A regression of cmd dev -d/-D noticed on some vmcores as: dev: invalid structure member offset: blk_mq_tag_set_shared_tags FILE: dev.c LINE: 4468 FUNCTION: blk_mq_queue_tag_busy_iter() MAJOR GENDISK NAME REQUEST_QUEUE TOTAL ASYNC SYNC [crash] error trace: 91aa85 => 91a552 => 94d6ba => 94d647 94d647: OFFSET_verify.part.0+55 94d6ba: OFFSET_verify+42 91a552: get_diskio_1+2194 91aa85: display_all_diskio+1253 The root cause is, though upstream kernel have defined BLK_MQ_F_TAG_HCTX_SHARED as (1 << 3), the value might be set different, e.g. [1]. So a single blk_mq_is_shared_tags() check is not sufficient. This patch will resolve BLK_MQ_F_TAG_HCTX_SHARED at runtime and add shared_tags member check within blk_mq_tag_set struct as an enhancment. [1]: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-8/-/blob... Fixes: 62486400d35b ("Add blk_mq shared tags support for dev -d/-D") Signed-off-by: Tao Liu <ltao(a)redhat.com&gt; --- v2 -> v3: replace arg_to_datatype() to enumerator_value(). --- dev.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-) diff --git a/dev.c b/dev.c index 8391d71..5ab6855 100644 --- a/dev.c +++ b/dev.c @@ -4326,11 +4326,25 @@ struct bt_iter_data { #define MQ_RQ_IN_FLIGHT 1 #define REQ_OP_BITS 8 #define REQ_OP_MASK ((1 << REQ_OP_BITS) - 1) -#define BLK_MQ_F_TAG_HCTX_SHARED (1 << 3) static bool blk_mq_is_shared_tags(unsigned int flags) { - return flags & BLK_MQ_F_TAG_HCTX_SHARED; + static long value = -1; + static bool value_fetched = false; + struct datatype_member dm; + + if (value_fetched) + goto out; + + value_fetched = true; + if (enumerator_value("BLK_MQ_F_TAG_HCTX_SHARED", &value)) + value = dm.value; +out: + if (value < 0) + /* Invalid BLK_MQ_F_TAG_HCTX_SHARED */ + return false; + else + return flags & value; } static uint op_is_write(uint op) @@ -4464,7 +4478,7 @@ static void blk_mq_queue_tag_busy_iter(ulong q, ulong *hctx, uint cnt, readmem(addr + OFFSET(blk_mq_tag_set_flags), KVADDR, &flags, sizeof(uint), "blk_mq_tag_set.flags", RETURN_ON_ERROR); - if (blk_mq_is_shared_tags(flags)) { + if (blk_mq_is_shared_tags(flags) && VALID_MEMBER(blk_mq_tag_set_shared_tags)) { addr = addr + OFFSET(blk_mq_tag_set_shared_tags); queue_for_each_hw_ctx(q, addr, bitmap_tags_is_ptr, dio); return; -- 2.47.0