This is a note to let you know that I've just added the patch titled
dm thin metadata: Fix ABBA deadlock by resetting dm_bufio_client
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
dm-thin-metadata-fix-abba-deadlock-by-resetting-dm_b.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
commit b521537e2b33db4a11fb2f50277c92c280b67b4a
Author: Li Lingfeng <[email protected]>
Date: Mon Jun 5 15:03:16 2023 +0800
dm thin metadata: Fix ABBA deadlock by resetting dm_bufio_client
[ Upstream commit d48300120627a1cb98914738fff38b424625b8ad ]
As described in commit 8111964f1b85 ("dm thin: Fix ABBA deadlock between
shrink_slab and dm_pool_abort_metadata"), ABBA deadlocks will be
triggered because shrinker_rwsem currently needs to held by
dm_pool_abort_metadata() as a side-effect of thin-pool metadata
operation failure.
The following three problem scenarios have been noticed:
1) Described by commit 8111964f1b85 ("dm thin: Fix ABBA deadlock between
shrink_slab and dm_pool_abort_metadata")
2) shrinker_rwsem and throttle->lock
P1(drop cache) P2(kworker)
drop_caches_sysctl_handler
drop_slab
shrink_slab
down_read(&shrinker_rwsem) - LOCK A
do_shrink_slab
super_cache_scan
prune_icache_sb
dispose_list
evict
ext4_evict_inode
ext4_clear_inode
ext4_discard_preallocations
ext4_mb_load_buddy_gfp
ext4_mb_init_cache
ext4_wait_block_bitmap
__ext4_error
ext4_handle_error
ext4_commit_super
...
dm_submit_bio
do_worker
throttle_work_update
down_write(&t->lock) -- LOCK B
process_deferred_bios
commit
metadata_operation_failed
dm_pool_abort_metadata
dm_block_manager_create
dm_bufio_client_create
register_shrinker
down_write(&shrinker_rwsem)
-- LOCK A
thin_map
thin_bio_map
thin_defer_bio_with_throttle
throttle_lock
down_read(&t->lock) - LOCK B
3) shrinker_rwsem and wait_on_buffer
P1(drop cache) P2(kworker)
drop_caches_sysctl_handler
drop_slab
shrink_slab
down_read(&shrinker_rwsem) - LOCK A
do_shrink_slab
...
ext4_wait_block_bitmap
__ext4_error
ext4_handle_error
jbd2_journal_abort
jbd2_journal_update_sb_errno
jbd2_write_superblock
submit_bh
// LOCK B
// RELEASE B
do_worker
throttle_work_update
down_write(&t->lock) - LOCK B
process_deferred_bios
process_bio
commit
metadata_operation_failed
dm_pool_abort_metadata
dm_block_manager_create
dm_bufio_client_create
register_shrinker
register_shrinker_prepared
down_write(&shrinker_rwsem) - LOCK A
bio_endio
wait_on_buffer
__wait_on_buffer
Fix these by resetting dm_bufio_client without holding shrinker_rwsem.
Fixes: 8111964f1b85 ("dm thin: Fix ABBA deadlock between shrink_slab and
dm_pool_abort_metadata")
Cc: [email protected]
Signed-off-by: Li Lingfeng <[email protected]>
Signed-off-by: Mike Snitzer <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
index 382c5cc471952..100a6a236d92a 100644
--- a/drivers/md/dm-bufio.c
+++ b/drivers/md/dm-bufio.c
@@ -1914,6 +1914,13 @@ void dm_bufio_client_destroy(struct dm_bufio_client *c)
}
EXPORT_SYMBOL_GPL(dm_bufio_client_destroy);
+void dm_bufio_client_reset(struct dm_bufio_client *c)
+{
+ drop_buffers(c);
+ flush_work(&c->shrink_work);
+}
+EXPORT_SYMBOL_GPL(dm_bufio_client_reset);
+
void dm_bufio_set_sector_offset(struct dm_bufio_client *c, sector_t start)
{
c->start = start;
diff --git a/drivers/md/dm-thin-metadata.c b/drivers/md/dm-thin-metadata.c
index 4a0e15109997b..bb0e0a270f62a 100644
--- a/drivers/md/dm-thin-metadata.c
+++ b/drivers/md/dm-thin-metadata.c
@@ -597,6 +597,8 @@ static int __format_metadata(struct dm_pool_metadata *pmd)
r = dm_tm_create_with_sm(pmd->bm, THIN_SUPERBLOCK_LOCATION,
&pmd->tm, &pmd->metadata_sm);
if (r < 0) {
+ pmd->tm = NULL;
+ pmd->metadata_sm = NULL;
DMERR("tm_create_with_sm failed");
return r;
}
@@ -605,6 +607,7 @@ static int __format_metadata(struct dm_pool_metadata *pmd)
if (IS_ERR(pmd->data_sm)) {
DMERR("sm_disk_create failed");
r = PTR_ERR(pmd->data_sm);
+ pmd->data_sm = NULL;
goto bad_cleanup_tm;
}
@@ -635,11 +638,15 @@ static int __format_metadata(struct dm_pool_metadata *pmd)
bad_cleanup_nb_tm:
dm_tm_destroy(pmd->nb_tm);
+ pmd->nb_tm = NULL;
bad_cleanup_data_sm:
dm_sm_destroy(pmd->data_sm);
+ pmd->data_sm = NULL;
bad_cleanup_tm:
dm_tm_destroy(pmd->tm);
+ pmd->tm = NULL;
dm_sm_destroy(pmd->metadata_sm);
+ pmd->metadata_sm = NULL;
return r;
}
@@ -705,6 +712,8 @@ static int __open_metadata(struct dm_pool_metadata *pmd)
sizeof(disk_super->metadata_space_map_root),
&pmd->tm, &pmd->metadata_sm);
if (r < 0) {
+ pmd->tm = NULL;
+ pmd->metadata_sm = NULL;
DMERR("tm_open_with_sm failed");
goto bad_unlock_sblock;
}
@@ -714,6 +723,7 @@ static int __open_metadata(struct dm_pool_metadata *pmd)
if (IS_ERR(pmd->data_sm)) {
DMERR("sm_disk_open failed");
r = PTR_ERR(pmd->data_sm);
+ pmd->data_sm = NULL;
goto bad_cleanup_tm;
}
@@ -740,9 +750,12 @@ static int __open_metadata(struct dm_pool_metadata *pmd)
bad_cleanup_data_sm:
dm_sm_destroy(pmd->data_sm);
+ pmd->data_sm = NULL;
bad_cleanup_tm:
dm_tm_destroy(pmd->tm);
+ pmd->tm = NULL;
dm_sm_destroy(pmd->metadata_sm);
+ pmd->metadata_sm = NULL;
bad_unlock_sblock:
dm_bm_unlock(sblock);
@@ -789,9 +802,13 @@ static void __destroy_persistent_data_objects(struct
dm_pool_metadata *pmd,
bool destroy_bm)
{
dm_sm_destroy(pmd->data_sm);
+ pmd->data_sm = NULL;
dm_sm_destroy(pmd->metadata_sm);
+ pmd->metadata_sm = NULL;
dm_tm_destroy(pmd->nb_tm);
+ pmd->nb_tm = NULL;
dm_tm_destroy(pmd->tm);
+ pmd->tm = NULL;
if (destroy_bm)
dm_block_manager_destroy(pmd->bm);
}
@@ -999,8 +1016,7 @@ int dm_pool_metadata_close(struct dm_pool_metadata *pmd)
__func__, r);
}
pmd_write_unlock(pmd);
- if (!pmd->fail_io)
- __destroy_persistent_data_objects(pmd, true);
+ __destroy_persistent_data_objects(pmd, true);
kfree(pmd);
return 0;
@@ -1875,53 +1891,29 @@ static void __set_abort_with_changes_flags(struct
dm_pool_metadata *pmd)
int dm_pool_abort_metadata(struct dm_pool_metadata *pmd)
{
int r = -EINVAL;
- struct dm_block_manager *old_bm = NULL, *new_bm = NULL;
/* fail_io is double-checked with pmd->root_lock held below */
if (unlikely(pmd->fail_io))
return r;
- /*
- * Replacement block manager (new_bm) is created and old_bm destroyed
outside of
- * pmd root_lock to avoid ABBA deadlock that would result (due to
life-cycle of
- * shrinker associated with the block manager's bufio client vs pmd
root_lock).
- * - must take shrinker_rwsem without holding pmd->root_lock
- */
- new_bm = dm_block_manager_create(pmd->bdev, THIN_METADATA_BLOCK_SIZE <<
SECTOR_SHIFT,
- THIN_MAX_CONCURRENT_LOCKS);
-
pmd_write_lock(pmd);
if (pmd->fail_io) {
pmd_write_unlock(pmd);
- goto out;
+ return r;
}
-
__set_abort_with_changes_flags(pmd);
+
+ /* destroy data_sm/metadata_sm/nb_tm/tm */
__destroy_persistent_data_objects(pmd, false);
- old_bm = pmd->bm;
- if (IS_ERR(new_bm)) {
- DMERR("could not create block manager during abort");
- pmd->bm = NULL;
- r = PTR_ERR(new_bm);
- goto out_unlock;
- }
- pmd->bm = new_bm;
+ /* reset bm */
+ dm_block_manager_reset(pmd->bm);
+
+ /* rebuild data_sm/metadata_sm/nb_tm/tm */
r = __open_or_format_metadata(pmd, false);
- if (r) {
- pmd->bm = NULL;
- goto out_unlock;
- }
- new_bm = NULL;
-out_unlock:
if (r)
pmd->fail_io = true;
pmd_write_unlock(pmd);
- dm_block_manager_destroy(old_bm);
-out:
- if (new_bm && !IS_ERR(new_bm))
- dm_block_manager_destroy(new_bm);
-
return r;
}
diff --git a/drivers/md/persistent-data/dm-block-manager.c
b/drivers/md/persistent-data/dm-block-manager.c
index 1f40100908d7c..2bbfbb704c751 100644
--- a/drivers/md/persistent-data/dm-block-manager.c
+++ b/drivers/md/persistent-data/dm-block-manager.c
@@ -415,6 +415,12 @@ void dm_block_manager_destroy(struct dm_block_manager *bm)
}
EXPORT_SYMBOL_GPL(dm_block_manager_destroy);
+void dm_block_manager_reset(struct dm_block_manager *bm)
+{
+ dm_bufio_client_reset(bm->bufio);
+}
+EXPORT_SYMBOL_GPL(dm_block_manager_reset);
+
unsigned int dm_bm_block_size(struct dm_block_manager *bm)
{
return dm_bufio_get_block_size(bm->bufio);
diff --git a/drivers/md/persistent-data/dm-block-manager.h
b/drivers/md/persistent-data/dm-block-manager.h
index 58a23b8ec1902..4371d85d3c258 100644
--- a/drivers/md/persistent-data/dm-block-manager.h
+++ b/drivers/md/persistent-data/dm-block-manager.h
@@ -35,6 +35,7 @@ struct dm_block_manager *dm_block_manager_create(
struct block_device *bdev, unsigned int block_size,
unsigned int max_held_per_thread);
void dm_block_manager_destroy(struct dm_block_manager *bm);
+void dm_block_manager_reset(struct dm_block_manager *bm);
unsigned int dm_bm_block_size(struct dm_block_manager *bm);
dm_block_t dm_bm_nr_blocks(struct dm_block_manager *bm);
diff --git a/drivers/md/persistent-data/dm-space-map.h
b/drivers/md/persistent-data/dm-space-map.h
index a015cd11f6e97..85aa0a3974fe0 100644
--- a/drivers/md/persistent-data/dm-space-map.h
+++ b/drivers/md/persistent-data/dm-space-map.h
@@ -76,7 +76,8 @@ struct dm_space_map {
static inline void dm_sm_destroy(struct dm_space_map *sm)
{
- sm->destroy(sm);
+ if (sm)
+ sm->destroy(sm);
}
static inline int dm_sm_extend(struct dm_space_map *sm, dm_block_t
extra_blocks)
diff --git a/drivers/md/persistent-data/dm-transaction-manager.c
b/drivers/md/persistent-data/dm-transaction-manager.c
index 39885f8355847..557a3ecfe75a0 100644
--- a/drivers/md/persistent-data/dm-transaction-manager.c
+++ b/drivers/md/persistent-data/dm-transaction-manager.c
@@ -197,6 +197,9 @@ EXPORT_SYMBOL_GPL(dm_tm_create_non_blocking_clone);
void dm_tm_destroy(struct dm_transaction_manager *tm)
{
+ if (!tm)
+ return;
+
if (!tm->is_clone)
wipe_shadow_table(tm);
diff --git a/include/linux/dm-bufio.h b/include/linux/dm-bufio.h
index 1262d92ab88fc..2e71ca35942e9 100644
--- a/include/linux/dm-bufio.h
+++ b/include/linux/dm-bufio.h
@@ -37,6 +37,8 @@ dm_bufio_client_create(struct block_device *bdev, unsigned
int block_size,
*/
void dm_bufio_client_destroy(struct dm_bufio_client *c);
+void dm_bufio_client_reset(struct dm_bufio_client *c);
+
/*
* Set the sector range.
* When this function is called, there must be no I/O in progress on the bufio
