[moderation] [ext4?] KCSAN: data-race in delete_from_page_cache_batch / file_write_and_wait_range (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: dc855b77719f Merge tag 'irq-drivers-2026-02-09' of git://g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=100cce5a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=ed0e3ea32b528eea
dashboard link: https://syzkaller.appspot.com/bug?extid=0cf50a4bcd3a77890c26
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
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/aebc7a8edb2f/disk-dc855b77.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ca4d10e847b9/vmlinux-dc855b77.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2e8a563693dd/bzImage-dc855b77.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0cf50a...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in delete_from_page_cache_batch / file_write_and_wait_range

read-write to 0xffff88811a91d478 of 8 bytes by task 6727 on cpu 0:
page_cache_delete_batch mm/filemap.c:317 [inline]
delete_from_page_cache_batch+0x553/0x740 mm/filemap.c:336
truncate_inode_pages_range+0x1fe/0x7e0 mm/truncate.c:405
truncate_inode_pages+0x24/0x30 mm/truncate.c:485
ext4_truncate_failed_write fs/ext4/truncate.h:21 [inline]
ext4_write_end+0x540/0x730 fs/ext4/inode.c:1491
generic_perform_write+0x311/0x490 mm/filemap.c:4335
ext4_buffered_write_iter+0x1ee/0x3c0 fs/ext4/file.c:300
ext4_file_write_iter+0x380/0xf70 fs/ext4/file.c:-1
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x5a6/0x9f0 fs/read_write.c:688
ksys_write+0xdc/0x1a0 fs/read_write.c:740
__do_sys_write fs/read_write.c:751 [inline]
__se_sys_write fs/read_write.c:748 [inline]
__x64_sys_write+0x40/0x50 fs/read_write.c:748
x64_sys_call+0x27e1/0x3020 arch/x86/include/generated/asm/syscalls_64.h:2
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811a91d478 of 8 bytes by task 6745 on cpu 1:
mapping_needs_writeback mm/filemap.c:634 [inline]
file_write_and_wait_range+0x65/0x2f0 mm/filemap.c:785
generic_buffers_fsync_noflush+0x45/0x130 fs/buffer.c:610
ext4_fsync_nojournal fs/ext4/fsync.c:88 [inline]
ext4_sync_file+0x1aa/0x680 fs/ext4/fsync.c:147
vfs_fsync_range fs/sync.c:188 [inline]
vfs_fsync fs/sync.c:202 [inline]
do_fsync fs/sync.c:213 [inline]
__do_sys_fdatasync fs/sync.c:223 [inline]
__se_sys_fdatasync fs/sync.c:221 [inline]
__x64_sys_fdatasync+0x83/0xe0 fs/sync.c:221
x64_sys_call+0x2d1f/0x3020 arch/x86/include/generated/asm/syscalls_64.h:76
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000016 -> 0x0000000000000015

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 6745 Comm: syz.8.751 Tainted: G W syzkaller #0 PREEMPT(full)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
==================================================================


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