[moderation] [mm?] KCSAN: data-race in scan_swap_map_slots / scan_swap_map_slots

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 33cc938e65a9 Linux 6.7-rc4
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1620464ae80000
kernel config: https://syzkaller.appspot.com/x/.config?x=ac34c1f29a8029df
dashboard link: https://syzkaller.appspot.com/bug?extid=5753f436c6a28cd8e35e
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [ak...@linux-foundation.org linux-...@vger.kernel.org linu...@kvack.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6a0655688b57/disk-33cc938e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/89a66df4cc89/vmlinux-33cc938e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/621e82bbfa03/bzImage-33cc938e.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5753f4...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in scan_swap_map_slots / scan_swap_map_slots

write to 0xffff88810286b670 of 4 bytes by task 12242 on cpu 1:
swap_range_alloc mm/swapfile.c:702 [inline]
scan_swap_map_slots+0x96e/0x1240 mm/swapfile.c:920
get_swap_pages+0x31d/0x480 mm/swapfile.c:1097
refill_swap_slots_cache mm/swap_slots.c:266 [inline]
folio_alloc_swap+0x2d0/0x4a0 mm/swap_slots.c:334
add_to_swap+0x18/0x80 mm/swap_state.c:185
shrink_folio_list+0x1421/0x2540 mm/vmscan.c:1209
reclaim_folio_list+0x7b/0x1d0 mm/vmscan.c:2100
reclaim_pages+0x220/0x280 mm/vmscan.c:2136
madvise_cold_or_pageout_pte_range+0x98c/0x9f0 mm/madvise.c:515
walk_pmd_range mm/pagewalk.c:143 [inline]
walk_pud_range mm/pagewalk.c:221 [inline]
walk_p4d_range mm/pagewalk.c:256 [inline]
walk_pgd_range+0x80a/0xec0 mm/pagewalk.c:293
__walk_page_range+0xc2/0x320 mm/pagewalk.c:395
walk_page_range+0x2c7/0x3f0 mm/pagewalk.c:521
madvise_pageout_page_range mm/madvise.c:574 [inline]
madvise_pageout mm/madvise.c:601 [inline]
madvise_vma_behavior mm/madvise.c:1020 [inline]
madvise_walk_vmas mm/madvise.c:1249 [inline]
do_madvise+0x1b27/0x26f0 mm/madvise.c:1429
__do_sys_madvise mm/madvise.c:1442 [inline]
__se_sys_madvise mm/madvise.c:1440 [inline]
__x64_sys_madvise+0x60/0x70 mm/madvise.c:1440
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff88810286b670 of 4 bytes by task 12240 on cpu 0:
scan_swap_map_slots+0x1e7/0x1240 mm/swapfile.c:852
get_swap_pages+0x31d/0x480 mm/swapfile.c:1097
refill_swap_slots_cache mm/swap_slots.c:266 [inline]
folio_alloc_swap+0x2d0/0x4a0 mm/swap_slots.c:334
add_to_swap+0x18/0x80 mm/swap_state.c:185
shrink_folio_list+0x1421/0x2540 mm/vmscan.c:1209
reclaim_folio_list+0x7b/0x1d0 mm/vmscan.c:2100
reclaim_pages+0x220/0x280 mm/vmscan.c:2136
madvise_cold_or_pageout_pte_range+0x98c/0x9f0 mm/madvise.c:515
walk_pmd_range mm/pagewalk.c:143 [inline]
walk_pud_range mm/pagewalk.c:221 [inline]
walk_p4d_range mm/pagewalk.c:256 [inline]
walk_pgd_range+0x80a/0xec0 mm/pagewalk.c:293
__walk_page_range+0xc2/0x320 mm/pagewalk.c:395
walk_page_range+0x2c7/0x3f0 mm/pagewalk.c:521
madvise_pageout_page_range mm/madvise.c:574 [inline]
madvise_pageout mm/madvise.c:601 [inline]
madvise_vma_behavior mm/madvise.c:1020 [inline]
madvise_walk_vmas mm/madvise.c:1249 [inline]
do_madvise+0x1b27/0x26f0 mm/madvise.c:1429
__do_sys_madvise mm/madvise.c:1442 [inline]
__se_sys_madvise mm/madvise.c:1440 [inline]
__x64_sys_madvise+0x60/0x70 mm/madvise.c:1440
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x0000070f -> 0x00000722

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 12240 Comm: syz-executor.2 Not tainted 6.7.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.