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BUG: KCSAN: data-race in __mark_inode_dirty / other_inode_match

write to 0xffff88812122a300 of 8 bytes by task 7147 on cpu 0:
 __mark_inode_dirty+0x1c1/0x940 fs/fs-writeback.c:2289
 generic_update_time+0x184/0x270 fs/inode.c:1682
 update_time+0x7d/0x90 fs/inode.c:1695
 touch_atime+0x13f/0x150 fs/inode.c:1766
 pick_link fs/namei.c:1624 [inline]
 step_into+0xab5/0x1090 fs/namei.c:1702
 walk_component+0xde/0x390 fs/namei.c:1852
 lookup_last fs/namei.c:2295 [inline]
 path_lookupat.isra.0+0x119/0x350 fs/namei.c:2319
 filename_lookup+0x145/0x2c0 fs/namei.c:2352
 user_path_at_empty+0x47/0x60 fs/namei.c:2632
 user_path_at include/linux/namei.h:59 [inline]
 ksys_umount+0xee/0xaf0 fs/namespace.c:1683
 __do_sys_umount fs/namespace.c:1709 [inline]
 __se_sys_umount fs/namespace.c:1707 [inline]
 __x64_sys_umount+0x35/0x50 fs/namespace.c:1707
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88812122a300 of 8 bytes by task 23712 on cpu 1:
 other_inode_match+0x6a/0x570 fs/ext4/inode.c:4875
 find_inode_nowait+0x12f/0x160 fs/inode.c:1446
 ext4_update_other_inodes_time fs/ext4/inode.c:4923 [inline]
 ext4_do_update_inode fs/ext4/inode.c:5049 [inline]
 ext4_mark_iloc_dirty+0x12ad/0x1580 fs/ext4/inode.c:5603
 ext4_mark_inode_dirty+0xe6/0x420 fs/ext4/inode.c:5796
 ext4_ext_truncate+0x52/0x120 fs/ext4/extents.c:4340
 ext4_truncate+0x87d/0x9e0 fs/ext4/inode.c:4214
 ext4_setattr+0xe43/0x1290 fs/ext4/inode.c:5388
 notify_change+0x82b/0xad0 fs/attr.c:336
 do_truncate+0xf9/0x180 fs/open.c:64
 handle_truncate fs/namei.c:2887 [inline]
 do_open fs/namei.c:3233 [inline]
 path_openat+0x1e51/0x23d0 fs/namei.c:3346
 do_filp_open+0x11e/0x1b0 fs/namei.c:3373
 do_sys_openat2+0x52e/0x680 fs/open.c:1148
 do_sys_open+0xa2/0x110 fs/open.c:1164
 ksys_open include/linux/syscalls.h:1386 [inline]
 __do_sys_creat fs/open.c:1232 [inline]
 __se_sys_creat fs/open.c:1230 [inline]
 __x64_sys_creat+0x42/0x60 fs/open.c:1230
 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: 23712 Comm: syz-executor.2 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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