==================================================================
BUG: KCSAN: data-race in atime_needs_update / touch_atime

write to 0xffff88811a173258 of 4 bytes by task 37 on cpu 1:
 inode_set_atime_to_ts include/linux/fs.h:1804 [inline]
 inode_update_timestamps fs/inode.c:2076 [inline]
 generic_update_time fs/inode.c:2098 [inline]
 inode_update_time fs/inode.c:2118 [inline]
 touch_atime+0x1e8/0x340 fs/inode.c:2190
 file_accessed include/linux/fs.h:2672 [inline]
 shmem_file_read_iter+0x477/0x540 mm/shmem.c:3444
 lo_rw_aio+0x6a0/0x760 drivers/block/loop.c:-1
 do_req_filebacked drivers/block/loop.c:-1 [inline]
 loop_handle_cmd drivers/block/loop.c:1919 [inline]
 loop_process_work+0x52d/0xa60 drivers/block/loop.c:1954
 loop_workfn+0x31/0x40 drivers/block/loop.c:1978
 process_one_work kernel/workqueue.c:3263 [inline]
 process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3346
 worker_thread+0x582/0x770 kernel/workqueue.c:3427
 kthread+0x489/0x510 kernel/kthread.c:463
 ret_from_fork+0x122/0x1b0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff88811a173258 of 4 bytes by task 1823 on cpu 0:
 atime_needs_update+0x25f/0x3e0 fs/inode.c:-1
 touch_atime+0x4a/0x340 fs/inode.c:2173
 file_accessed include/linux/fs.h:2672 [inline]
 shmem_file_read_iter+0x477/0x540 mm/shmem.c:3444
 lo_rw_aio+0x6a0/0x760 drivers/block/loop.c:-1
 do_req_filebacked drivers/block/loop.c:-1 [inline]
 loop_handle_cmd drivers/block/loop.c:1919 [inline]
 loop_process_work+0x52d/0xa60 drivers/block/loop.c:1954
 loop_rootcg_workfn+0x22/0x30 drivers/block/loop.c:1985
 process_one_work kernel/workqueue.c:3263 [inline]
 process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3346
 worker_thread+0x582/0x770 kernel/workqueue.c:3427
 kthread+0x489/0x510 kernel/kthread.c:463
 ret_from_fork+0x122/0x1b0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x3ac1f8ee -> 0x3b5a8f6f

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 1823 Comm: kworker/u8:9 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Workqueue: loop0 loop_rootcg_workfn
==================================================================