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BUG: KCSAN: data-race in __delete_from_page_cache / drop_pagecache_sb

read-write to 0xffff88810748a8b8 of 8 bytes by task 26448 on cpu 1:
 page_cache_delete mm/filemap.c:154 [inline]
 __delete_from_page_cache+0x26e/0x340 mm/filemap.c:239
 __remove_mapping+0x3e4/0x480 mm/vmscan.c:928
 remove_mapping+0x22/0x60 mm/vmscan.c:950
 invalidate_complete_page mm/truncate.c:215 [inline]
 invalidate_inode_page+0x15d/0x190 mm/truncate.c:264
 __invalidate_mapping_pages+0x40d/0x760 mm/truncate.c:592
 invalidate_mapping_pages+0x23/0x30 mm/truncate.c:635
 drop_pagecache_sb+0x14d/0x1b0 fs/drop_caches.c:38
 iterate_supers+0x106/0x190 fs/super.c:694
 drop_caches_sysctl_handler+0x94/0x1a0 fs/drop_caches.c:61
 proc_sys_call_handler+0x329/0x4e0 fs/proc/proc_sysctl.c:591
 proc_sys_write+0x1e/0x30 fs/proc/proc_sysctl.c:617
 call_write_iter include/linux/fs.h:1901 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0x6d4/0x7c0 fs/read_write.c:605
 ksys_write+0xce/0x180 fs/read_write.c:658
 __do_sys_write fs/read_write.c:670 [inline]
 __se_sys_write fs/read_write.c:667 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:667
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88810748a8b8 of 8 bytes by task 26442 on cpu 0:
 drop_pagecache_sb+0xbf/0x1b0 fs/drop_caches.c:30
 iterate_supers+0x106/0x190 fs/super.c:694
 drop_caches_sysctl_handler+0x94/0x1a0 fs/drop_caches.c:61
 proc_sys_call_handler+0x329/0x4e0 fs/proc/proc_sysctl.c:591
 proc_sys_write+0x1e/0x30 fs/proc/proc_sysctl.c:617
 call_write_iter include/linux/fs.h:1901 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0x6d4/0x7c0 fs/read_write.c:605
 ksys_write+0xce/0x180 fs/read_write.c:658
 __do_sys_write fs/read_write.c:670 [inline]
 __se_sys_write fs/read_write.c:667 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:667
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 26442 Comm: syz-executor.5 Not tainted 5.11.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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