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BUG: KCSAN: data-race in delete_from_page_cache_batch / folio_mapping

write to 0xffffea0006833658 of 8 bytes by task 30629 on cpu 1:
 page_cache_delete_batch mm/filemap.c:311 [inline]
 delete_from_page_cache_batch+0x310/0x720 mm/filemap.c:337
 truncate_inode_pages_range+0x1fe/0x7e0 mm/truncate.c:405
 truncate_inode_pages+0x24/0x30 mm/truncate.c:485
 kill_bdev block/bdev.c:91 [inline]
 set_blocksize+0x1ed/0x270 block/bdev.c:207
 sb_set_blocksize+0x93/0x170 block/bdev.c:240
 sb_min_blocksize+0x53/0x60 block/bdev.c:255
 ext4_load_super fs/ext4/super.c:5133 [inline]
 __ext4_fill_super fs/ext4/super.c:5354 [inline]
 ext4_fill_super+0x398/0x37c0 fs/ext4/super.c:5824
 get_tree_bdev_flags+0x291/0x300 fs/super.c:1694
 get_tree_bdev+0x1f/0x30 fs/super.c:1717
 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5856
 vfs_get_tree+0x57/0x1d0 fs/super.c:1754
 fc_mount fs/namespace.c:1193 [inline]
 do_new_mount_fc fs/namespace.c:3758 [inline]
 do_new_mount+0x288/0x8d0 fs/namespace.c:3834
 path_mount+0x4d0/0xbc0 fs/namespace.c:4154
 do_mount fs/namespace.c:4167 [inline]
 __do_sys_mount fs/namespace.c:4383 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4360
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4360
 x64_sys_call+0x2d61/0x3020 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffea0006833658 of 8 bytes by task 21484 on cpu 0:
 folio_mapping+0xa1/0xe0 mm/util.c:732
 folio_evictable mm/internal.h:584 [inline]
 lru_add+0x8d/0x460 mm/swap.c:136
 folio_batch_move_lru+0x1d3/0x290 mm/swap.c:172
 lru_add_drain_cpu+0x66/0x210 mm/swap.c:654
 lru_add_drain mm/swap.c:743 [inline]
 __folio_batch_release+0x44/0xb0 mm/swap.c:1065
 folio_batch_release include/linux/folio_batch.h:101 [inline]
 writeback_get_folio mm/page-writeback.c:2430 [inline]
 writeback_iter+0x41a/0x800 mm/page-writeback.c:2533
 blkdev_writepages+0xa7/0x100 block/fops.c:485
 do_writepages+0x1c6/0x310 mm/page-writeback.c:2575
 filemap_writeback mm/filemap.c:388 [inline]
 filemap_flush_range mm/filemap.c:437 [inline]
 filemap_flush+0xee/0x130 mm/filemap.c:452
 sync_blockdev_nowait+0x29/0x40 block/bdev.c:264
 sync_filesystem+0xe2/0x190 fs/sync.c:60
 generic_shutdown_super+0x4c/0x220 fs/super.c:625
 kill_block_super+0x2a/0x70 fs/super.c:1725
 ext4_kill_sb+0x42/0x80 fs/ext4/super.c:7492
 deactivate_locked_super+0x75/0x1c0 fs/super.c:476
 deactivate_super+0x97/0xa0 fs/super.c:509
 cleanup_mnt+0x2bb/0x330 fs/namespace.c:1312
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1319
 task_work_run+0x130/0x1a0 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
 exit_to_user_mode_loop+0x1f4/0x6f0 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:328 [inline]
 do_syscall_64+0x232/0x3b0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff88810048a928 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 21484 Comm: syz-executor Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
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EXT4-fs (loop6): unmounting filesystem 00000000-0000-0000-0000-000000000000.