[syzbot] [gfs2?] KASAN: slab-use-after-free Write in gfs2_qd_dealloc (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 01c6df60d5d4 Add linux-next specific files for 20250411
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=13deaa3f980000
kernel config: https://syzkaller.appspot.com/x/.config?x=db03cefa26ecf825
dashboard link: https://syzkaller.appspot.com/bug?extid=42a37bf8045847d8f9d2
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/928246b3f3d5/disk-01c6df60.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/79a68c4e1134/vmlinux-01c6df60.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9caf8c293819/bzImage-01c6df60.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+42a37b...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
BUG: KASAN: slab-use-after-free in atomic_dec_and_test include/linux/atomic/atomic-instrumented.h:1383 [inline]
BUG: KASAN: slab-use-after-free in gfs2_qd_dealloc+0x83/0xf0 fs/gfs2/quota.c:112
Write of size 4 at addr ffff888033e98a80 by task kworker/u8:3/53

CPU: 1 UID: 0 PID: 53 Comm: kworker/u8:3 Not tainted 6.15.0-rc1-next-20250411-syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: bat_events batadv_tt_purge
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:408 [inline]
print_report+0x16e/0x5b0 mm/kasan/report.c:521
kasan_report+0x143/0x180 mm/kasan/report.c:634
check_region_inline mm/kasan/generic.c:-1 [inline]
kasan_check_range+0x28f/0x2a0 mm/kasan/generic.c:189
instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
atomic_dec_and_test include/linux/atomic/atomic-instrumented.h:1383 [inline]
gfs2_qd_dealloc+0x83/0xf0 fs/gfs2/quota.c:112
rcu_do_batch kernel/rcu/tree.c:2546 [inline]
rcu_core+0xaac/0x17a0 kernel/rcu/tree.c:2802
handle_softirqs+0x2d6/0x9b0 kernel/softirq.c:579
do_softirq+0x11f/0x1e0 kernel/softirq.c:480
</IRQ>
<TASK>
__local_bh_enable_ip+0x1be/0x200 kernel/softirq.c:407
spin_unlock_bh include/linux/spinlock.h:396 [inline]
batadv_tt_local_purge+0x2a0/0x340 net/batman-adv/translation-table.c:1315
batadv_tt_purge+0x35/0xa40 net/batman-adv/translation-table.c:3509
process_one_work kernel/workqueue.c:3238 [inline]
process_scheduled_works+0xac3/0x18e0 kernel/workqueue.c:3319
worker_thread+0x870/0xd50 kernel/workqueue.c:3400
kthread+0x7b7/0x940 kernel/kthread.c:464
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>

Allocated by task 6071:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
__kasan_kmalloc+0x9d/0xb0 mm/kasan/common.c:394
kasan_kmalloc include/linux/kasan.h:260 [inline]
__kmalloc_cache_noprof+0x236/0x370 mm/slub.c:4362
kmalloc_noprof include/linux/slab.h:905 [inline]
kzalloc_noprof include/linux/slab.h:1039 [inline]
init_sbd fs/gfs2/ops_fstype.c:77 [inline]
gfs2_fill_super+0x13e/0x27b0 fs/gfs2/ops_fstype.c:1140
get_tree_bdev_flags+0x490/0x5c0 fs/super.c:1686
gfs2_get_tree+0x54/0x220 fs/gfs2/ops_fstype.c:1330
vfs_get_tree+0x90/0x2b0 fs/super.c:1809
do_new_mount+0x2cf/0xb70 fs/namespace.c:3879
do_mount fs/namespace.c:4219 [inline]
__do_sys_mount fs/namespace.c:4430 [inline]
__se_sys_mount+0x38c/0x400 fs/namespace.c:4407
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 6071:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:576
poison_slab_object mm/kasan/common.c:247 [inline]
__kasan_slab_free+0x59/0x70 mm/kasan/common.c:264
kasan_slab_free include/linux/kasan.h:233 [inline]
slab_free_hook mm/slub.c:2389 [inline]
slab_free mm/slub.c:4646 [inline]
kfree+0x198/0x430 mm/slub.c:4845
free_sbd fs/gfs2/ops_fstype.c:69 [inline]
gfs2_fill_super+0x14bf/0x27b0 fs/gfs2/ops_fstype.c:1313
get_tree_bdev_flags+0x490/0x5c0 fs/super.c:1686
gfs2_get_tree+0x54/0x220 fs/gfs2/ops_fstype.c:1330
vfs_get_tree+0x90/0x2b0 fs/super.c:1809
do_new_mount+0x2cf/0xb70 fs/namespace.c:3879
do_mount fs/namespace.c:4219 [inline]
__do_sys_mount fs/namespace.c:4430 [inline]
__se_sys_mount+0x38c/0x400 fs/namespace.c:4407
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888033e98000
which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 2688 bytes inside of
freed 8192-byte region [ffff888033e98000, ffff888033e9a000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x33e98
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801b042280 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000020002 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801b042280 dead000000000100 dead000000000122
head: 0000000000000000 0000000000020002 00000000f5000000 0000000000000000
head: 00fff00000000003 ffffea0000cfa601 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5487, tgid 5487 (run-parts), ts 55699630622, free_ts 55641758587
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x1f4/0x240 mm/page_alloc.c:1718
prep_new_page mm/page_alloc.c:1726 [inline]
get_page_from_freelist+0x360a/0x37a0 mm/page_alloc.c:3700
__alloc_frozen_pages_noprof+0x211/0x5b0 mm/page_alloc.c:4982
alloc_pages_mpol+0x339/0x690 mm/mempolicy.c:2301
alloc_slab_page mm/slub.c:2459 [inline]
allocate_slab+0x8f/0x3a0 mm/slub.c:2623
new_slab mm/slub.c:2676 [inline]
___slab_alloc+0xc3b/0x1500 mm/slub.c:3862
__slab_alloc+0x58/0xa0 mm/slub.c:3952
__slab_alloc_node mm/slub.c:4027 [inline]
slab_alloc_node mm/slub.c:4188 [inline]
__kmalloc_cache_noprof+0x26a/0x370 mm/slub.c:4357
kmalloc_noprof include/linux/slab.h:905 [inline]
kzalloc_noprof include/linux/slab.h:1039 [inline]
tomoyo_print_bprm security/tomoyo/audit.c:26 [inline]
tomoyo_init_log+0x121e/0x2150 security/tomoyo/audit.c:264
tomoyo_supervisor+0x3c0/0x18b0 security/tomoyo/common.c:2198
tomoyo_audit_env_log security/tomoyo/environ.c:36 [inline]
tomoyo_env_perm+0x17b/0x220 security/tomoyo/environ.c:63
tomoyo_environ security/tomoyo/domain.c:672 [inline]
tomoyo_find_next_domain+0x1497/0x1dd0 security/tomoyo/domain.c:888
tomoyo_bprm_check_security+0x11a/0x180 security/tomoyo/tomoyo.c:102
security_bprm_check+0x86/0x250 security/security.c:1302
search_binary_handler fs/exec.c:1768 [inline]
exec_binprm fs/exec.c:1810 [inline]
bprm_execve+0x903/0x1430 fs/exec.c:1862
do_execveat_common+0x57c/0x710 fs/exec.c:1968
page last free pid 5485 tgid 5485 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1262 [inline]
__free_frozen_pages+0xde8/0x10a0 mm/page_alloc.c:2725
__slab_free+0x2c6/0x390 mm/slub.c:4557
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x9a/0x140 mm/kasan/quarantine.c:179
kasan_quarantine_reduce+0x14f/0x170 mm/kasan/quarantine.c:286
__kasan_slab_alloc+0x23/0x80 mm/kasan/common.c:329
kasan_slab_alloc include/linux/kasan.h:250 [inline]
slab_post_alloc_hook mm/slub.c:4151 [inline]
slab_alloc_node mm/slub.c:4200 [inline]
__do_kmalloc_node mm/slub.c:4330 [inline]
__kmalloc_noprof+0x238/0x4d0 mm/slub.c:4343
kmalloc_noprof include/linux/slab.h:909 [inline]
tomoyo_add_entry security/tomoyo/common.c:2132 [inline]
tomoyo_supervisor+0xc94/0x18b0 security/tomoyo/common.c:2204
tomoyo_audit_path_log security/tomoyo/file.c:168 [inline]
tomoyo_path_permission+0x243/0x360 security/tomoyo/file.c:587
tomoyo_check_open_permission+0x309/0x4f0 security/tomoyo/file.c:777
security_file_open+0xac/0x250 security/security.c:3114
do_dentry_open+0x320/0x1960 fs/open.c:933
vfs_open+0x3b/0x370 fs/open.c:1086
do_open fs/namei.c:3849 [inline]
path_openat+0x2caf/0x35d0 fs/namei.c:4008
do_filp_open+0x284/0x4e0 fs/namei.c:4035
do_sys_openat2+0x12b/0x1d0 fs/open.c:1429
do_sys_open fs/open.c:1444 [inline]
__do_sys_openat fs/open.c:1460 [inline]
__se_sys_openat fs/open.c:1455 [inline]
__x64_sys_openat+0x249/0x2a0 fs/open.c:1455

Memory state around the buggy address:
ffff888033e98980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888033e98a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888033e98a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888033e98b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888033e98b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 01a412d06bc5 Merge tag 'pull-ufs-fix' of git://git.kernel...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=150e6fd4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=8adfe52da0de2761
dashboard link: https://syzkaller.appspot.com/bug?extid=42a37bf8045847d8f9d2
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=132aff22580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=144380a2580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-01a412d0.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8229e4edb67d/vmlinux-01a412d0.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8e07d86da9da/bzImage-01a412d0.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/5c2db4a05d12/mount_0.gz
fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=110e6fd4580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+42a37b...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
BUG: KASAN: slab-use-after-free in atomic_dec_and_test include/linux/atomic/atomic-instrumented.h:1383 [inline]

BUG: KASAN: slab-use-after-free in gfs2_qd_dealloc+0x81/0xe0 fs/gfs2/quota.c:112
Write of size 4 at addr ffff888036404a80 by task pool_workqueue_/3

CPU: 0 UID: 0 PID: 3 Comm: pool_workqueue_ Not tainted 6.16.0-rc7-syzkaller-00018-g01a412d06bc5 #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
<IRQ>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0xca/0x230 mm/kasan/report.c:480
kasan_report+0x118/0x150 mm/kasan/report.c:593
check_region_inline mm/kasan/generic.c:-1 [inline]
kasan_check_range+0x2b0/0x2c0 mm/kasan/generic.c:189

instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
atomic_dec_and_test include/linux/atomic/atomic-instrumented.h:1383 [inline]

gfs2_qd_dealloc+0x81/0xe0 fs/gfs2/quota.c:112
rcu_do_batch kernel/rcu/tree.c:2576 [inline]
rcu_core+0xca5/0x1710 kernel/rcu/tree.c:2832
handle_softirqs+0x286/0x870 kernel/softirq.c:579
__do_softirq kernel/softirq.c:613 [inline]
invoke_softirq kernel/softirq.c:453 [inline]
__irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:680
irq_exit_rcu+0x9/0x30 kernel/softirq.c:696
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1050
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:lockdep_unregister_key+0x2c5/0x310 kernel/locking/lockdep.c:6619
Code: 65 48 8b 05 3d 20 02 11 48 3b 44 24 10 0f 84 26 fe ff ff e8 fd 17 d1 09 e8 28 19 d1 09 41 f7 c7 00 02 00 00 74 bd fb 40 84 ed <75> bc eb cd 90 0f 0b 90 e9 19 ff ff ff 90 0f 0b 90 e9 2a ff ff ff
RSP: 0018:ffffc90000157c00 EFLAGS: 00000246
RAX: de469ecdd1056e00 RBX: ffff8880408f6538 RCX: de469ecdd1056e00
RDX: ffffffff93643318 RSI: ffffffff8d9ace67 RDI: ffffffff8be29ec0
RBP: ffff8880408f6500 R08: 0000000000000000 R09: ffffffff81ab49a8
R10: dffffc0000000000 R11: fffffbfff1f43f5f R12: 0000000000000000
R13: 0000000000001000 R14: 0000000000000001 R15: 0000000000000202
wq_unregister_lockdep kernel/workqueue.c:4818 [inline]
pwq_release_workfn+0x6d5/0x870 kernel/workqueue.c:5114
kthread_worker_fn+0x504/0xb60 kernel/kthread.c:1010
kthread+0x70e/0x8a0 kernel/kthread.c:464
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>

Allocated by task 5598:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
__kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:394
kasan_kmalloc include/linux/kasan.h:260 [inline]
__kmalloc_cache_noprof+0x230/0x3d0 mm/slub.c:4359

kmalloc_noprof include/linux/slab.h:905 [inline]
kzalloc_noprof include/linux/slab.h:1039 [inline]

init_sbd fs/gfs2/ops_fstype.c:78 [inline]
gfs2_fill_super+0x11c/0x20e0 fs/gfs2/ops_fstype.c:1128
get_tree_bdev_flags+0x40b/0x4d0 fs/super.c:1681
gfs2_get_tree+0x51/0x1e0 fs/gfs2/ops_fstype.c:1335
vfs_get_tree+0x92/0x2b0 fs/super.c:1804
do_new_mount+0x24a/0xa40 fs/namespace.c:3902
do_mount fs/namespace.c:4239 [inline]
__do_sys_mount fs/namespace.c:4450 [inline]
__se_sys_mount+0x317/0x410 fs/namespace.c:4427
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

Freed by task 5598:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576
poison_slab_object mm/kasan/common.c:247 [inline]
__kasan_slab_free+0x62/0x70 mm/kasan/common.c:264
kasan_slab_free include/linux/kasan.h:233 [inline]
slab_free_hook mm/slub.c:2381 [inline]
slab_free mm/slub.c:4643 [inline]
kfree+0x18e/0x440 mm/slub.c:4842
free_sbd fs/gfs2/ops_fstype.c:71 [inline]
gfs2_fill_super+0x153d/0x20e0 fs/gfs2/ops_fstype.c:1319
get_tree_bdev_flags+0x40b/0x4d0 fs/super.c:1681
gfs2_get_tree+0x51/0x1e0 fs/gfs2/ops_fstype.c:1335
vfs_get_tree+0x92/0x2b0 fs/super.c:1804
do_new_mount+0x24a/0xa40 fs/namespace.c:3902
do_mount fs/namespace.c:4239 [inline]
__do_sys_mount fs/namespace.c:4450 [inline]
__se_sys_mount+0x317/0x410 fs/namespace.c:4427
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

The buggy address belongs to the object at ffff888036404000

which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 2688 bytes inside of

freed 8192-byte region [ffff888036404000, ffff888036406000)

The buggy address belongs to the physical page:

page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x36400

head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0

anon flags: 0x4fff00000000040(head|node=1|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 04fff00000000040 ffff88801a442280 0000000000000000 0000000000000001
raw: 0000000000000000 0000000080020002 00000000f5000000 0000000000000000
head: 04fff00000000040 ffff88801a442280 0000000000000000 0000000000000001
head: 0000000000000000 0000000080020002 00000000f5000000 0000000000000000
head: 04fff00000000003 ffffea0000d90001 00000000ffffffff 00000000ffffffff

head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated

page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5553, tgid 5553 (syz.0.17), ts 108777604926, free_ts 108757444960
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1704
prep_new_page mm/page_alloc.c:1712 [inline]
get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3669
__alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4959
alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2419
alloc_slab_page mm/slub.c:2451 [inline]
allocate_slab+0x8a/0x3b0 mm/slub.c:2619
new_slab mm/slub.c:2673 [inline]
___slab_alloc+0xbfc/0x1480 mm/slub.c:3859
__slab_alloc mm/slub.c:3949 [inline]
__slab_alloc_node mm/slub.c:4024 [inline]
slab_alloc_node mm/slub.c:4185 [inline]
__kmalloc_cache_noprof+0x296/0x3d0 mm/slub.c:4354

kmalloc_noprof include/linux/slab.h:905 [inline]
kzalloc_noprof include/linux/slab.h:1039 [inline]

init_sbd fs/gfs2/ops_fstype.c:78 [inline]
gfs2_fill_super+0x11c/0x20e0 fs/gfs2/ops_fstype.c:1128
get_tree_bdev_flags+0x40b/0x4d0 fs/super.c:1681
gfs2_get_tree+0x51/0x1e0 fs/gfs2/ops_fstype.c:1335
vfs_get_tree+0x92/0x2b0 fs/super.c:1804
do_new_mount+0x24a/0xa40 fs/namespace.c:3902
do_mount fs/namespace.c:4239 [inline]
__do_sys_mount fs/namespace.c:4450 [inline]
__se_sys_mount+0x317/0x410 fs/namespace.c:4427
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
page last free pid 5562 tgid 5562 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1248 [inline]
__free_frozen_pages+0xc71/0xe70 mm/page_alloc.c:2706
discard_slab mm/slub.c:2717 [inline]
__put_partials+0x161/0x1c0 mm/slub.c:3186
put_cpu_partial+0x17c/0x250 mm/slub.c:3261
__slab_free+0x2f7/0x400 mm/slub.c:4513
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x97/0x140 mm/kasan/quarantine.c:179
kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
__kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:329
kasan_slab_alloc include/linux/kasan.h:250 [inline]
slab_post_alloc_hook mm/slub.c:4148 [inline]
slab_alloc_node mm/slub.c:4197 [inline]
kmem_cache_alloc_noprof+0x1c1/0x3c0 mm/slub.c:4204
vm_area_alloc+0x24/0x140 mm/vma_init.c:31
__mmap_new_vma mm/vma.c:2452 [inline]
__mmap_region mm/vma.c:2622 [inline]
mmap_region+0xcc7/0x1f30 mm/vma.c:2692
do_mmap+0xc45/0x10d0 mm/mmap.c:561
vm_mmap_pgoff+0x31b/0x4c0 mm/util.c:579
ksys_mmap_pgoff+0x51f/0x760 mm/mmap.c:607
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

Memory state around the buggy address:

ffff888036404980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888036404a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888036404a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888036404b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888036404b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess):
0: 65 48 8b 05 3d 20 02 mov %gs:0x1102203d(%rip),%rax # 0x11022045
7: 11
8: 48 3b 44 24 10 cmp 0x10(%rsp),%rax
d: 0f 84 26 fe ff ff je 0xfffffe39
13: e8 fd 17 d1 09 call 0x9d11815
18: e8 28 19 d1 09 call 0x9d11945
1d: 41 f7 c7 00 02 00 00 test $0x200,%r15d
24: 74 bd je 0xffffffe3
26: fb sti
27: 40 84 ed test %bpl,%bpl
* 2a: 75 bc jne 0xffffffe8 <-- trapping instruction
2c: eb cd jmp 0xfffffffb
2e: 90 nop
2f: 0f 0b ud2
31: 90 nop
32: e9 19 ff ff ff jmp 0xffffff50
37: 90 nop
38: 0f 0b ud2
3a: 90 nop
3b: e9 2a ff ff ff jmp 0xffffff6a


---
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.

[Andrew Price]

#syz test

--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -66,6 +66,8 @@ void free_sbd(struct gfs2_sbd *sdp)
{
struct super_block *sb = sdp->sd_vfs;

+ /* Wait for rcu_call(gfs2_qd_dealloc) */
+ rcu_barrier();
free_percpu(sdp->sd_lkstats);
sb->s_fs_info = NULL;
kfree(sdp);

[syzbot]

Hello,

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

------------[ cut here ]------------
gfs2_meta_aops does not implement migrate_folio
WARNING: CPU: 0 PID: 30 at mm/migrate.c:944 fallback_migrate_folio mm/migrate.c:942 [inline]
WARNING: CPU: 0 PID: 30 at mm/migrate.c:944 move_to_new_folio+0x696/0x7a0 mm/migrate.c:996
Modules linked in:
CPU: 0 UID: 0 PID: 30 Comm: kcompactd1 Not tainted 6.16.0-rc7-syzkaller-g25fae0b93d1d-dirty #0 PREEMPT(full)

Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014

RIP: 0010:fallback_migrate_folio mm/migrate.c:942 [inline]
RIP: 0010:move_to_new_folio+0x696/0x7a0 mm/migrate.c:996
Code: 0d 01 90 42 80 7c 3d 00 00 74 0a 48 8b 7c 24 20 e8 2f 53 fe ff 48 8b 44 24 20 48 8b 30 48 c7 c7 20 bb 97 8b e8 bb b7 5e ff 90 <0f> 0b 90 90 49 bf 00 00 00 00 00 fc ff df e9 7e fd ff ff e8 62 d2
RSP: 0018:ffffc90000516fd0 EFLAGS: 00010246
RAX: daec11f2299abc00 RBX: ffffea000100abc0 RCX: ffff888030f88000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002
RBP: 1ffff1100887b921 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff1bfaa6c R12: ffffea00014e3d40
R13: ffff8880443dc7e8 R14: ffffea000100abc8 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff88808d218000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fce2e39a000 CR3: 0000000057fda000 CR4: 0000000000352ef0
Call Trace:
<TASK>
migrate_folio_move mm/migrate.c:1301 [inline]
migrate_folios_move mm/migrate.c:1653 [inline]
migrate_pages_batch+0x1c34/0x2830 mm/migrate.c:1900
migrate_pages_sync mm/migrate.c:1930 [inline]
migrate_pages+0x1bcc/0x2930 mm/migrate.c:2039
compact_zone+0x23f4/0x4ad0 mm/compaction.c:2683
compact_node+0x1d2/0x280 mm/compaction.c:2952
kcompactd+0xbc8/0x1290 mm/compaction.c:3250

kthread+0x70e/0x8a0 kernel/kthread.c:464
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>

Tested on:

commit: 25fae0b9 Merge tag 'drm-fixes-2025-07-24' of https://g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12eac0a2580000

kernel config: https://syzkaller.appspot.com/x/.config?x=8adfe52da0de2761
dashboard link: https://syzkaller.appspot.com/bug?extid=42a37bf8045847d8f9d2
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7

patch: https://syzkaller.appspot.com/x/patch.diff?x=118ee0a2580000

[Andrew Price]

On 24/07/2025 12:57, syzbot wrote:
> Hello,
>
> syzbot has tested the proposed patch but the reproducer is still triggering an issue:
> WARNING in move_to_new_folio
>
> ------------[ cut here ]------------
> gfs2_meta_aops does not implement migrate_folio

This is a separate issue, fixed in for-next.

Andy