Messages in this thread | | | Subject | Re: [PATCH v3] dm thin: Fix ABBA deadlock between shrink_slab and dm_pool_abort_metadata | From | Zhihao Cheng <> | Date | Thu, 1 Dec 2022 10:10:59 +0800 |
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> On Wed, Nov 30 2022 at 8:31P -0500 > Zhihao Cheng <chengzhihao1@huawei.com> wrote: > >> Following concurrent processes: >> >> P1(drop cache) P2(kworker) [...] >> 2.31.1 >> > > I've picked your patch up and folded into these following changes: > > diff --git a/drivers/md/dm-thin-metadata.c b/drivers/md/dm-thin-metadata.c > index 7729372519b8..1a62226ac34e 100644 > --- a/drivers/md/dm-thin-metadata.c > +++ b/drivers/md/dm-thin-metadata.c > @@ -776,12 +776,15 @@ static int __create_persistent_data_objects(struct dm_pool_metadata *pmd, bool f > return r; > } > > -static void __destroy_persistent_data_objects(struct dm_pool_metadata *pmd) > +static void __destroy_persistent_data_objects(struct dm_pool_metadata *pmd, > + bool destroy_bm) > { > dm_sm_destroy(pmd->data_sm); > dm_sm_destroy(pmd->metadata_sm); > dm_tm_destroy(pmd->nb_tm); > dm_tm_destroy(pmd->tm); > + if (destroy_bm) > + dm_block_manager_destroy(pmd->bm); > } > > static int __begin_transaction(struct dm_pool_metadata *pmd) > @@ -987,10 +990,8 @@ 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); > - dm_block_manager_destroy(pmd->bm); > - } > + if (!pmd->fail_io) > + __destroy_persistent_data_objects(pmd, true); > > kfree(pmd); > return 0; > @@ -1863,9 +1864,16 @@ int dm_pool_abort_metadata(struct dm_pool_metadata *pmd) > int r = -EINVAL; > struct dm_block_manager *old_bm = NULL, *new_bm = NULL; > > - if (pmd->fail_io) > - return -EINVAL; > + /* 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); > > @@ -1876,11 +1884,10 @@ int dm_pool_abort_metadata(struct dm_pool_metadata *pmd) > } > > __set_abort_with_changes_flags(pmd); > - __destroy_persistent_data_objects(pmd); > + __destroy_persistent_data_objects(pmd, false); > old_bm = pmd->bm; > if (IS_ERR(new_bm)) { > - /* Return back if creating dm_block_manager failed. */ > - DMERR("could not create block manager"); > + DMERR("could not create block manager during abort"); > pmd->bm = NULL; > r = PTR_ERR(new_bm); > goto out_unlock; >
Hi,Mike This version is great, thanks for reviewing and modifying.
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