On Wed, Jul 09, 2025 at 10:39:29AM -0700, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 733923397fd9 Merge tag 'pwm/for-6.16-rc6-fixes' of git://g.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=13f53582580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=b309c907eaab29da > dashboard link: https://syzkaller.appspot.com/bug?extid=3470c9ffee63e4abafeb > compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7 > > Unfortunately, I don't have any reproducer for this issue yet. > > Downloadable assets: > disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-73392339.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/be7feaa77b8c/vmlinux-73392339.xz > kernel image: https://storage.googleapis.com/syzbot-assets/a663b3e31463/bzImage-73392339.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+3470c9ffee63e4abafeb@xxxxxxxxxxxxxxxxxxxxxxxxx > > ====================================================== > WARNING: possible circular locking dependency detected > 6.16.0-rc5-syzkaller-00038-g733923397fd9 #0 Not tainted > ------------------------------------------------------ > syz.0.0/5339 is trying to acquire lock: > ffffffff8e247500 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:318 [inline] > ffffffff8e247500 (fs_reclaim){+.+.}-{0:0}, at: prepare_alloc_pages+0x153/0x610 mm/page_alloc.c:4727 > > but task is already holding lock: > ffff888053415098 (&xfs_nondir_ilock_class){++++}-{4:4}, at: xfs_ilock_attr_map_shared+0x92/0xd0 fs/xfs/xfs_inode.c:85 > > which lock already depends on the new lock. > > > the existing dependency chain (in reverse order) is: > > -> #1 (&xfs_nondir_ilock_class){++++}-{4:4}: > lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871 > down_write_nested+0x9d/0x200 kernel/locking/rwsem.c:1693 > xfs_reclaim_inode fs/xfs/xfs_icache.c:1045 [inline] > xfs_icwalk_process_inode fs/xfs/xfs_icache.c:1737 [inline] > xfs_icwalk_ag+0x12c5/0x1ab0 fs/xfs/xfs_icache.c:1819 > xfs_icwalk fs/xfs/xfs_icache.c:1867 [inline] > xfs_reclaim_inodes_nr+0x1e3/0x260 fs/xfs/xfs_icache.c:1111 > super_cache_scan+0x41b/0x4b0 fs/super.c:228 > do_shrink_slab+0x6ec/0x1110 mm/shrinker.c:437 > shrink_slab+0xd74/0x10d0 mm/shrinker.c:664 > shrink_one+0x28a/0x7c0 mm/vmscan.c:4939 > shrink_many mm/vmscan.c:5000 [inline] > lru_gen_shrink_node mm/vmscan.c:5078 [inline] > shrink_node+0x314e/0x3760 mm/vmscan.c:6060 > kswapd_shrink_node mm/vmscan.c:6911 [inline] > balance_pgdat mm/vmscan.c:7094 [inline] > kswapd+0x147c/0x2830 mm/vmscan.c:7359 > kthread+0x70e/0x8a0 kernel/kthread.c:464 > ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 > > -> #0 (fs_reclaim){+.+.}-{0:0}: > check_prev_add kernel/locking/lockdep.c:3168 [inline] > check_prevs_add kernel/locking/lockdep.c:3287 [inline] > validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3911 > __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5240 > lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5871 > __fs_reclaim_acquire mm/page_alloc.c:4045 [inline] > fs_reclaim_acquire+0x72/0x100 mm/page_alloc.c:4059 > might_alloc include/linux/sched/mm.h:318 [inline] > prepare_alloc_pages+0x153/0x610 mm/page_alloc.c:4727 > __alloc_frozen_pages_noprof+0x123/0x370 mm/page_alloc.c:4948 > alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2419 > alloc_frozen_pages_noprof mm/mempolicy.c:2490 [inline] > alloc_pages_noprof+0xa9/0x190 mm/mempolicy.c:2510 > get_free_pages_noprof+0xf/0x80 mm/page_alloc.c:5018 > __kasan_populate_vmalloc mm/kasan/shadow.c:362 [inline] > kasan_populate_vmalloc+0x33/0x1a0 mm/kasan/shadow.c:417 > alloc_vmap_area+0xd51/0x1490 mm/vmalloc.c:2084 > __get_vm_area_node+0x1f8/0x300 mm/vmalloc.c:3179 > __vmalloc_node_range_noprof+0x301/0x12f0 mm/vmalloc.c:3845 > __vmalloc_node_noprof mm/vmalloc.c:3948 [inline] > __vmalloc_noprof+0xb1/0xf0 mm/vmalloc.c:3962 > xfs_buf_alloc_backing_mem fs/xfs/xfs_buf.c:239 [inline] KASAN is still failing to pass through __GFP_NOLOCKDEP allocation context flags. It's also failing to pass through other important context restrictions like GFP_NOFS, GFP_NOIO, __GFP_NOFAIL, etc. Fundamentally, it's a bug to be doing nested GFP_KERNEL allocations inside an allocation context that has a more restricted allocation context... #syz set subsystems: kasan -- Dave Chinner david@xxxxxxxxxxxxx
