syzbot

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BUG: KCSAN: data-race in touch_atime / touch_atime

write to 0xffff88811bcb0c90 of 4 bytes by task 3444 on cpu 0:
 inode_set_atime_to_ts include/linux/fs.h:1687 [inline]
 inode_update_timestamps fs/inode.c:2034 [inline]
 generic_update_time fs/inode.c:2056 [inline]
 inode_update_time fs/inode.c:2076 [inline]
 touch_atime+0x1e8/0x340 fs/inode.c:2148
 file_accessed include/linux/fs.h:2663 [inline]
 shmem_file_read_iter+0x477/0x540 mm/shmem.c:3508
 lo_rw_aio+0x69d/0x760 drivers/block/loop.c:-1
 do_req_filebacked drivers/block/loop.c:-1 [inline]
 loop_handle_cmd drivers/block/loop.c:1910 [inline]
 loop_process_work+0x52d/0xa60 drivers/block/loop.c:1945
 loop_rootcg_workfn+0x22/0x30 drivers/block/loop.c:1976
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3319
 worker_thread+0x582/0x770 kernel/workqueue.c:3400
 kthread+0x486/0x510 kernel/kthread.c:463
 ret_from_fork+0xda/0x150 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff88811bcb0c90 of 4 bytes by task 37 on cpu 1:
 inode_get_atime_nsec include/linux/fs.h:1672 [inline]
 inode_get_atime include/linux/fs.h:1678 [inline]
 inode_update_timestamps fs/inode.c:2031 [inline]
 generic_update_time fs/inode.c:2056 [inline]
 inode_update_time fs/inode.c:2076 [inline]
 touch_atime+0x194/0x340 fs/inode.c:2148
 file_accessed include/linux/fs.h:2663 [inline]
 shmem_file_read_iter+0x477/0x540 mm/shmem.c:3508
 lo_rw_aio+0x69d/0x760 drivers/block/loop.c:-1
 do_req_filebacked drivers/block/loop.c:-1 [inline]
 loop_handle_cmd drivers/block/loop.c:1910 [inline]
 loop_process_work+0x52d/0xa60 drivers/block/loop.c:1945
 loop_workfn+0x31/0x40 drivers/block/loop.c:1969
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3319
 worker_thread+0x582/0x770 kernel/workqueue.c:3400
 kthread+0x486/0x510 kernel/kthread.c:463
 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: 0x29ab3215 -> 0x2a777aaa

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 37 Comm: kworker/u8:2 Tainted: G        W           6.16.0-syzkaller-12245-g2988dfed8a5d #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: loop3 loop_workfn
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