[moderation] [exfat?] KCSAN: data-race in mark_buffer_dirty_inode / mark_buffer_dirty_inode (10)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8f2c057754b2 Merge tag 'arm64-fixes' of git://git.kernel.o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16eeabf3180000
kernel config: https://syzkaller.appspot.com/x/.config?x=6a1ac6d65bf295c5
dashboard link: https://syzkaller.appspot.com/bug?extid=babfc115ed72bb9699bd
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/a33fe5ef376d/disk-8f2c0577.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/950c71b27f5b/vmlinux-8f2c0577.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f648e03a3000/bzImage-8f2c0577.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+babfc1...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in mark_buffer_dirty_inode / mark_buffer_dirty_inode

write to 0xffff888121551670 of 8 bytes by task 20350 on cpu 0:
mark_buffer_dirty_inode+0x18d/0x1c0 fs/buffer.c:684
fat_mirror_bhs+0x247/0x340 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:2105
__block_write_begin fs/buffer.c:2154 [inline]
block_write_begin+0x7b/0x170 fs/buffer.c:2213
cont_write_begin+0x486/0x6b0 fs/buffer.c:2567
fat_write_begin+0x61/0xf0 fs/fat/inode.c:230
cont_expand_zero fs/buffer.c:2494 [inline]
cont_write_begin+0x186/0x6b0 fs/buffer.c:2557
fat_write_begin+0x61/0xf0 fs/fat/inode.c:230
generic_perform_write+0x1d5/0x410 mm/filemap.c:3974
__generic_file_write_iter+0xa1/0x120 mm/filemap.c:4069
generic_file_write_iter+0x7d/0x1d0 mm/filemap.c:4095
do_iter_readv_writev+0x339/0x3e0
vfs_writev+0x2e9/0x860 fs/read_write.c:971
do_pwritev fs/read_write.c:1072 [inline]
__do_sys_pwritev2 fs/read_write.c:1131 [inline]
__se_sys_pwritev2+0x10c/0x1d0 fs/read_write.c:1122
__x64_sys_pwritev2+0x78/0x90 fs/read_write.c:1122
x64_sys_call+0xf52/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:329
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888121551670 of 8 bytes by task 20432 on cpu 1:
mark_buffer_dirty_inode+0x96/0x1c0 fs/buffer.c:680
fat_mirror_bhs+0x247/0x340 fs/fat/fatent.c:398
fat_alloc_clusters+0x994/0xa80 fs/fat/fatent.c:543
fat_add_cluster+0x47/0xe0 fs/fat/inode.c:108
fat_fallocate+0x129/0x1d0 fs/fat/file.c:292
vfs_fallocate+0x380/0x3e0 fs/open.c:330
do_vfs_ioctl+0x1481/0x1560 fs/ioctl.c:883
__do_sys_ioctl fs/ioctl.c:902 [inline]
__se_sys_ioctl+0x81/0x150 fs/ioctl.c:890
__x64_sys_ioctl+0x43/0x50 fs/ioctl.c:890
x64_sys_call+0x155d/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:17
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000000 -> 0xffff8881052d8e30

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 20432 Comm: syz-executor.2 Tainted: G W 6.9.0-rc3-syzkaller-00344-g8f2c057754b2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
==================================================================


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