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Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <67506987.050a0220.17bd51.006f.GAE@google.com> References: <67506987.050a0220.17bd51.006f.GAE@google.com> To: syzbot Cc: dhowells@redhat.com, jlayton@kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, netfs@lists.linux.dev, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] [netfs?] kernel BUG in iov_iter_revert (2) Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <1203229.1733323398.1@warthog.procyon.org.uk> Content-Transfer-Encoding: quoted-printable Date: Wed, 04 Dec 2024 14:43:18 +0000 Message-ID: <1203250.1733323398@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 This looks like it's probably a separate bug. David syzbot wrote: > syzbot has tested the proposed patch but the reproducer is still trigger= ing an issue: > possible deadlock in __submit_bio > = > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D > WARNING: possible circular locking dependency detected > 6.13.0-rc1-syzkaller-dirty #0 Not tainted > ------------------------------------------------------ > kswapd0/75 is trying to acquire lock: > ffff888034c41438 (&q->q_usage_counter(io)#37){++++}-{0:0}, at: __submit_= bio+0x2c6/0x560 block/blk-core.c:629 > = > but task is already holding lock: > ffffffff8ea35b00 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c= :6864 [inline] > ffffffff8ea35b00 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xbf1/0x36f0 mm/vm= scan.c:7246 > = > which lock already depends on the new lock. > = > = > the existing dependency chain (in reverse order) is: > = > -> #1 (fs_reclaim){+.+.}-{0:0}: > lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849 > __fs_reclaim_acquire mm/page_alloc.c:3851 [inline] > fs_reclaim_acquire+0x88/0x130 mm/page_alloc.c:3865 > might_alloc include/linux/sched/mm.h:318 [inline] > slab_pre_alloc_hook mm/slub.c:4055 [inline] > slab_alloc_node mm/slub.c:4133 [inline] > __do_kmalloc_node mm/slub.c:4282 [inline] > __kmalloc_node_noprof+0xb2/0x4d0 mm/slub.c:4289 > __kvmalloc_node_noprof+0x72/0x190 mm/util.c:650 > sbitmap_init_node+0x2d4/0x670 lib/sbitmap.c:132 > scsi_realloc_sdev_budget_map+0x2a7/0x460 drivers/scsi/scsi_scan.c= :246 > scsi_add_lun drivers/scsi/scsi_scan.c:1106 [inline] > scsi_probe_and_add_lun+0x3173/0x4bd0 drivers/scsi/scsi_scan.c:128= 7 > __scsi_add_device+0x228/0x2f0 drivers/scsi/scsi_scan.c:1622 > ata_scsi_scan_host+0x236/0x740 drivers/ata/libata-scsi.c:4575 > async_run_entry_fn+0xa8/0x420 kernel/async.c:129 > process_one_work kernel/workqueue.c:3229 [inline] > process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3310 > worker_thread+0x870/0xd30 kernel/workqueue.c:3391 > kthread+0x2f0/0x390 kernel/kthread.c:389 > ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 > = > -> #0 (&q->q_usage_counter(io)#37){++++}-{0:0}: > check_prev_add kernel/locking/lockdep.c:3161 [inline] > check_prevs_add kernel/locking/lockdep.c:3280 [inline] > validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904 > __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226 > lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849 > bio_queue_enter block/blk.h:75 [inline] > blk_mq_submit_bio+0x1536/0x2390 block/blk-mq.c:3091 > __submit_bio+0x2c6/0x560 block/blk-core.c:629 > __submit_bio_noacct_mq block/blk-core.c:710 [inline] > submit_bio_noacct_nocheck+0x4d3/0xe30 block/blk-core.c:739 > swap_writepage_bdev_async mm/page_io.c:451 [inline] > __swap_writepage+0x5fc/0x1400 mm/page_io.c:474 > swap_writepage+0x8f4/0x1170 mm/page_io.c:289 > pageout mm/vmscan.c:689 [inline] > shrink_folio_list+0x3c0e/0x8cb0 mm/vmscan.c:1367 > evict_folios+0x5568/0x7be0 mm/vmscan.c:4593 > try_to_shrink_lruvec+0x9a6/0xc70 mm/vmscan.c:4789 > shrink_one+0x3b9/0x850 mm/vmscan.c:4834 > shrink_many mm/vmscan.c:4897 [inline] > lru_gen_shrink_node mm/vmscan.c:4975 [inline] > shrink_node+0x37c5/0x3e50 mm/vmscan.c:5956 > kswapd_shrink_node mm/vmscan.c:6785 [inline] > balance_pgdat mm/vmscan.c:6977 [inline] > kswapd+0x1ca9/0x36f0 mm/vmscan.c:7246 > kthread+0x2f0/0x390 kernel/kthread.c:389 > ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 > = > other info that might help us debug this: > = > Possible unsafe locking scenario: > = > CPU0 CPU1 > ---- ---- > lock(fs_reclaim); > lock(&q->q_usage_counter(io)#37); > lock(fs_reclaim); > rlock(&q->q_usage_counter(io)#37); > = > *** DEADLOCK *** > = > 1 lock held by kswapd0/75: > #0: ffffffff8ea35b00 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vms= can.c:6864 [inline] > #0: ffffffff8ea35b00 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xbf1/0x36f0 = mm/vmscan.c:7246 > = > stack backtrace: > CPU: 0 UID: 0 PID: 75 Comm: kswapd0 Not tainted 6.13.0-rc1-syzkaller-dir= ty #0 > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1= .16.3-2~bpo12+1 04/01/2014 > Call Trace: > > __dump_stack lib/dump_stack.c:94 [inline] > dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 > print_circular_bug+0x13a/0x1b0 kernel/locking/lockdep.c:2074 > check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2206 > check_prev_add kernel/locking/lockdep.c:3161 [inline] > check_prevs_add kernel/locking/lockdep.c:3280 [inline] > validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904 > __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226 > lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849 > bio_queue_enter block/blk.h:75 [inline] > blk_mq_submit_bio+0x1536/0x2390 block/blk-mq.c:3091 > __submit_bio+0x2c6/0x560 block/blk-core.c:629 > __submit_bio_noacct_mq block/blk-core.c:710 [inline] > submit_bio_noacct_nocheck+0x4d3/0xe30 block/blk-core.c:739 > swap_writepage_bdev_async mm/page_io.c:451 [inline] > __swap_writepage+0x5fc/0x1400 mm/page_io.c:474 > swap_writepage+0x8f4/0x1170 mm/page_io.c:289 > pageout mm/vmscan.c:689 [inline] > shrink_folio_list+0x3c0e/0x8cb0 mm/vmscan.c:1367 > evict_folios+0x5568/0x7be0 mm/vmscan.c:4593 > try_to_shrink_lruvec+0x9a6/0xc70 mm/vmscan.c:4789 > shrink_one+0x3b9/0x850 mm/vmscan.c:4834 > shrink_many mm/vmscan.c:4897 [inline] > lru_gen_shrink_node mm/vmscan.c:4975 [inline] > shrink_node+0x37c5/0x3e50 mm/vmscan.c:5956 > kswapd_shrink_node mm/vmscan.c:6785 [inline] > balance_pgdat mm/vmscan.c:6977 [inline] > kswapd+0x1ca9/0x36f0 mm/vmscan.c:7246 > kthread+0x2f0/0x390 kernel/kthread.c:389 > ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 >