syzbot

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BUG: KCSAN: data-race in folios_put_refs / need_mlock_drain

write to 0xffff888237c26a48 of 1 bytes by task 3413 on cpu 0:
 folio_batch_reinit include/linux/pagevec.h:50 [inline]
 folios_put_refs+0x285/0x2d0 mm/swap.c:991
 folios_put include/linux/mm.h:1419 [inline]
 mlock_folio_batch+0x1a5b/0x1a70 mm/mlock.c:209
 mlock_folio+0x1ac/0x200 mm/mlock.c:259
 mlock_pte_range+0x28d/0x590 mm/mlock.c:397
 walk_pmd_range mm/pagewalk.c:130 [inline]
 walk_pud_range mm/pagewalk.c:224 [inline]
 walk_p4d_range mm/pagewalk.c:262 [inline]
 walk_pgd_range+0xa4a/0x14e0 mm/pagewalk.c:303
 __walk_page_range+0xdd/0x340 mm/pagewalk.c:410
 walk_page_range_mm+0x37a/0x4c0 mm/pagewalk.c:506
 walk_page_range+0x56/0x70 mm/pagewalk.c:585
 mlock_vma_pages_range+0xf5/0x170 mm/mlock.c:448
 mlock_fixup+0x1e6/0x210 mm/mlock.c:507
 apply_mlockall_flags+0x1f9/0x280 mm/mlock.c:734
 __do_sys_mlockall mm/mlock.c:766 [inline]
 __se_sys_mlockall+0x24a/0x3d0 mm/mlock.c:745
 __x64_sys_mlockall+0x1f/0x30 mm/mlock.c:745
 x64_sys_call+0xd68/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:152
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888237c26a48 of 1 bytes by task 3414 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:784 [inline]
 __lru_add_drain_all+0x220/0x3f0 mm/swap.c:872
 lru_cache_disable+0x1f/0x30 mm/swap.c:925
 do_mbind mm/mempolicy.c:1456 [inline]
 kernel_mbind mm/mempolicy.c:1682 [inline]
 __do_sys_mbind mm/mempolicy.c:1756 [inline]
 __se_sys_mbind+0x496/0xac0 mm/mempolicy.c:1752
 __x64_sys_mbind+0x78/0x90 mm/mempolicy.c:1752
 x64_sys_call+0x2932/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:238
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x01 -> 0x00

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3414 Comm: syz.9.9958 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
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