INFO: task can't die in shrink_inactive_list (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    03430750 Add linux-next specific files for 20201116
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=13f80e5e500000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a1c4c3f27041fdb8
dashboard link: https://syzkaller.appspot.com/bug?extid=e5a33e700b1dd0da20a2
compiler:       gcc (GCC) 10.1.0-syz 20200507
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12f7bc5a500000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10934cf2500000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e5a33e700b1dd0da20a2@xxxxxxxxxxxxxxxxxxxxxxxxx

INFO: task syz-executor880:8534 can't die for more than 143 seconds.
task:syz-executor880 state:R  running task     stack:25304 pid: 8534 ppid:  8504 flags:0x00004006
Call Trace:
 context_switch kernel/sched/core.c:4269 [inline]
 __schedule+0x890/0x2030 kernel/sched/core.c:5019
 preempt_schedule_common+0x45/0xc0 kernel/sched/core.c:5179
 preempt_schedule_thunk+0x16/0x18 arch/x86/entry/thunk_64.S:40
 __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline]
 _raw_spin_unlock_irq+0x3c/0x40 kernel/locking/spinlock.c:199
 spin_unlock_irq include/linux/spinlock.h:404 [inline]
 shrink_inactive_list+0x4b1/0xce0 mm/vmscan.c:1974
 shrink_list mm/vmscan.c:2167 [inline]
 shrink_lruvec+0x61b/0x11b0 mm/vmscan.c:2462
 shrink_node_memcgs mm/vmscan.c:2650 [inline]
 shrink_node+0x839/0x1d60 mm/vmscan.c:2767
 shrink_zones mm/vmscan.c:2970 [inline]
 do_try_to_free_pages+0x38b/0x1440 mm/vmscan.c:3025
 try_to_free_pages+0x29f/0x720 mm/vmscan.c:3264
 __perform_reclaim mm/page_alloc.c:4360 [inline]
 __alloc_pages_direct_reclaim mm/page_alloc.c:4381 [inline]
 __alloc_pages_slowpath.constprop.0+0x917/0x2510 mm/page_alloc.c:4785
 __alloc_pages_nodemask+0x5f0/0x730 mm/page_alloc.c:4995
 alloc_pages_current+0x191/0x2a0 mm/mempolicy.c:2271
 alloc_pages include/linux/gfp.h:547 [inline]
 __page_cache_alloc mm/filemap.c:977 [inline]
 __page_cache_alloc+0x2ce/0x360 mm/filemap.c:962
 page_cache_ra_unbounded+0x3a1/0x920 mm/readahead.c:216
 do_page_cache_ra+0xf9/0x140 mm/readahead.c:267
 do_sync_mmap_readahead mm/filemap.c:2721 [inline]
 filemap_fault+0x19d0/0x2940 mm/filemap.c:2809
 __do_fault+0x10d/0x4d0 mm/memory.c:3623
 do_shared_fault mm/memory.c:4071 [inline]
 do_fault mm/memory.c:4149 [inline]
 handle_pte_fault mm/memory.c:4385 [inline]
 __handle_mm_fault mm/memory.c:4520 [inline]
 handle_mm_fault+0x3033/0x55d0 mm/memory.c:4618
 do_user_addr_fault+0x55b/0xba0 arch/x86/mm/fault.c:1377
 handle_page_fault arch/x86/mm/fault.c:1434 [inline]
 exc_page_fault+0x9e/0x180 arch/x86/mm/fault.c:1490
 asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:580
RIP: 0033:0x400e71
Code: Unable to access opcode bytes at RIP 0x400e47.
RSP: 002b:00007f8a5353fdc0 EFLAGS: 00010246
RAX: 6c756e2f7665642f RBX: 00000000006dbc38 RCX: 0000000000402824
RDX: 928195da81441750 RSI: 0000000000000000 RDI: 00000000006dbc30
RBP: 00000000006dbc30 R08: 0000000000000000 R09: 00007f8a53540700
R10: 00007f8a535409d0 R11: 0000000000000202 R12: 00000000006dbc3c
R13: 00007ffe80747a5f R14: 00007f8a535409c0 R15: 0000000000000001

Showing all locks held in the system:
1 lock held by khungtaskd/1659:
 #0: ffffffff8b339ce0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6252
1 lock held by kswapd0/2195:
1 lock held by kswapd1/2196:
1 lock held by in:imklog/8191:
 #0: ffff8880125b1270 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:932
1 lock held by cron/8189:
2 locks held by syz-executor880/8502:
2 locks held by syz-executor880/8505:
2 locks held by syz-executor880/8507:
2 locks held by syz-executor880/11706:
2 locks held by syz-executor880/11709:
3 locks held by syz-executor880/12008:
2 locks held by syz-executor880/12015:

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