[PATCH] dm thin: Fix ABBA deadlock by resetting dm_bufio_client

From: Li Lingfeng
Date: Mon Jun 05 2023 - 03:25:59 EST

Next message: Mark Rutland: "Re: [PATCH V11 01/10] drivers: perf: arm_pmu: Add new sched_task() callback"
Previous message: Hongyu Xie: "[PACTH v4 -next] tty: serial: add panic serial helper"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

As described in commit 8111964f1b85 ("dm thin: Fix ABBA deadlock between
shrink_slab and dm_pool_abort_metadata"), ABBA deadlock will be triggered
since shrinker_rwsem need to be held when operations failed on dm pool
metadata.

We have noticed the following three problem scenarios:
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.

Signed-off-by: Li Lingfeng <lilingfeng3@xxxxxxxxxx>
---
drivers/md/dm-bufio.c | 7 +++
drivers/md/dm-thin-metadata.c | 58 ++++++++-----------
drivers/md/persistent-data/dm-block-manager.c | 6 ++
drivers/md/persistent-data/dm-block-manager.h | 1 +
drivers/md/persistent-data/dm-space-map.h | 3 +-
.../persistent-data/dm-transaction-manager.c | 3 +
include/linux/dm-bufio.h | 2 +
7 files changed, 46 insertions(+), 34 deletions(-)

diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
index eea977662e81..a7079b38756a 100644
--- a/drivers/md/dm-bufio.c
+++ b/drivers/md/dm-bufio.c
@@ -2592,6 +2592,13 @@ 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 9f5cb52c5763..63d92d388ee6 100644
--- a/drivers/md/dm-thin-metadata.c
+++ b/drivers/md/dm-thin-metadata.c
@@ -603,6 +603,8 @@ 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;
}
@@ -611,6 +613,7 @@ 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;
}

@@ -641,11 +644,15 @@ 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;
}
@@ -711,6 +718,8 @@ 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;
}
@@ -720,6 +729,7 @@ 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;
}

@@ -746,9 +756,12 @@ 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);

@@ -795,9 +808,13 @@ 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);
}
@@ -1005,8 +1022,7 @@ 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;
@@ -1877,53 +1893,29 @@ 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_mutex 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 7bdfc23f758a..0e010e1204aa 100644
--- a/drivers/md/persistent-data/dm-block-manager.c
+++ b/drivers/md/persistent-data/dm-block-manager.c
@@ -421,6 +421,12 @@ 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 5746b0f82a03..f706d3de8d5a 100644
--- a/drivers/md/persistent-data/dm-block-manager.h
+++ b/drivers/md/persistent-data/dm-block-manager.h
@@ -36,6 +36,7 @@ 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 dab490353781..6bf69922b5ad 100644
--- a/drivers/md/persistent-data/dm-space-map.h
+++ b/drivers/md/persistent-data/dm-space-map.h
@@ -77,7 +77,8 @@ 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 6dc016248baf..c88fa6266203 100644
--- a/drivers/md/persistent-data/dm-transaction-manager.c
+++ b/drivers/md/persistent-data/dm-transaction-manager.c
@@ -199,6 +199,9 @@ 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 681656a1c03d..75e7d8cbb532 100644
--- a/include/linux/dm-bufio.h
+++ b/include/linux/dm-bufio.h
@@ -38,6 +38,8 @@ 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
--
2.31.1

Next message: Mark Rutland: "Re: [PATCH V11 01/10] drivers: perf: arm_pmu: Add new sched_task() callback"
Previous message: Hongyu Xie: "[PACTH v4 -next] tty: serial: add panic serial helper"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]