syzbot

EXT4-fs (loop8): unmounting filesystem 00000000-0000-0000-0000-000000000000.
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BUG: KCSAN: data-race in mlock_folio / need_mlock_drain

read-write to 0xffff888237c27248 of 1 bytes by task 17070 on cpu 0:
 folio_batch_add include/linux/folio_batch.h:77 [inline]
 mlock_folio+0x14d/0x240 mm/mlock.c:257
 mlock_vma_folio mm/internal.h:1199 [inline]
 __folio_add_file_rmap mm/rmap.c:1715 [inline]
 folio_add_file_rmap_ptes+0x1d0/0x1e0 mm/rmap.c:1732
 set_pte_range+0x2c1/0x4f0 mm/memory.c:5635
 filemap_map_order0_folio mm/filemap.c:3862 [inline]
 filemap_map_pages+0x5b8/0xea0 mm/filemap.c:3932
 do_fault_around mm/memory.c:5867 [inline]
 do_read_fault mm/memory.c:5900 [inline]
 do_fault mm/memory.c:6043 [inline]
 do_pte_missing mm/memory.c:4566 [inline]
 handle_pte_fault mm/memory.c:6427 [inline]
 __handle_mm_fault mm/memory.c:6565 [inline]
 handle_mm_fault+0x1508/0x2e70 mm/memory.c:6734
 faultin_page mm/gup.c:1126 [inline]
 __get_user_pages+0x1290/0x1f10 mm/gup.c:1428
 populate_vma_page_range mm/gup.c:1860 [inline]
 __mm_populate+0x242/0x390 mm/gup.c:1963
 do_mlock+0x47c/0x520 mm/mlock.c:659
 __do_sys_mlock mm/mlock.c:667 [inline]
 __se_sys_mlock mm/mlock.c:665 [inline]
 __x64_sys_mlock+0x36/0x50 mm/mlock.c:665
 x64_sys_call+0x1ab3/0x3020 arch/x86/include/generated/asm/syscalls_64.h:150
 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 0xffff888237c27248 of 1 bytes by task 15812 on cpu 1:
 folio_batch_count include/linux/folio_batch.h:56 [inline]
 need_mlock_drain+0x30/0x50 mm/mlock.c:235
 cpu_needs_drain mm/swap.c:792 [inline]
 __lru_add_drain_all+0x273/0x450 mm/swap.c:883
 lru_add_drain_all+0x10/0x20 mm/swap.c:899
 invalidate_bdev+0x47/0x70 block/bdev.c:101
 ext4_put_super+0x610/0x7b0 fs/ext4/super.c:1355
 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: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+0x211/0x820 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:230 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
 do_syscall_64+0x232/0x3b0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 15812 Comm: syz-executor Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
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