Hi all, While fuzzing with trinity inside a KVM tools guest running the latest -next kernel I've stumbled on the following spew: [ 9037.524924] BUG: Bad page state in process trinity-c2179 pfn:197750f [ 9037.529243] page:ffffea0065dd43c0 count:0 mapcount:1 mapping: (null) index:0x2f0f [ 9037.530154] flags: 0x4afffff80040018(uptodate|dirty|swapbacked) [ 9037.530834] page dumped because: nonzero mapcount [ 9037.531404] Modules linked in: [ 9037.531778] CPU: 18 PID: 15342 Comm: trinity-c2179 Not tainted 4.4.0-rc1-next-20151118-sasha-00042-g1ccc6e8 #2642 [ 9037.532856] 0000000000000012 00000000ac7ad40b ffff880fcc7e7ab0 ffffffff96e4ca9b [ 9037.533928] ffffea0065dd43c0 1ffffffff4305048 ffffffff9ed37240 ffff880fcc7e7ae0 [ 9037.534803] ffffffff9569db5b 04afffff80040018 ffffea0065dd43e0 ffffea0065dd43c0 [ 9037.535760] Call Trace: [ 9037.537046] dump_stack (lib/dump_stack.c:52) [ 9037.538995] bad_page (include/linux/compiler.h:246 ./arch/x86/include/asm/atomic.h:39 include/linux/mm.h:418 mm/page_alloc.c:443) [ 9037.539580] free_pages_prepare (mm/page_alloc.c:994) [ 9037.540370] free_hot_cold_page (mm/page_alloc.c:2058) [ 9037.541742] __put_page (mm/swap.c:73 mm/swap.c:97) [ 9037.542408] do_wp_page (include/linux/mm.h:479 mm/memory.c:2323) [ 9037.545165] handle_mm_fault (mm/memory.c:3312 mm/memory.c:3406 mm/memory.c:3435) [ 9037.549248] __do_page_fault (arch/x86/mm/fault.c:1239) [ 9037.550326] trace_do_page_fault (arch/x86/mm/fault.c:1331 include/linux/jump_label.h:133 include/linux/context_tracking_state.h:30 include/linux/context_tracking.h:50 arch/x86/mm/fault.c:1332) [ 9037.550954] do_async_page_fault (arch/x86/kernel/kvm.c:265) [ 9037.552334] async_page_fault (arch/x86/entry/entry_64.S:980) [ 9037.553252] Disabling lock debugging due to kernel taint [ 9037.553830] page:ffffea0065dd43c0 count:0 mapcount:0 mapping: (null) index:0x2f0f [ 9037.554780] flags: 0x4afffff80040018(uptodate|dirty|swapbacked) [ 9037.555669] page dumped because: VM_BUG_ON_PAGE(!PageLocked(page)) [ 9037.556545] ------------[ cut here ]------------ [ 9037.557058] kernel BUG at mm/swapfile.c:929! [ 9037.557319] invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC KASAN [ 9037.557319] Modules linked in: [ 9037.557319] CPU: 18 PID: 15342 Comm: trinity-c2179 Tainted: G B 4.4.0-rc1-next-20151118-sasha-00042-g1ccc6e8 #2642 [ 9037.557319] task: ffff880fcc7d8000 ti: ffff880fcc7e0000 task.ti: ffff880fcc7e0000 [ 9037.557319] RIP: reuse_swap_page (mm/swapfile.c:929 (discriminator 1)) [ 9037.557319] RSP: 0000:ffff880fcc7e7bb0 EFLAGS: 00010282 [ 9037.557319] RAX: ffff880fcc7d8000 RBX: ffffea0065dd43c0 RCX: 0000000000000000 [ 9037.557319] RDX: 0000000000000000 RSI: ffffffff9e99f229 RDI: ffffea0065dd43f8 [ 9037.557319] RBP: ffff880fcc7e7bd0 R08: 0000000000000001 R09: 0000000000000000 [ 9037.557319] R10: fffffbfff4857d8a R11: 702864656b636f4c R12: ffffea0065dd43e0 [ 9037.557319] R13: ffffea0065dd43c0 R14: ffffea0065dd43e0 R15: ffff880fd0e93000 [ 9037.557319] FS: 00007fa70dec1700(0000) GS:ffff8819b2600000(0000) knlGS:0000000000000000 [ 9037.557319] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 9037.557319] CR2: 00007fa7021ef000 CR3: 0000000fcec93000 CR4: 00000000000006a0 [ 9037.557319] Stack: [ 9037.557319] ffffea0065dd43c0 ffff88198247f830 ffffea0065dd43e0 ffffea0065dd43c0 [ 9037.557319] ffff880fcc7e7cc8 ffffffff95720287 ffff880f00000002 0000000000000000 [ 9037.557319] 0000001956263067 ffff881956263f78 1ffff101f98fcf84 ffff880fcc400080 [ 9037.557319] Call Trace: [ 9037.557319] do_wp_page (mm/memory.c:2325) [ 9037.557319] handle_mm_fault (mm/memory.c:3312 mm/memory.c:3406 mm/memory.c:3435) [ 9037.557319] __do_page_fault (arch/x86/mm/fault.c:1239) [ 9037.557319] trace_do_page_fault (arch/x86/mm/fault.c:1331 include/linux/jump_label.h:133 include/linux/context_tracking_state.h:30 include/linux/context_tracking.h:50 arch/x86/mm/fault.c:1332) [ 9037.557319] do_async_page_fault (arch/x86/kernel/kvm.c:265) [ 9037.557319] async_page_fault (arch/x86/entry/entry_64.S:980) [ 9037.557319] Code: 03 80 3c 02 00 74 08 4c 89 ef e8 eb 30 04 00 49 8b 45 00 a8 01 75 16 e8 2e 35 04 00 48 c7 c6 a0 ed d4 9e 48 89 df e8 ef 12 fb ff <0f> 0b e8 18 35 04 00 4c 89 e2 48 b8 00 00 00 00 00 fc ff df 48 All code ======== 0: 03 80 3c 02 00 74 add 0x7400023c(%rax),%eax 6: 08 4c 89 ef or %cl,-0x11(%rcx,%rcx,4) a: e8 eb 30 04 00 callq 0x430fa f: 49 8b 45 00 mov 0x0(%r13),%rax 13: a8 01 test $0x1,%al 15: 75 16 jne 0x2d 17: e8 2e 35 04 00 callq 0x4354a 1c: 48 c7 c6 a0 ed d4 9e mov $0xffffffff9ed4eda0,%rsi 23: 48 89 df mov %rbx,%rdi 26: e8 ef 12 fb ff callq 0xfffffffffffb131a 2b:* 0f 0b ud2 <-- trapping instruction 2d: e8 18 35 04 00 callq 0x4354a 32: 4c 89 e2 mov %r12,%rdx 35: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax 3c: fc ff df 3f: 48 rex.W ... Code starting with the faulting instruction =========================================== 0: 0f 0b ud2 2: e8 18 35 04 00 callq 0x4351f 7: 4c 89 e2 mov %r12,%rdx a: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax 11: fc ff df 14: 48 rex.W ... [ 9037.557319] RIP reuse_swap_page (mm/swapfile.c:929 (discriminator 1)) [ 9037.557319] RSP <ffff880fcc7e7bb0> -- 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>