kernel panic: System is deadlocked on memory

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: d31958b3 Add linux-next specific files for 20200710
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=11a2fe13100000
kernel config: https://syzkaller.appspot.com/x/.config?x=3fe4fccb94cbc1a6
dashboard link: https://syzkaller.appspot.com/bug?extid=98be80110b9043885626
compiler: gcc (GCC) 10.1.0-syz 20200507
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=101ec967100000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14a77000900000

The issue was bisected to:

commit e642d9be463d02c735cd99a9a904063324ee03d6
Author: Yafang Shao <laoar...@gmail.com>
Date: Fri Jul 10 04:58:08 2020 +0000

mm, oom: make the calculation of oom badness more accurate

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1432bd77100000
final oops: https://syzkaller.appspot.com/x/report.txt?x=1632bd77100000
console output: https://syzkaller.appspot.com/x/log.txt?x=1232bd77100000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+98be80...@syzkaller.appspotmail.com
Fixes: e642d9be463d ("mm, oom: make the calculation of oom badness more accurate")

Out of memory and no killable processes...
Kernel panic - not syncing: System is deadlocked on memory
CPU: 0 PID: 6810 Comm: syz-executor919 Not tainted 5.8.0-rc4-next-20200710-syzkaller #0
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+0x18f/0x20d lib/dump_stack.c:118
panic+0x2e3/0x75c kernel/panic.c:231
out_of_memory mm/oom_kill.c:1106 [inline]
out_of_memory.cold+0xa6/0x182 mm/oom_kill.c:1041
pagefault_out_of_memory+0x109/0x11c mm/oom_kill.c:1135
mm_fault_error+0x123/0x380 arch/x86/mm/fault.c:930
do_user_addr_fault+0x5f8/0xbf0 arch/x86/mm/fault.c:1317
handle_page_fault arch/x86/mm/fault.c:1351 [inline]
exc_page_fault+0xab/0x170 arch/x86/mm/fault.c:1404
asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:544
RIP: 0033:0x40154d
Code: Bad RIP value.
RSP: 002b:00007ffddf4649b0 EFLAGS: 00010202
RAX: 0000000000000001 RBX: 0000000000000000 RCX: fffffffffffffffd
RDX: 0000000000000001 RSI: 00007ffddf4665e0 RDI: ffffffffffffffff
RBP: 00007ffddf4665e0 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000064 R11: 0000000000000246 R12: ffffffffffffffff
R13: 0000000000000003 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
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For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this issue, for details see:
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[Yafang Shao]

Thanks for the report.
This issue has been already fixed by
"mm-oom-make-the-calculation-of-oom-badness-more-accurate-v3", which
is already in the -next tree.


--
Thanks
Yafang

[Stephen Rothwell]

Hi all,

#syz fix: mm-oom-make-the-calculation-of-oom-badness-more-accurate-v3

--
Cheers,
Stephen Rothwell

[Dmitry Vyukov]

The final patch title is:

#syz fix: mm, oom: make the calculation of oom badness more accurate


> --
> Cheers,
> Stephen Rothwell