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
