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authormonty_pavel@sina.com <monty_pavel@sina.com>2017-11-25 01:43:50 +0800
committerMike Snitzer <snitzer@redhat.com>2017-12-04 10:23:10 -0500
commit7e6358d244e4706fe612a77b9c36519a33600ac0 (patch)
treefa6d4e26588d81aab30dfbf4bff8235a789a54a6 /drivers/md/dm-snap.c
parentafc567a4977b2d798e05153dd131a3c8d4758c0c (diff)
dm: fix various targets to dm_register_target after module __init resources created
A NULL pointer is seen if two concurrent "vgchange -ay -K <vg name>" processes race to load the dm-thin-pool module: PID: 25992 TASK: ffff883cd7d23500 CPU: 4 COMMAND: "vgchange" #0 [ffff883cd743d600] machine_kexec at ffffffff81038fa9 0000001 [ffff883cd743d660] crash_kexec at ffffffff810c5992 0000002 [ffff883cd743d730] oops_end at ffffffff81515c90 0000003 [ffff883cd743d760] no_context at ffffffff81049f1b 0000004 [ffff883cd743d7b0] __bad_area_nosemaphore at ffffffff8104a1a5 0000005 [ffff883cd743d800] bad_area at ffffffff8104a2ce 0000006 [ffff883cd743d830] __do_page_fault at ffffffff8104aa6f 0000007 [ffff883cd743d950] do_page_fault at ffffffff81517bae 0000008 [ffff883cd743d980] page_fault at ffffffff81514f95 [exception RIP: kmem_cache_alloc+108] RIP: ffffffff8116ef3c RSP: ffff883cd743da38 RFLAGS: 00010046 RAX: 0000000000000004 RBX: ffffffff81121b90 RCX: ffff881bf1e78cc0 RDX: 0000000000000000 RSI: 00000000000000d0 RDI: 0000000000000000 RBP: ffff883cd743da68 R8: ffff881bf1a4eb00 R9: 0000000080042000 R10: 0000000000002000 R11: 0000000000000000 R12: 00000000000000d0 R13: 0000000000000000 R14: 00000000000000d0 R15: 0000000000000246 ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0018 0000009 [ffff883cd743da70] mempool_alloc_slab at ffffffff81121ba5 0000010 [ffff883cd743da80] mempool_create_node at ffffffff81122083 0000011 [ffff883cd743dad0] mempool_create at ffffffff811220f4 0000012 [ffff883cd743dae0] pool_ctr at ffffffffa08de049 [dm_thin_pool] 0000013 [ffff883cd743dbd0] dm_table_add_target at ffffffffa0005f2f [dm_mod] 0000014 [ffff883cd743dc30] table_load at ffffffffa0008ba9 [dm_mod] 0000015 [ffff883cd743dc90] ctl_ioctl at ffffffffa0009dc4 [dm_mod] The race results in a NULL pointer because: Process A (vgchange -ay -K): a. send DM_LIST_VERSIONS_CMD ioctl; b. pool_target not registered; c. modprobe dm_thin_pool and wait until end. Process B (vgchange -ay -K): a. send DM_LIST_VERSIONS_CMD ioctl; b. pool_target registered; c. table_load->dm_table_add_target->pool_ctr; d. _new_mapping_cache is NULL and panic. Note: 1. process A and process B are two concurrent processes. 2. pool_target can be detected by process B but _new_mapping_cache initialization has not ended. To fix dm-thin-pool, and other targets (cache, multipath, and snapshot) with the same problem, simply dm_register_target() after all resources created during module init (as labelled with __init) are finished. Cc: stable@vger.kernel.org Signed-off-by: monty <monty_pavel@sina.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md/dm-snap.c')
-rw-r--r--drivers/md/dm-snap.c48
1 files changed, 24 insertions, 24 deletions
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 1113b42e1eda..a0613bd8ed00 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -2411,24 +2411,6 @@ static int __init dm_snapshot_init(void)
return r;
}
- r = dm_register_target(&snapshot_target);
- if (r < 0) {
- DMERR("snapshot target register failed %d", r);
- goto bad_register_snapshot_target;
- }
-
- r = dm_register_target(&origin_target);
- if (r < 0) {
- DMERR("Origin target register failed %d", r);
- goto bad_register_origin_target;
- }
-
- r = dm_register_target(&merge_target);
- if (r < 0) {
- DMERR("Merge target register failed %d", r);
- goto bad_register_merge_target;
- }
-
r = init_origin_hash();
if (r) {
DMERR("init_origin_hash failed.");
@@ -2449,19 +2431,37 @@ static int __init dm_snapshot_init(void)
goto bad_pending_cache;
}
+ r = dm_register_target(&snapshot_target);
+ if (r < 0) {
+ DMERR("snapshot target register failed %d", r);
+ goto bad_register_snapshot_target;
+ }
+
+ r = dm_register_target(&origin_target);
+ if (r < 0) {
+ DMERR("Origin target register failed %d", r);
+ goto bad_register_origin_target;
+ }
+
+ r = dm_register_target(&merge_target);
+ if (r < 0) {
+ DMERR("Merge target register failed %d", r);
+ goto bad_register_merge_target;
+ }
+
return 0;
-bad_pending_cache:
- kmem_cache_destroy(exception_cache);
-bad_exception_cache:
- exit_origin_hash();
-bad_origin_hash:
- dm_unregister_target(&merge_target);
bad_register_merge_target:
dm_unregister_target(&origin_target);
bad_register_origin_target:
dm_unregister_target(&snapshot_target);
bad_register_snapshot_target:
+ kmem_cache_destroy(pending_cache);
+bad_pending_cache:
+ kmem_cache_destroy(exception_cache);
+bad_exception_cache:
+ exit_origin_hash();
+bad_origin_hash:
dm_exception_store_exit();
return r;