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BUG: KCSAN: data-race in file_update_time / inode_update_timestamps

read to 0xffff8881189b00f4 of 4 bytes by task 28038 on cpu 1:
 inode_get_mtime_nsec include/linux/fs.h:1634 [inline]
 inode_get_mtime include/linux/fs.h:1640 [inline]
 inode_needs_update_time fs/inode.c:2332 [inline]
 file_update_time+0x8b/0x2b0 fs/inode.c:2379
 fault_dirty_shared_page+0xde/0x340 mm/memory.c:3218
 do_shared_fault mm/memory.c:5414 [inline]
 do_fault mm/memory.c:5460 [inline]
 do_pte_missing mm/memory.c:3979 [inline]
 handle_pte_fault mm/memory.c:5801 [inline]
 __handle_mm_fault mm/memory.c:5944 [inline]
 handle_mm_fault+0x1389/0x2ac0 mm/memory.c:6112
 do_user_addr_fault arch/x86/mm/fault.c:1338 [inline]
 handle_page_fault arch/x86/mm/fault.c:1481 [inline]
 exc_page_fault+0x3b9/0x650 arch/x86/mm/fault.c:1539
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

write to 0xffff8881189b00f4 of 4 bytes by task 28039 on cpu 0:
 inode_set_mtime_to_ts include/linux/fs.h:1648 [inline]
 inode_update_timestamps+0x139/0x250 fs/inode.c:2070
 generic_update_time fs/inode.c:2105 [inline]
 inode_update_time fs/inode.c:2125 [inline]
 __file_update_time fs/inode.c:2353 [inline]
 file_modified_flags+0x287/0x320 fs/inode.c:2424
 file_modified+0x17/0x20 fs/inode.c:2440
 shmem_fallocate+0x80a/0x860 mm/shmem.c:3630
 vfs_fallocate+0x368/0x3b0 fs/open.c:327
 ksys_fallocate fs/open.c:351 [inline]
 __do_sys_fallocate fs/open.c:356 [inline]
 __se_sys_fallocate fs/open.c:354 [inline]
 __x64_sys_fallocate+0x78/0xc0 fs/open.c:354
 x64_sys_call+0x43c/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:286
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x12a050ae -> 0x132f1f44

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 28039 Comm: syz.8.8791 Not tainted 6.13.0-rc5-syzkaller-00006-g56e6a3499e14 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
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