mm: kernel BUG at mm/mremap.c:68!

mm: kernel BUG at mm/mremap.c:68!

[Sasha Levin]

Hi all,

While fuzzing with trinity inside a KVM tools guest running latest -next
kernel I've stumbled on the following:

[ 2977.289180] kernel BUG at mm/mremap.c:68!
[ 2977.290064] invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
[ 2977.290231] Dumping ftrace buffer:
[ 2977.290231]    (ftrace buffer empty)
[ 2977.290231] Modules linked in:
[ 2977.290231] CPU: 20 PID: 36563 Comm: trinity-c383 Tainted: G        W     3.14.0-rc6-next-20140317-sasha-00012-ge933921-dirty #226
[ 2977.290231] task: ffff880bf79d3000 ti: ffff880bfb5c8000 task.ti: ffff880bfb5c8000
[ 2977.290231] RIP:  alloc_new_pmd (mm/mremap.c:68)
[ 2977.290231] RSP: 0018:ffff880bfb5c9d78  EFLAGS: 00010286
[ 2977.290231] RAX: 00000004b2a008e7 RBX: ffff880c28ab2000 RCX: ffff880000000000
[ 2977.290231] RDX: 00003ffffffff000 RSI: ffff880bc678c800 RDI: 00000004b2a008e7
[ 2977.290231] RBP: ffff880bfb5c9d98 R08: 0000000000000000 R09: 0000000000000000
[ 2977.290231] R10: 0000000000000001 R11: 00007f9847e76000 R12: ffff880c28ab3000
[ 2977.290231] R13: ffff880c27a6f000 R14: 0000000000100000 R15: ffff880c16e3b1f0
[ 2977.290231] FS:  00007f9847c67700(0000) GS:ffff88052ba00000(0000) knlGS:0000000000000000
[ 2977.290231] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[ 2977.290231] CR2: 0000000000697280 CR3: 0000000bf79af000 CR4: 00000000000006a0
[ 2977.290231] DR0: 0000000000698000 DR1: 0000000000698000 DR2: 0000000000000000
[ 2977.290231] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000600
[ 2977.290231] Stack:
[ 2977.290231]  0000000000102000 00007f9847c76000 ffff880bc678c800 0000000000002000
[ 2977.290231]  ffff880bfb5c9e28 ffffffff812a31a1 0000000000000000 0000000000000282
[ 2977.290231]  ffff880bfb5c9e08 ffff880504497400 00007f9847e76000 0000000000002000
[ 2977.290231] Call Trace:
[ 2977.290231]  move_page_tables (mm/mremap.c:193)
[ 2977.290231]  move_vma (mm/mremap.c:271)
[ 2977.290231]  mremap_to (mm/mremap.c:439)
[ 2977.290231]  ? SyS_mremap (mm/mremap.c:500 mm/mremap.c:470)
[ 2977.290231]  SyS_mremap (mm/mremap.c:501 mm/mremap.c:470)
[ 2977.290231]  ? syscall_trace_enter (include/linux/context_tracking.h:27 arch/x86/kernel/ptrace.c:1461)
[ 2977.290231]  tracesys (arch/x86/kernel/entry_64.S:749)
[ 2977.290231] Code: 3f 49 8b 3c 24 48 83 3d 43 ae ba 04 00 75 11 0f 0b 0f 1f 80 00 00 00 00 eb fe 66 0f 1f 44 00 00 48 89 f8 66 66 66 90 84 c0 79 15 <0f> 0b 0f 1f 00 eb fe 66 0f 1f 44 00 00 45 31 e4 0f 1f 44 00 00
[ 2977.290231] RIP  alloc_new_pmd (mm/mremap.c:68)
[ 2977.290231]  RSP <ffff880bfb5c9d78>


Thanks,
Sasha

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