Currently, for double invoke call_rcu(), will dump rcu_head objects memory info, if the objects is not allocated from the slab allocator, the vmalloc_dump_obj() will be invoke and the vmap_area_lock spinlock need to be held, since the call_rcu() can be invoked in interrupt context, therefore, there is a possibility of spinlock deadlock scenarios. And in Preempt-RT kernel, the rcutorture test also trigger the following lockdep warning: BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 1, name: swapper/0 preempt_count: 1, expected: 0 RCU nest depth: 1, expected: 1 3 locks held by swapper/0/1: #0: ffffffffb534ee80 (fullstop_mutex){+.+.}-{4:4}, at: torture_init_begin+0x24/0xa0 #1: ffffffffb5307940 (rcu_read_lock){....}-{1:3}, at: rcu_torture_init+0x1ec7/0x2370 #2: ffffffffb536af40 (vmap_area_lock){+.+.}-{3:3}, at: find_vmap_area+0x1f/0x70 irq event stamp: 565512 hardirqs last enabled at (565511): [<ffffffffb379b138>] __call_rcu_common+0x218/0x940 hardirqs last disabled at (565512): [<ffffffffb5804262>] rcu_torture_init+0x20b2/0x2370 softirqs last enabled at (399112): [<ffffffffb36b2586>] __local_bh_enable_ip+0x126/0x170 softirqs last disabled at (399106): [<ffffffffb43fef59>] inet_register_protosw+0x9/0x1d0 Preemption disabled at: [<ffffffffb58040c3>] rcu_torture_init+0x1f13/0x2370 CPU: 0 PID: 1 Comm: swapper/0 Tainted: G W 6.5.0-rc4-rt2-yocto-preempt-rt+ #15 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.2-0-gea1b7a073390-prebuilt.qemu.org 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x68/0xb0 dump_stack+0x14/0x20 __might_resched+0x1aa/0x280 ? __pfx_rcu_torture_err_cb+0x10/0x10 rt_spin_lock+0x53/0x130 ? find_vmap_area+0x1f/0x70 find_vmap_area+0x1f/0x70 vmalloc_dump_obj+0x20/0x60 mem_dump_obj+0x22/0x90 __call_rcu_common+0x5bf/0x940 ? debug_smp_processor_id+0x1b/0x30 call_rcu_hurry+0x14/0x20 rcu_torture_init+0x1f82/0x2370 ? __pfx_rcu_torture_leak_cb+0x10/0x10 ? __pfx_rcu_torture_leak_cb+0x10/0x10 ? __pfx_rcu_torture_init+0x10/0x10 do_one_initcall+0x6c/0x300 ? debug_smp_processor_id+0x1b/0x30 kernel_init_freeable+0x2b9/0x540 ? __pfx_kernel_init+0x10/0x10 kernel_init+0x1f/0x150 ret_from_fork+0x40/0x50 ? __pfx_kernel_init+0x10/0x10 ret_from_fork_asm+0x1b/0x30 </TASK> The statistics about the source of 'rhp', the kmem_valid_obj() accounts for more than 97.5%, and vmalloc accounts for less than 1%, this statistic comes from leizhen. this commit therefore drop vmalloc_dump_obj() from mem_dump_obj() and only check whether is vmalloc address. Signed-off-by: Zqiang <qiang.zhang1211@xxxxxxxxx> --- include/linux/vmalloc.h | 5 ----- mm/util.c | 7 +++---- mm/vmalloc.c | 14 -------------- 3 files changed, 3 insertions(+), 23 deletions(-) diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h index c720be70c8dd..d7c4e112a4ad 100644 --- a/include/linux/vmalloc.h +++ b/include/linux/vmalloc.h @@ -289,10 +289,5 @@ pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms) int register_vmap_purge_notifier(struct notifier_block *nb); int unregister_vmap_purge_notifier(struct notifier_block *nb); -#if defined(CONFIG_MMU) && defined(CONFIG_PRINTK) -bool vmalloc_dump_obj(void *object); -#else -static inline bool vmalloc_dump_obj(void *object) { return false; } -#endif #endif /* _LINUX_VMALLOC_H */ diff --git a/mm/util.c b/mm/util.c index ddfbb22dc187..fbc007adc108 100644 --- a/mm/util.c +++ b/mm/util.c @@ -1066,10 +1066,9 @@ void mem_dump_obj(void *object) if (kmem_dump_obj(object)) return; - if (vmalloc_dump_obj(object)) - return; - - if (virt_addr_valid(object)) + if (is_vmalloc_addr(object)) + type = "vmalloc memory"; + else if (virt_addr_valid(object)) type = "non-slab/vmalloc memory"; else if (object == NULL) type = "NULL pointer"; diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 93cf99aba335..224af955bcb5 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -4271,20 +4271,6 @@ void pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms) } #endif /* CONFIG_SMP */ -#ifdef CONFIG_PRINTK -bool vmalloc_dump_obj(void *object) -{ - struct vm_struct *vm; - void *objp = (void *)PAGE_ALIGN((unsigned long)object); - - vm = find_vm_area(objp); - if (!vm) - return false; - pr_cont(" %u-page vmalloc region starting at %#lx allocated at %pS\n", - vm->nr_pages, (unsigned long)vm->addr, vm->caller); - return true; -} -#endif #ifdef CONFIG_PROC_FS static void *s_start(struct seq_file *m, loff_t *pos) -- 2.17.1