mm: sleeping function called from invalid context shmem_undo_range

[Dmitry Vyukov]

Hello,

I've got the following report while running syzkaller fuzzer on
fd694aaa46c7ed811b72eb47d5eb11ce7ab3f7f1:

BUG: sleeping function called from invalid context at mm/shmem.c:852
in_atomic(): 1, irqs_disabled(): 0, pid: 529, name: khugepaged
3 locks held by khugepaged/529:
 #0:  (shrinker_rwsem){++++..}, at: [<ffffffff818d7ef1>]
shrink_slab.part.59+0x121/0xd30 mm/vmscan.c:451
 #1:  (&type->s_umount_key#29){++++..}, at: [<ffffffff81a63630>]
trylock_super+0x20/0x100 fs/super.c:392
 #2:  (&(&sbinfo->shrinklist_lock)->rlock){+.+.-.}, at:
[<ffffffff818fd83e>] spin_lock include/linux/spinlock.h:302 [inline]
 #2:  (&(&sbinfo->shrinklist_lock)->rlock){+.+.-.}, at:
[<ffffffff818fd83e>] shmem_unused_huge_shrink+0x28e/0x1490
mm/shmem.c:427
CPU: 2 PID: 529 Comm: khugepaged Not tainted 4.10.0-rc5+ #201
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:15 [inline]
 dump_stack+0x2ee/0x3ef lib/dump_stack.c:51
 ___might_sleep+0x47e/0x650 kernel/sched/core.c:7780
 shmem_undo_range+0xb20/0x2710 mm/shmem.c:852
 shmem_truncate_range+0x27/0xa0 mm/shmem.c:939
 shmem_evict_inode+0x35f/0xca0 mm/shmem.c:1030
 evict+0x46e/0x980 fs/inode.c:553
 iput_final fs/inode.c:1515 [inline]
 iput+0x589/0xb20 fs/inode.c:1542
 shmem_unused_huge_shrink+0xbad/0x1490 mm/shmem.c:446
 shmem_unused_huge_scan+0x10c/0x170 mm/shmem.c:512
 super_cache_scan+0x376/0x450 fs/super.c:106
 do_shrink_slab mm/vmscan.c:378 [inline]
 shrink_slab.part.59+0x543/0xd30 mm/vmscan.c:481
 shrink_slab mm/vmscan.c:2592 [inline]
 shrink_node+0x2c7/0x870 mm/vmscan.c:2592
 shrink_zones mm/vmscan.c:2734 [inline]
 do_try_to_free_pages+0x369/0xc80 mm/vmscan.c:2776
 try_to_free_pages+0x3c6/0x900 mm/vmscan.c:2982
 __perform_reclaim mm/page_alloc.c:3301 [inline]
 __alloc_pages_direct_reclaim mm/page_alloc.c:3322 [inline]
 __alloc_pages_slowpath+0xa24/0x1c30 mm/page_alloc.c:3683
 __alloc_pages_nodemask+0x544/0xae0 mm/page_alloc.c:3848
 __alloc_pages include/linux/gfp.h:426 [inline]
 __alloc_pages_node include/linux/gfp.h:439 [inline]
 khugepaged_alloc_page+0xc2/0x1b0 mm/khugepaged.c:750
 collapse_huge_page+0x182/0x1fe0 mm/khugepaged.c:955
 khugepaged_scan_pmd+0xfdf/0x12a0 mm/khugepaged.c:1208
 khugepaged_scan_mm_slot mm/khugepaged.c:1727 [inline]
 khugepaged_do_scan mm/khugepaged.c:1808 [inline]
 khugepaged+0xe9b/0x1590 mm/khugepaged.c:1853
 kthread+0x326/0x3f0 kernel/kthread.c:227
 ret_from_fork+0x31/0x40 arch/x86/entry/entry_64.S:430