On Wed, Nov 19, 2025 at 12:51 PM <devel-request(a)lists.crash-utility.osci.io&gt; wrote: > > Date: Wed, 19 Nov 2025 15:36:29 +1300 > From: Tao Liu <ltao(a)redhat.com&gt; > Subject: [Crash-utility] [PATCH] Add blk_mq_tag_set shared_tags check > To: devel(a)lists.crash-utility.osci.io > Cc: Tao Liu <ltao(a)redhat.com&gt; > Message-ID: <20251119023628.15998-2-ltao(a)redhat.com&gt; > Content-Type: text/plain; charset="US-ASCII"; x-default=true > > 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 We should be able to get the value of BLK_MQ_F_TAG_HCTX_SHARED via the dump_enumerator_list(), and then test it in the following function:

static bool blk_mq_is_shared_tags(unsigned int flags) { return flags & BLK_MQ_F_TAG_HCTX_SHARED; } That can follow the changes once the upstream kernel modifies the value. > blk_mq_is_shared_tags() check is not sufficient. This patch will add shared_tagsblk_mq_is_shared_tags() check is not sufficient. This patch will add shared_tags > member check within blk_mq_tag_set struct as an enhancment. Anyway, this change looks good, so: Ack Lianbo > [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; > --- > dev.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/dev.c b/dev.c > index 8391d71..27318e8 100644 > --- a/dev.c > +++ b/dev.c > @@ -4464,7 +4464,7 @@ 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

On Thu, Nov 20, 2025 at 4:37 AM Tao Liu <ltao(a)redhat.com&gt; wrote: > > Hi lianbo, > > On Wed, Nov 19, 2025 at 10:31 PM lijiang <lijiang(a)redhat.com&gt; wrote: > > > > On Wed, Nov 19, 2025 at 12:51 PM <devel-request(a)lists.crash-utility.osci.io&gt; wrote: > >> > >> Date: Wed, 19 Nov 2025 15:36:29 +1300 > >> From: Tao Liu <ltao(a)redhat.com&gt; > >> Subject: [Crash-utility] [PATCH] Add blk_mq_tag_set shared_tags check > >> To: devel(a)lists.crash-utility.osci.io > >> Cc: Tao Liu <ltao(a)redhat.com&gt; > >> Message-ID: <20251119023628.15998-2-ltao(a)redhat.com&gt; > >> Content-Type: text/plain; charset="US-ASCII"; x-default=true > >> > >> 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 > > > > > > We should be able to get the value of BLK_MQ_F_TAG_HCTX_SHARED via the dump_enumerator_list(), and then test it in the following function: > > Please see [1], I removed (1<<3) and resolved it at runtime. > dump_enumerator_list() is not appropriate, but I used > arg_to_datatype(). Can you try the enumerator_value()? Looks more appropriate. E.g: enumerator_value("BLK_MQ_F_TAG_HCTX_SHARED", &value);

Thanks Lianbo > In dump_enumerator_list("BLK_MQ_F_TAG_HCTX_SHARED"), > > if (!arg_to_datatype(e, dm, RETURN_ON_ERROR) || > (dm->size < 0) || (dm->type != ENUM) || dm->tagname) > > dm->tagname is not NULL and will make dump_enumerator_list return false: > > (gdb) p dm > $1 = {name = 0xe4911b "BLK_MQ_F_TAG_HCTX_SHARED", member = 0x0, type = > 8192, size = 0, member_offset = 0, member_size = 0, > member_typecode = 0, flags = 0, tagname = 0xd41dfd "(unknown)", > value = 8, vaddr = 0} > > [1]: https://www.mail-archive.com/devel@lists.crash-utility.osci.io/msg01841.html > > > > > static bool blk_mq_is_shared_tags(unsigned int flags) > > { > > return flags & BLK_MQ_F_TAG_HCTX_SHARED; > > } > > > > That can follow the changes once the upstream kernel modifies the value. > > > >> blk_mq_is_shared_tags() check is not sufficient. This patch will add shared_tagsblk_mq_is_shared_tags() check is not sufficient. This patch will add shared_tags > >> member check within blk_mq_tag_set struct as an enhancment. > > > > > > Anyway, this change looks good, so: Ack > > > > Lianbo > > > >> [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; > >> --- > >> dev.c | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/dev.c b/dev.c > >> index 8391d71..27318e8 100644 > >> --- a/dev.c > >> +++ b/dev.c > >> @@ -4464,7 +4464,7 @@ 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 >

I will apply the v1, aka "Add blk_mq_tag_set shared_tags check", and fix the "runtime get BLK_MQ_F_TAG_HCTX_SHARED" later, since v3 has some problems and we are running out of time before release. On Thu, Nov 20, 2025 at 4:25 PM Tao Liu <ltao(a)redhat.com&gt; wrote: > > On Thu, Nov 20, 2025 at 3:56 PM lijiang <lijiang(a)redhat.com&gt; wrote: > > > > On Thu, Nov 20, 2025 at 4:37 AM Tao Liu <ltao(a)redhat.com&gt; wrote: > >> > >> Hi lianbo, > >> > >> On Wed, Nov 19, 2025 at 10:31 PM lijiang <lijiang(a)redhat.com&gt; wrote: > >> > > >> > On Wed, Nov 19, 2025 at 12:51 PM <devel-request(a)lists.crash-utility.osci.io&gt; wrote: > >> >> > >> >> Date: Wed, 19 Nov 2025 15:36:29 +1300 > >> >> From: Tao Liu <ltao(a)redhat.com&gt; > >> >> Subject: [Crash-utility] [PATCH] Add blk_mq_tag_set shared_tags check > >> >> To: devel(a)lists.crash-utility.osci.io > >> >> Cc: Tao Liu <ltao(a)redhat.com&gt; > >> >> Message-ID: <20251119023628.15998-2-ltao(a)redhat.com&gt; > >> >> Content-Type: text/plain; charset="US-ASCII"; x-default=true > >> >> > >> >> 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 > >> > > >> > > >> > We should be able to get the value of BLK_MQ_F_TAG_HCTX_SHARED via the dump_enumerator_list(), and then test it in the following function: > >> > >> Please see [1], I removed (1<<3) and resolved it at runtime. > >> dump_enumerator_list() is not appropriate, but I used > >> arg_to_datatype(). > > > > > > Can you try the enumerator_value()? Looks more appropriate. E.g: > > > > enumerator_value("BLK_MQ_F_TAG_HCTX_SHARED", &value); > > Sure, looks better. > > Please see v3: https://www.mail-archive.com/devel@lists.crash-utility.osci.io/msg01845.html > > Thanks, > Tao Liu > > > > > > > Thanks > > Lianbo > > > >> In dump_enumerator_list("BLK_MQ_F_TAG_HCTX_SHARED"), > >> > >> if (!arg_to_datatype(e, dm, RETURN_ON_ERROR) || > >> (dm->size < 0) || (dm->type != ENUM) || dm->tagname) > >> > >> dm->tagname is not NULL and will make dump_enumerator_list return false: > >> > >> (gdb) p dm > >> $1 = {name = 0xe4911b "BLK_MQ_F_TAG_HCTX_SHARED", member = 0x0, type = > >> 8192, size = 0, member_offset = 0, member_size = 0, > >> member_typecode = 0, flags = 0, tagname = 0xd41dfd "(unknown)", > >> value = 8, vaddr = 0} > >> > >> [1]: https://www.mail-archive.com/devel@lists.crash-utility.osci.io/msg01841.html > >> > >> > > >> > static bool blk_mq_is_shared_tags(unsigned int flags) > >> > { > >> > return flags & BLK_MQ_F_TAG_HCTX_SHARED; > >> > } > >> > > >> > That can follow the changes once the upstream kernel modifies the value. > >> > > >> >> blk_mq_is_shared_tags() check is not sufficient. This patch will add shared_tagsblk_mq_is_shared_tags() check is not sufficient. This patch will add shared_tags > >> >> member check within blk_mq_tag_set struct as an enhancment. > >> > > >> > > >> > Anyway, this change looks good, so: Ack > >> > > >> > Lianbo > >> > > >> >> [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; > >> >> --- > >> >> dev.c | 2 +- > >> >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> >> > >> >> diff --git a/dev.c b/dev.c > >> >> index 8391d71..27318e8 100644 > >> >> --- a/dev.c > >> >> +++ b/dev.c > >> >> @@ -4464,7 +4464,7 @@ 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 > >>