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BUG: KCSAN: data-race in delete_from_page_cache_batch / page_mapping

write to 0xffffea0002a0e458 of 8 bytes by task 26844 on cpu 0:
 page_cache_delete_batch mm/filemap.c:326 [inline]
 delete_from_page_cache_batch+0x674/0x790 mm/filemap.c:357
 truncate_inode_pages_range+0x593/0x1120 mm/truncate.c:366
 truncate_inode_pages+0x2e/0x40 mm/truncate.c:476
 kill_bdev+0x89/0xb0 fs/block_dev.c:86
 set_blocksize+0x1dd/0x210 fs/block_dev.c:136
 sb_set_blocksize+0x3d/0xc0 fs/block_dev.c:145
 sb_min_blocksize+0xa5/0xc0 fs/block_dev.c:161
 ext4_fill_super+0x368/0x7a30 fs/ext4/super.c:3668
 mount_bdev+0x262/0x2d0 fs/super.c:1415
 ext4_mount+0x3e/0x60 fs/ext4/super.c:6026
 legacy_get_tree+0x7e/0xf0 fs/fs_context.c:647
 vfs_get_tree+0x56/0x1a0 fs/super.c:1545
 do_new_mount fs/namespace.c:2822 [inline]
 do_mount+0x1004/0x14f0 fs/namespace.c:3142
 ksys_mount+0xe8/0x160 fs/namespace.c:3351
 __do_sys_mount fs/namespace.c:3365 [inline]
 __se_sys_mount fs/namespace.c:3362 [inline]
 __x64_sys_mount+0x70/0x90 fs/namespace.c:3362
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffffea0002a0e458 of 8 bytes by task 26854 on cpu 1:
 page_mapping+0x185/0x2a0 mm/util.c:675
 page_evictable+0x3a/0x110 mm/vmscan.c:4313
 __pagevec_lru_add_fn+0xe1/0x810 mm/swap.c:961
 pagevec_lru_move_fn+0xfe/0x180 mm/swap.c:211
 __pagevec_lru_add mm/swap.c:985 [inline]
 __lru_cache_add+0x120/0x1d0 mm/swap.c:411
 lru_cache_add_anon+0x9e/0x130 mm/swap.c:423
 shmem_getpage_gfp+0x470/0x1390 mm/shmem.c:1885
 shmem_getpage mm/shmem.c:154 [inline]
 shmem_file_read_iter+0x224/0x720 mm/shmem.c:2564
 call_read_iter include/linux/fs.h:1896 [inline]
 do_iter_readv_writev+0x54b/0x5b0 fs/read_write.c:691
 do_iter_read+0x1fc/0x3d0 fs/read_write.c:933
 vfs_iter_read+0x5c/0x80 fs/read_write.c:947
 lo_read_simple drivers/block/loop.c:351 [inline]
 do_req_filebacked drivers/block/loop.c:625 [inline]
 loop_handle_cmd drivers/block/loop.c:1952 [inline]
 loop_queue_work+0x92c/0x1623 drivers/block/loop.c:1966
 kthread_worker_fn+0x1c3/0x3a0 kernel/kthread.c:671
 loop_kthread_worker_fn+0x50/0x70 drivers/block/loop.c:901
 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 26854 Comm: loop4 Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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