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BUG: KCSAN: data-race in ext4_setattr / filemap_fault

write to 0xffff888134669718 of 8 bytes by task 10706 on cpu 0:
 i_size_write include/linux/fs.h:907 [inline]
 ext4_setattr+0xd6b/0xf00 fs/ext4/inode.c:5435
 notify_change+0x924/0xbf0 fs/attr.c:410
 do_truncate fs/open.c:65 [inline]
 do_sys_ftruncate+0x323/0x430 fs/open.c:193
 __do_sys_ftruncate fs/open.c:204 [inline]
 __se_sys_ftruncate fs/open.c:202 [inline]
 __x64_sys_ftruncate+0x2f/0x40 fs/open.c:202
 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 0xffff888134669718 of 8 bytes by task 10704 on cpu 1:
 i_size_read include/linux/fs.h:885 [inline]
 filemap_fault+0x87/0x8b0 mm/filemap.c:3093
 __do_fault mm/memory.c:3868 [inline]
 do_read_fault mm/memory.c:4183 [inline]
 do_fault mm/memory.c:4312 [inline]
 handle_pte_fault mm/memory.c:4570 [inline]
 __handle_mm_fault mm/memory.c:4705 [inline]
 handle_mm_fault+0xba6/0x1590 mm/memory.c:4803
 do_user_addr_fault+0x617/0xb90 arch/x86/mm/fault.c:1397
 handle_page_fault arch/x86/mm/fault.c:1484 [inline]
 exc_page_fault+0x91/0x290 arch/x86/mm/fault.c:1540
 asm_exc_page_fault+0x1e/0x30
 __get_user_4+0x1c/0x30
 perf_copy_attr+0x34/0x650 kernel/events/core.c:11800
 __do_sys_perf_event_open kernel/events/core.c:12129 [inline]
 __se_sys_perf_event_open+0xca/0x27c0 kernel/events/core.c:12102
 __x64_sys_perf_event_open+0x63/0x70 kernel/events/core.c:12102
 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: 0x0000000000000000 -> 0x0000000000008979

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 10704 Comm: syz-executor.5 Tainted: G        W         5.17.0-rc2-syzkaller-00054-g27bb0b18c208 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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