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BUG: KCSAN: data-race in file_update_time / generic_update_time

write to 0xffff888129e2a6a8 of 16 bytes by task 21356 on cpu 1:
 generic_update_time+0x109/0x270 fs/inode.c:1660
 update_time fs/inode.c:1683 [inline]
 file_update_time+0x237/0x300 fs/inode.c:1898
 filemap_page_mkwrite+0xae/0x1d0 mm/filemap.c:2699
 do_page_mkwrite+0x100/0x210 mm/memory.c:2208
 do_shared_fault mm/memory.c:3554 [inline]
 do_fault mm/memory.c:3622 [inline]
 handle_pte_fault mm/memory.c:3849 [inline]
 __handle_mm_fault+0x2089/0x2c70 mm/memory.c:3973
 handle_mm_fault+0x21b/0x530 mm/memory.c:4010
 faultin_page mm/gup.c:640 [inline]
 __get_user_pages+0x485/0x1160 mm/gup.c:845
 __get_user_pages_locked mm/gup.c:1066 [inline]
 get_user_pages_unlocked+0x19b/0x3f0 mm/gup.c:1688
 __gup_longterm_unlocked mm/gup.c:2375 [inline]
 get_user_pages_fast+0x307/0x340 mm/gup.c:2430
 iov_iter_get_pages+0x1d3/0x7c0 lib/iov_iter.c:1287
 __bio_iov_iter_get_pages block/bio.c:885 [inline]
 bio_iov_iter_get_pages+0x100/0x5a0 block/bio.c:941
 __blkdev_direct_IO fs/block_dev.c:386 [inline]
 blkdev_direct_IO+0x5ec/0xac0 fs/block_dev.c:476
 generic_file_read_iter+0x1b0/0x1440 mm/filemap.c:2303
 blkdev_read_iter+0xb2/0xe0 fs/block_dev.c:2010
 call_read_iter include/linux/fs.h:1889 [inline]
 do_iter_readv_writev+0x54b/0x5b0 fs/read_write.c:691
 do_iter_read+0x1fc/0x3d0 fs/read_write.c:933
 vfs_readv+0x9c/0xf0 fs/read_write.c:997
 do_preadv+0x131/0x1d0 fs/read_write.c:1089
 __do_sys_preadv fs/read_write.c:1139 [inline]
 __se_sys_preadv fs/read_write.c:1134 [inline]
 __x64_sys_preadv+0x61/0x80 fs/read_write.c:1134
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888129e2a6b0 of 8 bytes by task 21353 on cpu 0:
 timespec64_equal include/linux/time64.h:52 [inline]
 file_update_time+0xee/0x300 fs/inode.c:1882
 filemap_page_mkwrite+0xae/0x1d0 mm/filemap.c:2699
 do_page_mkwrite+0x100/0x210 mm/memory.c:2208
 do_shared_fault mm/memory.c:3554 [inline]
 do_fault mm/memory.c:3622 [inline]
 handle_pte_fault mm/memory.c:3849 [inline]
 __handle_mm_fault+0x2089/0x2c70 mm/memory.c:3973
 handle_mm_fault+0x21b/0x530 mm/memory.c:4010
 faultin_page mm/gup.c:640 [inline]
 __get_user_pages+0x485/0x1160 mm/gup.c:845
 __get_user_pages_locked mm/gup.c:1066 [inline]
 get_user_pages_unlocked+0x19b/0x3f0 mm/gup.c:1688
 __gup_longterm_unlocked mm/gup.c:2375 [inline]
 get_user_pages_fast+0x307/0x340 mm/gup.c:2430
 iov_iter_get_pages+0x1d3/0x7c0 lib/iov_iter.c:1287
 __bio_iov_iter_get_pages block/bio.c:885 [inline]
 bio_iov_iter_get_pages+0x100/0x5a0 block/bio.c:941
 __blkdev_direct_IO fs/block_dev.c:386 [inline]
 blkdev_direct_IO+0x5ec/0xac0 fs/block_dev.c:476
 generic_file_read_iter+0x1b0/0x1440 mm/filemap.c:2303
 blkdev_read_iter+0xb2/0xe0 fs/block_dev.c:2010
 call_read_iter include/linux/fs.h:1889 [inline]
 do_iter_readv_writev+0x54b/0x5b0 fs/read_write.c:691
 do_iter_read+0x1fc/0x3d0 fs/read_write.c:933
 vfs_readv+0x9c/0xf0 fs/read_write.c:997
 do_preadv+0x131/0x1d0 fs/read_write.c:1089
 __do_sys_preadv fs/read_write.c:1139 [inline]
 __se_sys_preadv fs/read_write.c:1134 [inline]
 __x64_sys_preadv+0x61/0x80 fs/read_write.c:1134
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 21353 Comm: syz-executor.5 Not tainted 5.4.0-rc7+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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