<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/block, branch v6.1.1</title>
<subtitle>Clone of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git</subtitle>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/'/>
<entry>
<title>Merge tag 'block-6.1-2022-11-25' of git://git.kernel.dk/linux</title>
<updated>2022-11-26T01:50:57+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-11-26T01:50:57+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=990f320031209ecfdb1bef33798970506d10dae8'/>
<id>990f320031209ecfdb1bef33798970506d10dae8</id>
<content type='text'>
Pull block fixes from Jens Axboe:

 - A few fixes for s390 sads (Stefan, Colin)

 - Ensure that ublk doesn't reorder requests, as that can be problematic
   on devices that need specific ordering (Ming)

 - Fix a queue reference leak in disk allocation handling (Christoph)

* tag 'block-6.1-2022-11-25' of git://git.kernel.dk/linux:
  ublk_drv: don't forward io commands in reserve order
  s390/dasd: fix possible buffer overflow in copy_pair_show
  s390/dasd: fix no record found for raw_track_access
  s390/dasd: increase printing of debug data payload
  s390/dasd: Fix spelling mistake "Ivalid" -&gt; "Invalid"
  blk-mq: fix queue reference leak on blk_mq_alloc_disk_for_queue failure
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull block fixes from Jens Axboe:

 - A few fixes for s390 sads (Stefan, Colin)

 - Ensure that ublk doesn't reorder requests, as that can be problematic
   on devices that need specific ordering (Ming)

 - Fix a queue reference leak in disk allocation handling (Christoph)

* tag 'block-6.1-2022-11-25' of git://git.kernel.dk/linux:
  ublk_drv: don't forward io commands in reserve order
  s390/dasd: fix possible buffer overflow in copy_pair_show
  s390/dasd: fix no record found for raw_track_access
  s390/dasd: increase printing of debug data payload
  s390/dasd: Fix spelling mistake "Ivalid" -&gt; "Invalid"
  blk-mq: fix queue reference leak on blk_mq_alloc_disk_for_queue failure
</pre>
</div>
</content>
</entry>
<entry>
<title>blk-mq: fix queue reference leak on blk_mq_alloc_disk_for_queue failure</title>
<updated>2022-11-22T22:58:08+00:00</updated>
<author>
<name>Christoph Hellwig</name>
<email>hch@lst.de</email>
</author>
<published>2022-11-22T07:27:53+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=22c17e279a1b03bad7987e4a4192b289b890f293'/>
<id>22c17e279a1b03bad7987e4a4192b289b890f293</id>
<content type='text'>
Drop the request queue reference just acquired when __alloc_disk_node
failed.

Fixes: 6f8191fdf41d ("block: simplify disk shutdown")
Reported-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
Reviewed-by: Damien Le Moal &lt;damien.lemoal@opensource.wdc.com&gt;
Link: https://lore.kernel.org/r/20221122072753.426077-1-hch@lst.de
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Drop the request queue reference just acquired when __alloc_disk_node
failed.

Fixes: 6f8191fdf41d ("block: simplify disk shutdown")
Reported-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
Reviewed-by: Damien Le Moal &lt;damien.lemoal@opensource.wdc.com&gt;
Link: https://lore.kernel.org/r/20221122072753.426077-1-hch@lst.de
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'block-6.1-2022-11-18' of git://git.kernel.dk/linux</title>
<updated>2022-11-18T21:59:45+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-11-18T21:59:45+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=f4408c3dfcbcc7669caa48786973e88635f3d5e8'/>
<id>f4408c3dfcbcc7669caa48786973e88635f3d5e8</id>
<content type='text'>
Pull block fixes from Jens Axboe:

 - NVMe pull request via Christoph:
      - Two more bogus nid quirks (Bean Huo, Tiago Dias Ferreira)
      - Memory leak fix in nvmet (Sagi Grimberg)

 - Regression fix for block cgroups pinning the wrong blkcg, causing
   leaks of cgroups and blkcgs (Chris)

 - UAF fix for drbd setup error handling (Dan)

 - Fix DMA alignment propagation in DM (Keith)

* tag 'block-6.1-2022-11-18' of git://git.kernel.dk/linux:
  dm-log-writes: set dma_alignment limit in io_hints
  dm-integrity: set dma_alignment limit in io_hints
  block: make blk_set_default_limits() private
  dm-crypt: provide dma_alignment limit in io_hints
  block: make dma_alignment a stacking queue_limit
  nvmet: fix a memory leak in nvmet_auth_set_key
  nvme-pci: add NVME_QUIRK_BOGUS_NID for Netac NV7000
  drbd: use after free in drbd_create_device()
  nvme-pci: add NVME_QUIRK_BOGUS_NID for Micron Nitro
  blk-cgroup: properly pin the parent in blkcg_css_online
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull block fixes from Jens Axboe:

 - NVMe pull request via Christoph:
      - Two more bogus nid quirks (Bean Huo, Tiago Dias Ferreira)
      - Memory leak fix in nvmet (Sagi Grimberg)

 - Regression fix for block cgroups pinning the wrong blkcg, causing
   leaks of cgroups and blkcgs (Chris)

 - UAF fix for drbd setup error handling (Dan)

 - Fix DMA alignment propagation in DM (Keith)

* tag 'block-6.1-2022-11-18' of git://git.kernel.dk/linux:
  dm-log-writes: set dma_alignment limit in io_hints
  dm-integrity: set dma_alignment limit in io_hints
  block: make blk_set_default_limits() private
  dm-crypt: provide dma_alignment limit in io_hints
  block: make dma_alignment a stacking queue_limit
  nvmet: fix a memory leak in nvmet_auth_set_key
  nvme-pci: add NVME_QUIRK_BOGUS_NID for Netac NV7000
  drbd: use after free in drbd_create_device()
  nvme-pci: add NVME_QUIRK_BOGUS_NID for Micron Nitro
  blk-cgroup: properly pin the parent in blkcg_css_online
</pre>
</div>
</content>
</entry>
<entry>
<title>block: make blk_set_default_limits() private</title>
<updated>2022-11-16T22:58:11+00:00</updated>
<author>
<name>Keith Busch</name>
<email>kbusch@kernel.org</email>
</author>
<published>2022-11-10T18:44:59+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=b3228254bb6e91e57f920227f72a1a7d81925d81'/>
<id>b3228254bb6e91e57f920227f72a1a7d81925d81</id>
<content type='text'>
There are no external users of this function.

Signed-off-by: Keith Busch &lt;kbusch@kernel.org&gt;
Reviewed-by: Christoph Hellwig &lt;hch@lst.de&gt;
Link: https://lore.kernel.org/r/20221110184501.2451620-4-kbusch@meta.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
There are no external users of this function.

Signed-off-by: Keith Busch &lt;kbusch@kernel.org&gt;
Reviewed-by: Christoph Hellwig &lt;hch@lst.de&gt;
Link: https://lore.kernel.org/r/20221110184501.2451620-4-kbusch@meta.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>block: make dma_alignment a stacking queue_limit</title>
<updated>2022-11-16T22:58:11+00:00</updated>
<author>
<name>Keith Busch</name>
<email>kbusch@kernel.org</email>
</author>
<published>2022-11-10T18:44:57+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=c964d62f5cab7b43dd0534f22a96eab386c6ec5d'/>
<id>c964d62f5cab7b43dd0534f22a96eab386c6ec5d</id>
<content type='text'>
Device mappers had always been getting the default 511 dma mask, but
the underlying device might have a larger alignment requirement. Since
this value is used to determine alloweable direct-io alignment, this
needs to be a stackable limit.

Signed-off-by: Keith Busch &lt;kbusch@kernel.org&gt;
Reviewed-by: Christoph Hellwig &lt;hch@lst.de&gt;
Link: https://lore.kernel.org/r/20221110184501.2451620-2-kbusch@meta.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Device mappers had always been getting the default 511 dma mask, but
the underlying device might have a larger alignment requirement. Since
this value is used to determine alloweable direct-io alignment, this
needs to be a stackable limit.

Signed-off-by: Keith Busch &lt;kbusch@kernel.org&gt;
Reviewed-by: Christoph Hellwig &lt;hch@lst.de&gt;
Link: https://lore.kernel.org/r/20221110184501.2451620-2-kbusch@meta.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>blk-cgroup: properly pin the parent in blkcg_css_online</title>
<updated>2022-11-14T19:13:19+00:00</updated>
<author>
<name>Chris Mason</name>
<email>clm@fb.com</email>
</author>
<published>2022-11-14T18:19:30+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=d7dbd43f4a828fa1d9a8614d5b0ac40aee6375fe'/>
<id>d7dbd43f4a828fa1d9a8614d5b0ac40aee6375fe</id>
<content type='text'>
blkcg_css_online is supposed to pin the blkcg of the parent, but
397c9f46ee4d refactored things and along the way, changed it to pin the
css instead.  This results in extra pins, and we end up leaking blkcgs
and cgroups.

Fixes: 397c9f46ee4d ("blk-cgroup: move blkcg_{pin,unpin}_online out of line")
Signed-off-by: Chris Mason &lt;clm@fb.com&gt;
Spotted-by: Rik van Riel &lt;riel@surriel.com&gt;
Cc: &lt;stable@vger.kernel.org&gt; # v5.19+
Acked-by: Johannes Weiner &lt;hannes@cmpxchg.org&gt;
Link: https://lore.kernel.org/r/20221114181930.2093706-1-clm@fb.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
blkcg_css_online is supposed to pin the blkcg of the parent, but
397c9f46ee4d refactored things and along the way, changed it to pin the
css instead.  This results in extra pins, and we end up leaking blkcgs
and cgroups.

Fixes: 397c9f46ee4d ("blk-cgroup: move blkcg_{pin,unpin}_online out of line")
Signed-off-by: Chris Mason &lt;clm@fb.com&gt;
Spotted-by: Rik van Riel &lt;riel@surriel.com&gt;
Cc: &lt;stable@vger.kernel.org&gt; # v5.19+
Acked-by: Johannes Weiner &lt;hannes@cmpxchg.org&gt;
Link: https://lore.kernel.org/r/20221114181930.2093706-1-clm@fb.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'block-6.1-2022-11-11' of git://git.kernel.dk/linux</title>
<updated>2022-11-11T22:08:30+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-11-11T22:08:30+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=b0b6e2c9d3543c0926a7df5ee6e36507ad491dea'/>
<id>b0b6e2c9d3543c0926a7df5ee6e36507ad491dea</id>
<content type='text'>
Pull block fixes from Jens Axboe:

 - NVMe pull request via Christoph:
        - Quiet user passthrough command errors (Keith Busch)
        - Fix memory leak in nvmet_subsys_attr_model_store_locked
        - Fix a memory leak in nvmet-auth (Sagi Grimberg)

 - Fix a potential NULL point deref in bfq (Yu)

 - Allocate command/response buffers separately for DMA for sed-opal,
   rather than rely on embedded alignment (Serge)

* tag 'block-6.1-2022-11-11' of git://git.kernel.dk/linux:
  nvmet: fix a memory leak
  nvmet: fix memory leak in nvmet_subsys_attr_model_store_locked
  nvme: quiet user passthrough command errors
  block: sed-opal: kmalloc the cmd/resp buffers
  block, bfq: fix null pointer dereference in bfq_bio_bfqg()
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull block fixes from Jens Axboe:

 - NVMe pull request via Christoph:
        - Quiet user passthrough command errors (Keith Busch)
        - Fix memory leak in nvmet_subsys_attr_model_store_locked
        - Fix a memory leak in nvmet-auth (Sagi Grimberg)

 - Fix a potential NULL point deref in bfq (Yu)

 - Allocate command/response buffers separately for DMA for sed-opal,
   rather than rely on embedded alignment (Serge)

* tag 'block-6.1-2022-11-11' of git://git.kernel.dk/linux:
  nvmet: fix a memory leak
  nvmet: fix memory leak in nvmet_subsys_attr_model_store_locked
  nvme: quiet user passthrough command errors
  block: sed-opal: kmalloc the cmd/resp buffers
  block, bfq: fix null pointer dereference in bfq_bio_bfqg()
</pre>
</div>
</content>
</entry>
<entry>
<title>block: sed-opal: kmalloc the cmd/resp buffers</title>
<updated>2022-11-08T14:14:35+00:00</updated>
<author>
<name>Serge Semin</name>
<email>Sergey.Semin@baikalelectronics.ru</email>
</author>
<published>2022-11-07T20:39:44+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=f829230dd51974c1f4478900ed30bb77ba530b40'/>
<id>f829230dd51974c1f4478900ed30bb77ba530b40</id>
<content type='text'>
In accordance with [1] the DMA-able memory buffers must be
cacheline-aligned otherwise the cache writing-back and invalidation
performed during the mapping may cause the adjacent data being lost. It's
specifically required for the DMA-noncoherent platforms [2]. Seeing the
opal_dev.{cmd,resp} buffers are implicitly used for DMAs in the NVME and
SCSI/SD drivers in framework of the nvme_sec_submit() and sd_sec_submit()
methods respectively they must be cacheline-aligned to prevent the denoted
problem. One of the option to guarantee that is to kmalloc the buffers
[2]. Let's explicitly allocate them then instead of embedding into the
opal_dev structure instance.

Note this fix was inspired by the commit c94b7f9bab22 ("nvme-hwmon:
kmalloc the NVME SMART log buffer").

[1] Documentation/core-api/dma-api.rst
[2] Documentation/core-api/dma-api-howto.rst

Fixes: 455a7b238cd6 ("block: Add Sed-opal library")
Signed-off-by: Serge Semin &lt;Sergey.Semin@baikalelectronics.ru&gt;
Reviewed-by: Christoph Hellwig &lt;hch@lst.de&gt;
Link: https://lore.kernel.org/r/20221107203944.31686-1-Sergey.Semin@baikalelectronics.ru
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
In accordance with [1] the DMA-able memory buffers must be
cacheline-aligned otherwise the cache writing-back and invalidation
performed during the mapping may cause the adjacent data being lost. It's
specifically required for the DMA-noncoherent platforms [2]. Seeing the
opal_dev.{cmd,resp} buffers are implicitly used for DMAs in the NVME and
SCSI/SD drivers in framework of the nvme_sec_submit() and sd_sec_submit()
methods respectively they must be cacheline-aligned to prevent the denoted
problem. One of the option to guarantee that is to kmalloc the buffers
[2]. Let's explicitly allocate them then instead of embedding into the
opal_dev structure instance.

Note this fix was inspired by the commit c94b7f9bab22 ("nvme-hwmon:
kmalloc the NVME SMART log buffer").

[1] Documentation/core-api/dma-api.rst
[2] Documentation/core-api/dma-api-howto.rst

Fixes: 455a7b238cd6 ("block: Add Sed-opal library")
Signed-off-by: Serge Semin &lt;Sergey.Semin@baikalelectronics.ru&gt;
Reviewed-by: Christoph Hellwig &lt;hch@lst.de&gt;
Link: https://lore.kernel.org/r/20221107203944.31686-1-Sergey.Semin@baikalelectronics.ru
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>block, bfq: fix null pointer dereference in bfq_bio_bfqg()</title>
<updated>2022-11-08T14:13:25+00:00</updated>
<author>
<name>Yu Kuai</name>
<email>yukuai3@huawei.com</email>
</author>
<published>2022-11-08T10:34:34+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=f02be9002c480cd3ec0fcf184ad27cf531bd6ece'/>
<id>f02be9002c480cd3ec0fcf184ad27cf531bd6ece</id>
<content type='text'>
Out test found a following problem in kernel 5.10, and the same problem
should exist in mainline:

BUG: kernel NULL pointer dereference, address: 0000000000000094
PGD 0 P4D 0
Oops: 0000 [#1] SMP
CPU: 7 PID: 155 Comm: kworker/7:1 Not tainted 5.10.0-01932-g19e0ace2ca1d-dirty 4
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-b4
Workqueue: kthrotld blk_throtl_dispatch_work_fn
RIP: 0010:bfq_bio_bfqg+0x52/0xc0
Code: 94 00 00 00 00 75 2e 48 8b 40 30 48 83 05 35 06 c8 0b 01 48 85 c0 74 3d 4b
RSP: 0018:ffffc90001a1fba0 EFLAGS: 00010002
RAX: ffff888100d60400 RBX: ffff8881132e7000 RCX: 0000000000000000
RDX: 0000000000000017 RSI: ffff888103580a18 RDI: ffff888103580a18
RBP: ffff8881132e7000 R08: 0000000000000000 R09: ffffc90001a1fe10
R10: 0000000000000a20 R11: 0000000000034320 R12: 0000000000000000
R13: ffff888103580a18 R14: ffff888114447000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88881fdc0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000094 CR3: 0000000100cdb000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 bfq_bic_update_cgroup+0x3c/0x350
 ? ioc_create_icq+0x42/0x270
 bfq_init_rq+0xfd/0x1060
 bfq_insert_requests+0x20f/0x1cc0
 ? ioc_create_icq+0x122/0x270
 blk_mq_sched_insert_requests+0x86/0x1d0
 blk_mq_flush_plug_list+0x193/0x2a0
 blk_flush_plug_list+0x127/0x170
 blk_finish_plug+0x31/0x50
 blk_throtl_dispatch_work_fn+0x151/0x190
 process_one_work+0x27c/0x5f0
 worker_thread+0x28b/0x6b0
 ? rescuer_thread+0x590/0x590
 kthread+0x153/0x1b0
 ? kthread_flush_work+0x170/0x170
 ret_from_fork+0x1f/0x30
Modules linked in:
CR2: 0000000000000094
---[ end trace e2e59ac014314547 ]---
RIP: 0010:bfq_bio_bfqg+0x52/0xc0
Code: 94 00 00 00 00 75 2e 48 8b 40 30 48 83 05 35 06 c8 0b 01 48 85 c0 74 3d 4b
RSP: 0018:ffffc90001a1fba0 EFLAGS: 00010002
RAX: ffff888100d60400 RBX: ffff8881132e7000 RCX: 0000000000000000
RDX: 0000000000000017 RSI: ffff888103580a18 RDI: ffff888103580a18
RBP: ffff8881132e7000 R08: 0000000000000000 R09: ffffc90001a1fe10
R10: 0000000000000a20 R11: 0000000000034320 R12: 0000000000000000
R13: ffff888103580a18 R14: ffff888114447000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88881fdc0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000094 CR3: 0000000100cdb000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Root cause is quite complex:

1) use bfq elevator for the test device.
2) create a cgroup CG
3) config blk throtl in CG

   blkg_conf_prep
    blkg_create

4) create a thread T1 and issue async io in CG:

   bio_init
    bio_associate_blkg
   ...
   submit_bio
    submit_bio_noacct
     blk_throtl_bio -&gt; io is throttled
     // io submit is done

5) switch elevator:

   bfq_exit_queue
    blkcg_deactivate_policy
     list_for_each_entry(blkg, &amp;q-&gt;blkg_list, q_node)
      blkg-&gt;pd[] = NULL
      // bfq policy is removed

5) thread t1 exist, then remove the cgroup CG:

   blkcg_unpin_online
    blkcg_destroy_blkgs
     blkg_destroy
      list_del_init(&amp;blkg-&gt;q_node)
      // blkg is removed from queue list

6) switch elevator back to bfq

 bfq_init_queue
  bfq_create_group_hierarchy
   blkcg_activate_policy
    list_for_each_entry_reverse(blkg, &amp;q-&gt;blkg_list)
     // blkg is removed from list, hence bfq policy is still NULL

7) throttled io is dispatched to bfq:

 bfq_insert_requests
  bfq_init_rq
   bfq_bic_update_cgroup
    bfq_bio_bfqg
     bfqg = blkg_to_bfqg(blkg)
     // bfqg is NULL because bfq policy is NULL

The problem is only possible in bfq because only bfq can be deactivated and
activated while queue is online, while others can only be deactivated while
the device is removed.

Fix the problem in bfq by checking if blkg is online before calling
blkg_to_bfqg().

Signed-off-by: Yu Kuai &lt;yukuai3@huawei.com&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Link: https://lore.kernel.org/r/20221108103434.2853269-1-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Out test found a following problem in kernel 5.10, and the same problem
should exist in mainline:

BUG: kernel NULL pointer dereference, address: 0000000000000094
PGD 0 P4D 0
Oops: 0000 [#1] SMP
CPU: 7 PID: 155 Comm: kworker/7:1 Not tainted 5.10.0-01932-g19e0ace2ca1d-dirty 4
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-b4
Workqueue: kthrotld blk_throtl_dispatch_work_fn
RIP: 0010:bfq_bio_bfqg+0x52/0xc0
Code: 94 00 00 00 00 75 2e 48 8b 40 30 48 83 05 35 06 c8 0b 01 48 85 c0 74 3d 4b
RSP: 0018:ffffc90001a1fba0 EFLAGS: 00010002
RAX: ffff888100d60400 RBX: ffff8881132e7000 RCX: 0000000000000000
RDX: 0000000000000017 RSI: ffff888103580a18 RDI: ffff888103580a18
RBP: ffff8881132e7000 R08: 0000000000000000 R09: ffffc90001a1fe10
R10: 0000000000000a20 R11: 0000000000034320 R12: 0000000000000000
R13: ffff888103580a18 R14: ffff888114447000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88881fdc0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000094 CR3: 0000000100cdb000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 bfq_bic_update_cgroup+0x3c/0x350
 ? ioc_create_icq+0x42/0x270
 bfq_init_rq+0xfd/0x1060
 bfq_insert_requests+0x20f/0x1cc0
 ? ioc_create_icq+0x122/0x270
 blk_mq_sched_insert_requests+0x86/0x1d0
 blk_mq_flush_plug_list+0x193/0x2a0
 blk_flush_plug_list+0x127/0x170
 blk_finish_plug+0x31/0x50
 blk_throtl_dispatch_work_fn+0x151/0x190
 process_one_work+0x27c/0x5f0
 worker_thread+0x28b/0x6b0
 ? rescuer_thread+0x590/0x590
 kthread+0x153/0x1b0
 ? kthread_flush_work+0x170/0x170
 ret_from_fork+0x1f/0x30
Modules linked in:
CR2: 0000000000000094
---[ end trace e2e59ac014314547 ]---
RIP: 0010:bfq_bio_bfqg+0x52/0xc0
Code: 94 00 00 00 00 75 2e 48 8b 40 30 48 83 05 35 06 c8 0b 01 48 85 c0 74 3d 4b
RSP: 0018:ffffc90001a1fba0 EFLAGS: 00010002
RAX: ffff888100d60400 RBX: ffff8881132e7000 RCX: 0000000000000000
RDX: 0000000000000017 RSI: ffff888103580a18 RDI: ffff888103580a18
RBP: ffff8881132e7000 R08: 0000000000000000 R09: ffffc90001a1fe10
R10: 0000000000000a20 R11: 0000000000034320 R12: 0000000000000000
R13: ffff888103580a18 R14: ffff888114447000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88881fdc0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000094 CR3: 0000000100cdb000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Root cause is quite complex:

1) use bfq elevator for the test device.
2) create a cgroup CG
3) config blk throtl in CG

   blkg_conf_prep
    blkg_create

4) create a thread T1 and issue async io in CG:

   bio_init
    bio_associate_blkg
   ...
   submit_bio
    submit_bio_noacct
     blk_throtl_bio -&gt; io is throttled
     // io submit is done

5) switch elevator:

   bfq_exit_queue
    blkcg_deactivate_policy
     list_for_each_entry(blkg, &amp;q-&gt;blkg_list, q_node)
      blkg-&gt;pd[] = NULL
      // bfq policy is removed

5) thread t1 exist, then remove the cgroup CG:

   blkcg_unpin_online
    blkcg_destroy_blkgs
     blkg_destroy
      list_del_init(&amp;blkg-&gt;q_node)
      // blkg is removed from queue list

6) switch elevator back to bfq

 bfq_init_queue
  bfq_create_group_hierarchy
   blkcg_activate_policy
    list_for_each_entry_reverse(blkg, &amp;q-&gt;blkg_list)
     // blkg is removed from list, hence bfq policy is still NULL

7) throttled io is dispatched to bfq:

 bfq_insert_requests
  bfq_init_rq
   bfq_bic_update_cgroup
    bfq_bio_bfqg
     bfqg = blkg_to_bfqg(blkg)
     // bfqg is NULL because bfq policy is NULL

The problem is only possible in bfq because only bfq can be deactivated and
activated while queue is online, while others can only be deactivated while
the device is removed.

Fix the problem in bfq by checking if blkg is online before calling
blkg_to_bfqg().

Signed-off-by: Yu Kuai &lt;yukuai3@huawei.com&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Link: https://lore.kernel.org/r/20221108103434.2853269-1-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'block-6.1-2022-11-05' of git://git.kernel.dk/linux</title>
<updated>2022-11-05T16:02:28+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-11-05T16:02:28+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=4869f5750afdb10a0e9cfa0252fce33e53ab681e'/>
<id>4869f5750afdb10a0e9cfa0252fce33e53ab681e</id>
<content type='text'>
Pull block fixes from Jens Axboe:

 - Fixes for the ublk driver (Ming)

 - Fixes for error handling memory leaks (Chen Jun, Chen Zhongjin)

 - Explicitly clear the last request in a chain when the plug is
   flushed, as it may have already been issued (Al)

* tag 'block-6.1-2022-11-05' of git://git.kernel.dk/linux:
  block: blk_add_rq_to_plug(): clear stale 'last' after flush
  blk-mq: Fix kmemleak in blk_mq_init_allocated_queue
  block: Fix possible memory leak for rq_wb on add_disk failure
  ublk_drv: add ublk_queue_cmd() for cleanup
  ublk_drv: avoid to touch io_uring cmd in blk_mq io path
  ublk_drv: comment on ublk_driver entry of Kconfig
  ublk_drv: return flag of UBLK_F_URING_CMD_COMP_IN_TASK in case of module
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull block fixes from Jens Axboe:

 - Fixes for the ublk driver (Ming)

 - Fixes for error handling memory leaks (Chen Jun, Chen Zhongjin)

 - Explicitly clear the last request in a chain when the plug is
   flushed, as it may have already been issued (Al)

* tag 'block-6.1-2022-11-05' of git://git.kernel.dk/linux:
  block: blk_add_rq_to_plug(): clear stale 'last' after flush
  blk-mq: Fix kmemleak in blk_mq_init_allocated_queue
  block: Fix possible memory leak for rq_wb on add_disk failure
  ublk_drv: add ublk_queue_cmd() for cleanup
  ublk_drv: avoid to touch io_uring cmd in blk_mq io path
  ublk_drv: comment on ublk_driver entry of Kconfig
  ublk_drv: return flag of UBLK_F_URING_CMD_COMP_IN_TASK in case of module
</pre>
</div>
</content>
</entry>
</feed>
