linux-stable.git/drivers/md/dm-cache-target.c, branch linux-rolling-lts Linux kernel stable tree dm cache: fix missing return in invalidate_committed's error path 2026-05-23T11:06:42+00:00 Ming-Hung Tsai mtsai@redhat.com 2026-04-10T13:08:01+00:00 9769c143015cba7fbb3225940ff183d121ad234e [ Upstream commit 8c0ee19db81f0fa1ff25fd75b22b17c0cc2acde3 ] In passthrough mode, dm-cache defers write submission until after metadata commit completes via the invalidate_committed() continuation. On commit error, invalidate_committed() calls invalidate_complete() to end the bio and free the migration struct, after which it should return immediately. The patch 4ca8b8bd952d ("dm cache: fix write hang in passthrough mode") omitted this early return, causing execution to fall through into the success path on error. This results in use-after-free on the migration struct in the subsequent calls. Fix by adding the missing return after the invalidate_complete() call. Fixes: 4ca8b8bd952d ("dm cache: fix write hang in passthrough mode") Reported-by: Dan Carpenter <error27@gmail.com> Closes: https://lore.kernel.org/dm-devel/adjMq6T5RRjv_uxM@stanley.mountain/ Signed-off-by: Ming-Hung Tsai <mtsai@redhat.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 8c0ee19db81f0fa1ff25fd75b22b17c0cc2acde3 ]

In passthrough mode, dm-cache defers write submission until after
metadata commit completes via the invalidate_committed() continuation.
On commit error, invalidate_committed() calls invalidate_complete() to
end the bio and free the migration struct, after which it should return
immediately.

The patch 4ca8b8bd952d ("dm cache: fix write hang in passthrough mode")
omitted this early return, causing execution to fall through into the
success path on error. This results in use-after-free on the migration
struct in the subsequent calls.

Fix by adding the missing return after the invalidate_complete() call.

Fixes: 4ca8b8bd952d ("dm cache: fix write hang in passthrough mode")
Reported-by: Dan Carpenter <error27@gmail.com>
Closes: https://lore.kernel.org/dm-devel/adjMq6T5RRjv_uxM@stanley.mountain/
Signed-off-by: Ming-Hung Tsai <mtsai@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
dm cache: fix dirty mapping checking in passthrough mode switching 2026-05-23T11:06:34+00:00 Ming-Hung Tsai mtsai@redhat.com 2026-02-09T07:54:10+00:00 21c503d60a257e54ca3ac58e2721bd24501d5bde [ Upstream commit 322586745bd1a0e5f3559fd1635fdeb4dbd1d6b8 ] As mentioned in commit 9b1cc9f251af ("dm cache: share cache-metadata object across inactive and active DM tables"), dm-cache assumed table reload occurs after suspension, while LVM's table preload breaks this assumption. The dirty mapping check for passthrough mode was designed around this assumption and is performed during table creation, causing the check to fail with preload while metadata updates are ongoing. This risks loading dirty mappings into passthrough mode, resulting in data loss. Reproduce steps: 1. Create a writeback cache with zero migration_threshold to produce dirty mappings dmsetup create cmeta --table "0 8192 linear /dev/sdc 0" dmsetup create cdata --table "0 131072 linear /dev/sdc 8192" dmsetup create corig --table "0 262144 linear /dev/sdc 262144" dd if=/dev/zero of=/dev/mapper/cmeta bs=4k count=1 oflag=direct dmsetup create cache --table "0 262144 cache /dev/mapper/cmeta \ /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writeback smq \ 2 migration_threshold 0" 2. Preload a table in passthrough mode dmsetup reload cache --table "0 262144 cache /dev/mapper/cmeta \ /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 passthrough smq 0" 3. Write to the first cache block to make it dirty fio --filename=/dev/mapper/cache --name=populate --rw=write --bs=4k \ --direct=1 --size=64k 4. Resume the inactive table. Now it's possible to load the dirty block into passthrough mode. dmsetup resume cache Fix by moving the checks to the preresume phase to support table preloading. Also remove the unused function dm_cache_metadata_all_clean. Fixes: 2ee57d587357 ("dm cache: add passthrough mode") Signed-off-by: Ming-Hung Tsai <mtsai@redhat.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 322586745bd1a0e5f3559fd1635fdeb4dbd1d6b8 ]

As mentioned in commit 9b1cc9f251af ("dm cache: share cache-metadata
object across inactive and active DM tables"), dm-cache assumed table
reload occurs after suspension, while LVM's table preload breaks this
assumption. The dirty mapping check for passthrough mode was designed
around this assumption and is performed during table creation, causing
the check to fail with preload while metadata updates are ongoing. This
risks loading dirty mappings into passthrough mode, resulting in data
loss.

Reproduce steps:

1. Create a writeback cache with zero migration_threshold to produce
   dirty mappings

dmsetup create cmeta --table "0 8192 linear /dev/sdc 0"
dmsetup create cdata --table "0 131072 linear /dev/sdc 8192"
dmsetup create corig --table "0 262144 linear /dev/sdc 262144"
dd if=/dev/zero of=/dev/mapper/cmeta bs=4k count=1 oflag=direct
dmsetup create cache --table "0 262144 cache /dev/mapper/cmeta \
/dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writeback smq \
2 migration_threshold 0"

2. Preload a table in passthrough mode

dmsetup reload cache --table "0 262144 cache /dev/mapper/cmeta \
/dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 passthrough smq 0"

3. Write to the first cache block to make it dirty

fio --filename=/dev/mapper/cache --name=populate --rw=write --bs=4k \
--direct=1 --size=64k

4. Resume the inactive table. Now it's possible to load the dirty block
   into passthrough mode.

dmsetup resume cache

Fix by moving the checks to the preresume phase to support table
preloading. Also remove the unused function dm_cache_metadata_all_clean.

Fixes: 2ee57d587357 ("dm cache: add passthrough mode")
Signed-off-by: Ming-Hung Tsai <mtsai@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
dm cache: fix concurrent write failure in passthrough mode 2026-05-23T11:06:34+00:00 Ming-Hung Tsai mtsai@redhat.com 2026-02-09T07:54:09+00:00 cb8b250b427782b1ec16dd5b2201dcf139ee9512 [ Upstream commit e4f66341779d0cf4c83c74793753a84094286d9e ] When bio prison cell lock acquisition fails due to concurrent writes to the same block in passthrough mode, dm-cache incorrectly returns an I/O error instead of properly handling the concurrency. This can occur in both process and workqueue contexts when invalidate_lock() is called for exclusive access to a data block. Fix this by deferring the write bios to ensure proper block device behavior. Reproduce steps: 1. Create a cache device dmsetup create cmeta --table "0 8192 linear /dev/sdc 0" dmsetup create cdata --table "0 131072 linear /dev/sdc 8192" dmsetup create corig --table "0 262144 linear /dev/sdc 262144" dd if=/dev/zero of=/dev/mapper/cmeta bs=4k count=1 oflag=direct dmsetup create cache --table "0 262144 cache /dev/mapper/cmeta \ /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0" 2. Promote the first data block into cache fio --filename=/dev/mapper/cache --name=populate --rw=write --bs=4k \ --direct=1 --size=64k 3. Reload the cache into passthrough mode dmsetup suspend cache dmsetup reload cache --table "0 262144 cache /dev/mapper/cmeta \ /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 passthrough smq 0" dmsetup resume cache 4. Write to the first cached block concurrently. Sometimes one of the processes will receive I/O errors. fio --filename=/dev/mapper/cache --name test --rw=randwrite --bs=4k \ --randrepeat=0 --direct=1 --numjobs=2 --size 64k <snip> fio-3.41 fio: io_u error on file /dev/mapper/cache: Input/output error: write offset=4096, buflen=4096 fio: pid=106, err=5/file:io_u.c:2008, func=io_u error, error=Input/output error test: (groupid=0, jobs=1): err= 0: pid=105 test: (groupid=0, jobs=1): err= 5 (file:io_u.c:2008, func=io_u error, error=Input/output error): pid=106 <snip> Fixes: b29d4986d0da ("dm cache: significant rework to leverage dm-bio-prison-v2") Signed-off-by: Ming-Hung Tsai <mtsai@redhat.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit e4f66341779d0cf4c83c74793753a84094286d9e ]

When bio prison cell lock acquisition fails due to concurrent writes to
the same block in passthrough mode, dm-cache incorrectly returns an I/O
error instead of properly handling the concurrency. This can occur in
both process and workqueue contexts when invalidate_lock() is called for
exclusive access to a data block. Fix this by deferring the write bios
to ensure proper block device behavior.

Reproduce steps:

1. Create a cache device

dmsetup create cmeta --table "0 8192 linear /dev/sdc 0"
dmsetup create cdata --table "0 131072 linear /dev/sdc 8192"
dmsetup create corig --table "0 262144 linear /dev/sdc 262144"
dd if=/dev/zero of=/dev/mapper/cmeta bs=4k count=1 oflag=direct
dmsetup create cache --table "0 262144 cache /dev/mapper/cmeta \
/dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0"

2. Promote the first data block into cache

fio --filename=/dev/mapper/cache --name=populate --rw=write --bs=4k \
--direct=1 --size=64k

3. Reload the cache into passthrough mode

dmsetup suspend cache
dmsetup reload cache --table "0 262144 cache /dev/mapper/cmeta \
/dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 passthrough smq 0"
dmsetup resume cache

4. Write to the first cached block concurrently. Sometimes one of the
   processes will receive I/O errors.

fio --filename=/dev/mapper/cache --name test --rw=randwrite --bs=4k \
--randrepeat=0 --direct=1 --numjobs=2 --size 64k

 <snip>
 fio-3.41
 fio: io_u error on file /dev/mapper/cache: Input/output error: write offset=4096, buflen=4096
 fio: pid=106, err=5/file:io_u.c:2008, func=io_u error, error=Input/output error
 test: (groupid=0, jobs=1): err= 0: pid=105
 test: (groupid=0, jobs=1): err= 5 (file:io_u.c:2008, func=io_u error, error=Input/output error): pid=106
 <snip>

Fixes: b29d4986d0da ("dm cache: significant rework to leverage dm-bio-prison-v2")
Signed-off-by: Ming-Hung Tsai <mtsai@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
dm cache: fix write hang in passthrough mode 2026-05-23T11:06:34+00:00 Ming-Hung Tsai mtsai@redhat.com 2026-02-09T07:54:07+00:00 b8ace9e96983abb20ccf39edce8a60f1bb0b83d8 [ Upstream commit 4ca8b8bd952df7c3ccdc68af9bd3419d0839a04b ] The invalidate_remove() function has incomplete logic for handling write hit bios after cache invalidation. It sets up the remapping for the overwrite_bio but then drops it immediately without submission, causing write operations to hang. Fix by adding a new invalidate_committed() continuation that submits the remapped writes to the cache origin after metadata commit completes, while using the overwrite_endio hook to ensure proper completion sequencing. This maintains existing coherency. Also improve error handling in invalidate_complete() to preserve the original error status instead of using bio_io_error() unconditionally. Fixes: b29d4986d0da ("dm cache: significant rework to leverage dm-bio-prison-v2") Signed-off-by: Ming-Hung Tsai <mtsai@redhat.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 4ca8b8bd952df7c3ccdc68af9bd3419d0839a04b ]

The invalidate_remove() function has incomplete logic for handling write
hit bios after cache invalidation. It sets up the remapping for the
overwrite_bio but then drops it immediately without submission, causing
write operations to hang.

Fix by adding a new invalidate_committed() continuation that submits
the remapped writes to the cache origin after metadata commit completes,
while using the overwrite_endio hook to ensure proper completion
sequencing. This maintains existing coherency. Also improve error
handling in invalidate_complete() to preserve the original error status
instead of using bio_io_error() unconditionally.

Fixes: b29d4986d0da ("dm cache: significant rework to leverage dm-bio-prison-v2")
Signed-off-by: Ming-Hung Tsai <mtsai@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
dm cache: fix write path cache coherency in passthrough mode 2026-05-23T11:06:34+00:00 Ming-Hung Tsai mtsai@redhat.com 2026-02-09T07:54:06+00:00 788ac6c94d04d966f903a91c64767013514945ff [ Upstream commit 0c5eef0aad508231d8e43ff8392692925e131b68 ] In passthrough mode, dm-cache defers write bio submission until cache invalidation completes to maintain existing coherency, requiring the target map function to return DM_MAPIO_SUBMITTED. The current map_bio() returns DM_MAPIO_REMAPPED, violating the required ordering constraint. Reproduce steps: 1. Create a cache device dmsetup create cmeta --table "0 8192 linear /dev/sdc 0" dmsetup create cdata --table "0 131072 linear /dev/sdc 8192" dmsetup create corig --table "0 262144 linear /dev/sdc 262144" dd if=/dev/zero of=/dev/mapper/cmeta bs=4k count=1 oflag=direct dmsetup create cache --table "0 262144 cache /dev/mapper/cmeta \ /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0" 2. Promote the first data block into the cache fio --filename=/dev/mapper/cache --name=populate --rw=write --bs=4k \ --direct=1 --size=64k 3. Reload the cache into passthrough mode dmsetup suspend cache dmsetup reload cache --table "0 262144 cache /dev/mapper/cmeta \ /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 passthrough smq 0" dmsetup resume cache 4. Write to the first data block, and check io ordering using ftrace echo 1 > /sys/kernel/debug/tracing/events/block/block_bio_queue/enable echo 1 > /sys/kernel/debug/tracing/events/block/block_bio_complete/enable echo 1 > /sys/kernel/debug/tracing/events/block/block_rq_complete/enable fio --filename=/dev/mapper/cache --name=test --rw=write --bs=64k \ --direct=1 --size 64k 5. ftrace logs show that write operations to the cache origin (252:2) and metadata operations (252:0) are unsynchronized: the origin write occurs before metadata commit. <snip> fio-146 [000] ..... 420.139562: block_bio_queue: 252,3 WS 0 + 128 [fio] fio-146 [000] ..... 420.149395: block_bio_queue: 252,2 WS 0 + 128 [fio] fio-146 [000] ..... 420.149763: block_bio_queue: 8,32 WS 262144 + 128 [fio] fio-146 [000] dNh1. 420.151446: block_rq_complete: 8,32 WS () 262144 + 128 be,0,4 [0] fio-146 [000] dNh1. 420.152731: block_bio_complete: 252,2 WS 0 + 128 [0] fio-146 [000] dNh1. 420.154229: block_bio_complete: 252,3 WS 0 + 128 [0] kworker/0:0-9 [000] ..... 420.160530: block_bio_queue: 252,0 W 408 + 8 [kworker/0:0] kworker/0:0-9 [000] ..... 420.161641: block_bio_queue: 8,32 W 408 + 8 [kworker/0:0] kworker/0:0-9 [000] ..... 420.162533: block_bio_queue: 252,0 W 416 + 8 [kworker/0:0] kworker/0:0-9 [000] ..... 420.162821: block_bio_queue: 8,32 W 416 + 8 [kworker/0:0] <snip> Fixes: b29d4986d0da ("dm cache: significant rework to leverage dm-bio-prison-v2") Signed-off-by: Ming-Hung Tsai <mtsai@redhat.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 0c5eef0aad508231d8e43ff8392692925e131b68 ]

In passthrough mode, dm-cache defers write bio submission until cache
invalidation completes to maintain existing coherency, requiring the
target map function to return DM_MAPIO_SUBMITTED. The current map_bio()
returns DM_MAPIO_REMAPPED, violating the required ordering constraint.

Reproduce steps:

1. Create a cache device

dmsetup create cmeta --table "0 8192 linear /dev/sdc 0"
dmsetup create cdata --table "0 131072 linear /dev/sdc 8192"
dmsetup create corig --table "0 262144 linear /dev/sdc 262144"
dd if=/dev/zero of=/dev/mapper/cmeta bs=4k count=1 oflag=direct
dmsetup create cache --table "0 262144 cache /dev/mapper/cmeta \
/dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0"

2. Promote the first data block into the cache

fio --filename=/dev/mapper/cache --name=populate --rw=write --bs=4k \
--direct=1 --size=64k

3. Reload the cache into passthrough mode

dmsetup suspend cache
dmsetup reload cache --table "0 262144 cache /dev/mapper/cmeta \
/dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 passthrough smq 0"
dmsetup resume cache

4. Write to the first data block, and check io ordering using ftrace

echo 1 > /sys/kernel/debug/tracing/events/block/block_bio_queue/enable
echo 1 > /sys/kernel/debug/tracing/events/block/block_bio_complete/enable
echo 1 > /sys/kernel/debug/tracing/events/block/block_rq_complete/enable
fio --filename=/dev/mapper/cache --name=test --rw=write --bs=64k \
--direct=1 --size 64k

5. ftrace logs show that write operations to the cache origin (252:2)
   and metadata operations (252:0) are unsynchronized: the origin write
   occurs before metadata commit.

 <snip>
       fio-146  [000] .....  420.139562: block_bio_queue: 252,3 WS 0 + 128 [fio]
       fio-146  [000] .....  420.149395: block_bio_queue: 252,2 WS 0 + 128 [fio]
       fio-146  [000] .....  420.149763: block_bio_queue: 8,32 WS 262144 + 128 [fio]
       fio-146  [000] dNh1.  420.151446: block_rq_complete: 8,32 WS () 262144 + 128 be,0,4 [0]
       fio-146  [000] dNh1.  420.152731: block_bio_complete: 252,2 WS 0 + 128 [0]
       fio-146  [000] dNh1.  420.154229: block_bio_complete: 252,3 WS 0 + 128 [0]
 kworker/0:0-9  [000] .....  420.160530: block_bio_queue: 252,0 W 408 + 8 [kworker/0:0]
 kworker/0:0-9  [000] .....  420.161641: block_bio_queue: 8,32 W 408 + 8 [kworker/0:0]
 kworker/0:0-9  [000] .....  420.162533: block_bio_queue: 252,0 W 416 + 8 [kworker/0:0]
 kworker/0:0-9  [000] .....  420.162821: block_bio_queue: 8,32 W 416 + 8 [kworker/0:0]
 <snip>

Fixes: b29d4986d0da ("dm cache: significant rework to leverage dm-bio-prison-v2")
Signed-off-by: Ming-Hung Tsai <mtsai@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
dm cache: fix null-deref with concurrent writes in passthrough mode 2026-05-23T11:06:34+00:00 Ming-Hung Tsai mtsai@redhat.com 2026-02-09T07:54:05+00:00 25dcc1989c194ba2b5fb6d03cbb9b83814ac0d15 [ Upstream commit 7d1f98d668ee34c1d15bdc0420fdd062f24a27c0 ] In passthrough mode, when dm-cache starts to invalidate a cache entry and bio prison cell lock fails due to concurrent write to the same cached block, mg->cell remains NULL. The error path in invalidate_complete() attempts to unlock and free the cell unconditionally, causing a NULL pointer dereference: KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] CPU: 0 UID: 0 PID: 134 Comm: fio Not tainted 6.19.0-rc7 #3 PREEMPT RIP: 0010:dm_cell_unlock_v2+0x3f/0x210 <snip> Call Trace: invalidate_complete+0xef/0x430 map_bio+0x130f/0x1a10 cache_map+0x320/0x6b0 __map_bio+0x458/0x510 dm_submit_bio+0x40e/0x16d0 __submit_bio+0x419/0x870 <snip> Reproduce steps: 1. Create a cache device dmsetup create cmeta --table "0 8192 linear /dev/sdc 0" dmsetup create cdata --table "0 131072 linear /dev/sdc 8192" dmsetup create corig --table "0 262144 linear /dev/sdc 262144" dd if=/dev/zero of=/dev/mapper/cmeta bs=4k count=1 oflag=direct dmsetup create cache --table "0 262144 cache /dev/mapper/cmeta \ /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0" 2. Promote the first data block into cache fio --filename=/dev/mapper/cache --name=populate --rw=write --bs=4k \ --direct=1 --size=64k 3. Reload the cache into passthrough mode dmsetup suspend cache dmsetup reload cache --table "0 262144 cache /dev/mapper/cmeta \ /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 passthrough smq 0" dmsetup resume cache 4. Write to the first cached block concurrently fio --filename=/dev/mapper/cache --name test --rw=randwrite --bs=4k \ --randrepeat=0 --direct=1 --numjobs=2 --size 64k Fix by checking if mg->cell is valid before attempting to unlock it. Fixes: b29d4986d0da ("dm cache: significant rework to leverage dm-bio-prison-v2") Signed-off-by: Ming-Hung Tsai <mtsai@redhat.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 7d1f98d668ee34c1d15bdc0420fdd062f24a27c0 ]

In passthrough mode, when dm-cache starts to invalidate a cache
entry and bio prison cell lock fails due to concurrent write to
the same cached block, mg->cell remains NULL. The error path in
invalidate_complete() attempts to unlock and free the cell
unconditionally, causing a NULL pointer dereference:

KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 UID: 0 PID: 134 Comm: fio Not tainted 6.19.0-rc7 #3 PREEMPT
RIP: 0010:dm_cell_unlock_v2+0x3f/0x210
<snip>
Call Trace:
 invalidate_complete+0xef/0x430
 map_bio+0x130f/0x1a10
 cache_map+0x320/0x6b0
 __map_bio+0x458/0x510
 dm_submit_bio+0x40e/0x16d0
 __submit_bio+0x419/0x870
<snip>

Reproduce steps:

1. Create a cache device

dmsetup create cmeta --table "0 8192 linear /dev/sdc 0"
dmsetup create cdata --table "0 131072 linear /dev/sdc 8192"
dmsetup create corig --table "0 262144 linear /dev/sdc 262144"
dd if=/dev/zero of=/dev/mapper/cmeta bs=4k count=1 oflag=direct
dmsetup create cache --table "0 262144 cache /dev/mapper/cmeta \
/dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0"

2. Promote the first data block into cache

fio --filename=/dev/mapper/cache --name=populate --rw=write --bs=4k \
--direct=1 --size=64k

3. Reload the cache into passthrough mode

dmsetup suspend cache
dmsetup reload cache --table "0 262144 cache /dev/mapper/cmeta \
/dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 passthrough smq 0"
dmsetup resume cache

4. Write to the first cached block concurrently

fio --filename=/dev/mapper/cache --name test --rw=randwrite --bs=4k \
--randrepeat=0 --direct=1 --numjobs=2 --size 64k

Fix by checking if mg->cell is valid before attempting to unlock it.

Fixes: b29d4986d0da ("dm cache: significant rework to leverage dm-bio-prison-v2")
Signed-off-by: Ming-Hung Tsai <mtsai@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
dm: add WQ_PERCPU to alloc_workqueue users 2026-05-23T11:06:23+00:00 Marco Crivellari marco.crivellari@suse.com 2026-01-13T11:03:02+00:00 3f1e2902b5ecb821f99fe4c0c6781d93ee1a23cc [ Upstream commit d4880868670198df321627a949e7b7f2d76cf54e ] This continues the effort to refactor workqueue APIs, which began with the introduction of new workqueues and a new alloc_workqueue flag in: commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq") commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag") The refactoring is going to alter the default behavior of alloc_workqueue() to be unbound by default. With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND), any alloc_workqueue() caller that doesn’t explicitly specify WQ_UNBOUND must now use WQ_PERCPU. For more details see the Link tag below. In order to keep alloc_workqueue() behavior identical, explicitly request WQ_PERCPU. Link: https://lore.kernel.org/all/20250221112003.1dSuoGyc@linutronix.de/ Suggested-by: Tejun Heo <tj@kernel.org> Signed-off-by: Marco Crivellari <marco.crivellari@suse.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Stable-dep-of: e4979f4fac4d ("md: remove unused static md_wq workqueue") Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit d4880868670198df321627a949e7b7f2d76cf54e ]

This continues the effort to refactor workqueue APIs, which began with
the introduction of new workqueues and a new alloc_workqueue flag in:

   commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq")
   commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag")

The refactoring is going to alter the default behavior of
alloc_workqueue() to be unbound by default.

With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND),
any alloc_workqueue() caller that doesn’t explicitly specify WQ_UNBOUND
must now use WQ_PERCPU. For more details see the Link tag below.

In order to keep alloc_workqueue() behavior identical, explicitly request
WQ_PERCPU.

Link: https://lore.kernel.org/all/20250221112003.1dSuoGyc@linutronix.de/
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Stable-dep-of: e4979f4fac4d ("md: remove unused static md_wq workqueue")
Signed-off-by: Sasha Levin <sashal@kernel.org>
dm cache: support shrinking the origin device 2025-03-06T15:13:47+00:00 Ming-Hung Tsai mtsai@redhat.com 2025-03-06T08:41:51+00:00 c2662b1544cbd8ea3181381bb899b8e681dfedc7 This patch introduces formal support for shrinking the cache origin by reducing the cache target length via table reloads. Cache blocks mapped beyond the new target length must be clean and are invalidated during preresume. If any dirty blocks exist in the area being removed, the preresume operation fails without setting the NEEDS_CHECK flag in superblock, and the resume ioctl returns EFBIG. The cache device remains suspended until a table reload with target length that fits existing mappings is performed. Without this patch, reducing the cache target length could result in io errors (RHBZ: 2134334), out-of-bounds memory access to the discard bitset, and security concerns regarding data leakage. Verification steps: 1. create a cache metadata with some cached blocks mapped to the tail of the origin device. Here we use cache_restore v1.0 to build a metadata with one clean block mapped to the last origin block. cat <<EOF >> cmeta.xml <superblock uuid="" block_size="128" nr_cache_blocks="512" \ policy="smq" hint_width="4"> <mappings> <mapping cache_block="0" origin_block="4095" dirty="false"/> </mappings> </superblock> EOF dmsetup create cmeta --table "0 8192 linear /dev/sdc 0" cache_restore -i cmeta.xml -o /dev/mapper/cmeta --metadata-version=2 dmsetup remove cmeta 2. bring up the cache whilst shrinking the cache origin by one block: dmsetup create cmeta --table "0 8192 linear /dev/sdc 0" dmsetup create cdata --table "0 65536 linear /dev/sdc 8192" dmsetup create corig --table "0 524160 linear /dev/sdc 262144" dmsetup create cache --table "0 524160 cache /dev/mapper/cmeta \ /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0" 3. check the number of cached data blocks via dmsetup status. It is expected to be zero. dmsetup status cache | cut -d ' ' -f 7 In addition to the script above, this patch can be verified using the "cache/resize" tests in dmtest-python: ./dmtest run --rx cache/resize/shrink_origin --result-set default Signed-off-by: Ming-Hung Tsai <mtsai@redhat.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> 
This patch introduces formal support for shrinking the cache origin by
reducing the cache target length via table reloads. Cache blocks mapped
beyond the new target length must be clean and are invalidated during
preresume. If any dirty blocks exist in the area being removed, the
preresume operation fails without setting the NEEDS_CHECK flag in
superblock, and the resume ioctl returns EFBIG. The cache device remains
suspended until a table reload with target length that fits existing
mappings is performed.

Without this patch, reducing the cache target length could result in
io errors (RHBZ: 2134334), out-of-bounds memory access to the discard
bitset, and security concerns regarding data leakage.

Verification steps:

1. create a cache metadata with some cached blocks mapped to the tail
   of the origin device. Here we use cache_restore v1.0 to build a
   metadata with one clean block mapped to the last origin block.

cat <<EOF >> cmeta.xml
<superblock uuid="" block_size="128" nr_cache_blocks="512" \
policy="smq" hint_width="4">
  <mappings>
    <mapping cache_block="0" origin_block="4095" dirty="false"/>
  </mappings>
</superblock>
EOF
dmsetup create cmeta --table "0 8192 linear /dev/sdc 0"
cache_restore -i cmeta.xml -o /dev/mapper/cmeta --metadata-version=2
dmsetup remove cmeta

2. bring up the cache whilst shrinking the cache origin by one block:

dmsetup create cmeta --table "0 8192 linear /dev/sdc 0"
dmsetup create cdata --table "0 65536 linear /dev/sdc 8192"
dmsetup create corig --table "0 524160 linear /dev/sdc 262144"
dmsetup create cache --table "0 524160 cache /dev/mapper/cmeta \
/dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0"

3. check the number of cached data blocks via dmsetup status. It is
   expected to be zero.

dmsetup status cache | cut -d ' ' -f 7

In addition to the script above, this patch can be verified using the
"cache/resize" tests in dmtest-python:

./dmtest run --rx cache/resize/shrink_origin --result-set default

Signed-off-by: Ming-Hung Tsai <mtsai@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
dm cache: prevent BUG_ON by blocking retries on failed device resumes 2025-03-06T15:13:30+00:00 Ming-Hung Tsai mtsai@redhat.com 2025-03-06T08:41:50+00:00 5da692e2262b8f81993baa9592f57d12c2703dea A cache device failing to resume due to mapping errors should not be retried, as the failure leaves a partially initialized policy object. Repeating the resume operation risks triggering BUG_ON when reloading cache mappings into the incomplete policy object. Reproduce steps: 1. create a cache metadata consisting of 512 or more cache blocks, with some mappings stored in the first array block of the mapping array. Here we use cache_restore v1.0 to build the metadata. cat <<EOF >> cmeta.xml <superblock uuid="" block_size="128" nr_cache_blocks="512" \ policy="smq" hint_width="4"> <mappings> <mapping cache_block="0" origin_block="0" dirty="false"/> </mappings> </superblock> EOF dmsetup create cmeta --table "0 8192 linear /dev/sdc 0" cache_restore -i cmeta.xml -o /dev/mapper/cmeta --metadata-version=2 dmsetup remove cmeta 2. wipe the second array block of the mapping array to simulate data degradations. mapping_root=$(dd if=/dev/sdc bs=1c count=8 skip=192 \ 2>/dev/null | hexdump -e '1/8 "%u\n"') ablock=$(dd if=/dev/sdc bs=1c count=8 skip=$((4096*mapping_root+2056)) \ 2>/dev/null | hexdump -e '1/8 "%u\n"') dd if=/dev/zero of=/dev/sdc bs=4k count=1 seek=$ablock 3. try bringing up the cache device. The resume is expected to fail due to the broken array block. dmsetup create cmeta --table "0 8192 linear /dev/sdc 0" dmsetup create cdata --table "0 65536 linear /dev/sdc 8192" dmsetup create corig --table "0 524288 linear /dev/sdc 262144" dmsetup create cache --notable dmsetup load cache --table "0 524288 cache /dev/mapper/cmeta \ /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0" dmsetup resume cache 4. try resuming the cache again. An unexpected BUG_ON is triggered while loading cache mappings. dmsetup resume cache Kernel logs: (snip) ------------[ cut here ]------------ kernel BUG at drivers/md/dm-cache-policy-smq.c:752! Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI CPU: 0 UID: 0 PID: 332 Comm: dmsetup Not tainted 6.13.4 #3 RIP: 0010:smq_load_mapping+0x3e5/0x570 Fix by disallowing resume operations for devices that failed the initial attempt. Signed-off-by: Ming-Hung Tsai <mtsai@redhat.com> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> 
A cache device failing to resume due to mapping errors should not be
retried, as the failure leaves a partially initialized policy object.
Repeating the resume operation risks triggering BUG_ON when reloading
cache mappings into the incomplete policy object.

Reproduce steps:

1. create a cache metadata consisting of 512 or more cache blocks,
   with some mappings stored in the first array block of the mapping
   array. Here we use cache_restore v1.0 to build the metadata.

cat <<EOF >> cmeta.xml
<superblock uuid="" block_size="128" nr_cache_blocks="512" \
policy="smq" hint_width="4">
  <mappings>
    <mapping cache_block="0" origin_block="0" dirty="false"/>
  </mappings>
</superblock>
EOF
dmsetup create cmeta --table "0 8192 linear /dev/sdc 0"
cache_restore -i cmeta.xml -o /dev/mapper/cmeta --metadata-version=2
dmsetup remove cmeta

2. wipe the second array block of the mapping array to simulate
   data degradations.

mapping_root=$(dd if=/dev/sdc bs=1c count=8 skip=192 \
2>/dev/null | hexdump -e '1/8 "%u\n"')
ablock=$(dd if=/dev/sdc bs=1c count=8 skip=$((4096*mapping_root+2056)) \
2>/dev/null | hexdump -e '1/8 "%u\n"')
dd if=/dev/zero of=/dev/sdc bs=4k count=1 seek=$ablock

3. try bringing up the cache device. The resume is expected to fail
   due to the broken array block.

dmsetup create cmeta --table "0 8192 linear /dev/sdc 0"
dmsetup create cdata --table "0 65536 linear /dev/sdc 8192"
dmsetup create corig --table "0 524288 linear /dev/sdc 262144"
dmsetup create cache --notable
dmsetup load cache --table "0 524288 cache /dev/mapper/cmeta \
/dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0"
dmsetup resume cache

4. try resuming the cache again. An unexpected BUG_ON is triggered
   while loading cache mappings.

dmsetup resume cache

Kernel logs:

(snip)
------------[ cut here ]------------
kernel BUG at drivers/md/dm-cache-policy-smq.c:752!
Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 332 Comm: dmsetup Not tainted 6.13.4 #3
RIP: 0010:smq_load_mapping+0x3e5/0x570

Fix by disallowing resume operations for devices that failed the
initial attempt.

Signed-off-by: Ming-Hung Tsai <mtsai@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Merge tag 'for-6.13/block-20241118' of git://git.kernel.dk/linux 2024-11-19T00:50:08+00:00 Linus Torvalds torvalds@linux-foundation.org 2024-11-19T00:50:08+00:00 77a0cfafa9af9c0d5b43534eb90d530c189edca1 Pull block updates from Jens Axboe: - NVMe updates via Keith: - Use uring_cmd helper (Pavel) - Host Memory Buffer allocation enhancements (Christoph) - Target persistent reservation support (Guixin) - Persistent reservation tracing (Guixen) - NVMe 2.1 specification support (Keith) - Rotational Meta Support (Matias, Wang, Keith) - Volatile cache detection enhancment (Guixen) - MD updates via Song: - Maintainers update - raid5 sync IO fix - Enhance handling of faulty and blocked devices - raid5-ppl atomic improvement - md-bitmap fix - Support for manually defining embedded partition tables - Zone append fixes and cleanups - Stop sending the queued requests in the plug list to the driver ->queue_rqs() handle in reverse order. - Zoned write plug cleanups - Cleanups disk stats tracking and add support for disk stats for passthrough IO - Add preparatory support for file system atomic writes - Add lockdep support for queue freezing. Already found a bunch of issues, and some fixes for that are in here. More will be coming. - Fix race between queue stopping/quiescing and IO queueing - ublk recovery improvements - Fix ublk mmap for 64k pages - Various fixes and cleanups * tag 'for-6.13/block-20241118' of git://git.kernel.dk/linux: (118 commits) MAINTAINERS: Update git tree for mdraid subsystem block: make struct rq_list available for !CONFIG_BLOCK block/genhd: use seq_put_decimal_ull for diskstats decimal values block: don't reorder requests in blk_mq_add_to_batch block: don't reorder requests in blk_add_rq_to_plug block: add a rq_list type block: remove rq_list_move virtio_blk: reverse request order in virtio_queue_rqs nvme-pci: reverse request order in nvme_queue_rqs btrfs: validate queue limits block: export blk_validate_limits nvmet: add tracing of reservation commands nvme: parse reservation commands's action and rtype to string nvmet: report ns's vwc not present md/raid5: Increase r5conf.cache_name size block: remove the ioprio field from struct request block: remove the write_hint field from struct request nvme: check ns's volatile write cache not present nvme: add rotational support nvme: use command set independent id ns if available ... 
Pull block updates from Jens Axboe:

 - NVMe updates via Keith:
      - Use uring_cmd helper (Pavel)
      - Host Memory Buffer allocation enhancements (Christoph)
      - Target persistent reservation support (Guixin)
      - Persistent reservation tracing (Guixen)
      - NVMe 2.1 specification support (Keith)
      - Rotational Meta Support (Matias, Wang, Keith)
      - Volatile cache detection enhancment (Guixen)

 - MD updates via Song:
      - Maintainers update
      - raid5 sync IO fix
      - Enhance handling of faulty and blocked devices
      - raid5-ppl atomic improvement
      - md-bitmap fix

 - Support for manually defining embedded partition tables

 - Zone append fixes and cleanups

 - Stop sending the queued requests in the plug list to the driver
   ->queue_rqs() handle in reverse order.

 - Zoned write plug cleanups

 - Cleanups disk stats tracking and add support for disk stats for
   passthrough IO

 - Add preparatory support for file system atomic writes

 - Add lockdep support for queue freezing. Already found a bunch of
   issues, and some fixes for that are in here. More will be coming.

 - Fix race between queue stopping/quiescing and IO queueing

 - ublk recovery improvements

 - Fix ublk mmap for 64k pages

 - Various fixes and cleanups

* tag 'for-6.13/block-20241118' of git://git.kernel.dk/linux: (118 commits)
  MAINTAINERS: Update git tree for mdraid subsystem
  block: make struct rq_list available for !CONFIG_BLOCK
  block/genhd: use seq_put_decimal_ull for diskstats decimal values
  block: don't reorder requests in blk_mq_add_to_batch
  block: don't reorder requests in blk_add_rq_to_plug
  block: add a rq_list type
  block: remove rq_list_move
  virtio_blk: reverse request order in virtio_queue_rqs
  nvme-pci: reverse request order in nvme_queue_rqs
  btrfs: validate queue limits
  block: export blk_validate_limits
  nvmet: add tracing of reservation commands
  nvme: parse reservation commands's action and rtype to string
  nvmet: report ns's vwc not present
  md/raid5: Increase r5conf.cache_name size
  block: remove the ioprio field from struct request
  block: remove the write_hint field from struct request
  nvme: check ns's volatile write cache not present
  nvme: add rotational support
  nvme: use command set independent id ns if available
  ...