Re: BUG: Bad page state (6)

[Dmitry Vyukov]

On Thu, Feb 28, 2019 at 11:32 AM syzbot
<syzbot+6f5a9b79b75b66078bf0@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    42fd8df9d1d9 Add linux-next specific files for 20190228
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=179ba9e0c00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=c0f38652d28b522f
> dashboard link: https://syzkaller.appspot.com/bug?extid=6f5a9b79b75b66078bf0
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12ed6bd0c00000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10690c8ac00000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+6f5a9b79b75b66078bf0@xxxxxxxxxxxxxxxxxxxxxxxxx

+Jens, Eric,

Looks similar to:
https://groups.google.com/forum/#!msg/syzkaller-bugs/E3v3XQweVBw/6BPrkIYJIgAJ
Perhaps the fixing commit is not in the build yet?


> BUG: Bad page state in process syz-executor193  pfn:9225a
> page:ffffea0002489680 count:0 mapcount:0 mapping:ffff88808652fd80 index:0x81
> shmem_aops
> name:"memfd:cgroup2"
> flags: 0x1fffc000008000e(referenced|uptodate|dirty|swapbacked)
> raw: 01fffc000008000e ffff88809277fac0 ffff88809277fac0 ffff88808652fd80
> raw: 0000000000000081 0000000000000000 00000000ffffffff 0000000000000000
> page dumped because: non-NULL mapping
> Modules linked in:
> CPU: 0 PID: 7659 Comm: syz-executor193 Not tainted 5.0.0-rc8-next-20190228
> #45
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
>   __dump_stack lib/dump_stack.c:77 [inline]
>   dump_stack+0x172/0x1f0 lib/dump_stack.c:113
>   bad_page.cold+0xda/0xff mm/page_alloc.c:586
>   free_pages_check_bad+0x142/0x1a0 mm/page_alloc.c:1013
>   free_pages_check mm/page_alloc.c:1022 [inline]
>   free_pages_prepare mm/page_alloc.c:1112 [inline]
>   free_pcp_prepare mm/page_alloc.c:1137 [inline]
>   free_unref_page_prepare mm/page_alloc.c:3001 [inline]
>   free_unref_page_list+0x31d/0xc40 mm/page_alloc.c:3070
>   release_pages+0x60d/0x1940 mm/swap.c:794
>   pagevec_lru_move_fn+0x218/0x2a0 mm/swap.c:213
>   activate_page_drain mm/swap.c:297 [inline]
>   lru_add_drain_cpu+0x3b1/0x520 mm/swap.c:596
>   lru_add_drain+0x20/0x60 mm/swap.c:647
>   exit_mmap+0x290/0x530 mm/mmap.c:3134
>   __mmput kernel/fork.c:1047 [inline]
>   mmput+0x15f/0x4c0 kernel/fork.c:1068
>   exit_mm kernel/exit.c:546 [inline]
>   do_exit+0x816/0x2fa0 kernel/exit.c:863
>   do_group_exit+0x135/0x370 kernel/exit.c:980
>   __do_sys_exit_group kernel/exit.c:991 [inline]
>   __se_sys_exit_group kernel/exit.c:989 [inline]
>   __x64_sys_exit_group+0x44/0x50 kernel/exit.c:989
>   do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
>   entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x442a58
> Code: 00 00 be 3c 00 00 00 eb 19 66 0f 1f 84 00 00 00 00 00 48 89 d7 89 f0
> 0f 05 48 3d 00 f0 ff ff 77 21 f4 48 89 d7 44 89 c0 0f 05 <48> 3d 00 f0 ff
> ff 76 e0 f7 d8 64 41 89 01 eb d8 0f 1f 84 00 00 00
> RSP: 002b:00007ffe99e2faf8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000442a58
> RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
> RBP: 00000000004c2468 R08: 00000000000000e7 R09: ffffffffffffffd0
> R10: 0000000002000005 R11: 0000000000000246 R12: 0000000000000001
> R13: 00000000006d4180 R14: 0000000000000000 R15: 0000000000000000
>
>
> ---
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