syzbot

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BUG: KCSAN: data-race in munlock_folio / need_mlock_drain

read-write to 0xffff888237c27010 of 1 bytes by task 31588 on cpu 0:
 folio_batch_add include/linux/pagevec.h:77 [inline]
 munlock_folio+0x44/0x120 mm/mlock.c:301
 munlock_vma_folio mm/internal.h:1060 [inline]
 __folio_remove_rmap mm/rmap.c:1762 [inline]
 folio_remove_rmap_ptes+0x197/0x1a0 mm/rmap.c:1779
 zap_present_folio_ptes mm/memory.c:1650 [inline]
 zap_present_ptes mm/memory.c:1708 [inline]
 do_zap_pte_range mm/memory.c:1810 [inline]
 zap_pte_range mm/memory.c:1854 [inline]
 zap_pmd_range mm/memory.c:1946 [inline]
 zap_pud_range mm/memory.c:1975 [inline]
 zap_p4d_range mm/memory.c:1996 [inline]
 unmap_page_range+0x144c/0x2530 mm/memory.c:2017
 unmap_single_vma mm/memory.c:2059 [inline]
 unmap_vmas+0x23d/0x3a0 mm/memory.c:2101
 exit_mmap+0x1ae/0x6b0 mm/mmap.c:1277
 __mmput+0x28/0x1c0 kernel/fork.c:1173
 mmput+0x40/0x50 kernel/fork.c:1196
 exit_mm+0xe4/0x180 kernel/exit.c:581
 do_exit+0x427/0x15d0 kernel/exit.c:959
 do_group_exit+0x139/0x140 kernel/exit.c:1112
 __do_sys_exit_group kernel/exit.c:1123 [inline]
 __se_sys_exit_group kernel/exit.c:1121 [inline]
 __x64_sys_exit_group+0x1f/0x20 kernel/exit.c:1121
 x64_sys_call+0x2fff/0x3000 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd8/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888237c27010 of 1 bytes by task 31717 on cpu 1:
 folio_batch_count include/linux/pagevec.h:56 [inline]
 need_mlock_drain+0x30/0x50 mm/mlock.c:235
 cpu_needs_drain mm/swap.c:786 [inline]
 __lru_add_drain_all+0x273/0x450 mm/swap.c:877
 lru_cache_disable+0x1f/0x30 mm/swap.c:930
 do_mbind mm/mempolicy.c:1526 [inline]
 kernel_mbind mm/mempolicy.c:1752 [inline]
 __do_sys_mbind mm/mempolicy.c:1826 [inline]
 __se_sys_mbind+0x496/0xac0 mm/mempolicy.c:1822
 __x64_sys_mbind+0x78/0x90 mm/mempolicy.c:1822
 x64_sys_call+0x2a2b/0x3000 arch/x86/include/generated/asm/syscalls_64.h:238
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd8/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 31717 Comm: syz.0.14883 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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