<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/block, branch v4.4.210</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>compat_ioctl: block: handle Persistent Reservations</title>
<updated>2020-01-12T10:22:42+00:00</updated>
<author>
<name>Arnd Bergmann</name>
<email>arnd@arndb.de</email>
</author>
<published>2019-11-29T10:28:22+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=c9d9978e6da938b81eb836a5f6af20c080bca698'/>
<id>c9d9978e6da938b81eb836a5f6af20c080bca698</id>
<content type='text'>
commit b2c0fcd28772f99236d261509bcd242135677965 upstream.

These were added to blkdev_ioctl() in linux-5.5 but not
blkdev_compat_ioctl, so add them now.

Cc: &lt;stable@vger.kernel.org&gt; # v4.4+
Fixes: bbd3e064362e ("block: add an API for Persistent Reservations")
Signed-off-by: Arnd Bergmann &lt;arnd@arndb.de&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

Fold in followup patch from Arnd with missing pr.h header include.

Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit b2c0fcd28772f99236d261509bcd242135677965 upstream.

These were added to blkdev_ioctl() in linux-5.5 but not
blkdev_compat_ioctl, so add them now.

Cc: &lt;stable@vger.kernel.org&gt; # v4.4+
Fixes: bbd3e064362e ("block: add an API for Persistent Reservations")
Signed-off-by: Arnd Bergmann &lt;arnd@arndb.de&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

Fold in followup patch from Arnd with missing pr.h header include.

Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>blk-mq: make sure that line break can be printed</title>
<updated>2019-12-21T09:35:37+00:00</updated>
<author>
<name>Ming Lei</name>
<email>ming.lei@redhat.com</email>
</author>
<published>2019-11-04T08:26:53+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=1f888f82e5c88cc92c28b61f05e6003fd762aedb'/>
<id>1f888f82e5c88cc92c28b61f05e6003fd762aedb</id>
<content type='text'>
commit d2c9be89f8ebe7ebcc97676ac40f8dec1cf9b43a upstream.

8962842ca5ab ("blk-mq: avoid sysfs buffer overflow with too many CPU cores")
avoids sysfs buffer overflow, and reserves one character for line break.
However, the last snprintf() doesn't get correct 'size' parameter passed
in, so fixed it.

Fixes: 8962842ca5ab ("blk-mq: avoid sysfs buffer overflow with too many CPU cores")
Signed-off-by: Ming Lei &lt;ming.lei@redhat.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Cc: Nobuhiro Iwamatsu &lt;nobuhiro1.iwamatsu@toshiba.co.jp&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit d2c9be89f8ebe7ebcc97676ac40f8dec1cf9b43a upstream.

8962842ca5ab ("blk-mq: avoid sysfs buffer overflow with too many CPU cores")
avoids sysfs buffer overflow, and reserves one character for line break.
However, the last snprintf() doesn't get correct 'size' parameter passed
in, so fixed it.

Fixes: 8962842ca5ab ("blk-mq: avoid sysfs buffer overflow with too many CPU cores")
Signed-off-by: Ming Lei &lt;ming.lei@redhat.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Cc: Nobuhiro Iwamatsu &lt;nobuhiro1.iwamatsu@toshiba.co.jp&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>blk-mq: avoid sysfs buffer overflow with too many CPU cores</title>
<updated>2019-12-21T09:35:24+00:00</updated>
<author>
<name>Ming Lei</name>
<email>ming.lei@redhat.com</email>
</author>
<published>2019-11-02T08:02:15+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=6eca9292c59b7a5719276e0e78ea3f0deb7b6cbe'/>
<id>6eca9292c59b7a5719276e0e78ea3f0deb7b6cbe</id>
<content type='text'>
commit 8962842ca5abdcf98e22ab3b2b45a103f0408b95 upstream.

It is reported that sysfs buffer overflow can be triggered if the system
has too many CPU cores(&gt;841 on 4K PAGE_SIZE) when showing CPUs of
hctx via /sys/block/$DEV/mq/$N/cpu_list.

Use snprintf to avoid the potential buffer overflow.

This version doesn't change the attribute format, and simply stops
showing CPU numbers if the buffer is going to overflow.

Cc: stable@vger.kernel.org
Fixes: 676141e48af7("blk-mq: don't dump CPU -&gt; hw queue map on driver load")
Signed-off-by: Ming Lei &lt;ming.lei@redhat.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 8962842ca5abdcf98e22ab3b2b45a103f0408b95 upstream.

It is reported that sysfs buffer overflow can be triggered if the system
has too many CPU cores(&gt;841 on 4K PAGE_SIZE) when showing CPUs of
hctx via /sys/block/$DEV/mq/$N/cpu_list.

Use snprintf to avoid the potential buffer overflow.

This version doesn't change the attribute format, and simply stops
showing CPU numbers if the buffer is going to overflow.

Cc: stable@vger.kernel.org
Fixes: 676141e48af7("blk-mq: don't dump CPU -&gt; hw queue map on driver load")
Signed-off-by: Ming Lei &lt;ming.lei@redhat.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>block: blk_init_allocated_queue() set q-&gt;fq as NULL in the fail case</title>
<updated>2019-08-11T10:20:46+00:00</updated>
<author>
<name>xiao jin</name>
<email>jin.xiao@intel.com</email>
</author>
<published>2018-07-30T06:11:12+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=e6ea77dd5a6a72583453e8703583ce0ef538aea4'/>
<id>e6ea77dd5a6a72583453e8703583ce0ef538aea4</id>
<content type='text'>
commit 54648cf1ec2d7f4b6a71767799c45676a138ca24 upstream.

We find the memory use-after-free issue in __blk_drain_queue()
on the kernel 4.14. After read the latest kernel 4.18-rc6 we
think it has the same problem.

Memory is allocated for q-&gt;fq in the blk_init_allocated_queue().
If the elevator init function called with error return, it will
run into the fail case to free the q-&gt;fq.

Then the __blk_drain_queue() uses the same memory after the free
of the q-&gt;fq, it will lead to the unpredictable event.

The patch is to set q-&gt;fq as NULL in the fail case of
blk_init_allocated_queue().

Fixes: commit 7c94e1c157a2 ("block: introduce blk_flush_queue to drive flush machinery")
Cc: &lt;stable@vger.kernel.org&gt;
Reviewed-by: Ming Lei &lt;ming.lei@redhat.com&gt;
Reviewed-by: Bart Van Assche &lt;bart.vanassche@wdc.com&gt;
Signed-off-by: xiao jin &lt;jin.xiao@intel.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
[groeck: backport to v4.4.y/v4.9.y (context change)]
Signed-off-by: Guenter Roeck &lt;linux@roeck-us.net&gt;
Signed-off-by: Alessio Balsini &lt;balsini@android.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit 54648cf1ec2d7f4b6a71767799c45676a138ca24 upstream.

We find the memory use-after-free issue in __blk_drain_queue()
on the kernel 4.14. After read the latest kernel 4.18-rc6 we
think it has the same problem.

Memory is allocated for q-&gt;fq in the blk_init_allocated_queue().
If the elevator init function called with error return, it will
run into the fail case to free the q-&gt;fq.

Then the __blk_drain_queue() uses the same memory after the free
of the q-&gt;fq, it will lead to the unpredictable event.

The patch is to set q-&gt;fq as NULL in the fail case of
blk_init_allocated_queue().

Fixes: commit 7c94e1c157a2 ("block: introduce blk_flush_queue to drive flush machinery")
Cc: &lt;stable@vger.kernel.org&gt;
Reviewed-by: Ming Lei &lt;ming.lei@redhat.com&gt;
Reviewed-by: Bart Van Assche &lt;bart.vanassche@wdc.com&gt;
Signed-off-by: xiao jin &lt;jin.xiao@intel.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
[groeck: backport to v4.4.y/v4.9.y (context change)]
Signed-off-by: Guenter Roeck &lt;linux@roeck-us.net&gt;
Signed-off-by: Alessio Balsini &lt;balsini@android.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>take floppy compat ioctls to sodding floppy.c</title>
<updated>2019-08-04T07:34:51+00:00</updated>
<author>
<name>Al Viro</name>
<email>viro@zeniv.linux.org.uk</email>
</author>
<published>2017-06-27T19:47:56+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=0a18fbb5b02b611e34de7948291d7b96f637d465'/>
<id>0a18fbb5b02b611e34de7948291d7b96f637d465</id>
<content type='text'>
[ Upstream commit 229b53c9bf4e1132a4aa6feb9632a7a1f1d08c5c ]

all other drivers recognizing those ioctls are very much *not*
biarch.

Signed-off-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 229b53c9bf4e1132a4aa6feb9632a7a1f1d08c5c ]

all other drivers recognizing those ioctls are very much *not*
biarch.

Signed-off-by: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>block: do not leak memory in bio_copy_user_iov()</title>
<updated>2019-04-27T07:33:55+00:00</updated>
<author>
<name>Jérôme Glisse</name>
<email>jglisse@redhat.com</email>
</author>
<published>2019-04-10T20:27:51+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=f449309b7f43ae6aa457a2ee75e1e00783bc8f2d'/>
<id>f449309b7f43ae6aa457a2ee75e1e00783bc8f2d</id>
<content type='text'>
commit a3761c3c91209b58b6f33bf69dd8bb8ec0c9d925 upstream.

When bio_add_pc_page() fails in bio_copy_user_iov() we should free
the page we just allocated otherwise we are leaking it.

Cc: linux-block@vger.kernel.org
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: stable@vger.kernel.org
Reviewed-by: Chaitanya Kulkarni &lt;chaitanya.kulkarni@wdc.com&gt;
Signed-off-by: Jérôme Glisse &lt;jglisse@redhat.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit a3761c3c91209b58b6f33bf69dd8bb8ec0c9d925 upstream.

When bio_add_pc_page() fails in bio_copy_user_iov() we should free
the page we just allocated otherwise we are leaking it.

Cc: linux-block@vger.kernel.org
Cc: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: stable@vger.kernel.org
Reviewed-by: Chaitanya Kulkarni &lt;chaitanya.kulkarni@wdc.com&gt;
Signed-off-by: Jérôme Glisse &lt;jglisse@redhat.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>partitions/aix: fix usage of uninitialized lv_info and lvname structures</title>
<updated>2018-09-19T20:48:59+00:00</updated>
<author>
<name>Mauricio Faria de Oliveira</name>
<email>mfo@canonical.com</email>
</author>
<published>2018-07-26T01:46:28+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=a169d7c844a9ed24d110ae4333ed1edf451bf22f'/>
<id>a169d7c844a9ed24d110ae4333ed1edf451bf22f</id>
<content type='text'>
[ Upstream commit 14cb2c8a6c5dae57ee3e2da10fa3db2b9087e39e ]

The if-block that sets a successful return value in aix_partition()
uses 'lvip[].pps_per_lv' and 'n[].name' potentially uninitialized.

For example, if 'numlvs' is zero or alloc_lvn() fails, neither is
initialized, but are used anyway if alloc_pvd() succeeds after it.

So, make the alloc_pvd() call conditional on their initialization.

This has been hit when attaching an apparently corrupted/stressed
AIX LUN, misleading the kernel to pr_warn() invalid data and hang.

    [...] partition (null) (11 pp's found) is not contiguous
    [...] partition (null) (2 pp's found) is not contiguous
    [...] partition (null) (3 pp's found) is not contiguous
    [...] partition (null) (64 pp's found) is not contiguous

Fixes: 6ceea22bbbc8 ("partitions: add aix lvm partition support files")
Signed-off-by: Mauricio Faria de Oliveira &lt;mfo@canonical.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Sasha Levin &lt;alexander.levin@microsoft.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 14cb2c8a6c5dae57ee3e2da10fa3db2b9087e39e ]

The if-block that sets a successful return value in aix_partition()
uses 'lvip[].pps_per_lv' and 'n[].name' potentially uninitialized.

For example, if 'numlvs' is zero or alloc_lvn() fails, neither is
initialized, but are used anyway if alloc_pvd() succeeds after it.

So, make the alloc_pvd() call conditional on their initialization.

This has been hit when attaching an apparently corrupted/stressed
AIX LUN, misleading the kernel to pr_warn() invalid data and hang.

    [...] partition (null) (11 pp's found) is not contiguous
    [...] partition (null) (2 pp's found) is not contiguous
    [...] partition (null) (3 pp's found) is not contiguous
    [...] partition (null) (64 pp's found) is not contiguous

Fixes: 6ceea22bbbc8 ("partitions: add aix lvm partition support files")
Signed-off-by: Mauricio Faria de Oliveira &lt;mfo@canonical.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Sasha Levin &lt;alexander.levin@microsoft.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>partitions/aix: append null character to print data from disk</title>
<updated>2018-09-19T20:48:59+00:00</updated>
<author>
<name>Mauricio Faria de Oliveira</name>
<email>mfo@canonical.com</email>
</author>
<published>2018-07-26T01:46:29+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=77d3c98f661ed3bb9d675b9af9763c01d82ebc9c'/>
<id>77d3c98f661ed3bb9d675b9af9763c01d82ebc9c</id>
<content type='text'>
[ Upstream commit d43fdae7bac2def8c4314b5a49822cb7f08a45f1 ]

Even if properly initialized, the lvname array (i.e., strings)
is read from disk, and might contain corrupt data (e.g., lack
the null terminating character for strings).

So, make sure the partition name string used in pr_warn() has
the null terminating character.

Fixes: 6ceea22bbbc8 ("partitions: add aix lvm partition support files")
Suggested-by: Daniel J. Axtens &lt;daniel.axtens@canonical.com&gt;
Signed-off-by: Mauricio Faria de Oliveira &lt;mfo@canonical.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Sasha Levin &lt;alexander.levin@microsoft.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit d43fdae7bac2def8c4314b5a49822cb7f08a45f1 ]

Even if properly initialized, the lvname array (i.e., strings)
is read from disk, and might contain corrupt data (e.g., lack
the null terminating character for strings).

So, make sure the partition name string used in pr_warn() has
the null terminating character.

Fixes: 6ceea22bbbc8 ("partitions: add aix lvm partition support files")
Suggested-by: Daniel J. Axtens &lt;daniel.axtens@canonical.com&gt;
Signed-off-by: Mauricio Faria de Oliveira &lt;mfo@canonical.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Sasha Levin &lt;alexander.levin@microsoft.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>block,blkcg: use __GFP_NOWARN for best-effort allocations in blkcg</title>
<updated>2018-09-19T20:48:56+00:00</updated>
<author>
<name>Tejun Heo</name>
<email>tj@kernel.org</email>
</author>
<published>2016-11-21T23:03:32+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=29a2875cf481b8db367a0a8aed54d4b30640558e'/>
<id>29a2875cf481b8db367a0a8aed54d4b30640558e</id>
<content type='text'>
commit e00f4f4d0ff7e13b9115428a245b49108d625f09 upstream.

blkcg allocates some per-cgroup data structures with GFP_NOWAIT and
when that fails falls back to operations which aren't specific to the
cgroup.  Occassional failures are expected under pressure and falling
back to non-cgroup operation is the right thing to do.

Unfortunately, I forgot to add __GFP_NOWARN to these allocations and
these expected failures end up creating a lot of noise.  Add
__GFP_NOWARN.

Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Reported-by: Marc MERLIN &lt;marc@merlins.org&gt;
Reported-by: Vlastimil Babka &lt;vbabka@suse.cz&gt;
Signed-off-by: Jens Axboe &lt;axboe@fb.com&gt;
Signed-off-by: Amit Pundir &lt;amit.pundir@linaro.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit e00f4f4d0ff7e13b9115428a245b49108d625f09 upstream.

blkcg allocates some per-cgroup data structures with GFP_NOWAIT and
when that fails falls back to operations which aren't specific to the
cgroup.  Occassional failures are expected under pressure and falling
back to non-cgroup operation is the right thing to do.

Unfortunately, I forgot to add __GFP_NOWARN to these allocations and
these expected failures end up creating a lot of noise.  Add
__GFP_NOWARN.

Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Reported-by: Marc MERLIN &lt;marc@merlins.org&gt;
Reported-by: Vlastimil Babka &lt;vbabka@suse.cz&gt;
Signed-off-by: Jens Axboe &lt;axboe@fb.com&gt;
Signed-off-by: Amit Pundir &lt;amit.pundir@linaro.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
<entry>
<title>cfq: Give a chance for arming slice idle timer in case of group_idle</title>
<updated>2018-09-19T20:48:55+00:00</updated>
<author>
<name>Ritesh Harjani</name>
<email>riteshh@codeaurora.org</email>
</author>
<published>2017-08-09T12:58:32+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=39223f841425da99c2b0174d8bc42ee1bb29a5ad'/>
<id>39223f841425da99c2b0174d8bc42ee1bb29a5ad</id>
<content type='text'>
commit b3193bc0dca9bb69c8ba1ec1a318105c76eb4172 upstream.

In below scenario blkio cgroup does not work as per their assigned
weights :-
1. When the underlying device is nonrotational with a single HW queue
with depth of &gt;= CFQ_HW_QUEUE_MIN
2. When the use case is forming two blkio cgroups cg1(weight 1000) &amp;
cg2(wight 100) and two processes(file1 and file2) doing sync IO in
their respective blkio cgroups.

For above usecase result of fio (without this patch):-
file1: (groupid=0, jobs=1): err= 0: pid=685: Thu Jan  1 19:41:49 1970
  write: IOPS=1315, BW=41.1MiB/s (43.1MB/s)(1024MiB/24906msec)
&lt;...&gt;
file2: (groupid=0, jobs=1): err= 0: pid=686: Thu Jan  1 19:41:49 1970
  write: IOPS=1295, BW=40.5MiB/s (42.5MB/s)(1024MiB/25293msec)
&lt;...&gt;
// both the process BW is equal even though they belong to diff.
cgroups with weight of 1000(cg1) and 100(cg2)

In above case (for non rotational NCQ devices),
as soon as the request from cg1 is completed and even
though it is provided with higher set_slice=10, because of CFQ
algorithm when the driver tries to fetch the request, CFQ expires
this group without providing any idle time nor weight priority
and schedules another cfq group (in this case cg2).
And thus both cfq groups(cg1 &amp; cg2) keep alternating to get the
disk time and hence loses the cgroup weight based scheduling.

Below patch gives a chance to cfq algorithm (cfq_arm_slice_timer)
to arm the slice timer in case group_idle is enabled.
In case if group_idle is also not required (including for nonrotational
NCQ drives), we need to explicitly set group_idle = 0 from sysfs for
such cases.

With this patch result of fio(for above usecase) :-
file1: (groupid=0, jobs=1): err= 0: pid=690: Thu Jan  1 00:06:08 1970
  write: IOPS=1706, BW=53.3MiB/s (55.9MB/s)(1024MiB/19197msec)
&lt;..&gt;
file2: (groupid=0, jobs=1): err= 0: pid=691: Thu Jan  1 00:06:08 1970
  write: IOPS=1043, BW=32.6MiB/s (34.2MB/s)(1024MiB/31401msec)
&lt;..&gt;
// In this processes BW is as per their respective cgroups weight.

Signed-off-by: Ritesh Harjani &lt;riteshh@codeaurora.org&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Amit Pundir &lt;amit.pundir@linaro.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit b3193bc0dca9bb69c8ba1ec1a318105c76eb4172 upstream.

In below scenario blkio cgroup does not work as per their assigned
weights :-
1. When the underlying device is nonrotational with a single HW queue
with depth of &gt;= CFQ_HW_QUEUE_MIN
2. When the use case is forming two blkio cgroups cg1(weight 1000) &amp;
cg2(wight 100) and two processes(file1 and file2) doing sync IO in
their respective blkio cgroups.

For above usecase result of fio (without this patch):-
file1: (groupid=0, jobs=1): err= 0: pid=685: Thu Jan  1 19:41:49 1970
  write: IOPS=1315, BW=41.1MiB/s (43.1MB/s)(1024MiB/24906msec)
&lt;...&gt;
file2: (groupid=0, jobs=1): err= 0: pid=686: Thu Jan  1 19:41:49 1970
  write: IOPS=1295, BW=40.5MiB/s (42.5MB/s)(1024MiB/25293msec)
&lt;...&gt;
// both the process BW is equal even though they belong to diff.
cgroups with weight of 1000(cg1) and 100(cg2)

In above case (for non rotational NCQ devices),
as soon as the request from cg1 is completed and even
though it is provided with higher set_slice=10, because of CFQ
algorithm when the driver tries to fetch the request, CFQ expires
this group without providing any idle time nor weight priority
and schedules another cfq group (in this case cg2).
And thus both cfq groups(cg1 &amp; cg2) keep alternating to get the
disk time and hence loses the cgroup weight based scheduling.

Below patch gives a chance to cfq algorithm (cfq_arm_slice_timer)
to arm the slice timer in case group_idle is enabled.
In case if group_idle is also not required (including for nonrotational
NCQ drives), we need to explicitly set group_idle = 0 from sysfs for
such cases.

With this patch result of fio(for above usecase) :-
file1: (groupid=0, jobs=1): err= 0: pid=690: Thu Jan  1 00:06:08 1970
  write: IOPS=1706, BW=53.3MiB/s (55.9MB/s)(1024MiB/19197msec)
&lt;..&gt;
file2: (groupid=0, jobs=1): err= 0: pid=691: Thu Jan  1 00:06:08 1970
  write: IOPS=1043, BW=32.6MiB/s (34.2MB/s)(1024MiB/31401msec)
&lt;..&gt;
// In this processes BW is as per their respective cgroups weight.

Signed-off-by: Ritesh Harjani &lt;riteshh@codeaurora.org&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
Signed-off-by: Amit Pundir &lt;amit.pundir@linaro.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;

</pre>
</div>
</content>
</entry>
</feed>
