Hello,
syzbot found the following crash on:
HEAD commit: 6d028043 Add linux-next specific files for 20190830 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=16cbf22a600000 kernel config: https://syzkaller.appspot.com/x/.config?x=82a6bec43ab0cb69 dashboard link: https://syzkaller.appspot.com/bug?extid=aaedc50d99a03250fe1f compiler: gcc (GCC) 9.0.0 20181231 (experimental) syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15269876600000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12685092600000
The bug was bisected to:
commit e58b341134ca751d9c12bacded12a8b4dd51368d Author: Stephen Rothwell sfr@canb.auug.org.au Date: Fri Aug 30 09:42:14 2019 +0000
Merge remote-tracking branch 'hmm/hmm'
bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=11ea65ea600000 final crash: https://syzkaller.appspot.com/x/report.txt?x=13ea65ea600000 console output: https://syzkaller.appspot.com/x/log.txt?x=15ea65ea600000
IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+aaedc50d99a03250fe1f@syzkaller.appspotmail.com Fixes: e58b341134ca ("Merge remote-tracking branch 'hmm/hmm'")
============================================ WARNING: possible recursive locking detected 5.3.0-rc6-next-20190830 #75 Not tainted -------------------------------------------- oom_reaper/1065 is trying to acquire lock: ffffffff8904ff60 (mmu_notifier_invalidate_range_start){+.+.}, at: __mmu_notifier_invalidate_range_end+0x0/0x360 mm/mmu_notifier.c:169
but task is already holding lock: ffffffff8904ff60 (mmu_notifier_invalidate_range_start){+.+.}, at: __oom_reap_task_mm+0x196/0x490 mm/oom_kill.c:542
other info that might help us debug this: Possible unsafe locking scenario:
CPU0 ---- lock(mmu_notifier_invalidate_range_start); lock(mmu_notifier_invalidate_range_start);
*** DEADLOCK ***
May be due to missing lock nesting notation
2 locks held by oom_reaper/1065: #0: ffff888094ad3990 (&mm->mmap_sem#2){++++}, at: oom_reap_task_mm mm/oom_kill.c:570 [inline] #0: ffff888094ad3990 (&mm->mmap_sem#2){++++}, at: oom_reap_task mm/oom_kill.c:613 [inline] #0: ffff888094ad3990 (&mm->mmap_sem#2){++++}, at: oom_reaper+0x3a7/0x1320 mm/oom_kill.c:651 #1: ffffffff8904ff60 (mmu_notifier_invalidate_range_start){+.+.}, at: __oom_reap_task_mm+0x196/0x490 mm/oom_kill.c:542
stack backtrace: CPU: 1 PID: 1065 Comm: oom_reaper Not tainted 5.3.0-rc6-next-20190830 #75 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 print_deadlock_bug kernel/locking/lockdep.c:2371 [inline] check_deadlock kernel/locking/lockdep.c:2412 [inline] validate_chain kernel/locking/lockdep.c:2955 [inline] __lock_acquire.cold+0x15d/0x385 kernel/locking/lockdep.c:3955 lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4487 __mmu_notifier_invalidate_range_end+0x3c/0x360 mm/mmu_notifier.c:193 mmu_notifier_invalidate_range_end include/linux/mmu_notifier.h:375 [inline] __oom_reap_task_mm+0x3fa/0x490 mm/oom_kill.c:552 oom_reap_task_mm mm/oom_kill.c:589 [inline] oom_reap_task mm/oom_kill.c:613 [inline] oom_reaper+0x2b2/0x1320 mm/oom_kill.c:651 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 oom_reaper: reaped process 10145 (syz-executor282), now anon-rss:16480kB, file-rss:872kB, shmem-rss:0kB oom_reaper: reaped process 10144 (syz-executor282), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB oom_reaper: reaped process 10158 (syz-executor282), now anon-rss:16824kB, file-rss:872kB, shmem-rss:0kB oom_reaper: reaped process 10187 (syz-executor282), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB oom_reaper: reaped process 10173 (syz-executor282), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB oom_reaper: reaped process 10139 (syz-executor282), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB
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