syzbot

==================================================================
BUG: KCSAN: data-race in __lru_add_drain_all / folios_put_refs

write to 0xffff888237d25a68 of 1 bytes by task 9419 on cpu 1:
 folio_batch_reinit include/linux/pagevec.h:50 [inline]
 folios_put_refs+0x285/0x2d0 mm/swap.c:986
 folios_put include/linux/mm.h:1639 [inline]
 folio_batch_move_lru+0x1fd/0x230 mm/swap.c:175
 __folio_batch_add_and_move mm/swap.c:196 [inline]
 folio_add_lru+0x14a/0x1f0 mm/swap.c:505
 shmem_alloc_and_add_folio mm/shmem.c:1952 [inline]
 shmem_get_folio_gfp+0x7ab/0xd40 mm/shmem.c:2533
 shmem_get_folio mm/shmem.c:2639 [inline]
 shmem_write_begin+0xa8/0x190 mm/shmem.c:3289
 generic_perform_write+0x181/0x490 mm/filemap.c:4103
 shmem_file_write_iter+0xc5/0xf0 mm/shmem.c:3464
 new_sync_write fs/read_write.c:591 [inline]
 vfs_write+0x49d/0x8d0 fs/read_write.c:684
 ksys_write+0xda/0x1a0 fs/read_write.c:736
 __do_sys_write fs/read_write.c:747 [inline]
 __se_sys_write fs/read_write.c:744 [inline]
 __x64_sys_write+0x40/0x50 fs/read_write.c:744
 x64_sys_call+0x2cdd/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:2
 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 0xffff888237d25a68 of 1 bytes by task 9408 on cpu 0:
 folio_batch_count include/linux/pagevec.h:56 [inline]
 cpu_needs_drain mm/swap.c:773 [inline]
 __lru_add_drain_all+0x12b/0x3f0 mm/swap.c:867
 lru_cache_disable+0x1f/0x30 mm/swap.c:920
 do_mbind mm/mempolicy.c:1342 [inline]
 kernel_mbind mm/mempolicy.c:1568 [inline]
 __do_sys_mbind mm/mempolicy.c:1642 [inline]
 __se_sys_mbind+0x496/0xac0 mm/mempolicy.c:1638
 __x64_sys_mbind+0x78/0x90 mm/mempolicy.c:1638
 x64_sys_call+0x14af/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:238
 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

value changed: 0x12 -> 0x00

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 9408 Comm: syz.2.2065 Tainted: G        W           6.15.0-rc5-syzkaller-00204-g0e1329d4045c #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
==================================================================