Message-ID: <68a7eee8.a00a0220.33401d.0167.GAE@google.com>
Date: Thu, 21 Aug 2025 21:15:36 -0700
From: syzbot <syzbot+baf59efef8862c9ba260@...kaller.appspotmail.com>
To: kent.overstreet@...ux.dev, linux-bcachefs@...r.kernel.org, 
	linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: [syzbot] [bcachefs?] INFO: task hung in bch2_mark_pagecache_reserved (3)

Hello,

syzbot found the following issue on:

HEAD commit:    8d561baae505 Merge tag 'x86_urgent_for_v6.17_rc2' of git:/..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1241eba2580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=98e114f4eb77e551
dashboard link: https://syzkaller.appspot.com/bug?extid=baf59efef8862c9ba260
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=172f1ba2580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11a79234580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/595e1e4d6418/disk-8d561baa.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ab14cc587702/vmlinux-8d561baa.xz
kernel image: https://storage.googleapis.com/syzbot-assets/368a3a55dcfb/bzImage-8d561baa.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/d90b312697dc/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+baf59efef8862c9ba260@...kaller.appspotmail.com

INFO: task syz.0.17:6129 blocked for more than 143 seconds.
      Tainted: G        W           6.17.0-rc1-syzkaller-00224-g8d561baae505 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.17        state:D stack:24520 pid:6129  tgid:6105  ppid:5963   task_flags:0x400140 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x16f3/0x4c20 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7058
 io_schedule+0x81/0xe0 kernel/sched/core.c:7903
 folio_wait_bit_common+0x6b5/0xb90 mm/filemap.c:1317
 folio_lock include/linux/pagemap.h:1133 [inline]
 bch2_mark_pagecache_reserved+0x33d/0xbb0 fs/bcachefs/fs-io-pagecache.c:314
 __bchfs_fallocate+0x1284/0x1870 fs/bcachefs/fs-io.c:733
 bchfs_fallocate+0x33f/0x680 fs/bcachefs/fs-io.c:789
 bch2_fallocate_dispatch+0x28d/0x410 fs/bcachefs/fs-io.c:836
 vfs_fallocate+0x672/0x7f0 fs/open.c:342
 ksys_fallocate fs/open.c:366 [inline]
 __do_sys_fallocate fs/open.c:371 [inline]
 __se_sys_fallocate fs/open.c:369 [inline]
 __x64_sys_fallocate+0xc0/0x110 fs/open.c:369
 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: 0033:0x7f72068bebe9
RSP: 002b:00007f7205f05038 EFLAGS: 00000246 ORIG_RAX: 000000000000011d
RAX: ffffffffffffffda RBX: 00007f7206ae6090 RCX: 00007f72068bebe9
RDX: 0000000000000005 RSI: 0000000000000001 RDI: 0000000000000007
RBP: 00007f7206941e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000007fff R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7206ae6128 R14: 00007f7206ae6090 R15: 00007ffc00c97a38
 </TASK>
INFO: task syz.0.17:6130 blocked for more than 143 seconds.
      Tainted: G        W           6.17.0-rc1-syzkaller-00224-g8d561baae505 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.17        state:D stack:26872 pid:6130  tgid:6105  ppid:5963   task_flags:0x440040 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x16f3/0x4c20 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7058
 __bch2_two_state_lock+0x1ea/0x370 fs/bcachefs/two_state_shared_lock.c:7
 bch2_two_state_lock fs/bcachefs/two_state_shared_lock.h:55 [inline]
 bch2_readahead+0x94f/0x1100 fs/bcachefs/fs-io-buffered.c:296
 read_pages+0x177/0x580 mm/readahead.c:160
 page_cache_ra_unbounded+0x2d3/0x740 mm/readahead.c:264
 filemap_get_pages+0x443/0x1df0 mm/filemap.c:2603
 filemap_splice_read+0x587/0xc60 mm/filemap.c:2991
 do_splice_read fs/splice.c:979 [inline]
 splice_direct_to_actor+0x4b1/0xcd0 fs/splice.c:1083
 do_splice_direct_actor fs/splice.c:1201 [inline]
 do_splice_direct+0x187/0x270 fs/splice.c:1227
 do_sendfile+0x4ec/0x7f0 fs/read_write.c:1370
 __do_sys_sendfile64 fs/read_write.c:1431 [inline]
 __se_sys_sendfile64+0x13e/0x190 fs/read_write.c:1417
 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: 0033:0x7f72068bebe9
RSP: 002b:00007f7205ee4038 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f7206ae6180 RCX: 00007f72068bebe9
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000004
RBP: 00007f7206941e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000100001 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7206ae6218 R14: 00007f7206ae6180 R15: 00007ffc00c97a38
 </TASK>
INFO: task syz.3.35:6346 blocked for more than 143 seconds.
      Tainted: G        W           6.17.0-rc1-syzkaller-00224-g8d561baae505 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.35        state:D stack:24520 pid:6346  tgid:6305  ppid:5970   task_flags:0x400140 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x16f3/0x4c20 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7058
 io_schedule+0x81/0xe0 kernel/sched/core.c:7903
 folio_wait_bit_common+0x6b5/0xb90 mm/filemap.c:1317
 folio_lock include/linux/pagemap.h:1133 [inline]
 bch2_mark_pagecache_reserved+0x33d/0xbb0 fs/bcachefs/fs-io-pagecache.c:314
 __bchfs_fallocate+0x1284/0x1870 fs/bcachefs/fs-io.c:733
 bchfs_fallocate+0x33f/0x680 fs/bcachefs/fs-io.c:789
 bch2_fallocate_dispatch+0x28d/0x410 fs/bcachefs/fs-io.c:836
 vfs_fallocate+0x672/0x7f0 fs/open.c:342
 ksys_fallocate fs/open.c:366 [inline]
 __do_sys_fallocate fs/open.c:371 [inline]
 __se_sys_fallocate fs/open.c:369 [inline]
 __x64_sys_fallocate+0xc0/0x110 fs/open.c:369
 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: 0033:0x7f556c76ebe9
RSP: 002b:00007f556bdb5038 EFLAGS: 00000246 ORIG_RAX: 000000000000011d
RAX: ffffffffffffffda RBX: 00007f556c996090 RCX: 00007f556c76ebe9
RDX: 0000000000000005 RSI: 0000000000000001 RDI: 0000000000000007
RBP: 00007f556c7f1e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000007fff R11: 0000000000000246 R12: 0000000000000000
R13: 00007f556c996128 R14: 00007f556c996090 R15: 00007ffe84a319a8
 </TASK>
INFO: task syz.3.35:6347 blocked for more than 143 seconds.
      Tainted: G        W           6.17.0-rc1-syzkaller-00224-g8d561baae505 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.35        state:D stack:27160 pid:6347  tgid:6305  ppid:5970   task_flags:0x440040 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5357 [inline]
 __schedule+0x16f3/0x4c20 kernel/sched/core.c:6961
 __schedule_loop kernel/sched/core.c:7043 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7058
 __bch2_two_state_lock+0x1ea/0x370 fs/bcachefs/two_state_shared_lock.c:7
 bch2_two_state_lock fs/bcachefs/two_state_shared_lock.h:55 [inline]
 bch2_readahead+0x94f/0x1100 fs/bcachefs/fs-io-buffered.c:296
 read_pages+0x177/0x580 mm/readahead.c:160
 page_cache_ra_unbounded+0x2d3/0x740 mm/readahead.c:264
 filemap_get_pages+0x443/0x1df0 mm/filemap.c:2603
 filemap_splice_read+0x587/0xc60 mm/filemap.c:2991
 do_splice_read fs/splice.c:979 [inline]
 splice_direct_to_actor+0x4b1/0xcd0 fs/splice.c:1083
 do_splice_direct_actor fs/splice.c:1201 [inline]
 do_splice_direct+0x187/0x270 fs/splice.c:1227
 do_sendfile+0x4ec/0x7f0 fs/read_write.c:1370
 __do_sys_sendfile64 fs/read_write.c:1431 [inline]
 __se_sys_sendfile64+0x13e/0x190 fs/read_write.c:1417
 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: 0033:0x7f556c76ebe9
RSP: 002b:00007f556bd94038 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f556c996180 RCX: 00007f556c76ebe9
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000004
RBP: 00007f556c7f1e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000100001 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f556c996218 R14: 00007f556c996180 R15: 00007ffe84a319a8
 </TASK>
INFO: lockdep is turned off.
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 38 Comm: khungtaskd Tainted: G        W           6.17.0-rc1-syzkaller-00224-g8d561baae505 #0 PREEMPT_{RT,(full)} 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 nmi_cpu_backtrace+0x39e/0x3d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:328 [inline]
 watchdog+0xf93/0xfe0 kernel/hung_task.c:491
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 17 Comm: pr/legacy Tainted: G        W           6.17.0-rc1-syzkaller-00224-g8d561baae505 #0 PREEMPT_{RT,(full)} 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
RIP: 0010:io_serial_in+0x77/0xc0 drivers/tty/serial/8250/8250_port.c:400
Code: e8 ce d8 7f fc 44 89 f9 d3 e3 49 83 ee 80 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 cf 0b df fc 41 03 1e 89 da ec <0f> b6 c0 5b 41 5c 41 5e 41 5f c3 cc cc cc cc cc 44 89 f9 80 e1 07
RSP: 0018:ffffc90000167890 EFLAGS: 00000202
RAX: 1ffffffff3274800 RBX: 00000000000003fd RCX: 0000000000000000
RDX: 00000000000003fd RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffffff993a4810 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffffff853e8220 R12: dffffc0000000000
R13: 0000000000000000 R14: ffffffff993a4580 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8881268c5000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f814fde4000 CR3: 000000005b504000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 serial_in drivers/tty/serial/8250/8250.h:137 [inline]
 serial_lsr_in drivers/tty/serial/8250/8250.h:159 [inline]
 wait_for_lsr+0x1aa/0x2f0 drivers/tty/serial/8250/8250_port.c:1984
 fifo_wait_for_lsr drivers/tty/serial/8250/8250_port.c:3288 [inline]
 serial8250_console_fifo_write drivers/tty/serial/8250/8250_port.c:3329 [inline]
 serial8250_console_write+0x1341/0x1b40 drivers/tty/serial/8250/8250_port.c:3396
 console_emit_next_record kernel/printk/printk.c:3118 [inline]
 console_flush_all+0x695/0xcd0 kernel/printk/printk.c:3226
 __console_flush_and_unlock+0xa4/0x240 kernel/printk/printk.c:3285
 legacy_kthread_func+0x13b/0x1a0 kernel/printk/printk.c:3638
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>


---
This report is generated by a bot. It may contain errors.
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If the report is already addressed, let syzbot know by replying with:
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If you want syzbot to run the reproducer, reply with:
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If you want to overwrite report's subsystems, reply with:
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(See the list of subsystem names on the web dashboard)

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