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BUG: KCSAN: data-race in atime_needs_update / touch_atime

read to 0xffff8881158700f0 of 4 bytes by task 5387 on cpu 0:
 atime_needs_update+0x261/0x3e0
 touch_atime+0x4a/0x350 fs/inode.c:2037
 file_accessed include/linux/fs.h:2480 [inline]
 shmem_file_read_iter+0x4b3/0x550 mm/shmem.c:3058
 do_iter_readv_writev+0x3b0/0x470
 vfs_iter_read+0x16e/0x3b0 fs/read_write.c:830
 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+0x7a6/0x1230 drivers/block/loop.c:1945
 loop_workfn+0x31/0x40 drivers/block/loop.c:1969
 process_one_work kernel/workqueue.c:3231 [inline]
 process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3312
 worker_thread+0x526/0x700 kernel/workqueue.c:3390
 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 0xffff8881158700f0 of 4 bytes by task 3286 on cpu 1:
 inode_set_atime_to_ts include/linux/fs.h:1569 [inline]
 inode_update_timestamps fs/inode.c:1940 [inline]
 generic_update_time fs/inode.c:1962 [inline]
 inode_update_time fs/inode.c:1982 [inline]
 touch_atime+0x1f3/0x350 fs/inode.c:2054
 file_accessed include/linux/fs.h:2480 [inline]
 shmem_file_read_iter+0x4b3/0x550 mm/shmem.c:3058
 do_iter_readv_writev+0x3b0/0x470
 vfs_iter_read+0x16e/0x3b0 fs/read_write.c:830
 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+0x7a6/0x1230 drivers/block/loop.c:1945
 loop_rootcg_workfn+0x22/0x30 drivers/block/loop.c:1976
 process_one_work kernel/workqueue.c:3231 [inline]
 process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3312
 worker_thread+0x526/0x700 kernel/workqueue.c:3390
 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: 0x12718fa8 -> 0x130a2628

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3286 Comm: kworker/u8:6 Not tainted 6.11.0-rc1-syzkaller-00293-gdefaf1a2113a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024
Workqueue: loop2 loop_rootcg_workfn
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