 00 00 00 mov 0xa8(%rbx),%ecx <-- trapping instruction 31: 85 c9 test %ecx,%ecx 33: 0f 84 ac 00 00 00 je 0xe5 39: 8d 71 01 lea 0x1(%rcx),%esi 3c: 89 c8 mov %ecx,%eax 3e: 48 8d 00 lea (%rax),%rax Code starting with the faulting instruction =========================================== 0: 8b 8b a8 00 00 00 mov 0xa8(%rbx),%ecx 6: 85 c9 test %ecx,%ecx 8: 0f 84 ac 00 00 00 je 0xba e: 8d 71 01 lea 0x1(%rcx),%esi 11: 89 c8 mov %ecx,%eax 13: 48 8d 00 lea (%rax),%rax [12192.070370] RIP page_get_anon_vma (./arch/x86/include/asm/atomic.h:27 ./arch/x86/include/asm/atomic.h:197 include/linux/atomic.h:17 mm/rmap.c:417) [12192.070370] RSP <ffff880272b0f7b8> [12192.070370] CR2: ffff88035615eca8 Thanks, Sasha -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. 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