[syzbot] [gfs2?] INFO: task hung in gfs2_recover_journal (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 785f0eb2f85d Add linux-next specific files for 20260320
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=11b352f6580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c584910d0d74158d
dashboard link: https://syzkaller.appspot.com/bug?extid=9013411dc43f3582823a
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15b352f6580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1528aada580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a1f7fd9c1a63/disk-785f0eb2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6c138da87c25/vmlinux-785f0eb2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/4d1be64e56db/bzImage-785f0eb2.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/b8d9a874b489/mount_0.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=16fc7ada580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+901341...@syzkaller.appspotmail.com

INFO: task kworker/0:3:5963 blocked in I/O wait for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/0:3 state:D stack:25400 pid:5963 tgid:5963 ppid:2 task_flags:0x4208060 flags:0x00080000
Workqueue: gfs2_recovery gfs2_recover_func
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5352 [inline]
__schedule+0x165c/0x5560 kernel/sched/core.c:6964
__schedule_loop kernel/sched/core.c:7047 [inline]
schedule+0x164/0x360 kernel/sched/core.c:7062
io_schedule+0x7f/0xd0 kernel/sched/core.c:7889
folio_wait_bit_common+0x6d8/0xbc0 mm/filemap.c:1324
folio_wait_locked include/linux/pagemap.h:1245 [inline]
gfs2_jhead_process_page+0x175/0x670 fs/gfs2/lops.c:470
gfs2_find_jhead+0xbd2/0xd30 fs/gfs2/lops.c:586
gfs2_recover_func+0x6cf/0x1f60 fs/gfs2/recovery.c:459
process_one_work+0x9a3/0x1710 kernel/workqueue.c:3288
process_scheduled_works kernel/workqueue.c:3379 [inline]
worker_thread+0xba8/0x11e0 kernel/workqueue.c:3465
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
INFO: task syz.0.18:6005 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.18 state:D stack:24120 pid:6005 tgid:6005 ppid:5953 task_flags:0x400140 flags:0x00080002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5352 [inline]
__schedule+0x165c/0x5560 kernel/sched/core.c:6964
__schedule_loop kernel/sched/core.c:7047 [inline]
schedule+0x164/0x360 kernel/sched/core.c:7062
bit_wait+0x11/0xd0 kernel/sched/wait_bit.c:240
__wait_on_bit+0xb9/0x310 kernel/sched/wait_bit.c:52
out_of_line_wait_on_bit+0x13b/0x190 kernel/sched/wait_bit.c:67
wait_on_bit include/linux/wait_bit.h:77 [inline]
gfs2_recover_journal+0xda/0x140 fs/gfs2/recovery.c:579
init_journal+0x16ad/0x2280 fs/gfs2/ops_fstype.c:794
init_inodes+0xdb/0x320 fs/gfs2/ops_fstype.c:844
gfs2_fill_super+0x1a38/0x21d0 fs/gfs2/ops_fstype.c:1250
get_tree_bdev_flags+0x431/0x4f0 fs/super.c:1694
gfs2_get_tree+0x51/0x1e0 fs/gfs2/ops_fstype.c:1332
vfs_get_tree+0x92/0x2a0 fs/super.c:1754
fc_mount fs/namespace.c:1193 [inline]
do_new_mount_fc fs/namespace.c:3764 [inline]
do_new_mount+0x341/0xd30 fs/namespace.c:3840
do_mount fs/namespace.c:4173 [inline]
__do_sys_mount fs/namespace.c:4372 [inline]
__se_sys_mount+0x31d/0x420 fs/namespace.c:4349
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f611259da0a
RSP: 002b:00007ffe1764d4e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffe1764d570 RCX: 00007f611259da0a
RDX: 0000200000037f40 RSI: 0000200000037f80 RDI: 00007ffe1764d530
RBP: 0000200000037f40 R08: 00007ffe1764d570 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000200000037f80
R13: 00007ffe1764d530 R14: 0000000000037fc4 R15: 0000200000000300
</TASK>

Showing all locks held in the system:
1 lock held by pool_workqueue_/3:
1 lock held by khungtaskd/30:
#0: ffffffff8e75d7e0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:312 [inline]
#0: ffffffff8e75d7e0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:850 [inline]
#0: ffffffff8e75d7e0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
2 locks held by getty/5600:
#0: ffff888037d8f0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc9000322b2e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13a0 drivers/tty/n_tty.c:2211
2 locks held by kworker/0:3/5963:
#0: ffff8880232a6140 ((wq_completion)gfs2_recovery){+.+.}-{0:0}, at: process_one_work+0x890/0x1710 kernel/workqueue.c:3260
#1: ffffc900043b7c40 ((work_completion)(&jd->jd_work)){+.+.}-{0:0}, at: process_one_work+0x8b7/0x1710 kernel/workqueue.c:3261
1 lock held by syz.0.18/6005:
#0: ffff8880346ce0d8 (&type->s_umount_key#54/1){+.+.}-{4:4}, at: alloc_super+0x28c/0xab0 fs/super.c:345
3 locks held by syz.1.203/6599:

=============================================

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 30 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x17a/0x300 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
__sys_info lib/sys_info.c:157 [inline]
sys_info+0x135/0x170 lib/sys_info.c:165
check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline]
watchdog+0xfd3/0x1030 kernel/hung_task.c:561
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 6599 Comm: syz.1.203 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:mark_lock+0xa4/0x190 kernel/locking/lockdep.c:4774
Code: 0e 48 c7 c6 19 03 06 8e 67 48 0f b9 3a 90 31 c9 4c 89 fe 4c 89 f7 b8 01 00 00 00 85 69 60 74 10 5b 41 5c 41 5d 41 5e 41 5f 5d <c3> cc cc cc cc cc 49 89 fe 49 89 f7 e8 5b 94 ff ff 89 c1 31 c0 85
RSP: 0018:ffffc90000a08840 EFLAGS: 00000006
RAX: 0000000000000001 RBX: ffff88801d3dc8e8 RCX: ffffffff93c65330
RDX: 0000000000000008 RSI: ffff88801d3dc8c8 RDI: ffff88801d3dbd00
RBP: ffff88801d3dc8c8 R08: ffffffff84b9d570 R09: ffffffff9a4fdcb8
R10: ffffc90000a08a60 R11: fffff5200014114e R12: 0000000000000003
R13: ffff88801d3dc8c8 R14: ffff88801d3dbd00 R15: 0000000000000003
FS: 000055557c000500(0000) GS:ffff888125548000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055910e737168 CR3: 000000006c700000 CR4: 00000000003526f0
Call Trace:
<IRQ>
mark_usage kernel/locking/lockdep.c:4674 [inline]
__lock_acquire+0x6b5/0x2cf0 kernel/locking/lockdep.c:5191
lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline]
_raw_spin_lock_irqsave+0x40/0x60 kernel/locking/spinlock.c:166
debug_object_assert_init+0xb0/0x370 lib/debugobjects.c:1035
debug_timer_assert_init kernel/time/timer.c:803 [inline]
debug_assert_init kernel/time/timer.c:848 [inline]
__mod_timer+0x4a/0xf30 kernel/time/timer.c:1025
dsp_cmx_send+0x1abe/0x1b40 drivers/isdn/mISDN/dsp_cmx.c:1839
call_timer_fn+0x192/0x5e0 kernel/time/timer.c:1748
expire_timers kernel/time/timer.c:1799 [inline]
__run_timers kernel/time/timer.c:2373 [inline]
__run_timer_base+0x652/0x8b0 kernel/time/timer.c:2385
run_timer_base kernel/time/timer.c:2394 [inline]
run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2404
handle_softirqs+0x22a/0x840 kernel/softirq.c:626
__do_softirq kernel/softirq.c:660 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0xca/0x220 kernel/softirq.c:739
irq_exit_rcu+0x9/0x30 kernel/softirq.c:756
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1061
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:console_trylock_spinning kernel/printk/printk.c:2039 [inline]
RIP: 0010:vprintk_emit+0x45d/0x560 kernel/printk/printk.c:2478
Code: 0f 84 44 ff ff ff e8 a2 09 21 00 fb eb 44 e8 9a 09 21 00 e8 75 7b 0b 0a 4d 85 f6 74 94 e8 8b 09 21 00 fb 48 c7 c7 00 fc 74 8e <31> f6 ba 01 00 00 00 31 c9 41 b8 01 00 00 00 45 31 c9 53 e8 cb 18
RSP: 0018:ffffc90004b06e00 EFLAGS: 00000293
RAX: ffffffff81a547f5 RBX: ffffffff81a5466f RCX: ffff88801d3dbd00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff8e74fc00
RBP: ffffc90004b06eb0 R08: ffffffff90123cf7 R09: 1ffffffff202479e
R10: dffffc0000000000 R11: fffffbfff202479f R12: 0000000000000000
R13: 000000000000002f R14: 0000000000000200 R15: 1ffff92000960dc4
_printk+0xdd/0x130 kernel/printk/printk.c:2504
set_capacity_and_notify+0x2c5/0x320 block/genhd.c:93
loop_set_size+0x44/0xb0 drivers/block/loop.c:220
loop_configure+0x9ac/0xdf0 drivers/block/loop.c:1079
lo_ioctl+0x447/0x1fb0 drivers/block/loop.c:1534
blkdev_ioctl+0x5e3/0x740 block/ioctl.c:804
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa17279c42b
Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <89> c2 3d 00 f0 ff ff 77 1c 48 8b 44 24 18 64 48 2b 04 25 28 00 00
RSP: 002b:00007ffde9d10a80 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007fa17279c42b
RDX: 0000000000000003 RSI: 0000000000004c00 RDI: 0000000000000004
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 00007ffde9d10bb0 R14: 00007ffde9d10b70 R15: 00007fa169800000
</TASK>


---
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 syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

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]

For archival purposes, forwarding an incoming command email to
linux-...@vger.kernel.org, syzkall...@googlegroups.com.

***

Subject: [PATCH] gfs2: fix hung task in gfs2_jhead_process_page
Author: karti...@gmail.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master


filemap_get_folio() can return an ERR_PTR if the folio is not
present in the page cache. This can happen when a crafted or
corrupted GFS2 filesystem image is mounted and journal recovery
is triggered.

gfs2_jhead_process_page() calls filemap_get_folio() without
checking the return value, and passes the result directly to
folio_wait_locked(). When an ERR_PTR is passed to
folio_wait_locked(), the kernel task gets stuck in uninterruptible
sleep (state D) forever, triggering the hung task watchdog.

This was reported by syzbot. The reproducer mounts a crafted GFS2
image which causes gfs2_find_jhead() to call
gfs2_jhead_process_page() on a page that was never properly
submitted for I/O, causing filemap_get_folio() to return
ERR_PTR(-ENOENT).

Fix this by checking the return value of filemap_get_folio() and
marking the journal head search as done if the folio is not found,
allowing the caller to return an error gracefully.

Reported-by: syzbot+901341...@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=9013411dc43f3582823a
Signed-off-by: Deepanshu Kartikey <Karti...@gmail.com>
---
fs/gfs2/lops.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/fs/gfs2/lops.c b/fs/gfs2/lops.c
index 797931eb5845..c2bb262318bb 100644
--- a/fs/gfs2/lops.c
+++ b/fs/gfs2/lops.c
@@ -467,6 +467,11 @@ static void gfs2_jhead_process_page(struct gfs2_jdesc *jd, unsigned long index,

folio = filemap_get_folio(jd->jd_inode->i_mapping, index);

+ if (IS_ERR(folio)) {
+ *done = true;
+ return ;
+ }
+
folio_wait_locked(folio);
if (!folio_test_uptodate(folio))
*done = true;
--
2.43.0

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING in gfs2_fill_super

loop1: detected capacity change from 0 to 32768
------------[ cut here ]------------
kmem_cache of name 'gfs2-bufdata/syz:syz' already exists
WARNING: mm/slab_common.c:112 at kmem_cache_sanity_check mm/slab_common.c:111 [inline], CPU#1: syz.1.18/6629
WARNING: mm/slab_common.c:112 at __kmem_cache_create_args+0xac/0x440 mm/slab_common.c:352, CPU#1: syz.1.18/6629
Modules linked in:
CPU: 1 UID: 0 PID: 6629 Comm: syz.1.18 Not tainted syzkaller #0 PREEMPT(full)

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026

RIP: 0010:kmem_cache_sanity_check mm/slab_common.c:111 [inline]
RIP: 0010:__kmem_cache_create_args+0xaf/0x440 mm/slab_common.c:352
Code: 86 8e 4d 8b 24 24 49 81 fc 18 68 86 8e 74 20 49 8b 7c 24 f8 48 89 de e8 3f 5c 9c 09 85 c0 75 e2 48 8d 3d 54 70 06 0e 48 89 de <67> 48 0f b9 3a 48 89 df be 20 00 00 00 e8 df 5d 9c 09 48 85 c0 0f
RSP: 0018:ffffc90002587948 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff88805dca3500 RCX: 0000000000000005
RDX: 000000005dca3504 RSI: ffff88805dca3500 RDI: ffffffff9016e0b0
RBP: 0000000000000000 R08: ffffffff901246f7 R09: 1ffffffff20248de
R10: dffffc0000000000 R11: fffffbfff20248df R12: ffff888035c9b920
R13: ffff88807cdf8000 R14: 0000000000000050 R15: ffffc90002587a60
FS: 00007f0e2aa0a6c0(0000) GS:ffff888125548000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00007fffebd18738 CR3: 000000007944c000 CR4: 00000000003526f0
Call Trace:
<TASK>
__kmem_cache_create include/linux/slab.h:390 [inline]
gfs2_fill_super+0x13a4/0x21d0 fs/gfs2/ops_fstype.c:1202
get_tree_bdev_flags+0x431/0x4f0 fs/super.c:1694
gfs2_get_tree+0x51/0x1e0 fs/gfs2/ops_fstype.c:1342

vfs_get_tree+0x92/0x2a0 fs/super.c:1754
fc_mount fs/namespace.c:1193 [inline]
do_new_mount_fc fs/namespace.c:3764 [inline]
do_new_mount+0x341/0xd30 fs/namespace.c:3840
do_mount fs/namespace.c:4173 [inline]
__do_sys_mount fs/namespace.c:4372 [inline]
__se_sys_mount+0x31d/0x420 fs/namespace.c:4349
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

RIP: 0033:0x7f0e29b9da0a
Code: 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f0e2aa09e58 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f0e2aa09ee0 RCX: 00007f0e29b9da0a
RDX: 0000200000037f40 RSI: 0000200000037f80 RDI: 00007f0e2aa09ea0
RBP: 0000200000037f40 R08: 00007f0e2aa09ee0 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 0000200000037f80

R13: 00007f0e2aa09ea0 R14: 0000000000037fc4 R15: 0000200000000300
</TASK>
----------------
Code disassembly (best guess):
0: 86 8e 4d 8b 24 24 xchg %cl,0x24248b4d(%rsi)
6: 49 81 fc 18 68 86 8e cmp $0xffffffff8e866818,%r12
d: 74 20 je 0x2f
f: 49 8b 7c 24 f8 mov -0x8(%r12),%rdi
14: 48 89 de mov %rbx,%rsi
17: e8 3f 5c 9c 09 call 0x99c5c5b
1c: 85 c0 test %eax,%eax
1e: 75 e2 jne 0x2
20: 48 8d 3d 54 70 06 0e lea 0xe067054(%rip),%rdi # 0xe06707b
27: 48 89 de mov %rbx,%rsi
* 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction
2f: 48 89 df mov %rbx,%rdi
32: be 20 00 00 00 mov $0x20,%esi
37: e8 df 5d 9c 09 call 0x99c5e1b
3c: 48 85 c0 test %rax,%rax
3f: 0f .byte 0xf


Tested on:

commit: 09c0f7f1 Add linux-next specific files for 20260323
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=13a59e16580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c0c30527ccbcb0f2

dashboard link: https://syzkaller.appspot.com/bug?extid=9013411dc43f3582823a
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

patch: https://syzkaller.appspot.com/x/patch.diff?x=11d9c1d6580000

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-...@vger.kernel.org, syzkall...@googlegroups.com.

***

Subject: [PATCH] gfs2: fix hung task in gfs2_jhead_process_page
Author: karti...@gmail.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master


filemap_get_folio() can return an ERR_PTR if the folio is not
present in the page cache. This can happen when a crafted or
corrupted GFS2 filesystem image is mounted and journal recovery
is triggered.

gfs2_jhead_process_page() calls filemap_get_folio() without
checking the return value, and passes the result directly to
folio_wait_locked(). When an ERR_PTR is passed to
folio_wait_locked(), the kernel task gets stuck in uninterruptible
sleep (state D) forever, triggering the hung task watchdog.

Fix this by checking the return value of filemap_get_folio().
If the folio is not found, record the error via filemap_set_wb_err()
so that gfs2_find_jhead() picks it up through filemap_check_wb_err()
and returns a proper error code to the caller. Without this,
gfs2_find_jhead() would return success despite the failure, leading
to further issues during mount such as duplicate kmem_cache creation.

Reported-by: syzbot+901341...@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=9013411dc43f3582823a
Signed-off-by: Deepanshu Kartikey <Karti...@gmail.com>
---

fs/gfs2/lops.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/fs/gfs2/lops.c b/fs/gfs2/lops.c
index 797931eb5845..a832904a09e3 100644
--- a/fs/gfs2/lops.c
+++ b/fs/gfs2/lops.c
@@ -467,6 +467,12 @@ static void gfs2_jhead_process_page(struct gfs2_jdesc *jd, unsigned long index,

folio = filemap_get_folio(jd->jd_inode->i_mapping, index);

+ if (IS_ERR(folio)) {

+ filemap_set_wb_err(jd->jd_inode->i_mapping, PTR_ERR(folio));

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING in gfs2_fill_super

loop1: detected capacity change from 0 to 32768
------------[ cut here ]------------
kmem_cache of name 'gfs2-bufdata/syz:syz' already exists

WARNING: mm/slab_common.c:112 at kmem_cache_sanity_check mm/slab_common.c:111 [inline], CPU#0: syz.1.21/6483
WARNING: mm/slab_common.c:112 at __kmem_cache_create_args+0xac/0x440 mm/slab_common.c:352, CPU#0: syz.1.21/6483
Modules linked in:
CPU: 0 UID: 0 PID: 6483 Comm: syz.1.21 Not tainted syzkaller #0 PREEMPT(full)

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:kmem_cache_sanity_check mm/slab_common.c:111 [inline]
RIP: 0010:__kmem_cache_create_args+0xaf/0x440 mm/slab_common.c:352
Code: 86 8e 4d 8b 24 24 49 81 fc 18 68 86 8e 74 20 49 8b 7c 24 f8 48 89 de e8 3f 5c 9c 09 85 c0 75 e2 48 8d 3d 54 70 06 0e 48 89 de <67> 48 0f b9 3a 48 89 df be 20 00 00 00 e8 df 5d 9c 09 48 85 c0 0f

RSP: 0018:ffffc90003477948 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff888026fe5f80 RCX: 0000000000000005
RDX: 0000000026fe5f04 RSI: ffff888026fe5f80 RDI: ffffffff9016e0b0

RBP: 0000000000000000 R08: ffffffff901246f7 R09: 1ffffffff20248de

R10: dffffc0000000000 R11: fffffbfff20248df R12: ffff888027604ba0
R13: ffff888078654000 R14: 0000000000000050 R15: ffffc90003477a60
FS: 00007fe28ae0f6c0(0000) GS:ffff888125448000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00007fe289f85900 CR3: 0000000026234000 CR4: 00000000003526f0

Call Trace:
<TASK>
__kmem_cache_create include/linux/slab.h:390 [inline]
gfs2_fill_super+0x13a4/0x21d0 fs/gfs2/ops_fstype.c:1202
get_tree_bdev_flags+0x431/0x4f0 fs/super.c:1694
gfs2_get_tree+0x51/0x1e0 fs/gfs2/ops_fstype.c:1342
vfs_get_tree+0x92/0x2a0 fs/super.c:1754
fc_mount fs/namespace.c:1193 [inline]
do_new_mount_fc fs/namespace.c:3764 [inline]
do_new_mount+0x341/0xd30 fs/namespace.c:3840
do_mount fs/namespace.c:4173 [inline]
__do_sys_mount fs/namespace.c:4372 [inline]
__se_sys_mount+0x31d/0x420 fs/namespace.c:4349
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

RIP: 0033:0x7fe289f9da0a

Code: 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48

RSP: 002b:00007fe28ae0ee58 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fe28ae0eee0 RCX: 00007fe289f9da0a
RDX: 0000200000037f40 RSI: 0000200000037f80 RDI: 00007fe28ae0eea0
RBP: 0000200000037f40 R08: 00007fe28ae0eee0 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 0000200000037f80

R13: 00007fe28ae0eea0 R14: 0000000000037fc4 R15: 0000200000000300

</TASK>
----------------
Code disassembly (best guess):
0: 86 8e 4d 8b 24 24 xchg %cl,0x24248b4d(%rsi)
6: 49 81 fc 18 68 86 8e cmp $0xffffffff8e866818,%r12
d: 74 20 je 0x2f
f: 49 8b 7c 24 f8 mov -0x8(%r12),%rdi
14: 48 89 de mov %rbx,%rsi
17: e8 3f 5c 9c 09 call 0x99c5c5b
1c: 85 c0 test %eax,%eax
1e: 75 e2 jne 0x2
20: 48 8d 3d 54 70 06 0e lea 0xe067054(%rip),%rdi # 0xe06707b
27: 48 89 de mov %rbx,%rsi
* 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction
2f: 48 89 df mov %rbx,%rdi
32: be 20 00 00 00 mov $0x20,%esi
37: e8 df 5d 9c 09 call 0x99c5e1b
3c: 48 85 c0 test %rax,%rax
3f: 0f .byte 0xf


Tested on:

commit: 09c0f7f1 Add linux-next specific files for 20260323
git tree: linux-next

console output: https://syzkaller.appspot.com/x/log.txt?x=16b46ada580000

kernel config: https://syzkaller.appspot.com/x/.config?x=c0c30527ccbcb0f2
dashboard link: https://syzkaller.appspot.com/bug?extid=9013411dc43f3582823a
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

patch: https://syzkaller.appspot.com/x/patch.diff?x=146f906a580000

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-...@vger.kernel.org, syzkall...@googlegroups.com.

***

Subject: [PATCH] gfs2: fix duplicate kmem_cache on repeated mount failure

Author: karti...@gmail.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master

When gfs2_fill_super() fails after the bufdata cache has been
created, the error path destroys the cache via fail_bufdata but
does not set sd_bufdata to NULL. The VFS then calls gfs2_put_super()
as part of mount cleanup, which destroys the cache a second time,
corrupting the slab state.

On the next mount attempt, kmem_cache_create() finds a ghost entry
with the same name and triggers a WARN, causing a kernel panic.

Fix this by setting sd_bufdata to NULL after destroying it in the
error path. kmem_cache_destroy(NULL) is a no-op, so the subsequent
call in gfs2_put_super() becomes safe.

Reported-by: syzbot+901341...@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=9013411dc43f3582823a

Fixes: f9d6fc9557e6 ("gfs2: per-filesystem bufdata cache")

Signed-off-by: Deepanshu Kartikey <Karti...@gmail.com>
---

fs/gfs2/lops.c | 3 +++
fs/gfs2/ops_fstype.c | 1 +
2 files changed, 4 insertions(+)

diff --git a/fs/gfs2/lops.c b/fs/gfs2/lops.c
index 797931eb5845..005584311eff 100644
--- a/fs/gfs2/lops.c
+++ b/fs/gfs2/lops.c
@@ -467,6 +467,9 @@ static void gfs2_jhead_process_page(struct gfs2_jdesc *jd, unsigned long index,

folio = filemap_get_folio(jd->jd_inode->i_mapping, index);

+ if (IS_ERR(folio))

+ return;

+
folio_wait_locked(folio);
if (!folio_test_uptodate(folio))
*done = true;

diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
index b44adb40635d..4cff08fa3b50 100644
--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -1315,6 +1315,7 @@ static int gfs2_fill_super(struct super_block *sb, struct fs_context *fc)
gfs2_sys_fs_del(sdp);
fail_bufdata:
kmem_cache_destroy(sdp->sd_bufdata);
+ sdp->sd_bufdata = NULL;
fail_delete_wq:
destroy_workqueue(sdp->sd_delete_wq);
fail_glock_wq:
--
2.43.0

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING in gfs2_fill_super

loop1: detected capacity change from 0 to 32768
------------[ cut here ]------------
kmem_cache of name 'gfs2-bufdata/syz:syz' already exists

WARNING: mm/slab_common.c:112 at kmem_cache_sanity_check mm/slab_common.c:111 [inline], CPU#0: syz.1.18/6515
WARNING: mm/slab_common.c:112 at __kmem_cache_create_args+0xac/0x440 mm/slab_common.c:352, CPU#0: syz.1.18/6515
Modules linked in:
CPU: 0 UID: 0 PID: 6515 Comm: syz.1.18 Not tainted syzkaller #0 PREEMPT(full)

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:kmem_cache_sanity_check mm/slab_common.c:111 [inline]
RIP: 0010:__kmem_cache_create_args+0xaf/0x440 mm/slab_common.c:352
Code: 86 8e 4d 8b 24 24 49 81 fc 18 68 86 8e 74 20 49 8b 7c 24 f8 48 89 de e8 3f 5c 9c 09 85 c0 75 e2 48 8d 3d 54 70 06 0e 48 89 de <67> 48 0f b9 3a 48 89 df be 20 00 00 00 e8 df 5d 9c 09 48 85 c0 0f

RSP: 0018:ffffc90003407948 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff8880563c5040 RCX: 0000000000000005
RDX: 00000000563c5004 RSI: ffff8880563c5040 RDI: ffffffff9016e0b0

RBP: 0000000000000000 R08: ffffffff901246f7 R09: 1ffffffff20248de

R10: dffffc0000000000 R11: fffffbfff20248df R12: ffff88814a3b6a60
R13: ffff888035dd4000 R14: 0000000000000050 R15: ffffc90003407a60
FS: 00007fdcb83716c0(0000) GS:ffff888125448000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00007fdcb7585900 CR3: 000000005e392000 CR4: 00000000003526f0

Call Trace:
<TASK>
__kmem_cache_create include/linux/slab.h:390 [inline]

gfs2_fill_super+0x13a7/0x21f0 fs/gfs2/ops_fstype.c:1202
get_tree_bdev_flags+0x431/0x4f0 fs/super.c:1694
gfs2_get_tree+0x51/0x1e0 fs/gfs2/ops_fstype.c:1343

vfs_get_tree+0x92/0x2a0 fs/super.c:1754
fc_mount fs/namespace.c:1193 [inline]
do_new_mount_fc fs/namespace.c:3764 [inline]
do_new_mount+0x341/0xd30 fs/namespace.c:3840
do_mount fs/namespace.c:4173 [inline]
__do_sys_mount fs/namespace.c:4372 [inline]
__se_sys_mount+0x31d/0x420 fs/namespace.c:4349
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

RIP: 0033:0x7fdcb759da0a

Code: 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48

RSP: 002b:00007fdcb8370e58 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fdcb8370ee0 RCX: 00007fdcb759da0a
RDX: 0000200000037f40 RSI: 0000200000037f80 RDI: 00007fdcb8370ea0
RBP: 0000200000037f40 R08: 00007fdcb8370ee0 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 0000200000037f80

R13: 00007fdcb8370ea0 R14: 0000000000037fc4 R15: 0000200000000300

</TASK>
----------------
Code disassembly (best guess):
0: 86 8e 4d 8b 24 24 xchg %cl,0x24248b4d(%rsi)
6: 49 81 fc 18 68 86 8e cmp $0xffffffff8e866818,%r12
d: 74 20 je 0x2f
f: 49 8b 7c 24 f8 mov -0x8(%r12),%rdi
14: 48 89 de mov %rbx,%rsi
17: e8 3f 5c 9c 09 call 0x99c5c5b
1c: 85 c0 test %eax,%eax
1e: 75 e2 jne 0x2
20: 48 8d 3d 54 70 06 0e lea 0xe067054(%rip),%rdi # 0xe06707b
27: 48 89 de mov %rbx,%rsi
* 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction
2f: 48 89 df mov %rbx,%rdi
32: be 20 00 00 00 mov $0x20,%esi
37: e8 df 5d 9c 09 call 0x99c5e1b
3c: 48 85 c0 test %rax,%rax
3f: 0f .byte 0xf


Tested on:

commit: 09c0f7f1 Add linux-next specific files for 20260323
git tree: linux-next

console output: https://syzkaller.appspot.com/x/log.txt?x=10f39e16580000

kernel config: https://syzkaller.appspot.com/x/.config?x=c0c30527ccbcb0f2
dashboard link: https://syzkaller.appspot.com/bug?extid=9013411dc43f3582823a
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

patch: https://syzkaller.appspot.com/x/patch.diff?x=132fc1d6580000