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BUG: KCSAN: data-race in atime_needs_update / touch_atime

read to 0xffff8881044460e8 of 4 bytes by task 3479 on cpu 1:
 atime_needs_update+0x261/0x3e0
 touch_atime+0x4a/0x350 fs/inode.c:2109
 file_accessed include/linux/fs.h:2528 [inline]
 shmem_file_read_iter+0x4aa/0x550 mm/shmem.c:3201
 do_iter_readv_writev+0x394/0x450
 vfs_iter_read+0x171/0x3b0 fs/read_write.c:923
 lo_read_simple drivers/block/loop.c:283 [inline]
 do_req_filebacked drivers/block/loop.c:516 [inline]
 loop_handle_cmd drivers/block/loop.c:1910 [inline]
 loop_process_work+0x79a/0x1220 drivers/block/loop.c:1945
 loop_rootcg_workfn+0x22/0x30 drivers/block/loop.c:1976
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3310
 worker_thread+0x51d/0x6f0 kernel/workqueue.c:3391
 kthread+0x1d1/0x210 kernel/kthread.c:389
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

write to 0xffff8881044460e8 of 4 bytes by task 3582 on cpu 0:
 inode_set_atime_to_ts include/linux/fs.h:1610 [inline]
 inode_update_timestamps fs/inode.c:2012 [inline]
 generic_update_time fs/inode.c:2034 [inline]
 inode_update_time fs/inode.c:2054 [inline]
 touch_atime+0x1f3/0x350 fs/inode.c:2126
 file_accessed include/linux/fs.h:2528 [inline]
 shmem_file_read_iter+0x4aa/0x550 mm/shmem.c:3201
 do_iter_readv_writev+0x394/0x450
 vfs_iter_read+0x171/0x3b0 fs/read_write.c:923
 lo_read_simple drivers/block/loop.c:283 [inline]
 do_req_filebacked drivers/block/loop.c:516 [inline]
 loop_handle_cmd drivers/block/loop.c:1910 [inline]
 loop_process_work+0x79a/0x1220 drivers/block/loop.c:1945
 loop_workfn+0x31/0x40 drivers/block/loop.c:1969
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3310
 worker_thread+0x51d/0x6f0 kernel/workqueue.c:3391
 kthread+0x1d1/0x210 kernel/kthread.c:389
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

value changed: 0x299b8dad -> 0x2b65512d

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3582 Comm: kworker/u8:64 Not tainted 6.11.0-syzkaller-10669-g11a299a7933e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Workqueue: loop0 loop_workfn
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