syzbot

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BUG: KCSAN: data-race in touch_atime / touch_atime

write to 0xffff88811c05c398 of 4 bytes by task 55 on cpu 0:
 inode_set_atime_to_ts include/linux/fs.h:1626 [inline]
 inode_update_atime fs/inode.c:2098 [inline]
 inode_update_time fs/inode.c:2156 [inline]
 generic_update_time fs/inode.c:2189 [inline]
 touch_atime+0x1d7/0x330 fs/inode.c:2267
 file_accessed include/linux/fs.h:2264 [inline]
 shmem_file_read_iter+0x3f4/0x4b0 mm/shmem.c:3458
 lo_rw_aio+0x67d/0x730 drivers/block/loop.c:-1
 do_req_filebacked drivers/block/loop.c:-1 [inline]
 loop_handle_cmd drivers/block/loop.c:1925 [inline]
 loop_process_work+0x56c/0xac0 drivers/block/loop.c:1960
 loop_workfn+0x31/0x40 drivers/block/loop.c:1984
 process_one_work kernel/workqueue.c:3302 [inline]
 process_scheduled_works+0x4f0/0x9c0 kernel/workqueue.c:3385
 worker_thread+0x58a/0x780 kernel/workqueue.c:3466
 kthread+0x22a/0x280 kernel/kthread.c:436
 ret_from_fork+0x146/0x330 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

write to 0xffff88811c05c398 of 4 bytes by task 12 on cpu 1:
 inode_set_atime_to_ts include/linux/fs.h:1626 [inline]
 inode_update_atime fs/inode.c:2098 [inline]
 inode_update_time fs/inode.c:2156 [inline]
 generic_update_time fs/inode.c:2189 [inline]
 touch_atime+0x1d7/0x330 fs/inode.c:2267
 file_accessed include/linux/fs.h:2264 [inline]
 shmem_file_read_iter+0x3f4/0x4b0 mm/shmem.c:3458
 lo_rw_aio+0x67d/0x730 drivers/block/loop.c:-1
 do_req_filebacked drivers/block/loop.c:-1 [inline]
 loop_handle_cmd drivers/block/loop.c:1925 [inline]
 loop_process_work+0x56c/0xac0 drivers/block/loop.c:1960
 loop_rootcg_workfn+0x22/0x30 drivers/block/loop.c:1991
 process_one_work kernel/workqueue.c:3302 [inline]
 process_scheduled_works+0x4f0/0x9c0 kernel/workqueue.c:3385
 worker_thread+0x58a/0x780 kernel/workqueue.c:3466
 kthread+0x22a/0x280 kernel/kthread.c:436
 ret_from_fork+0x146/0x330 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x3470af10 -> 0x35094590

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 12 Comm: kworker/u8:0 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Workqueue: loop7 loop_rootcg_workfn
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netdevsim netdevsim8 netdevsim0: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim8 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim8 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim8 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0