linux-kernel - Re: [syzbot] INFO: task can't die in reclaim

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Date:   Sat, 11 Dec 2021 13:11:18 -0800
From:   syzbot <syzbot+dcea9eda277e1090b35f@...kaller.appspotmail.com>
To:     akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, mgorman@...hsingularity.net,
        syzkaller-bugs@...glegroups.com, vbabka@...e.cz,
        willy@...radead.org
Subject: Re: [syzbot] INFO: task can't die in reclaim_throttle

syzbot has found a reproducer for the following issue on:

HEAD commit:    ea922272cbe5 Add linux-next specific files for 20211210
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=15175f75b00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c1359a19d2230002
dashboard link: https://syzkaller.appspot.com/bug?extid=dcea9eda277e1090b35f
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14d842b1b00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+dcea9eda277e1090b35f@...kaller.appspotmail.com

INFO: task syz-executor.1:3674 can't die for more than 143 seconds.
task:syz-executor.1  state:D stack:23920 pid: 3674 ppid:     1 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:4986 [inline]
 __schedule+0xab2/0x4d90 kernel/sched/core.c:6296
 schedule+0xd2/0x260 kernel/sched/core.c:6369
 schedule_timeout+0x14a/0x2a0 kernel/time/timer.c:1881
 reclaim_throttle+0x1ce/0x5e0 mm/vmscan.c:1072
 consider_reclaim_throttle mm/vmscan.c:3399 [inline]
 shrink_zones mm/vmscan.c:3486 [inline]
 do_try_to_free_pages+0x7cd/0x1620 mm/vmscan.c:3541
 try_to_free_mem_cgroup_pages+0x2cd/0x840 mm/vmscan.c:3855
 reclaim_high.constprop.0+0x190/0x250 mm/memcontrol.c:2299
 mem_cgroup_handle_over_high+0x18c/0x540 mm/memcontrol.c:2483
 tracehook_notify_resume include/linux/tracehook.h:198 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:175 [inline]
 exit_to_user_mode_prepare+0x1ab/0x290 kernel/entry/common.c:207
 __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline]
 syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300
 do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f345ee5e9d8
RSP: 002b:00007fff5c713cb0 EFLAGS: 00000287 ORIG_RAX: 0000000000000101
RAX: 0000000000000003 RBX: 0000000000000003 RCX: 00007f345ee5e9d8
RDX: 0000000000090800 RSI: 00007f345eeb8256 RDI: 00000000ffffff9c
RBP: 00007fff5c713d7c R08: 0000000000090800 R09: 00007f345eeb8256
R10: 0000000000000000 R11: 0000000000000287 R12: 0000000000000000
R13: 00000000000b3eac R14: 000000000000000b R15: 00007fff5c713de0
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/26:
 #0: ffffffff8bb818a0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:6460
1 lock held by klogd/2959:
2 locks held by getty/3289:
 #0: ffff88823bcca898 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:244
 #1: ffffc90002b962e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0xcf0/0x1230 drivers/tty/n_tty.c:2077
2 locks held by kworker/u4:1/3705:
 #0: ffff8880b9c39c98 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2b/0x120 kernel/sched/core.c:489
 #1: ffff8880b9c27988 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x3e7/0x4e0 kernel/sched/psi.c:891

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