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BUG: KCSAN: data-race in ext4_mark_iloc_dirty / ext4_writepages

write to 0xffff888120f2c910 of 8 bytes by task 24375 on cpu 0:
 mpage_map_and_submit_extent fs/ext4/inode.c:2476 [inline]
 ext4_writepages+0x12fd/0x1e10 fs/ext4/inode.c:2770
 do_writepages+0x6b/0x170 mm/page-writeback.c:2344
 __filemap_fdatawrite_range+0x1bb/0x220 mm/filemap.c:421
 __filemap_fdatawrite mm/filemap.c:429 [inline]
 filemap_flush+0x2a/0x40 mm/filemap.c:456
 ext4_alloc_da_blocks+0x72/0x170 fs/ext4/inode.c:3144
 ext4_release_file+0x107/0x200 fs/ext4/file.c:142
 __fput+0x1e9/0x500 fs/file_table.c:280
 ____fput+0x1b/0x30 fs/file_table.c:313
 task_work_run+0xba/0x120 kernel/task_work.c:123
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x2ae/0x2c0 arch/x86/entry/common.c:165
 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:279 [inline]
 do_syscall_64+0x38b/0x3b0 arch/x86/entry/common.c:305
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888120f2c910 of 8 bytes by task 24376 on cpu 1:
 ext4_isize fs/ext4/ext4.h:2999 [inline]
 ext4_do_update_inode fs/ext4/inode.c:4999 [inline]
 ext4_mark_iloc_dirty+0x8c1/0x1580 fs/ext4/inode.c:5603
 ext4_mark_inode_dirty+0xe6/0x420 fs/ext4/inode.c:5796
 ext4_dirty_inode+0xad/0xd0 fs/ext4/inode.c:5827
 __mark_inode_dirty+0x5b7/0x940 fs/fs-writeback.c:2258
 mark_inode_dirty include/linux/fs.h:2189 [inline]
 generic_write_end+0x24c/0x290 fs/buffer.c:2193
 ext4_da_write_end+0x162/0x690 fs/ext4/inode.c:3090
 generic_perform_write+0x1d7/0x320 mm/filemap.c:3313
 ext4_buffered_write_iter+0x14e/0x280 fs/ext4/file.c:270
 ext4_file_write_iter+0xf4/0xd30 fs/ext4/file.c:642
 call_write_iter include/linux/fs.h:1907 [inline]
 do_iter_readv_writev+0x4a7/0x5d0 fs/read_write.c:694
 do_iter_write fs/read_write.c:999 [inline]
 do_iter_write+0x137/0x3a0 fs/read_write.c:980
 vfs_iter_write+0x56/0x80 fs/read_write.c:1040
 iter_file_splice_write+0x530/0x830 fs/splice.c:760
 do_splice_from fs/splice.c:863 [inline]
 direct_splice_actor+0x97/0xb0 fs/splice.c:1037
 splice_direct_to_actor+0x22f/0x540 fs/splice.c:992
 do_splice_direct+0x152/0x1d0 fs/splice.c:1080
 do_sendfile+0x380/0x800 fs/read_write.c:1521
 __do_sys_sendfile64 fs/read_write.c:1576 [inline]
 __se_sys_sendfile64 fs/read_write.c:1568 [inline]
 __x64_sys_sendfile64+0xb8/0x140 fs/read_write.c:1568
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 24376 Comm: syz-executor.1 Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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