------------[ cut here ]------------
pgoff != vma->vm_start >> 12
WARNING: mm/vma.h:277 at assert_sane_pgoff mm/vma.h:277 [inline], CPU#2: syz.0.17/5930
WARNING: mm/vma.h:277 at vma_set_pgoff mm/vma.h:283 [inline], CPU#2: syz.0.17/5930
WARNING: mm/vma.h:277 at vma_add_pgoff mm/vma.h:314 [inline], CPU#2: syz.0.17/5930
WARNING: mm/vma.h:277 at __split_vma+0x162b/0x1de0 mm/vma.c:607, CPU#2: syz.0.17/5930
Modules linked in:
CPU: 2 UID: 0 PID: 5930 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:assert_sane_pgoff mm/vma.h:277 [inline]
RIP: 0010:vma_set_pgoff mm/vma.h:283 [inline]
RIP: 0010:vma_add_pgoff mm/vma.h:314 [inline]
RIP: 0010:__split_vma+0x162b/0x1de0 mm/vma.c:607
Code: 3c 02 00 0f 85 b1 07 00 00 4d 8b 27 48 89 ef 49 c1 ec 0c 4c 89 e6 e8 c4 15 9f ff 4c 39 e5 0f 84 63 fc ff ff e8 d6 1b 9f ff 90 <0f> 0b 90 e9 55 fc ff ff e8 c8 1b 9f ff 48 8b 54 24 30 48 b8 00 00
RSP: 0018:ffffc90002d475b0 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff88802b253310 RCX: 0000000000000000
RDX: ffff888024c62580 RSI: ffffffff826c205a RDI: ffff888024c62580
RBP: 0000000000080004 R08: 0000000000000006 R09: 0000000000080004
R10: 0000000000080ffe R11: 0000000000000000 R12: 0000000000080ffe
R13: ffff88802b253340 R14: ffffc90002d47b50 R15: ffff88802b2532c0
FS:  0000000000000000(0000) GS:ffff888096b67000(0063) knlGS:00000000f67c5b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000040443000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 vms_gather_munmap_vmas+0x1d2/0x1720 mm/vma.c:1507
 do_vmi_align_munmap+0x287/0x5f0 mm/vma.c:1675
 do_vmi_munmap+0x1f8/0x3e0 mm/vma.c:1732
 shrink_vma+0x1c5/0x380 mm/mremap.c:1421
 mremap_at mm/mremap.c:1652 [inline]
 do_mremap mm/mremap.c:2008 [inline]
 __do_sys_mremap+0x12d6/0x1780 mm/mremap.c:2064
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:79 [inline]
 __do_fast_syscall_32+0x13a/0x8b0 arch/x86/entry/syscall_32.c:291
 do_fast_syscall_32+0x32/0x70 arch/x86/entry/syscall_32.c:316
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf6fcefec
Code: Unable to access opcode bytes at 0xf6fcefc2.
RSP: 002b:00000000f67c550c EFLAGS: 00000292 ORIG_RAX: 00000000000000a3
RAX: ffffffffffffffda RBX: 0000000080ffd000 RCX: 0000000000002000
RDX: 0000000000001000 RSI: 0000000000000000 RDI: 0000000080ffe000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>