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BUG: KASAN: slab-out-of-bounds in find_first_bit+0xf7/0x100 lib/find_bit.c:107
Read of size 8 at addr ffff8801d76b6710 by task kswapd0/1535

CPU: 1 PID: 1535 Comm: kswapd0 Not tainted 4.18.0-rc4-next-20180710+ #3
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+0x1c9/0x2b4 lib/dump_stack.c:113
 print_address_description+0x6c/0x20b mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.7+0x242/0x30d mm/kasan/report.c:412
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 find_first_bit+0xf7/0x100 lib/find_bit.c:107
 shrink_slab_memcg mm/vmscan.c:580 [inline]
 shrink_slab+0x5d0/0xdb0 mm/vmscan.c:672
 shrink_node+0x429/0x16a0 mm/vmscan.c:2736
 kswapd_shrink_node mm/vmscan.c:3458 [inline]
 balance_pgdat+0x7ca/0x1010 mm/vmscan.c:3568
 kswapd+0x82e/0x12f0 mm/vmscan.c:3790
 kthread+0x345/0x410 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:415

Allocated by task 8980:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553
 __do_kmalloc_node mm/slab.c:3682 [inline]
 __kmalloc_node+0x47/0x70 mm/slab.c:3689
 kmalloc_node include/linux/slab.h:555 [inline]
 kvmalloc_node+0x65/0xf0 mm/util.c:423
 kvmalloc include/linux/mm.h:557 [inline]
 memcg_expand_one_shrinker_map mm/memcontrol.c:341 [inline]
 memcg_expand_shrinker_maps+0x1b1/0x3c0 mm/memcontrol.c:416
 prealloc_memcg_shrinker mm/vmscan.c:185 [inline]
 prealloc_shrinker+0x29e/0x450 mm/vmscan.c:366
 alloc_super+0x8dd/0xb10 fs/super.c:264
 sget_userns+0x276/0x860 fs/super.c:607
 sget+0x10b/0x150 fs/super.c:659
 mount_bdev+0x115/0x3e0 fs/super.c:1317
 msdos_mount+0x3c/0x50 fs/fat/namei_msdos.c:659
 legacy_get_tree+0x118/0x440 fs/fs_context.c:659
 vfs_get_tree+0x1cb/0x5c0 fs/super.c:1743
 do_new_mount fs/namespace.c:2567 [inline]
 do_mount+0x6c1/0x1fb0 fs/namespace.c:2889
 ksys_mount+0x12d/0x140 fs/namespace.c:3105
 __do_sys_mount fs/namespace.c:3119 [inline]
 __se_sys_mount fs/namespace.c:3116 [inline]
 __x64_sys_mount+0xbe/0x150 fs/namespace.c:3116
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 4341:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3498 [inline]
 kfree+0xd9/0x260 mm/slab.c:3813
 tty_ldisc_put+0x4c/0x70 drivers/tty/tty_ldisc.c:201
 tty_ldisc_kill+0x6e/0xc0 drivers/tty/tty_ldisc.c:624
 tty_ldisc_release+0xc5/0x280 drivers/tty/tty_ldisc.c:790
 tty_release_struct+0x1a/0x50 drivers/tty/tty_io.c:1589
 tty_release+0xeb5/0x1300 drivers/tty/tty_io.c:1762
 __fput+0x35d/0x930 fs/file_table.c:252
 ____fput+0x15/0x20 fs/file_table.c:288
 task_work_run+0x1ec/0x2a0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:193 [inline]
 exit_to_usermode_loop+0x318/0x380 arch/x86/entry/common.c:166
 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
 do_syscall_64+0x6be/0x820 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8801d76b6700
 which belongs to the cache kmalloc-32 of size 32
The buggy address is located 16 bytes inside of
 32-byte region [ffff8801d76b6700, ffff8801d76b6720)
The buggy address belongs to the page:
page:ffffea00075dad80 count:1 mapcount:0 mapping:ffff8801da8001c0 index:0xffff8801d76b6fc1
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffffea00075cf788 ffffea00074f3708 ffff8801da8001c0
raw: ffff8801d76b6fc1 ffff8801d76b6000 000000010000003f 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801d76b6600: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8801d76b6680: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
>ffff8801d76b6700: 00 00 06 fc fc fc fc fc fb fb fb fb fc fc fc fc
                         ^
 ffff8801d76b6780: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff8801d76b6800: 00 00 06 fc fc fc fc fc 00 00 06 fc fc fc fc fc
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