[moderation] [ext4?] KCSAN: data-race in get_tree_bdev_flags / super_cache_count (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4c06e63b9203 Merge tag 'for-6.16-rc4-tag' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15e0d48c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=eea96b85b0259840
dashboard link: https://syzkaller.appspot.com/bug?extid=1404cc1058004f1f96bc
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
CC: [adilger...@dilger.ca linux...@vger.kernel.org linux-...@vger.kernel.org ty...@mit.edu]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a29ad39ab029/disk-4c06e63b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ccd884b8dad2/vmlinux-4c06e63b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/96b61fc8e436/bzImage-4c06e63b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1404cc...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in get_tree_bdev_flags / super_cache_count

read-write to 0xffff88812b9f5050 of 8 bytes by task 4292 on cpu 1:
get_tree_bdev_flags+0x2e4/0x300 fs/super.c:1686
get_tree_bdev+0x1f/0x30 fs/super.c:1704
ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5756
vfs_get_tree+0x54/0x1d0 fs/super.c:1804
do_new_mount+0x207/0x680 fs/namespace.c:3902
path_mount+0x4a4/0xb20 fs/namespace.c:4226
do_mount fs/namespace.c:4239 [inline]
__do_sys_mount fs/namespace.c:4450 [inline]
__se_sys_mount+0x28f/0x2e0 fs/namespace.c:4427
__x64_sys_mount+0x67/0x80 fs/namespace.c:4427
x64_sys_call+0xd36/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:166
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88812b9f5050 of 8 bytes by task 4296 on cpu 0:
super_cache_count+0x30/0x160 fs/super.c:257
do_shrink_slab+0x60/0x680 mm/shrinker.c:384
shrink_slab_memcg mm/shrinker.c:550 [inline]
shrink_slab+0x448/0x760 mm/shrinker.c:628
shrink_node_memcgs mm/vmscan.c:6035 [inline]
shrink_node+0x6c3/0x2120 mm/vmscan.c:6074
shrink_zones mm/vmscan.c:6318 [inline]
do_try_to_free_pages+0x3f6/0xcd0 mm/vmscan.c:6380
try_to_free_mem_cgroup_pages+0x1ab/0x410 mm/vmscan.c:6708
try_charge_memcg+0x358/0x9e0 mm/memcontrol.c:2362
obj_cgroup_charge_pages+0xa6/0x150 mm/memcontrol.c:2803
__memcg_kmem_charge_page+0x9f/0x170 mm/memcontrol.c:2847
__alloc_frozen_pages_noprof+0x188/0x360 mm/page_alloc.c:4976
alloc_pages_mpol+0xb3/0x250 mm/mempolicy.c:2419
alloc_frozen_pages_noprof mm/mempolicy.c:2490 [inline]
alloc_pages_noprof+0x90/0x130 mm/mempolicy.c:2510
vm_area_alloc_pages mm/vmalloc.c:3634 [inline]
__vmalloc_area_node mm/vmalloc.c:3712 [inline]
__vmalloc_node_range_noprof+0x6f2/0xe00 mm/vmalloc.c:3885
__kvmalloc_node_noprof+0x30f/0x4e0 mm/slub.c:5037
ip_set_alloc+0x1f/0x30 net/netfilter/ipset/ip_set_core.c:261
hash_netiface_create+0x282/0x740 net/netfilter/ipset/ip_set_hash_gen.h:1568
ip_set_create+0x3c9/0x960 net/netfilter/ipset/ip_set_core.c:1109
nfnetlink_rcv_msg+0x4c6/0x590 net/netfilter/nfnetlink.c:303
netlink_rcv_skb+0x120/0x220 net/netlink/af_netlink.c:2534
nfnetlink_rcv+0x16b/0x1690 net/netfilter/nfnetlink.c:668
netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
netlink_unicast+0x5a1/0x670 net/netlink/af_netlink.c:1339
netlink_sendmsg+0x58b/0x6b0 net/netlink/af_netlink.c:1883
sock_sendmsg_nosec net/socket.c:712 [inline]
__sock_sendmsg+0x145/0x180 net/socket.c:727
____sys_sendmsg+0x31e/0x4e0 net/socket.c:2566
___sys_sendmsg+0x17b/0x1d0 net/socket.c:2620
__sys_sendmsg net/socket.c:2652 [inline]
__do_sys_sendmsg net/socket.c:2657 [inline]
__se_sys_sendmsg net/socket.c:2655 [inline]
__x64_sys_sendmsg+0xd4/0x160 net/socket.c:2655
x64_sys_call+0x2999/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:47
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000010810050 -> 0x0000000070810050

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 4296 Comm: syz.5.232 Not tainted 6.16.0-rc4-syzkaller-00123-g4c06e63b9203 #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.