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

read to 0xffff888104b1b828 of 4 bytes by task 56 on cpu 1:
 atime_needs_update+0x25f/0x3e0 fs/inode.c:-1
 touch_atime+0x4a/0x340 fs/inode.c:2132
 file_accessed include/linux/fs.h:2648 [inline]
 shmem_file_read_iter+0x477/0x540 mm/shmem.c:3443
 lo_rw_aio+0x6ed/0x7a0 include/linux/fs.h:-1
 do_req_filebacked drivers/block/loop.c:-1 [inline]
 loop_handle_cmd drivers/block/loop.c:1890 [inline]
 loop_process_work+0x52d/0xa60 drivers/block/loop.c:1925
 loop_workfn+0x31/0x40 drivers/block/loop.c:1949
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3321
 worker_thread+0x582/0x770 kernel/workqueue.c:3402
 kthread+0x486/0x510 kernel/kthread.c:464
 ret_from_fork+0xda/0x150 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

write to 0xffff888104b1b828 of 4 bytes by task 6626 on cpu 0:
 inode_set_atime_to_ts include/linux/fs.h:1682 [inline]
 inode_update_timestamps fs/inode.c:2035 [inline]
 generic_update_time fs/inode.c:2057 [inline]
 inode_update_time fs/inode.c:2077 [inline]
 touch_atime+0x1e8/0x340 fs/inode.c:2149
 file_accessed include/linux/fs.h:2648 [inline]
 shmem_file_read_iter+0x477/0x540 mm/shmem.c:3443
 lo_rw_aio+0x6ed/0x7a0 include/linux/fs.h:-1
 do_req_filebacked drivers/block/loop.c:-1 [inline]
 loop_handle_cmd drivers/block/loop.c:1890 [inline]
 loop_process_work+0x52d/0xa60 drivers/block/loop.c:1925
 loop_rootcg_workfn+0x22/0x30 drivers/block/loop.c:1956
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3321
 worker_thread+0x582/0x770 kernel/workqueue.c:3402
 kthread+0x486/0x510 kernel/kthread.c:464
 ret_from_fork+0xda/0x150 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x252e5a86 -> 0x265f8786

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 6626 Comm: kworker/u8:10 Not tainted 6.16.0-rc1-syzkaller-00203-g4774cfe3543a #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: loop4 loop_rootcg_workfn
==================================================================