Subject: Re: [syzbot] BUG: Bad page map (5)

From: syzbot <[email-masked]>
Date: Sun, 11 Sep 2022 21:27:32 -0700

syzbot has found a reproducer for the following issue on:

HEAD commit:    e47eb90a0a9a Add linux-next specific files for 20220901
git tree:       linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=17330430880000
kernel config:  https://syzkaller.appspot.com/x/.config?x=7933882276523081
dashboard link: https://syzkaller.appspot.com/bug?extid=915f3e317adb0e85835f
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=13397b77080000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1793564f080000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]

BUG: Bad page map in process syz-executor198  pte:8000000071c00227 pmd:74b30067
addr:0000000020563000 vm_flags:08100077 anon_vma:ffff8880547d2200 mapping:0000000000000000 index:20563
file:(null) fault:0x0 mmap:0x0 read_folio:0x0
CPU: 1 PID: 3614 Comm: syz-executor198 Not tainted 6.0.0-rc3-next-20220901-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
 print_bad_pte.cold+0x2a7/0x2d0 mm/memory.c:565
 vm_normal_page+0x10c/0x2a0 mm/memory.c:636
 hpage_collapse_scan_pmd+0x729/0x1da0 mm/khugepaged.c:1199
 madvise_collapse+0x481/0x910 mm/khugepaged.c:2433
 madvise_vma_behavior+0xd0a/0x1cc0 mm/madvise.c:1062
 madvise_walk_vmas+0x1c7/0x2b0 mm/madvise.c:1236
 do_madvise.part.0+0x24a/0x340 mm/madvise.c:1415
 do_madvise mm/madvise.c:1428 [inline]
 __do_sys_madvise mm/madvise.c:1428 [inline]
 __se_sys_madvise mm/madvise.c:1426 [inline]
 __x64_sys_madvise+0x113/0x150 mm/madvise.c:1426
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f770ba87929
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 11 15 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f770ba18308 EFLAGS: 00000246 ORIG_RAX: 000000000000001c
RAX: ffffffffffffffda RBX: 00007f770bb0f3f8 RCX: 00007f770ba87929
RDX: 0000000000000019 RSI: 0000000000600003 RDI: 0000000020000000
RBP: 00007f770bb0f3f0 R08: 00007f770ba18700 R09: 0000000000000000
R10: 00007f770ba18700 R11: 0000000000000246 R12: 00007f770bb0f3fc
R13: 00007ffc2d8b62ef R14: 00007f770ba18400 R15: 0000000000022000
 </TASK>