On 11/13/18 4:11 AM, zhe...@windriver.com wrote:
From: He Zhe <zhe...@windriver.com>
See https://lore.kernel.org/patchwork/patch/1011368/ for upstream status.
kmemleak_lock, as a rwlock on RT, can possibly be held in atomic context and
causes the follow BUG.
Thanks. I'm waiting to see if there's any upstream feedback, and
will wait a couple more days before deciding to merge.
The alternative to making this a raw lock would be to simply declare
it incompatible with -rt (Which is what we've done with different
debug mechanisms in the past). Since there really should be relatively
few (none??) -rt specific kmemleaks, and if you are really concerned
about -rt, you likely wouldn't be running with it enabled.
Bruce
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
The following call trace, caused by grabbing kmemleak_lock twice, 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...@windriver.com>
---
mm/kmemleak.c | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)
diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 9a085d5..2d00961 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);
}
/*
--
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