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BUG: KCSAN: data-race in filemap_fault / generic_write_end

write to 0xffff88811f1ba1a8 of 8 bytes by task 7408 on cpu 0:
 i_size_write include/linux/fs.h:907 [inline]
 generic_write_end+0x96/0x180 fs/buffer.c:2187
 ext4_da_write_end+0x448/0x510 fs/ext4/inode.c:3042
 generic_perform_write+0x261/0x400 mm/filemap.c:3776
 ext4_buffered_write_iter+0x19d/0x290 fs/ext4/file.c:268
 ext4_file_write_iter+0x227/0xda0
 call_write_iter include/linux/fs.h:2074 [inline]
 do_iter_readv_writev+0x2de/0x380 fs/read_write.c:725
 do_iter_write+0x192/0x5c0 fs/read_write.c:851
 vfs_iter_write+0x4c/0x70 fs/read_write.c:892
 iter_file_splice_write+0x43a/0x790 fs/splice.c:689
 do_splice_from fs/splice.c:767 [inline]
 direct_splice_actor+0x80/0xa0 fs/splice.c:936
 splice_direct_to_actor+0x345/0x650 fs/splice.c:891
 do_splice_direct+0x106/0x190 fs/splice.c:979
 do_sendfile+0x675/0xc40 fs/read_write.c:1245
 __do_sys_sendfile64 fs/read_write.c:1310 [inline]
 __se_sys_sendfile64 fs/read_write.c:1296 [inline]
 __x64_sys_sendfile64+0x102/0x140 fs/read_write.c:1296
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88811f1ba1a8 of 8 bytes by task 7409 on cpu 1:
 i_size_read include/linux/fs.h:885 [inline]
 filemap_fault+0x722/0x8b0 mm/filemap.c:3184
 __do_fault mm/memory.c:3868 [inline]
 do_cow_fault+0x208/0x4d0 mm/memory.c:4213
 do_fault mm/memory.c:4314 [inline]
 handle_pte_fault mm/memory.c:4570 [inline]
 __handle_mm_fault mm/memory.c:4705 [inline]
 handle_mm_fault+0x9b1/0x1590 mm/memory.c:4803
 faultin_page mm/gup.c:969 [inline]
 __get_user_pages+0x342/0xc10 mm/gup.c:1190
 populate_vma_page_range mm/gup.c:1522 [inline]
 __mm_populate+0x24d/0x370 mm/gup.c:1631
 mm_populate include/linux/mm.h:2702 [inline]
 vm_mmap_pgoff+0x160/0x1f0 mm/util.c:524
 ksys_mmap_pgoff+0x265/0x320 mm/mmap.c:1630
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000000003f3000 -> 0x00000000003f3288

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 7409 Comm: syz-executor.4 Not tainted 5.17.0-rc3-syzkaller-00116-gf1baf68e1383-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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