[moderation] [exfat?] KCSAN: data-race in mark_buffer_dirty_inode / mark_buffer_dirty_inode (11)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 061d1af7b030 Merge tag 'for-linus-2024060801' of git://git..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=109ef0ca980000
kernel config: https://syzkaller.appspot.com/x/.config?x=8c00b51a1d411353
dashboard link: https://syzkaller.appspot.com/bug?extid=ff1b76e1395639202c83
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [hiro...@mail.parknet.co.jp linki...@kernel.org linux-...@vger.kernel.org linux-...@vger.kernel.org sj155...@samsung.com]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/357e8c9ee3cc/disk-061d1af7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6fc84887955b/vmlinux-061d1af7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/86d046aa533a/bzImage-061d1af7.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ff1b76...@syzkaller.appspotmail.com

loop1: detected capacity change from 0 to 8192
==================================================================
BUG: KCSAN: data-race in mark_buffer_dirty_inode / mark_buffer_dirty_inode

write to 0xffff888107ad55a0 of 8 bytes by task 14093 on cpu 1:
mark_buffer_dirty_inode+0x18d/0x1c0 fs/buffer.c:684
fat_mirror_bhs+0x241/0x330 fs/fat/fatent.c:398
fat_alloc_clusters+0x994/0xa80 fs/fat/fatent.c:543
fat_add_cluster fs/fat/inode.c:108 [inline]
__fat_get_block fs/fat/inode.c:155 [inline]
fat_get_block+0x25c/0x5e0 fs/fat/inode.c:190
__block_write_begin_int+0x417/0xfa0 fs/buffer.c:2128
__block_write_begin fs/buffer.c:2177 [inline]
block_write_begin+0x7b/0x170 fs/buffer.c:2236
cont_write_begin+0x486/0x6b0 fs/buffer.c:2590
fat_write_begin+0x61/0xf0 fs/fat/inode.c:230
generic_perform_write+0x1d5/0x410 mm/filemap.c:4015
__generic_file_write_iter+0xa1/0x120 mm/filemap.c:4110
generic_file_write_iter+0x7d/0x1d0 mm/filemap.c:4136
new_sync_write fs/read_write.c:497 [inline]
vfs_write+0x78f/0x900 fs/read_write.c:590
ksys_write+0xeb/0x1b0 fs/read_write.c:643
__do_sys_write fs/read_write.c:655 [inline]
__se_sys_write fs/read_write.c:652 [inline]
__x64_sys_write+0x42/0x50 fs/read_write.c:652
x64_sys_call+0x27ef/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:2
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888107ad55a0 of 8 bytes by task 14083 on cpu 0:
mark_buffer_dirty_inode+0x96/0x1c0 fs/buffer.c:680
fat_mirror_bhs+0x241/0x330 fs/fat/fatent.c:398
fat_alloc_clusters+0x994/0xa80 fs/fat/fatent.c:543
fat_add_cluster fs/fat/inode.c:108 [inline]
__fat_get_block fs/fat/inode.c:155 [inline]
fat_get_block+0x25c/0x5e0 fs/fat/inode.c:190
__block_write_begin_int+0x417/0xfa0 fs/buffer.c:2128
__block_write_begin fs/buffer.c:2177 [inline]
block_write_begin+0x7b/0x170 fs/buffer.c:2236
cont_write_begin+0x486/0x6b0 fs/buffer.c:2590
fat_write_begin+0x61/0xf0 fs/fat/inode.c:230
cont_expand_zero fs/buffer.c:2517 [inline]
cont_write_begin+0x186/0x6b0 fs/buffer.c:2580
fat_write_begin+0x61/0xf0 fs/fat/inode.c:230
generic_perform_write+0x1d5/0x410 mm/filemap.c:4015
__generic_file_write_iter+0xa1/0x120 mm/filemap.c:4110
generic_file_write_iter+0x7d/0x1d0 mm/filemap.c:4136
new_sync_write fs/read_write.c:497 [inline]
vfs_write+0x78f/0x900 fs/read_write.c:590
ksys_write+0xeb/0x1b0 fs/read_write.c:643
__do_sys_write fs/read_write.c:655 [inline]
__se_sys_write fs/read_write.c:652 [inline]
__x64_sys_write+0x42/0x50 fs/read_write.c:652
x64_sys_call+0x27ef/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:2
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000000 -> 0xffff8881078ce368

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 14083 Comm: syz-executor.1 Not tainted 6.10.0-rc2-syzkaller-00361-g061d1af7b030 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
==================================================================


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