From: He Zhe zhe.he@windriver.com
kmemleak_lock, as a rwlock on RT, can possibly be held in atomic context and causes the follow BUG.
BUG: scheduling while atomic: migration/15/132/0x00000002 Modules linked in: iTCO_wdt iTCO_vendor_support intel_rapl pcc_cpufreq pnd2_edac intel_powerclamp coretemp crct10dif_pclmul crct10dif_common aesni_intel matroxfb_base aes_x86_64 matroxfb_g450 matroxfb_accel crypto_simd matroxfb_DAC1064 cryptd glue_helper g450_pll matroxfb_misc i2c_ismt i2c_i801 acpi_cpufreq Preemption disabled at: [<ffffffff8c927c11>] cpu_stopper_thread+0x71/0x100 CPU: 15 PID: 132 Comm: migration/15 Not tainted 4.19.0-rt1-preempt-rt #1 Hardware name: Intel Corp. Harcuvar/Server, BIOS HAVLCRB1.X64.0015.D62.1708310404 08/31/2017 Call Trace: dump_stack+0x4f/0x6a ? cpu_stopper_thread+0x71/0x100 __schedule_bug.cold.16+0x38/0x55 __schedule+0x484/0x6c0 schedule+0x3d/0xe0 rt_spin_lock_slowlock_locked+0x118/0x2a0 rt_spin_lock_slowlock+0x57/0x90 __rt_spin_lock+0x26/0x30 __write_rt_lock+0x23/0x1a0 ? intel_pmu_cpu_dying+0x67/0x70 rt_write_lock+0x2a/0x30 find_and_remove_object+0x1e/0x80 delete_object_full+0x10/0x20 kmemleak_free+0x32/0x50 kfree+0x104/0x1f0 ? x86_pmu_starting_cpu+0x30/0x30 intel_pmu_cpu_dying+0x67/0x70 x86_pmu_dying_cpu+0x1a/0x30 cpuhp_invoke_callback+0x92/0x700 take_cpu_down+0x70/0xa0 multi_cpu_stop+0x62/0xc0 ? cpu_stop_queue_work+0x130/0x130 cpu_stopper_thread+0x79/0x100 smpboot_thread_fn+0x20f/0x2d0 kthread+0x121/0x140 ? sort_range+0x30/0x30 ? kthread_park+0x90/0x90 ret_from_fork+0x35/0x40
And on v4.18 stable tree the following call trace, caused by grabbing kmemleak_lock again, is also observed.
kernel BUG at kernel/locking/rtmutex.c:1048! invalid opcode: 0000 [#1] PREEMPT SMP PTI CPU: 5 PID: 689 Comm: mkfs.ext4 Not tainted 4.18.16-rt9-preempt-rt #1 Hardware name: Intel Corp. Harcuvar/Server, BIOS HAVLCRB1.X64.0015.D62.1708310404 08/31/2017 RIP: 0010:rt_spin_lock_slowlock_locked+0x277/0x2a0 Code: e8 5e 64 61 ff e9 bc fe ff ff e8 54 64 61 ff e9 b7 fe ff ff 0f 0b e8 98 57 53 ff e9 43 fe ff ff e8 8e 57 53 ff e9 74 ff ff ff <0f> 0b 0f 0b 0f 0b 48 8b 43 10 48 85 c0 74 06 48 3b 58 38 75 0b 49 RSP: 0018:ffff936846d4f3b0 EFLAGS: 00010046 RAX: ffff8e3680361e00 RBX: ffffffff83a8b240 RCX: 0000000000000001 RDX: 0000000000000000 RSI: ffff8e3680361e00 RDI: ffffffff83a8b258 RBP: ffff936846d4f3e8 R08: ffff8e3680361e01 R09: ffffffff82adfdf0 R10: ffffffff827ede18 R11: 0000000000000000 R12: ffff936846d4f3f8 R13: ffff8e3680361e00 R14: ffff936846d4f3f8 R15: 0000000000000246 FS: 00007fc8b6bfd780(0000) GS:ffff8e369f340000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055fb5659e000 CR3: 00000007fdd14000 CR4: 00000000003406e0 Call Trace: ? preempt_count_add+0x74/0xc0 rt_spin_lock_slowlock+0x57/0x90 ? __kernel_text_address+0x12/0x40 ? __save_stack_trace+0x75/0x100 __rt_spin_lock+0x26/0x30 __write_rt_lock+0x23/0x1a0 rt_write_lock+0x2a/0x30 create_object+0x17d/0x2b0 kmemleak_alloc+0x34/0x50 kmem_cache_alloc+0x146/0x220 ? mempool_alloc_slab+0x15/0x20 mempool_alloc_slab+0x15/0x20 mempool_alloc+0x65/0x170 sg_pool_alloc+0x21/0x60 __sg_alloc_table+0x101/0x160 ? sg_free_table_chained+0x30/0x30 sg_alloc_table_chained+0x8b/0xb0 scsi_init_sgtable+0x31/0x90 scsi_init_io+0x44/0x130 sd_setup_write_same16_cmnd+0xef/0x150 sd_init_command+0x6bf/0xaa0 ? cgroup_base_stat_cputime_account_end.isra.0+0x26/0x60 ? elv_rb_del+0x2a/0x40 scsi_setup_cmnd+0x8e/0x140 scsi_prep_fn+0x5d/0x140 blk_peek_request+0xda/0x2f0 scsi_request_fn+0x33/0x550 ? cfq_rb_erase+0x23/0x40 __blk_run_queue+0x43/0x60 cfq_insert_request+0x2f3/0x5d0 __elv_add_request+0x160/0x290 blk_flush_plug_list+0x204/0x230 schedule+0x87/0xe0 __write_rt_lock+0x18b/0x1a0 rt_write_lock+0x2a/0x30 create_object+0x17d/0x2b0 kmemleak_alloc+0x34/0x50 __kmalloc_node+0x1cd/0x340 alloc_request_size+0x30/0x70 mempool_alloc+0x65/0x170 ? ioc_lookup_icq+0x54/0x70 get_request+0x4e3/0x8d0 ? wait_woken+0x80/0x80 blk_queue_bio+0x153/0x470 generic_make_request+0x1dc/0x3f0 submit_bio+0x49/0x140 ? next_bio+0x38/0x40 submit_bio_wait+0x59/0x90 blkdev_issue_discard+0x7a/0xd0 ? _raw_spin_unlock_irqrestore+0x18/0x50 blk_ioctl_discard+0xc7/0x110 blkdev_ioctl+0x57e/0x960 ? __wake_up+0x13/0x20 block_ioctl+0x3d/0x50 do_vfs_ioctl+0xa8/0x610 ? vfs_write+0x166/0x1b0 ksys_ioctl+0x67/0x90 __x64_sys_ioctl+0x1a/0x20 do_syscall_64+0x4d/0xf0 entry_SYSCALL_64_after_hwframe+0x44/0xa9
kmemleak is an error detecting feature. We would not expect as good performance as without it. As there is no raw rwlock defining helpers, we turn kmemleak_lock to a raw spinlock.
Signed-off-by: He Zhe zhe.he@windriver.com Cc: stable@vger.kernel.org Cc: catalin.marinas@arm.com Cc: bigeasy@linutronix.de Cc: tglx@linutronix.de Cc: rostedt@goodmis.org --- mm/kmemleak.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-)
diff --git a/mm/kmemleak.c b/mm/kmemleak.c index 17dd883..b68a3d0 100644 --- a/mm/kmemleak.c +++ b/mm/kmemleak.c @@ -26,7 +26,7 @@ * * The following locks and mutexes are used by kmemleak: * - * - kmemleak_lock (rwlock): protects the object_list modifications and + * - kmemleak_lock (raw spinlock): protects the object_list modifications and * accesses to the object_tree_root. The object_list is the main list * holding the metadata (struct kmemleak_object) for the allocated memory * blocks. The object_tree_root is a red black tree used to look-up @@ -197,7 +197,7 @@ static LIST_HEAD(gray_list); /* search tree for object boundaries */ static struct rb_root object_tree_root = RB_ROOT; /* rw_lock protecting the access to object_list and object_tree_root */ -static DEFINE_RWLOCK(kmemleak_lock); +static DEFINE_RAW_SPINLOCK(kmemleak_lock);
/* allocation caches for kmemleak internal data */ static struct kmem_cache *object_cache; @@ -491,9 +491,9 @@ static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias) struct kmemleak_object *object;
rcu_read_lock(); - read_lock_irqsave(&kmemleak_lock, flags); + raw_spin_lock_irqsave(&kmemleak_lock, flags); object = lookup_object(ptr, alias); - read_unlock_irqrestore(&kmemleak_lock, flags); + raw_spin_unlock_irqrestore(&kmemleak_lock, flags);
/* check whether the object is still available */ if (object && !get_object(object)) @@ -513,13 +513,13 @@ static struct kmemleak_object *find_and_remove_object(unsigned long ptr, int ali unsigned long flags; struct kmemleak_object *object;
- write_lock_irqsave(&kmemleak_lock, flags); + raw_spin_lock_irqsave(&kmemleak_lock, flags); object = lookup_object(ptr, alias); if (object) { rb_erase(&object->rb_node, &object_tree_root); list_del_rcu(&object->object_list); } - write_unlock_irqrestore(&kmemleak_lock, flags); + raw_spin_unlock_irqrestore(&kmemleak_lock, flags);
return object; } @@ -593,7 +593,7 @@ static struct kmemleak_object *create_object(unsigned long ptr, size_t size, /* kernel backtrace */ object->trace_len = __save_stack_trace(object->trace);
- write_lock_irqsave(&kmemleak_lock, flags); + raw_spin_lock_irqsave(&kmemleak_lock, flags);
min_addr = min(min_addr, ptr); max_addr = max(max_addr, ptr + size); @@ -624,7 +624,7 @@ static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
list_add_tail_rcu(&object->object_list, &object_list); out: - write_unlock_irqrestore(&kmemleak_lock, flags); + raw_spin_unlock_irqrestore(&kmemleak_lock, flags); return object; }
@@ -1310,7 +1310,7 @@ static void scan_block(void *_start, void *_end, unsigned long *end = _end - (BYTES_PER_POINTER - 1); unsigned long flags;
- read_lock_irqsave(&kmemleak_lock, flags); + raw_spin_lock_irqsave(&kmemleak_lock, flags); for (ptr = start; ptr < end; ptr++) { struct kmemleak_object *object; unsigned long pointer; @@ -1367,7 +1367,7 @@ static void scan_block(void *_start, void *_end, spin_unlock(&object->lock); } } - read_unlock_irqrestore(&kmemleak_lock, flags); + raw_spin_unlock_irqrestore(&kmemleak_lock, flags); }
/*