syzbot

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BUG: KCSAN: data-race in mlock_folio / need_mlock_drain

read-write to 0xffff888237d26610 of 1 bytes by task 10359 on cpu 1:
 folio_batch_add include/linux/pagevec.h:77 [inline]
 mlock_folio+0x128/0x200 mm/mlock.c:257
 mlock_vma_folio mm/internal.h:1008 [inline]
 __folio_add_file_rmap mm/rmap.c:1625 [inline]
 folio_add_file_rmap_ptes+0x19b/0x1a0 mm/rmap.c:1642
 set_pte_range+0x205/0x420 mm/memory.c:5256
 filemap_map_order0_folio mm/filemap.c:3683 [inline]
 filemap_map_pages+0x61f/0xab0 mm/filemap.c:3737
 do_fault_around mm/memory.c:5476 [inline]
 do_read_fault mm/memory.c:5509 [inline]
 do_fault mm/memory.c:5652 [inline]
 do_pte_missing mm/memory.c:4160 [inline]
 handle_pte_fault mm/memory.c:5997 [inline]
 __handle_mm_fault mm/memory.c:6140 [inline]
 handle_mm_fault+0x14dc/0x2ae0 mm/memory.c:6309
 faultin_page mm/gup.c:1193 [inline]
 __get_user_pages+0xde2/0x1d20 mm/gup.c:1491
 populate_vma_page_range mm/gup.c:1929 [inline]
 __mm_populate+0x243/0x3a0 mm/gup.c:2032
 mm_populate include/linux/mm.h:3487 [inline]
 __do_sys_mlockall mm/mlock.c:771 [inline]
 __se_sys_mlockall+0x368/0x3d0 mm/mlock.c:747
 __x64_sys_mlockall+0x1f/0x30 mm/mlock.c:747
 x64_sys_call+0x290a/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:152
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888237d26610 of 1 bytes by task 8103 on cpu 0:
 folio_batch_count include/linux/pagevec.h:56 [inline]
 need_mlock_drain+0x30/0x50 mm/mlock.c:235
 cpu_needs_drain mm/swap.c:779 [inline]
 __lru_add_drain_all+0x220/0x3f0 mm/swap.c:867
 lru_add_drain_all+0x10/0x20 mm/swap.c:883
 invalidate_bdev+0x47/0x70 block/bdev.c:101
 ext4_put_super+0x624/0x7d0 fs/ext4/super.c:1343
 generic_shutdown_super+0xe3/0x210 fs/super.c:642
 kill_block_super+0x2a/0x70 fs/super.c:1710
 ext4_kill_sb+0x42/0x80 fs/ext4/super.c:7393
 deactivate_locked_super+0x72/0x1c0 fs/super.c:473
 deactivate_super+0x97/0xa0 fs/super.c:506
 cleanup_mnt+0x269/0x2e0 fs/namespace.c:1435
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1442
 task_work_run+0x12e/0x1a0 kernel/task_work.c:227
 resume_user_mode_work+0x6a/0x70 include/linux/resume_user_mode.h:50
 exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x77/0xb0 kernel/entry/common.c:218
 do_syscall_64+0xdd/0x1a0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x03 -> 0x12

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 8103 Comm: syz-executor Not tainted 6.15.0-rc4-syzkaller-00291-g2a239ffbebb5 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
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