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BUG: KCSAN: data-race in ext4_es_lookup_extent / ext4_es_lookup_extent

write to 0xffff888218760428 of 8 bytes by task 7333 on cpu 0:
 ext4_es_lookup_extent+0x3d3/0x510 fs/ext4/extents_status.c:950
 ext4_da_map_blocks fs/ext4/inode.c:1871 [inline]
 ext4_da_get_block_prep+0x159/0xa60 fs/ext4/inode.c:1992
 __block_write_begin_int+0x2ea/0xf10 fs/buffer.c:1968
 __block_write_begin fs/buffer.c:2018 [inline]
 block_page_mkwrite+0x19f/0x230 fs/buffer.c:2480
 ext4_page_mkwrite+0x5af/0xce0 fs/ext4/inode.c:6238
 do_page_mkwrite+0x8f/0x1a0 mm/memory.c:2199
 do_shared_fault mm/memory.c:3545 [inline]
 do_fault mm/memory.c:3613 [inline]
 handle_pte_fault mm/memory.c:3840 [inline]
 __handle_mm_fault+0x20ea/0x2d00 mm/memory.c:3964
 handle_mm_fault+0x21b/0x520 mm/memory.c:4001
 do_user_addr_fault arch/x86/mm/fault.c:1441 [inline]
 __do_page_fault+0x3fb/0x9e0 arch/x86/mm/fault.c:1506
 do_page_fault+0x54/0x233 arch/x86/mm/fault.c:1530
 page_fault+0x34/0x40 arch/x86/entry/entry_64.S:1202

read to 0xffff888218760428 of 8 bytes by task 7332 on cpu 1:
 ext4_es_lookup_extent+0x3ba/0x510 fs/ext4/extents_status.c:950
 ext4_map_blocks+0xc2/0xf70 fs/ext4/inode.c:530
 ext4_getblk+0x30b/0x380 fs/ext4/inode.c:974
 ext4_bread+0x4a/0x190 fs/ext4/inode.c:1024
 __ext4_read_dirblock+0x3e/0x700 fs/ext4/namei.c:112
 ext4_add_entry+0x46b/0x8e0 fs/ext4/namei.c:2214
 ext4_add_nondir+0x31/0xa0 fs/ext4/namei.c:2553
 ext4_symlink+0x7c0/0x970 fs/ext4/namei.c:3331
 vfs_symlink fs/namei.c:4127 [inline]
 vfs_symlink+0x218/0x310 fs/namei.c:4113
 do_symlinkat+0x1a5/0x1e0 fs/namei.c:4154
 __do_sys_symlink fs/namei.c:4173 [inline]
 __se_sys_symlink fs/namei.c:4171 [inline]
 __x64_sys_symlink+0x3f/0x50 fs/namei.c:4171
 do_syscall_64+0xcf/0x2f0 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 7332 Comm: syz-executor.3 Not tainted 5.3.0+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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