syzbot

EXT4-fs (loop2): unmounting filesystem 00000000-0000-0000-0000-000000000000.
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BUG: KCSAN: data-race in find_get_block_common / has_bh_in_lru

read-write to 0xffff888237c27760 of 8 bytes by task 24705 on cpu 0:
 bh_lru_install fs/buffer.c:1342 [inline]
 find_get_block_common+0x459/0x8a0 fs/buffer.c:1407
 bdev_getblk+0x4d/0x3f0 include/linux/gfp.h:-1
 __bread_gfp+0x51/0x240 fs/buffer.c:1512
 sb_bread include/linux/buffer_head.h:346 [inline]
 fat_ent_bread+0xc9/0x1a0 fs/fat/fatent.c:109
 fat_ent_read+0x3b3/0x5c0 fs/fat/fatent.c:368
 fat_get_cluster+0x4de/0x820 fs/fat/cache.c:261
 fat_bmap_cluster fs/fat/cache.c:294 [inline]
 fat_get_mapped_cluster+0xe4/0x240 fs/fat/cache.c:315
 fat_bmap+0x254/0x280 fs/fat/cache.c:379
 __fat_get_block fs/fat/inode.c:129 [inline]
 fat_get_block+0xd3/0x5e0 fs/fat/inode.c:190
 block_read_full_folio+0x1fd/0x6a0 fs/buffer.c:2417
 do_mpage_readpage+0xcdc/0xe00 fs/mpage.c:314
 mpage_read_folio+0xbd/0x130 fs/mpage.c:395
 fat_read_folio+0x1c/0x30 fs/fat/inode.c:205
 filemap_read_folio+0x2e/0x110 mm/filemap.c:2496
 filemap_fault+0x5cf/0xb90 mm/filemap.c:3641
 __do_fault+0xbc/0x200 mm/memory.c:5363
 do_read_fault mm/memory.c:5798 [inline]
 do_fault mm/memory.c:5932 [inline]
 do_pte_missing mm/memory.c:4477 [inline]
 handle_pte_fault mm/memory.c:6316 [inline]
 __handle_mm_fault mm/memory.c:6454 [inline]
 handle_mm_fault+0x11d7/0x3020 mm/memory.c:6623
 faultin_page mm/gup.c:1126 [inline]
 __get_user_pages+0x1023/0x1ea0 mm/gup.c:1428
 populate_vma_page_range mm/gup.c:1860 [inline]
 __mm_populate+0x242/0x390 mm/gup.c:1963
 mm_populate include/linux/mm.h:3899 [inline]
 vm_mmap_pgoff+0x23b/0x2d0 mm/util.c:586
 ksys_mmap_pgoff+0x267/0x310 mm/mmap.c:605
 x64_sys_call+0x14df/0x3020 arch/x86/include/generated/asm/syscalls_64.h:10
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888237c27760 of 8 bytes by task 23571 on cpu 1:
 has_bh_in_lru+0x35/0x1f0 fs/buffer.c:1548
 cpu_needs_drain mm/swap.c:787 [inline]
 __lru_add_drain_all+0x287/0x450 mm/swap.c:877
 lru_add_drain_all+0x10/0x20 mm/swap.c:893
 invalidate_bdev+0x47/0x70 block/bdev.c:101
 ext4_put_super+0x624/0x7d0 fs/ext4/super.c:1353
 generic_shutdown_super+0xee/0x220 fs/super.c:646
 kill_block_super+0x2a/0x70 fs/super.c:1725
 ext4_kill_sb+0x42/0x80 fs/ext4/super.c:7459
 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:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
 do_syscall_64+0x249/0x370 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000000 -> 0xffff88810588a6e8

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 23571 Comm: syz-executor Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
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