Re: [syzbot] [ocfs2?] BUG: unable to handle kernel paging request in folio_unlock

From: syzbot
Date: Sun Feb 02 2025 - 00:08:34 EST

syzbot has found a reproducer for the following issue on:

HEAD commit: 69e858e0b8b2 Merge tag 'uml-for-linus-6.14-rc1' of git://g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=137be724580000
kernel config: https://syzkaller.appspot.com/x/.config?x=d033b14aeef39158
dashboard link: https://syzkaller.appspot.com/bug?extid=2d57a8e099fe62bd60f0
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17b1d5f8580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17c72d18580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-69e858e0.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a53b888c1f3f/vmlinux-69e858e0.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6b5e17edafc0/bzImage-69e858e0.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/4e6ad1d359e4/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2d57a8e099fe62bd60f0@xxxxxxxxxxxxxxxxxxxxxxxxx

R13: 00007fff1f775058 R14: 431bde82d7b634db R15: 00007fe1ac9c701d
</TASK>
(syz-executor147,5303,0):ocfs2_grab_folios_for_write:1080 ERROR: status = -12
(syz-executor147,5303,0):ocfs2_write_begin_nolock:1798 ERROR: status = -12
BUG: unable to handle page fault for address: fffffffffffffffc
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD e73c067 P4D e73c067 PUD e73e067 PMD 0
Oops: Oops: 0000 [#1] PREEMPT SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5303 Comm: syz-executor147 Not tainted 6.13.0-syzkaller-09760-g69e858e0b8b2 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:const_folio_flags include/linux/page-flags.h:310 [inline]
RIP: 0010:folio_test_locked include/linux/page-flags.h:510 [inline]
RIP: 0010:folio_unlock+0x3b/0x170 mm/filemap.c:1499
Code: 49 bf 00 00 00 00 00 fc ff df e8 b0 56 c7 ff 4d 8d 66 08 4d 89 e5 49 c1 ed 03 43 80 7c 3d 00 00 74 08 4c 89 e7 e8 95 eb 2d 00 <49> 8b 1c 24 48 89 de 48 83 e6 01 31 ff e8 63 5b c7 ff 48 83 e3 01
RSP: 0018:ffffc9000d327128 EFLAGS: 00010246
RAX: ffffffff81f81610 RBX: 1ffff1100232e806 RCX: ffff88801ce4a440
RDX: 0000000000000000 RSI: 0000000000000001 RDI: fffffffffffffff4
RBP: ffff888011974030 R08: ffffffff83ad8572 R09: 1ffffffff203680e
R10: dffffc0000000000 R11: fffffbfff203680f R12: fffffffffffffffc
R13: 1fffffffffffffff R14: fffffffffffffff4 R15: dffffc0000000000
FS: 00005555865c0380(0000) GS:ffff88801fc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffffc CR3: 0000000041da6000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
ocfs2_unlock_and_free_folios+0x71/0x1a0 fs/ocfs2/aops.c:772
ocfs2_free_write_ctxt fs/ocfs2/aops.c:820 [inline]
ocfs2_write_begin_nolock+0x3908/0x4e40 fs/ocfs2/aops.c:1837
ocfs2_write_begin+0x205/0x3a0 fs/ocfs2/aops.c:1889
generic_perform_write+0x346/0x990 mm/filemap.c:4189
ocfs2_file_write_iter+0x19af/0x2180 fs/ocfs2/file.c:2469
new_sync_write fs/read_write.c:586 [inline]
vfs_write+0xacf/0xd10 fs/read_write.c:679
ksys_write+0x18f/0x2b0 fs/read_write.c:731
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe1ac985889
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 d1 1a 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:00007fff1f774df8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fff1f774e10 RCX: 00007fe1ac985889
RDX: 00000000ffffff6a RSI: 0000000020000000 RDI: 0000000000000004
RBP: 0000000000000001 R08: 00007fff1f774b97 R09: 00005555865c1378
R10: 0000000000000001 R11: 0000000000000246 R12: 00007fff1f774e30
R13: 00007fff1f775058 R14: 431bde82d7b634db R15: 00007fe1ac9c701d
</TASK>
Modules linked in:
CR2: fffffffffffffffc
---[ end trace 0000000000000000 ]---
RIP: 0010:const_folio_flags include/linux/page-flags.h:310 [inline]
RIP: 0010:folio_test_locked include/linux/page-flags.h:510 [inline]
RIP: 0010:folio_unlock+0x3b/0x170 mm/filemap.c:1499
Code: 49 bf 00 00 00 00 00 fc ff df e8 b0 56 c7 ff 4d 8d 66 08 4d 89 e5 49 c1 ed 03 43 80 7c 3d 00 00 74 08 4c 89 e7 e8 95 eb 2d 00 <49> 8b 1c 24 48 89 de 48 83 e6 01 31 ff e8 63 5b c7 ff 48 83 e3 01
RSP: 0018:ffffc9000d327128 EFLAGS: 00010246
RAX: ffffffff81f81610 RBX: 1ffff1100232e806 RCX: ffff88801ce4a440
RDX: 0000000000000000 RSI: 0000000000000001 RDI: fffffffffffffff4
RBP: ffff888011974030 R08: ffffffff83ad8572 R09: 1ffffffff203680e
R10: dffffc0000000000 R11: fffffbfff203680f R12: fffffffffffffffc
R13: 1fffffffffffffff R14: fffffffffffffff4 R15: dffffc0000000000
FS: 00005555865c0380(0000) GS:ffff88801fc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffffc CR3: 0000000041da6000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 49 bf 00 00 00 00 00 movabs $0xdffffc0000000000,%r15
7: fc ff df
a: e8 b0 56 c7 ff call 0xffc756bf
f: 4d 8d 66 08 lea 0x8(%r14),%r12
13: 4d 89 e5 mov %r12,%r13
16: 49 c1 ed 03 shr $0x3,%r13
1a: 43 80 7c 3d 00 00 cmpb $0x0,0x0(%r13,%r15,1)
20: 74 08 je 0x2a
22: 4c 89 e7 mov %r12,%rdi
25: e8 95 eb 2d 00 call 0x2debbf
* 2a: 49 8b 1c 24 mov (%r12),%rbx <-- trapping instruction
2e: 48 89 de mov %rbx,%rsi
31: 48 83 e6 01 and $0x1,%rsi
35: 31 ff xor %edi,%edi
37: e8 63 5b c7 ff call 0xffc75b9f
3c: 48 83 e3 01 and $0x1,%rbx


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