On Fri, Apr 26, 2024 at 09:30:08AM -0700, Darrick J. Wong wrote: > On Thu, Apr 25, 2024 at 10:15:29PM -0700, syzbot wrote: > > Hello, > > > > syzbot found the following issue on: > > > > HEAD commit: 3b68086599f8 Merge tag 'sched_urgent_for_v6.9_rc5' of git:.. > > git tree: upstream > > console output: https://syzkaller.appspot.com/x/log.txt?x=158206bb180000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=f47e5e015c177e57 > > dashboard link: https://syzkaller.appspot.com/bug?extid=1619d847a7b9ba3a9137 > > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 > > > > Unfortunately, I don't have any reproducer for this issue yet. > > > > Downloadable assets: > > disk image: https://storage.googleapis.com/syzbot-assets/caa90b55d476/disk-3b680865.raw.xz > > vmlinux: https://storage.googleapis.com/syzbot-assets/17940f1c5e8f/vmlinux-3b680865.xz > > kernel image: https://storage.googleapis.com/syzbot-assets/b03bd6929a1c/bzImage-3b680865.xz > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > Reported-by: syzbot+1619d847a7b9ba3a9137@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > ====================================================== > > WARNING: possible circular locking dependency detected > > 6.9.0-rc4-syzkaller-00274-g3b68086599f8 #0 Not tainted > > ------------------------------------------------------ > > kswapd0/81 is trying to acquire lock: > > ffff8881a895a610 (sb_internal#3){.+.+}-{0:0}, at: xfs_fs_dirty_inode+0x158/0x250 fs/xfs/xfs_super.c:689 > > > > but task is already holding lock: > > ffffffff8e428e80 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6782 [inline] > > ffffffff8e428e80 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xb20/0x30c0 mm/vmscan.c:7164 > > > > which lock already depends on the new lock. > > > > > > the existing dependency chain (in reverse order) is: > > > > -> #2 (fs_reclaim){+.+.}-{0:0}: > > lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754 > > __fs_reclaim_acquire mm/page_alloc.c:3698 [inline] > > fs_reclaim_acquire+0x88/0x140 mm/page_alloc.c:3712 > > might_alloc include/linux/sched/mm.h:312 [inline] > > slab_pre_alloc_hook mm/slub.c:3746 [inline] > > slab_alloc_node mm/slub.c:3827 [inline] > > kmalloc_trace+0x47/0x360 mm/slub.c:3992 > > kmalloc include/linux/slab.h:628 [inline] > > add_stack_record_to_list mm/page_owner.c:177 [inline] There's the GFP_KERNEL allocation being warned about again. > > inc_stack_record_count mm/page_owner.c:219 [inline] > > __set_page_owner+0x561/0x810 mm/page_owner.c:334 > > set_page_owner include/linux/page_owner.h:32 [inline] > > post_alloc_hook+0x1ea/0x210 mm/page_alloc.c:1534 > > prep_new_page mm/page_alloc.c:1541 [inline] > > get_page_from_freelist+0x3410/0x35b0 mm/page_alloc.c:3317 > > __alloc_pages+0x256/0x6c0 mm/page_alloc.c:4575 > > __alloc_pages_node include/linux/gfp.h:238 [inline] > > alloc_pages_node include/linux/gfp.h:261 [inline] > > alloc_slab_page+0x5f/0x160 mm/slub.c:2175 > > allocate_slab mm/slub.c:2338 [inline] > > new_slab+0x84/0x2f0 mm/slub.c:2391 > > ___slab_alloc+0xc73/0x1260 mm/slub.c:3525 > > __slab_alloc mm/slub.c:3610 [inline] > > __slab_alloc_node mm/slub.c:3663 [inline] > > slab_alloc_node mm/slub.c:3835 [inline] > > kmem_cache_alloc+0x252/0x340 mm/slub.c:3852 > > kmem_cache_zalloc include/linux/slab.h:739 [inline] > > xfs_btree_alloc_cursor fs/xfs/libxfs/xfs_btree.h:679 [inline] > > xfs_refcountbt_init_cursor+0x65/0x2a0 fs/xfs/libxfs/xfs_refcount_btree.c:367 > > xfs_reflink_find_shared fs/xfs/xfs_reflink.c:147 [inline] > > xfs_reflink_trim_around_shared+0x53a/0x9d0 fs/xfs/xfs_reflink.c:194 > > xfs_buffered_write_iomap_begin+0xebf/0x1b40 fs/xfs/xfs_iomap.c:1062 > > Hm. We've taken an ILOCK in xfs_buffered_write_iomap_begin, and now > we're allocating a btree cursor but we don't have PF_MEMALLOC_NOFS set, > nor do we pass GFP_NOFS. > > Ah, because nothing in this code path sets PF_MEMALLOC_NOFS explicitly, > nor does it create a xfs_trans_alloc_empty, which would set that. Prior > to the removal of kmem_alloc, I think we were much more aggressive about > GFP_NOFS usage. > > Seeing as we're about to walk a btree, we probably want the empty > transaction to guard against btree cycle livelocks. Nothing like that is needed or desired, this is a just a bug in the memory allocation tracking code... -Dave. -- Dave Chinner david@xxxxxxxxxxxxx
