[moderation] [ext4?] KCSAN: data-race in __mark_inode_dirty / inode_cgwb_move_to_attached (8)

Hello,

syzbot found the following issue on:

HEAD commit: a29967be967e Merge tag 'v6.14-rc6-smb3-client-fixes' of gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16e40278580000
kernel config: https://syzkaller.appspot.com/x/.config?x=7c156d7c99647d9c
dashboard link: https://syzkaller.appspot.com/bug?extid=838e56e1d279904a0763
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [[email protected] [email protected] [email protected] [email protected]]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7a94fc152ed1/disk-a29967be.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/113dcb9e90d0/vmlinux-a29967be.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9103b403cdff/bzImage-a29967be.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email protected]

==================================================================
BUG: KCSAN: data-race in __mark_inode_dirty / inode_cgwb_move_to_attached

write to 0xffff8881065d8f38 of 4 bytes by task 3700 on cpu 1:
inode_cgwb_move_to_attached+0x9a/0x300 fs/fs-writeback.c:309
writeback_sb_inodes+0x6a6/0xa30 fs/fs-writeback.c:2005
wb_writeback+0x262/0x640 fs/fs-writeback.c:2156
wb_do_writeback fs/fs-writeback.c:2303 [inline]
wb_workfn+0x1a8/0x940 fs/fs-writeback.c:2343
process_one_work kernel/workqueue.c:3238 [inline]
process_scheduled_works+0x4db/0xa20 kernel/workqueue.c:3319
worker_thread+0x51d/0x6f0 kernel/workqueue.c:3400
kthread+0x4ae/0x520 kernel/kthread.c:464
ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

read to 0xffff8881065d8f38 of 4 bytes by task 25299 on cpu 0:
__mark_inode_dirty+0x58/0x7e0 fs/fs-writeback.c:2497
generic_update_time fs/inode.c:2112 [inline]
inode_update_time fs/inode.c:2125 [inline]
__file_update_time fs/inode.c:2353 [inline]
file_update_time+0x285/0x2b0 fs/inode.c:2383
ext4_page_mkwrite+0x19e/0xb70 fs/ext4/inode.c:6160
do_page_mkwrite mm/memory.c:3257 [inline]
wp_page_shared mm/memory.c:3658 [inline]
do_wp_page+0xca1/0x2340 mm/memory.c:3808
handle_pte_fault mm/memory.c:5923 [inline]
__handle_mm_fault mm/memory.c:6050 [inline]
handle_mm_fault+0xc63/0x2ac0 mm/memory.c:6219
do_user_addr_fault arch/x86/mm/fault.c:1337 [inline]
handle_page_fault arch/x86/mm/fault.c:1480 [inline]
exc_page_fault+0x3b9/0x650 arch/x86/mm/fault.c:1538
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

value changed: 0x00010002 -> 0x00000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 25299 Comm: syz.4.6605 Not tainted 6.14.0-rc6-syzkaller-00202-ga29967be967e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
==================================================================


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