====================================================== WARNING: possible circular locking dependency detected 6.13.0-rc7-syzkaller-g1950a0af2d55 #0 Not tainted ------------------------------------------------------ kworker/0:2H/8944 is trying to acquire lock: ffff80008fa1fc10 (cpu_hotplug_lock){++++}-{0:0}, at: acomp_ctx_get_cpu mm/zswap.c:886 [inline] ffff80008fa1fc10 (cpu_hotplug_lock){++++}-{0:0}, at: zswap_compress mm/zswap.c:908 [inline] ffff80008fa1fc10 (cpu_hotplug_lock){++++}-{0:0}, at: zswap_store_page mm/zswap.c:1439 [inline] ffff80008fa1fc10 (cpu_hotplug_lock){++++}-{0:0}, at: zswap_store+0x834/0x185c mm/zswap.c:1546 but task is already holding lock: ffff80008fc71b00 (fs_reclaim){+.+.}-{0:0}, at: __perform_reclaim mm/page_alloc.c:3926 [inline] ffff80008fc71b00 (fs_reclaim){+.+.}-{0:0}, at: __alloc_pages_direct_reclaim+0xd4/0x330 mm/page_alloc.c:3951 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (fs_reclaim){+.+.}-{0:0}: __fs_reclaim_acquire mm/page_alloc.c:3853 [inline] fs_reclaim_acquire+0x84/0x120 mm/page_alloc.c:3867 might_alloc include/linux/sched/mm.h:318 [inline] slab_pre_alloc_hook mm/slub.c:4070 [inline] slab_alloc_node mm/slub.c:4148 [inline] __kmalloc_cache_node_noprof+0x5c/0x434 mm/slub.c:4337 kmalloc_node_noprof include/linux/slab.h:924 [inline] alloc_worker kernel/workqueue.c:2645 [inline] create_worker+0x110/0x644 kernel/workqueue.c:2788 workqueue_prepare_cpu+0xf0/0x180 kernel/workqueue.c:6635 cpuhp_invoke_callback+0x404/0x704 kernel/cpu.c:194 __cpuhp_invoke_callback_range kernel/cpu.c:965 [inline] cpuhp_invoke_callback_range kernel/cpu.c:989 [inline] cpuhp_up_callbacks kernel/cpu.c:1020 [inline] _cpu_up+0x3c8/0x70c kernel/cpu.c:1690 cpu_up+0x150/0x1d8 kernel/cpu.c:1722 cpuhp_bringup_mask+0xb8/0x220 kernel/cpu.c:1788 bringup_nonboot_cpus+0x48/0x4c kernel/cpu.c:1896 smp_init+0x3c/0x12c kernel/smp.c:1009 kernel_init_freeable+0x30c/0x478 init/main.c:1569 kernel_init+0x24/0x2a0 init/main.c:1466 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:862 -> #0 (cpu_hotplug_lock){++++}-{0:0}: check_prev_add kernel/locking/lockdep.c:3161 [inline] check_prevs_add kernel/locking/lockdep.c:3280 [inline] validate_chain kernel/locking/lockdep.c:3904 [inline] __lock_acquire+0x34f0/0x7904 kernel/locking/lockdep.c:5226 lock_acquire+0x23c/0x724 kernel/locking/lockdep.c:5849 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] cpus_read_lock+0x58/0x2a4 kernel/cpu.c:490 acomp_ctx_get_cpu mm/zswap.c:886 [inline] zswap_compress mm/zswap.c:908 [inline] zswap_store_page mm/zswap.c:1439 [inline] zswap_store+0x834/0x185c mm/zswap.c:1546 swap_writepage+0x958/0xf80 mm/page_io.c:279 pageout mm/vmscan.c:696 [inline] shrink_folio_list+0x29a4/0x498c mm/vmscan.c:1374 shrink_inactive_list mm/vmscan.c:1967 [inline] shrink_list mm/vmscan.c:2205 [inline] shrink_lruvec+0x11dc/0x2758 mm/vmscan.c:5734 shrink_node_memcgs mm/vmscan.c:5936 [inline] shrink_node+0xf64/0x2668 mm/vmscan.c:5977 shrink_zones mm/vmscan.c:6222 [inline] do_try_to_free_pages+0x5a8/0x1618 mm/vmscan.c:6284 try_to_free_pages+0x8d8/0x1160 mm/vmscan.c:6534 __perform_reclaim mm/page_alloc.c:3929 [inline] __alloc_pages_direct_reclaim+0x144/0x330 mm/page_alloc.c:3951 __alloc_pages_slowpath+0x664/0xd64 mm/page_alloc.c:4382 __alloc_pages_noprof+0x3d4/0x6a8 mm/page_alloc.c:4766 alloc_pages_mpol_noprof+0x33c/0x5f0 mm/mempolicy.c:2269 alloc_pages_noprof+0x168/0x200 mm/mempolicy.c:2348 get_free_pages_noprof+0x1c/0xc4 mm/page_alloc.c:4800 fill_page_cache_func+0xcc/0x23c kernel/rcu/tree.c:3682 process_one_work+0x7a8/0x15cc kernel/workqueue.c:3236 process_scheduled_works kernel/workqueue.c:3317 [inline] worker_thread+0x97c/0xeec kernel/workqueue.c:3398 kthread+0x288/0x310 kernel/kthread.c:389 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:862 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(fs_reclaim); lock(cpu_hotplug_lock); lock(fs_reclaim); rlock(cpu_hotplug_lock); *** DEADLOCK *** 3 locks held by kworker/0:2H/8944: #0: ffff0000c0028d48 ((wq_completion)events_highpri){+.+.}-{0:0}, at: process_one_work+0x60c/0x15cc kernel/workqueue.c:3210 #1: ffff80009e4b7c20 ((work_completion)(&(&krcp->page_cache_work)->work)){+.+.}-{0:0}, at: process_one_work+0x6a4/0x15cc kernel/workqueue.c:3210 #2: ffff80008fc71b00 (fs_reclaim){+.+.}-{0:0}, at: __perform_reclaim mm/page_alloc.c:3926 [inline] #2: ffff80008fc71b00 (fs_reclaim){+.+.}-{0:0}, at: __alloc_pages_direct_reclaim+0xd4/0x330 mm/page_alloc.c:3951 stack backtrace: CPU: 0 UID: 0 PID: 8944 Comm: kworker/0:2H Not tainted 6.13.0-rc7-syzkaller-g1950a0af2d55 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 Workqueue: events_highpri fill_page_cache_func Call trace: show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:466 (C) __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:120 dump_stack+0x1c/0x28 lib/dump_stack.c:129 print_circular_bug+0x154/0x1c0 kernel/locking/lockdep.c:2074 check_noncircular+0x310/0x404 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 kernel/locking/lockdep.c:3904 [inline] __lock_acquire+0x34f0/0x7904 kernel/locking/lockdep.c:5226 lock_acquire+0x23c/0x724 kernel/locking/lockdep.c:5849 percpu_down_read include/linux/percpu-rwsem.h:51 [inline] cpus_read_lock+0x58/0x2a4 kernel/cpu.c:490 acomp_ctx_get_cpu mm/zswap.c:886 [inline] zswap_compress mm/zswap.c:908 [inline] zswap_store_page mm/zswap.c:1439 [inline] zswap_store+0x834/0x185c mm/zswap.c:1546 swap_writepage+0x958/0xf80 mm/page_io.c:279 pageout mm/vmscan.c:696 [inline] shrink_folio_list+0x29a4/0x498c mm/vmscan.c:1374 shrink_inactive_list mm/vmscan.c:1967 [inline] shrink_list mm/vmscan.c:2205 [inline] shrink_lruvec+0x11dc/0x2758 mm/vmscan.c:5734 shrink_node_memcgs mm/vmscan.c:5936 [inline] shrink_node+0xf64/0x2668 mm/vmscan.c:5977 shrink_zones mm/vmscan.c:6222 [inline] do_try_to_free_pages+0x5a8/0x1618 mm/vmscan.c:6284 try_to_free_pages+0x8d8/0x1160 mm/vmscan.c:6534 __perform_reclaim mm/page_alloc.c:3929 [inline] __alloc_pages_direct_reclaim+0x144/0x330 mm/page_alloc.c:3951 __alloc_pages_slowpath+0x664/0xd64 mm/page_alloc.c:4382 __alloc_pages_noprof+0x3d4/0x6a8 mm/page_alloc.c:4766 alloc_pages_mpol_noprof+0x33c/0x5f0 mm/mempolicy.c:2269 alloc_pages_noprof+0x168/0x200 mm/mempolicy.c:2348 get_free_pages_noprof+0x1c/0xc4 mm/page_alloc.c:4800 fill_page_cache_func+0xcc/0x23c kernel/rcu/tree.c:3682 process_one_work+0x7a8/0x15cc kernel/workqueue.c:3236 process_scheduled_works kernel/workqueue.c:3317 [inline] worker_thread+0x97c/0xeec kernel/workqueue.c:3398 kthread+0x288/0x310 kernel/kthread.c:389 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:862