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BUG: KCSAN: data-race in atime_needs_update / touch_atime

write to 0xffff88811bb303d8 of 4 bytes by task 1971 on cpu 1:
 inode_set_atime_to_ts include/linux/fs.h:1684 [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:2652 [inline]
 shmem_file_read_iter+0x477/0x540 mm/shmem.c:3443
 lo_rw_aio+0x6ea/0x7a0 include/linux/fs.h:-1
 do_req_filebacked drivers/block/loop.c:-1 [inline]
 loop_handle_cmd drivers/block/loop.c:1889 [inline]
 loop_process_work+0x52d/0xa60 drivers/block/loop.c:1924
 loop_workfn+0x31/0x40 drivers/block/loop.c:1948
 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+0xdd/0x150 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff88811bb303d8 of 4 bytes by task 41 on cpu 0:
 atime_needs_update+0x25f/0x3e0 fs/inode.c:-1
 touch_atime+0x4a/0x340 fs/inode.c:2132
 file_accessed include/linux/fs.h:2652 [inline]
 shmem_file_read_iter+0x477/0x540 mm/shmem.c:3443
 lo_rw_aio+0x6ea/0x7a0 include/linux/fs.h:-1
 do_req_filebacked drivers/block/loop.c:-1 [inline]
 loop_handle_cmd drivers/block/loop.c:1889 [inline]
 loop_process_work+0x52d/0xa60 drivers/block/loop.c:1924
 loop_rootcg_workfn+0x22/0x30 drivers/block/loop.c:1955
 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+0xdd/0x150 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x2b4e0ac6 -> 0x2beb19ad

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 41 Comm: kworker/u8:2 Not tainted 6.16.0-rc2-syzkaller-00278-g3f75bfff44be #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: loop0 loop_rootcg_workfn
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