Date:   Mon, 12 Nov 2018 18:17:15 +0800
From:   <zhe.he@...driver.com>
To:     <catalin.marinas@....com>, <stable@...r.kernel.org>,
        <bigeasy@...utronix.de>, <tglx@...utronix.de>,
        <rostedt@...dmis.org>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>, <linux-rt-users@...r.kernel.org>
Subject: [PATCH] kmemleak: Turn kmemleak_lock to raw spinlock on RT

From: He Zhe <zhe.he@...driver.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@...driver.com>
Cc: stable@...r.kernel.org
Cc: catalin.marinas@....com
Cc: bigeasy@...utronix.de
Cc: tglx@...utronix.de
Cc: rostedt@...dmis.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);
 }
 
 /*
-- 
2.7.4

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