[moderation] [fs?] KCSAN: data-race in path_openat / shrink_dentry_list (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: b6151c4e60e5 Merge tag 'erofs-for-6.19-rc5-fixes' of git:/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=116bf83a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c160236e1ef1e401
dashboard link: https://syzkaller.appspot.com/bug?extid=250d9e8d06f111eec4f7
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
CC: [bra...@kernel.org ja...@suse.cz linux-...@vger.kernel.org linux-...@vger.kernel.org vi...@zeniv.linux.org.uk]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/39e707a231a5/disk-b6151c4e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/63580ec462ab/vmlinux-b6151c4e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6503ebc38c29/bzImage-b6151c4e.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+250d9e...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in path_openat / shrink_dentry_list

read-write to 0xffff88811b029180 of 4 bytes by task 2679 on cpu 0:
d_shrink_del fs/dcache.c:516 [inline]
shrink_dentry_list+0x22d/0x3c0 fs/dcache.c:1156
prune_dcache_sb+0x80/0xb0 fs/dcache.c:1246
super_cache_scan+0x2a3/0x360 fs/super.c:222
do_shrink_slab+0x2ec/0x680 mm/shrinker.c:437
shrink_slab_memcg mm/shrinker.c:550 [inline]
shrink_slab+0x4f5/0x840 mm/shrinker.c:628
shrink_node_memcgs mm/vmscan.c:6022 [inline]
shrink_node+0x6a9/0x2010 mm/vmscan.c:6061
shrink_zones mm/vmscan.c:6300 [inline]
do_try_to_free_pages+0x3f6/0xcd0 mm/vmscan.c:6362
try_to_free_mem_cgroup_pages+0x1ab/0x410 mm/vmscan.c:6690
try_charge_memcg+0x383/0xa10 mm/memcontrol.c:2388
obj_cgroup_charge_pages+0xa6/0x150 mm/memcontrol.c:2823
__memcg_kmem_charge_page+0x9f/0x170 mm/memcontrol.c:2867
__alloc_frozen_pages_noprof+0x18f/0x360 mm/page_alloc.c:5227
alloc_pages_mpol+0xb3/0x260 mm/mempolicy.c:2486
alloc_frozen_pages_noprof mm/mempolicy.c:2557 [inline]
alloc_pages_noprof+0x90/0x130 mm/mempolicy.c:2577
vm_area_alloc_pages mm/vmalloc.c:3718 [inline]
__vmalloc_area_node mm/vmalloc.c:3863 [inline]
__vmalloc_node_range_noprof+0xa7b/0x1310 mm/vmalloc.c:4051
__bpf_map_area_alloc kernel/bpf/syscall.c:401 [inline]
bpf_map_area_alloc+0xfa/0x150 kernel/bpf/syscall.c:408
array_map_alloc+0x1d3/0x3c0 kernel/bpf/arraymap.c:142
array_of_map_alloc+0x3b/0x80 kernel/bpf/arraymap.c:1365
map_create+0x862/0xda0 kernel/bpf/syscall.c:1514
__sys_bpf+0x54e/0x7c0 kernel/bpf/syscall.c:6146
__do_sys_bpf kernel/bpf/syscall.c:6274 [inline]
__se_sys_bpf kernel/bpf/syscall.c:6272 [inline]
__x64_sys_bpf+0x41/0x50 kernel/bpf/syscall.c:6272
x64_sys_call+0x28e1/0x3000 arch/x86/include/generated/asm/syscalls_64.h:322
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811b029180 of 4 bytes by task 1956 on cpu 1:
__d_entry_type include/linux/dcache.h:416 [inline]
d_is_reg include/linux/dcache.h:451 [inline]
do_open fs/namei.c:4629 [inline]
path_openat+0x1cbe/0x23b0 fs/namei.c:4796
do_filp_open+0x109/0x230 fs/namei.c:4823
do_sys_openat2+0xa6/0x150 fs/open.c:1430
do_sys_open fs/open.c:1436 [inline]
__do_sys_openat fs/open.c:1452 [inline]
__se_sys_openat fs/open.c:1447 [inline]
__x64_sys_openat+0xf2/0x120 fs/open.c:1447
x64_sys_call+0x2b07/0x3000 arch/x86/include/generated/asm/syscalls_64.h:258
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xca/0x2b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00240404 -> 0x00200004

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 1956 Comm: syz-executor Tainted: G W syzkaller #0 PREEMPT(voluntary)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================


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