On Thu, Dec 5, 2024 at 7:42 PM Ming-Hung Tsai <mtsai@xxxxxxxxxx> wrote: > > Reproduce steps: > > 1. initialize a cache device > > 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 $262144" > dd if=/dev/zero of=/dev/mapper/cmeta bs=4k count=1 > dmsetup create cache --table "0 524288 cache /dev/mapper/cmeta \ > /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0" > > 2. wipe the second array block offline > > dmsteup remove cache cmeta cdata corig > mapping_root=$(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 reopen the cache device > > 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 --table "0 524288 cache /dev/mapper/cmeta \ > /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0" > > Kernel logs: > > (snip) > device-mapper: array: array_block_check failed: blocknr 0 != wanted 10 > device-mapper: block manager: array validator check failed for block 10 > device-mapper: array: get_ablock failed > device-mapper: cache metadata: dm_array_cursor_next for mapping failed > ------------[ cut here ]------------ > kernel BUG at drivers/md/dm-bufio.c:638! > > Fix by setting the cached block pointer to NULL on errors. > In addition to the reproducer described above, the patch can be verified using the "array_cursor/damaged" test in dm-unit: dm-unit run /pdata/array_cursor/damaged --kernel-dir <KERNEL_DIR>
