[moderation] [mm?] KCSAN: data-race in mlock_folio / need_mlock_drain (7)

Hello,

syzbot found the following issue on:

HEAD commit: 2a239ffbebb5 Merge tag 'sound-6.15-rc5' of git://git.kerne..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12e9d8d4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6bd11c5d4ce102b4
dashboard link: https://syzkaller.appspot.com/bug?extid=e0bc328118894c729324
compiler: Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2
CC: [[email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected]]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a37e08667ec3/disk-2a239ffb.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/611a1665e47f/vmlinux-2a239ffb.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c56f32f07145/bzImage-2a239ffb.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email protected]

==================================================================
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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