[moderation] [cgroups?] [mm?] KCSAN: data-race in mem_cgroup_track_foreign_dirty_slowpath / mem_cgroup_track_foreign_dirty_slowpath (8)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 5aca7966d2a7 Merge tag 'perf-tools-fixes-for-v6.17-2025-09..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12ce0c7c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6e0c213d0735f5dd
dashboard link: https://syzkaller.appspot.com/bug?extid=0492fe05fc68a3e1de42
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
CC: [ak...@linux-foundation.org cgr...@vger.kernel.org han...@cmpxchg.org linux-...@vger.kernel.org linu...@kvack.org mho...@kernel.org muchu...@linux.dev roman.g...@linux.dev shakee...@linux.dev]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/04d1ecac3902/disk-5aca7966.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f0d670e1aeec/vmlinux-5aca7966.xz
kernel image: https://storage.googleapis.com/syzbot-assets/fb2d183fb750/bzImage-5aca7966.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0492fe...@syzkaller.appspotmail.com

EXT4-fs (loop3): mounted filesystem 00000000-0000-0000-0000-000000000900 r/w without journal. Quota mode: none.
==================================================================
BUG: KCSAN: data-race in mem_cgroup_track_foreign_dirty_slowpath / mem_cgroup_track_foreign_dirty_slowpath

write to 0xffff888119790558 of 8 bytes by task 15982 on cpu 0:
mem_cgroup_track_foreign_dirty_slowpath+0x321/0x440 mm/memcontrol.c:3481
mem_cgroup_track_foreign_dirty include/linux/memcontrol.h:1567 [inline]
folio_account_dirtied mm/page-writeback.c:2700 [inline]
__folio_mark_dirty+0x3f8/0x4d0 mm/page-writeback.c:2741
mark_buffer_dirty+0x11e/0x210 fs/buffer.c:1206
block_commit_write fs/buffer.c:2218 [inline]
block_page_mkwrite+0x287/0x3d0 fs/buffer.c:2643
ext4_page_mkwrite+0x859/0xb90 fs/ext4/inode.c:6725
do_page_mkwrite mm/memory.c:3361 [inline]
do_shared_fault mm/memory.c:5649 [inline]
do_fault mm/memory.c:5711 [inline]
do_pte_missing mm/memory.c:4234 [inline]
handle_pte_fault mm/memory.c:6052 [inline]
__handle_mm_fault mm/memory.c:6195 [inline]
handle_mm_fault+0x15cb/0x2c20 mm/memory.c:6364
do_user_addr_fault+0x636/0x1090 arch/x86/mm/fault.c:1336
handle_page_fault arch/x86/mm/fault.c:1476 [inline]
exc_page_fault+0x62/0xa0 arch/x86/mm/fault.c:1532
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

read to 0xffff888119790558 of 8 bytes by task 15983 on cpu 1:
mem_cgroup_track_foreign_dirty_slowpath+0xd5/0x440 mm/memcontrol.c:3461
mem_cgroup_track_foreign_dirty include/linux/memcontrol.h:1567 [inline]
folio_account_dirtied mm/page-writeback.c:2700 [inline]
__folio_mark_dirty+0x3f8/0x4d0 mm/page-writeback.c:2741
mark_buffer_dirty+0x11e/0x210 fs/buffer.c:1206
folio_zero_new_buffers+0x28c/0x2e0 fs/buffer.c:2032
block_write_end+0x200/0x210 fs/buffer.c:2289
ext4_da_do_write_end fs/ext4/inode.c:3217 [inline]
ext4_da_write_end+0x1d3/0x800 fs/ext4/inode.c:3291
generic_perform_write+0x30f/0x490 mm/filemap.c:4196
ext4_buffered_write_iter+0x1ee/0x3c0 fs/ext4/file.c:299
ext4_file_write_iter+0x383/0xf00 fs/ext4/file.c:-1
new_sync_write fs/read_write.c:593 [inline]
vfs_write+0x52a/0x960 fs/read_write.c:686
ksys_write+0xda/0x1a0 fs/read_write.c:738
__do_sys_write fs/read_write.c:749 [inline]
__se_sys_write fs/read_write.c:746 [inline]
__x64_sys_write+0x40/0x50 fs/read_write.c:746
x64_sys_call+0x27fe/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:2
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: 0x0000000100000bb2 -> 0x0000000100000e17

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 15983 Comm: syz.3.4718 Tainted: G W syzkaller #0 PREEMPT(voluntary)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
==================================================================
EXT4-fs error (device loop3): ext4_mb_generate_buddy:1289: group 0, block bitmap and bg descriptor inconsistent: 25 vs 150994969 free clusters
EXT4-fs (loop3): Delayed block allocation failed for inode 18 at logical offset 0 with max blocks 2048 with error 28
EXT4-fs (loop3): This should not happen!! Data will be lost

EXT4-fs (loop3): Total free blocks count 0
EXT4-fs (loop3): Free/Dirty block details
EXT4-fs (loop3): free_blocks=2415919104
EXT4-fs (loop3): dirty_blocks=8208
EXT4-fs (loop3): Block reservation details
EXT4-fs (loop3): i_reserved_data_blocks=513


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