kernel/git/next/linux-next.git/drivers/md/dm-thin-metadata.c, branch master

dm thin metadata: fix superblock refcount leak on snapshot shadow failure

2026-07-11T13:18:51+00:00

__reserve_metadata_snap() increments THIN_SUPERBLOCK_LOCATION in the metadata space map before shadowing it. When dm_tm_shadow_block() fails, a reference is leaked in the metadata space map. Fix by adding the missing dm_sm_dec_block(). Signed-off-by: Genjian Zhang Signed-off-by: Mikulas Patocka Fixes: cc8394d86f04 ("dm thin: provide userspace access to pool metadata") Cc: stable@vger.kernel.org

dm thin metadata: fix metadata snapshot consistency on commit failure

2026-07-08T20:33:34+00:00

__reserve_metadata_snap() and __release_metadata_snap() modify the superblock's held_root directly in the block_manager's buffer. If the subsequent metadata commit fails, the held_root gets flushed to disk through the abort_transaction path, resulting in inconsistent metadata. Reproducer 1: __reserve_metadata_snap() 1. Create a 2 MiB metadata device and make the region after the 14th block inaccessible, to trigger metadata commit failure in the subsequent reserve_metadata_snap operation. The 14th block will be the shadow destination for the index block. dmsetup create tmeta --table "0 112 linear /dev/sdc 0 112 3984 error" 2. Create a 16 MiB thin-pool dmsetup create tdata --table "0 32768 zero" dd if=/dev/zero of=/dev/mapper/tmeta bs=4k count=1 dmsetup create tpool --table "0 32768 thin-pool /dev/mapper/tmeta \ /dev/mapper/tdata 128 0 1 skip_block_zeroing" 3. Take a metadata snapshot to trigger metadata commit failure and transaction abort. However, the held_root is written to disk, breaking metadata consistency. dmsetup message tpool 0 "reserve_metadata_snap" thin_check v1.2.2 result: Bad reference count for metadata block 6. Expected 2, but space map contains 1. Bad reference count for metadata block 7. Expected 2, but space map contains 1. Bad reference count for metadata block 13. Expected 1, but space map contains 0. Reproducer 2: __release_metadata_snap() 1. Create a 2 MiB metadata device and make the region after the 16th block inaccessible, to trigger metadata commit failure in the subsequent release_metadata_snap operation. The 16th block will be the shadow destination for the index block. dmsetup create tmeta --table "0 128 linear /dev/sdc 0 128 3968 error" 2. Create a 16 MiB thin-pool dmsetup create tdata --table "0 32768 zero" dd if=/dev/zero of=/dev/mapper/tmeta bs=4k count=1 dmsetup create tpool --table "0 32768 thin-pool /dev/mapper/tmeta \ /dev/mapper/tdata 128 0 1 skip_block_zeroing" 3. Reserve then release the metadata snapshot, to trigger metadata commit failure and transaction abort. The held_root gets removed from the on-disk superblock, causing inconsistent metadata. dmsetup message tpool 0 "reserve_metadata_snap" dmsetup message tpool 0 "release_metadata_snap" thin_check v1.2.2 result: Bad reference count for metadata block 6. Expected 1, but space map contains 2. Bad reference count for metadata block 7. Expected 1, but space map contains 2. 1 metadata blocks have leaked. Fix by deferring the held_root update to commit time. Additionally, move the existing-snapshot check in __reserve_metadata_snap before the shadow operation to avoid unnecessary work. In __release_metadata_snap, clear pmd->held_root before btree deletion so partial failure leaks blocks rather than leaving a stale reference, and unlock the snapshot block before decrementing its refcount. Fixes: 991d9fa02da0 ("dm: add thin provisioning target") Cc: stable@vger.kernel.org Signed-off-by: Ming-Hung Tsai Signed-off-by: Mikulas Patocka

Convert 'alloc_obj' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51+00:00

This was done entirely with mindless brute force, using git grep -l '\

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28+00:00

This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook

dm: Constify struct dm_block_validator

2024-07-19T10:08:15+00:00

'struct dm_block_validator' are not modified in these drivers. Constifying this structure moves some data to a read-only section, so increase overall security. On a x86_64, with allmodconfig, as an example: Before: ====== text data bss dec hex filename 32047 920 16 32983 80d7 drivers/md/dm-cache-metadata.o After: ===== text data bss dec hex filename 32075 896 16 32987 80db drivers/md/dm-cache-metadata.o Signed-off-by: Christophe JAILLET Signed-off-by: Mikulas Patocka

Merge tag 'for-6.5/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm

2023-06-30T19:16:00+00:00

Pull device mapper updates from Mike Snitzer: - Update DM crypt to allocate compound pages if possible - Fix DM crypt target's crypt_ctr_cipher_new return value on invalid AEAD cipher - Fix DM flakey testing target's write bio corruption feature to corrupt the data of a cloned bio instead of the original - Add random_read_corrupt and random_write_corrupt features to DM flakey target - Fix ABBA deadlock in DM thin metadata by resetting associated bufio client rather than destroying and recreating it - A couple other small DM thinp cleanups - Update DM core to support disabling block core IO stats accounting and optimize away code that isn't needed if stats are disabled - Other small DM core cleanups - Improve DM integrity target to not require so much memory on 32 bit systems. Also only allocate the recalculate buffer as needed (and increasingly reduce its size on allocation failure) - Update DM integrity to use %*ph for printing hexdump of a small buffer. Also update DM integrity documentation - Various DM core ioctl interface hardening. Now more careful about alignment of structures and processing of input passed to the kernel from userspace. Also disallow the creation of DM devices named "control", "." or ".." - Eliminate GFP_NOIO workarounds for __vmalloc and kvmalloc in DM core's ioctl and bufio code * tag 'for-6.5/dm-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm: (28 commits) dm: get rid of GFP_NOIO workarounds for __vmalloc and kvmalloc dm integrity: scale down the recalculate buffer if memory allocation fails dm integrity: only allocate recalculate buffer when needed dm integrity: reduce vmalloc space footprint on 32-bit architectures dm ioctl: Refuse to create device named "." or ".." dm ioctl: Refuse to create device named "control" dm ioctl: Avoid double-fetch of version dm ioctl: structs and parameter strings must not overlap dm ioctl: Avoid pointer arithmetic overflow dm ioctl: Check dm_target_spec is sufficiently aligned Documentation: dm-integrity: Document an example of how the tunables relate. Documentation: dm-integrity: Document default values. Documentation: dm-integrity: Document the meaning of "buffer". Documentation: dm-integrity: Fix minor grammatical error. dm integrity: Use %*ph for printing hexdump of a small buffer dm thin: disable discards for thin-pool if no_discard_passdown dm: remove stale/redundant dm_internal_{suspend,resume} prototypes in dm.h dm: skip dm-stats work in alloc_io() unless needed dm: avoid needless dm_io access if all IO accounting is disabled dm: support turning off block-core's io stats accounting ...

Merge tag 'mm-hotfixes-stable-2023-06-20-12-31' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2023-06-21T00:20:22+00:00

Pull hotfixes from Andrew Morton: "19 hotfixes. 8 of these are cc:stable. This includes a wholesale reversion of the post-6.4 series 'make slab shrink lockless'. After input from Dave Chinner it has been decided that we should go a different way [1]" Link: https://lkml.kernel.org/r/ZH6K0McWBeCjaf16@dread.disaster.area [1] * tag 'mm-hotfixes-stable-2023-06-20-12-31' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: selftests/mm: fix cross compilation with LLVM mailmap: add entries for Ben Dooks nilfs2: prevent general protection fault in nilfs_clear_dirty_page() Revert "mm: vmscan: make global slab shrink lockless" Revert "mm: vmscan: make memcg slab shrink lockless" Revert "mm: vmscan: add shrinker_srcu_generation" Revert "mm: shrinkers: make count and scan in shrinker debugfs lockless" Revert "mm: vmscan: hold write lock to reparent shrinker nr_deferred" Revert "mm: vmscan: remove shrinker_rwsem from synchronize_shrinkers()" Revert "mm: shrinkers: convert shrinker_rwsem to mutex" nilfs2: fix buffer corruption due to concurrent device reads scripts/gdb: fix SB_* constants parsing scripts: fix the gfp flags header path in gfp-translate udmabuf: revert 'Add support for mapping hugepages (v4)' mm/khugepaged: fix iteration in collapse_file memfd: check for non-NULL file_seals in memfd_create() syscall mm/vmalloc: do not output a spurious warning when huge vmalloc() fails mm/mprotect: fix do_mprotect_pkey() limit check writeback: fix dereferencing NULL mapping->host on writeback_page_template

Revert "mm: shrinkers: convert shrinker_rwsem to mutex"

2023-06-19T20:19:33+00:00

Patch series "revert shrinker_srcu related changes". This patch (of 7): This reverts commit cf2e309ebca7bb0916771839f9b580b06c778530. Kernel test robot reports -88.8% regression in stress-ng.ramfs.ops_per_sec test case [1], which is caused by commit f95bdb700bc6 ("mm: vmscan: make global slab shrink lockless"). The root cause is that SRCU has to be careful to not frequently check for SRCU read-side critical section exits. Therefore, even if no one is currently in the SRCU read-side critical section, synchronize_srcu() cannot return quickly. That's why unregister_shrinker() has become slower. After discussion, we will try to use the refcount+RCU method [2] proposed by Dave Chinner to continue to re-implement the lockless slab shrink. So revert the shrinker_mutex back to shrinker_rwsem first. [1]. https://lore.kernel.org/lkml/202305230837.db2c233f-yujie.liu@intel.com/ [2]. https://lore.kernel.org/lkml/ZIJhou1d55d4H1s0@dread.disaster.area/ Link: https://lkml.kernel.org/r/20230609081518.3039120-1-qi.zheng@linux.dev Link: https://lkml.kernel.org/r/20230609081518.3039120-2-qi.zheng@linux.dev Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-lkp/202305230837.db2c233f-yujie.liu@intel.com Signed-off-by: Qi Zheng Cc: Dave Chinner Cc: Kirill Tkhai Cc: Muchun Song Cc: Roman Gushchin Cc: Vlastimil Babka Cc: Yujie Liu Signed-off-by: Andrew Morton

dm thin metadata: Fix ABBA deadlock by resetting dm_bufio_client

2023-06-16T22:24:13+00:00

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: stable@vger.kernel.org Signed-off-by: Li Lingfeng Signed-off-by: Mike Snitzer

dm thin metadata: check fail_io before using data_sm

2023-06-15T16:46:59+00:00

Must check pmd->fail_io before using pmd->data_sm since pmd->data_sm may be destroyed by other processes. P1(kworker) P2(message) do_worker process_prepared process_prepared_discard_passdown_pt2 dm_pool_dec_data_range pool_message commit dm_pool_commit_metadata ↓ // commit failed metadata_operation_failed abort_transaction dm_pool_abort_metadata __open_or_format_metadata ↓ dm_sm_disk_open ↓ // open failed // pmd->data_sm is NULL dm_sm_dec_blocks ↓ // try to access pmd->data_sm --> UAF As shown above, if dm_pool_commit_metadata() and dm_pool_abort_metadata() fail in pool_message process, kworker may trigger UAF. Fixes: be500ed721a6 ("dm space maps: improve performance with inc/dec on ranges of blocks") Cc: stable@vger.kernel.org Signed-off-by: Li Lingfeng Signed-off-by: Mike Snitzer