[moderation] [bcachefs?] BUG: unable to handle kernel paging request in __bch2_writepage
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syzbot
Jun 5, 2025, 5:57:34 PM6/5/25
to syzkaller-upst...@googlegroups.com
Hello,
syzbot found the following issue on:
HEAD commit: 546b1c9e93c2 Merge tag 'bootconfig-v6.16' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12554570580000
kernel config: https://syzkaller.appspot.com/x/.config?x=d303a19c4f26ffa3
dashboard link: https://syzkaller.appspot.com/bug?extid=eec2cf70b6cfb731479f
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
CC: [kent.ov...@linux.dev linux-b...@vger.kernel.org linux-...@vger.kernel.org]
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/53d5335a5bba/disk-546b1c9e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/38ca89e5e5c9/vmlinux-546b1c9e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/903505d57114/bzImage-546b1c9e.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+eec2cf...@syzkaller.appspotmail.com
BUG: unable to handle page fault for address: fffffffffffffc98
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD df3d067 P4D df3d067 PUD df3f067 PMD 0
Oops: Oops: 0002 [#1] SMP KASAN PTI
CPU: 1 UID: 0 PID: 7881 Comm: syz.3.257 Not tainted 6.15.0-syzkaller-11173-g546b1c9e93c2 #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:bch2_writepage_io_alloc fs/bcachefs/fs-io-buffered.c:516 [inline]
RIP: 0010:__bch2_writepage+0x15b7/0x2790 fs/bcachefs/fs-io-buffered.c:644
Code: ff e8 3d 24 e9 fd 49 81 c6 98 fc ff ff 4d 89 37 4c 89 f0 48 c1 e8 03 80 3c 18 00 74 08 4c 89 f7 e8 1e 24 e9 fd 48 8b 44 24 68 <49> 89 06 4d 8b 37 48 8b 94 24 a0 00 00 00 48 89 d0 48 c1 e8 03 0f
RSP: 0018:ffffc900053e7168 EFLAGS: 00010246
RAX: ffff88804ee00798 RBX: dffffc0000000000 RCX: 0000000000080000
RDX: ffffc9000d1eb000 RSI: 00000000000015e7 RDI: 00000000000015e8
RBP: 0000000000000008 R08: ffff888051548908 R09: 1ffffd40002a6ac8
R10: dffffc0000000000 R11: fffff940002a6ac9 R12: 1ffff92000a7ce7c
R13: 0000000000000008 R14: fffffffffffffc98 R15: ffffc900053e73e0
FS: 00007f90ca3666c0(0000) GS:ffff888125d93000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffc98 CR3: 000000002937c000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
write_cache_pages+0x64/0x100 mm/page-writeback.c:2614
bch2_writepages+0x154/0x360 fs/bcachefs/fs-io-buffered.c:675
do_writepages+0x32b/0x550 mm/page-writeback.c:2636
filemap_fdatawrite_wbc mm/filemap.c:386 [inline]
__filemap_fdatawrite_range mm/filemap.c:419 [inline]
file_write_and_wait_range+0x22c/0x330 mm/filemap.c:794
bch2_fsync+0x127/0x330 fs/bcachefs/fs-io.c:245
generic_write_sync include/linux/fs.h:3027 [inline]
bch2_write_iter+0x2822/0x2b90 fs/bcachefs/fs-io-buffered.c:1097
do_iter_readv_writev+0x56b/0x7f0 fs/read_write.c:-1
vfs_writev+0x31a/0x960 fs/read_write.c:1057
do_pwritev fs/read_write.c:1153 [inline]
__do_sys_pwritev2 fs/read_write.c:1211 [inline]
__se_sys_pwritev2+0x179/0x290 fs/read_write.c:1202
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f90c958e969
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f90ca366038 EFLAGS: 00000246 ORIG_RAX: 0000000000000148
RAX: ffffffffffffffda RBX: 00007f90c97b5fa0 RCX: 00007f90c958e969
RDX: 0000000000000001 RSI: 00002000000001c0 RDI: 0000000000000008
RBP: 00007f90c9610ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000e7b R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f90c97b5fa0 R15: 00007fffc1948f58
</TASK>
Modules linked in:
CR2: fffffffffffffc98
---[ end trace 0000000000000000 ]---
RIP: 0010:bch2_writepage_io_alloc fs/bcachefs/fs-io-buffered.c:516 [inline]
RIP: 0010:__bch2_writepage+0x15b7/0x2790 fs/bcachefs/fs-io-buffered.c:644
Code: ff e8 3d 24 e9 fd 49 81 c6 98 fc ff ff 4d 89 37 4c 89 f0 48 c1 e8 03 80 3c 18 00 74 08 4c 89 f7 e8 1e 24 e9 fd 48 8b 44 24 68 <49> 89 06 4d 8b 37 48 8b 94 24 a0 00 00 00 48 89 d0 48 c1 e8 03 0f
RSP: 0018:ffffc900053e7168 EFLAGS: 00010246
RAX: ffff88804ee00798 RBX: dffffc0000000000 RCX: 0000000000080000
RDX: ffffc9000d1eb000 RSI: 00000000000015e7 RDI: 00000000000015e8
RBP: 0000000000000008 R08: ffff888051548908 R09: 1ffffd40002a6ac8
R10: dffffc0000000000 R11: fffff940002a6ac9 R12: 1ffff92000a7ce7c
R13: 0000000000000008 R14: fffffffffffffc98 R15: ffffc900053e73e0
FS: 00007f90ca3666c0(0000) GS:ffff888125d93000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffc98 CR3: 000000002937c000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 1 bytes skipped:
0: e8 3d 24 e9 fd call 0xfde92442
5: 49 81 c6 98 fc ff ff add $0xfffffffffffffc98,%r14
c: 4d 89 37 mov %r14,(%r15)
f: 4c 89 f0 mov %r14,%rax
12: 48 c1 e8 03 shr $0x3,%rax
16: 80 3c 18 00 cmpb $0x0,(%rax,%rbx,1)
1a: 74 08 je 0x24
1c: 4c 89 f7 mov %r14,%rdi
1f: e8 1e 24 e9 fd call 0xfde92442
24: 48 8b 44 24 68 mov 0x68(%rsp),%rax
* 29: 49 89 06 mov %rax,(%r14) <-- trapping instruction
2c: 4d 8b 37 mov (%r15),%r14
2f: 48 8b 94 24 a0 00 00 mov 0xa0(%rsp),%rdx
36: 00
37: 48 89 d0 mov %rdx,%rax
3a: 48 c1 e8 03 shr $0x3,%rax
3e: 0f .byte 0xf
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
syzbot found the following issue on:
HEAD commit: 546b1c9e93c2 Merge tag 'bootconfig-v6.16' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12554570580000
kernel config: https://syzkaller.appspot.com/x/.config?x=d303a19c4f26ffa3
dashboard link: https://syzkaller.appspot.com/bug?extid=eec2cf70b6cfb731479f
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
CC: [kent.ov...@linux.dev linux-b...@vger.kernel.org linux-...@vger.kernel.org]
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/53d5335a5bba/disk-546b1c9e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/38ca89e5e5c9/vmlinux-546b1c9e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/903505d57114/bzImage-546b1c9e.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+eec2cf...@syzkaller.appspotmail.com
BUG: unable to handle page fault for address: fffffffffffffc98
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD df3d067 P4D df3d067 PUD df3f067 PMD 0
Oops: Oops: 0002 [#1] SMP KASAN PTI
CPU: 1 UID: 0 PID: 7881 Comm: syz.3.257 Not tainted 6.15.0-syzkaller-11173-g546b1c9e93c2 #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:bch2_writepage_io_alloc fs/bcachefs/fs-io-buffered.c:516 [inline]
RIP: 0010:__bch2_writepage+0x15b7/0x2790 fs/bcachefs/fs-io-buffered.c:644
Code: ff e8 3d 24 e9 fd 49 81 c6 98 fc ff ff 4d 89 37 4c 89 f0 48 c1 e8 03 80 3c 18 00 74 08 4c 89 f7 e8 1e 24 e9 fd 48 8b 44 24 68 <49> 89 06 4d 8b 37 48 8b 94 24 a0 00 00 00 48 89 d0 48 c1 e8 03 0f
RSP: 0018:ffffc900053e7168 EFLAGS: 00010246
RAX: ffff88804ee00798 RBX: dffffc0000000000 RCX: 0000000000080000
RDX: ffffc9000d1eb000 RSI: 00000000000015e7 RDI: 00000000000015e8
RBP: 0000000000000008 R08: ffff888051548908 R09: 1ffffd40002a6ac8
R10: dffffc0000000000 R11: fffff940002a6ac9 R12: 1ffff92000a7ce7c
R13: 0000000000000008 R14: fffffffffffffc98 R15: ffffc900053e73e0
FS: 00007f90ca3666c0(0000) GS:ffff888125d93000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffc98 CR3: 000000002937c000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
write_cache_pages+0x64/0x100 mm/page-writeback.c:2614
bch2_writepages+0x154/0x360 fs/bcachefs/fs-io-buffered.c:675
do_writepages+0x32b/0x550 mm/page-writeback.c:2636
filemap_fdatawrite_wbc mm/filemap.c:386 [inline]
__filemap_fdatawrite_range mm/filemap.c:419 [inline]
file_write_and_wait_range+0x22c/0x330 mm/filemap.c:794
bch2_fsync+0x127/0x330 fs/bcachefs/fs-io.c:245
generic_write_sync include/linux/fs.h:3027 [inline]
bch2_write_iter+0x2822/0x2b90 fs/bcachefs/fs-io-buffered.c:1097
do_iter_readv_writev+0x56b/0x7f0 fs/read_write.c:-1
vfs_writev+0x31a/0x960 fs/read_write.c:1057
do_pwritev fs/read_write.c:1153 [inline]
__do_sys_pwritev2 fs/read_write.c:1211 [inline]
__se_sys_pwritev2+0x179/0x290 fs/read_write.c:1202
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f90c958e969
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f90ca366038 EFLAGS: 00000246 ORIG_RAX: 0000000000000148
RAX: ffffffffffffffda RBX: 00007f90c97b5fa0 RCX: 00007f90c958e969
RDX: 0000000000000001 RSI: 00002000000001c0 RDI: 0000000000000008
RBP: 00007f90c9610ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000e7b R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f90c97b5fa0 R15: 00007fffc1948f58
</TASK>
Modules linked in:
CR2: fffffffffffffc98
---[ end trace 0000000000000000 ]---
RIP: 0010:bch2_writepage_io_alloc fs/bcachefs/fs-io-buffered.c:516 [inline]
RIP: 0010:__bch2_writepage+0x15b7/0x2790 fs/bcachefs/fs-io-buffered.c:644
Code: ff e8 3d 24 e9 fd 49 81 c6 98 fc ff ff 4d 89 37 4c 89 f0 48 c1 e8 03 80 3c 18 00 74 08 4c 89 f7 e8 1e 24 e9 fd 48 8b 44 24 68 <49> 89 06 4d 8b 37 48 8b 94 24 a0 00 00 00 48 89 d0 48 c1 e8 03 0f
RSP: 0018:ffffc900053e7168 EFLAGS: 00010246
RAX: ffff88804ee00798 RBX: dffffc0000000000 RCX: 0000000000080000
RDX: ffffc9000d1eb000 RSI: 00000000000015e7 RDI: 00000000000015e8
RBP: 0000000000000008 R08: ffff888051548908 R09: 1ffffd40002a6ac8
R10: dffffc0000000000 R11: fffff940002a6ac9 R12: 1ffff92000a7ce7c
R13: 0000000000000008 R14: fffffffffffffc98 R15: ffffc900053e73e0
FS: 00007f90ca3666c0(0000) GS:ffff888125d93000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: fffffffffffffc98 CR3: 000000002937c000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 1 bytes skipped:
0: e8 3d 24 e9 fd call 0xfde92442
5: 49 81 c6 98 fc ff ff add $0xfffffffffffffc98,%r14
c: 4d 89 37 mov %r14,(%r15)
f: 4c 89 f0 mov %r14,%rax
12: 48 c1 e8 03 shr $0x3,%rax
16: 80 3c 18 00 cmpb $0x0,(%rax,%rbx,1)
1a: 74 08 je 0x24
1c: 4c 89 f7 mov %r14,%rdi
1f: e8 1e 24 e9 fd call 0xfde92442
24: 48 8b 44 24 68 mov 0x68(%rsp),%rax
* 29: 49 89 06 mov %rax,(%r14) <-- trapping instruction
2c: 4d 8b 37 mov (%r15),%r14
2f: 48 8b 94 24 a0 00 00 mov 0xa0(%rsp),%rdx
36: 00
37: 48 89 d0 mov %rdx,%rax
3a: 48 c1 e8 03 shr $0x3,%rax
3e: 0f .byte 0xf
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
syzbot
Sep 8, 2025, 10:16:21 PM9/8/25
to syzkaller-upst...@googlegroups.com
Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.
Crashes did not happen for a while, no reproducer and no activity.
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