<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/fs/buffer.c, branch v5.0.4</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>fs: ratelimit __find_get_block_slow() failure message.</title>
<updated>2019-02-06T19:58:56+00:00</updated>
<author>
<name>Tetsuo Handa</name>
<email>penguin-kernel@I-love.SAKURA.ne.jp</email>
</author>
<published>2019-01-21T13:49:37+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=43636c804df0126da669c261fc820fb22f62bfc2'/>
<id>43636c804df0126da669c261fc820fb22f62bfc2</id>
<content type='text'>
When something let __find_get_block_slow() hit all_mapped path, it calls
printk() for 100+ times per a second. But there is no need to print same
message with such high frequency; it is just asking for stall warning, or
at least bloating log files.

  [  399.866302][T15342] __find_get_block_slow() failed. block=1, b_blocknr=8
  [  399.873324][T15342] b_state=0x00000029, b_size=512
  [  399.878403][T15342] device loop0 blocksize: 4096
  [  399.883296][T15342] __find_get_block_slow() failed. block=1, b_blocknr=8
  [  399.890400][T15342] b_state=0x00000029, b_size=512
  [  399.895595][T15342] device loop0 blocksize: 4096
  [  399.900556][T15342] __find_get_block_slow() failed. block=1, b_blocknr=8
  [  399.907471][T15342] b_state=0x00000029, b_size=512
  [  399.912506][T15342] device loop0 blocksize: 4096

This patch reduces frequency to up to once per a second, in addition to
concatenating three lines into one.

  [  399.866302][T15342] __find_get_block_slow() failed. block=1, b_blocknr=8, b_state=0x00000029, b_size=512, device loop0 blocksize: 4096

Signed-off-by: Tetsuo Handa &lt;penguin-kernel@I-love.SAKURA.ne.jp&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Cc: Dmitry Vyukov &lt;dvyukov@google.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
When something let __find_get_block_slow() hit all_mapped path, it calls
printk() for 100+ times per a second. But there is no need to print same
message with such high frequency; it is just asking for stall warning, or
at least bloating log files.

  [  399.866302][T15342] __find_get_block_slow() failed. block=1, b_blocknr=8
  [  399.873324][T15342] b_state=0x00000029, b_size=512
  [  399.878403][T15342] device loop0 blocksize: 4096
  [  399.883296][T15342] __find_get_block_slow() failed. block=1, b_blocknr=8
  [  399.890400][T15342] b_state=0x00000029, b_size=512
  [  399.895595][T15342] device loop0 blocksize: 4096
  [  399.900556][T15342] __find_get_block_slow() failed. block=1, b_blocknr=8
  [  399.907471][T15342] b_state=0x00000029, b_size=512
  [  399.912506][T15342] device loop0 blocksize: 4096

This patch reduces frequency to up to once per a second, in addition to
concatenating three lines into one.

  [  399.866302][T15342] __find_get_block_slow() failed. block=1, b_blocknr=8, b_state=0x00000029, b_size=512, device loop0 blocksize: 4096

Signed-off-by: Tetsuo Handa &lt;penguin-kernel@I-love.SAKURA.ne.jp&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Cc: Dmitry Vyukov &lt;dvyukov@google.com&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>fs/: remove caller signal_pending branch predictions</title>
<updated>2019-01-04T21:13:48+00:00</updated>
<author>
<name>Davidlohr Bueso</name>
<email>dave@stgolabs.net</email>
</author>
<published>2019-01-03T23:28:58+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=08d405c8b845a4b871fa3606c9ebe0d0f3b74614'/>
<id>08d405c8b845a4b871fa3606c9ebe0d0f3b74614</id>
<content type='text'>
This is already done for us internally by the signal machinery.

[akpm@linux-foundation.org: fix fs/buffer.c]
Link: http://lkml.kernel.org/r/20181116002713.8474-7-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso &lt;dave@stgolabs.net&gt;
Reviewed-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This is already done for us internally by the signal machinery.

[akpm@linux-foundation.org: fix fs/buffer.c]
Link: http://lkml.kernel.org/r/20181116002713.8474-7-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso &lt;dave@stgolabs.net&gt;
Reviewed-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>blkcg: associate writeback bios with a blkg</title>
<updated>2018-12-08T05:26:37+00:00</updated>
<author>
<name>Dennis Zhou</name>
<email>dennis@kernel.org</email>
</author>
<published>2018-12-05T17:10:34+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=fd42df305f804ddc0d5ac028e944784283b2f92d'/>
<id>fd42df305f804ddc0d5ac028e944784283b2f92d</id>
<content type='text'>
One of the goals of this series is to remove a separate reference to
the css of the bio. This can and should be accessed via bio_blkcg(). In
this patch, wbc_init_bio() now requires a bio to have a device
associated with it.

Signed-off-by: Dennis Zhou &lt;dennis@kernel.org&gt;
Reviewed-by: Josef Bacik &lt;josef@toxicpanda.com&gt;
Acked-by: Tejun Heo &lt;tj@kernel.org&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
One of the goals of this series is to remove a separate reference to
the css of the bio. This can and should be accessed via bio_blkcg(). In
this patch, wbc_init_bio() now requires a bio to have a device
associated with it.

Signed-off-by: Dennis Zhou &lt;dennis@kernel.org&gt;
Reviewed-by: Josef Bacik &lt;josef@toxicpanda.com&gt;
Acked-by: Tejun Heo &lt;tj@kernel.org&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'for-linus-20181102' of git://git.kernel.dk/linux-block</title>
<updated>2018-11-02T18:25:48+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2018-11-02T18:25:48+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=5f21585384a4a69b8bfdd2cae7e3648ae805f57d'/>
<id>5f21585384a4a69b8bfdd2cae7e3648ae805f57d</id>
<content type='text'>
Pull block layer fixes from Jens Axboe:
 "The biggest part of this pull request is the revert of the blkcg
  cleanup series. It had one fix earlier for a stacked device issue, but
  another one was reported. Rather than play whack-a-mole with this,
  revert the entire series and try again for the next kernel release.

  Apart from that, only small fixes/changes.

  Summary:

   - Indentation fixup for mtip32xx (Colin Ian King)

   - The blkcg cleanup series revert (Dennis Zhou)

   - Two NVMe fixes. One fixing a regression in the nvme request
     initialization in this merge window, causing nvme-fc to not work.
     The other is a suspend/resume p2p resource issue (James, Keith)

   - Fix sg discard merge, allowing us to merge in cases where we didn't
     before (Jianchao Wang)

   - Call rq_qos_exit() after the queue is frozen, preventing a hang
     (Ming)

   - Fix brd queue setup, fixing an oops if we fail setting up all
     devices (Ming)"

* tag 'for-linus-20181102' of git://git.kernel.dk/linux-block:
  nvme-pci: fix conflicting p2p resource adds
  nvme-fc: fix request private initialization
  blkcg: revert blkcg cleanups series
  block: brd: associate with queue until adding disk
  block: call rq_qos_exit() after queue is frozen
  mtip32xx: clean an indentation issue, remove extraneous tabs
  block: fix the DISCARD request merge
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull block layer fixes from Jens Axboe:
 "The biggest part of this pull request is the revert of the blkcg
  cleanup series. It had one fix earlier for a stacked device issue, but
  another one was reported. Rather than play whack-a-mole with this,
  revert the entire series and try again for the next kernel release.

  Apart from that, only small fixes/changes.

  Summary:

   - Indentation fixup for mtip32xx (Colin Ian King)

   - The blkcg cleanup series revert (Dennis Zhou)

   - Two NVMe fixes. One fixing a regression in the nvme request
     initialization in this merge window, causing nvme-fc to not work.
     The other is a suspend/resume p2p resource issue (James, Keith)

   - Fix sg discard merge, allowing us to merge in cases where we didn't
     before (Jianchao Wang)

   - Call rq_qos_exit() after the queue is frozen, preventing a hang
     (Ming)

   - Fix brd queue setup, fixing an oops if we fail setting up all
     devices (Ming)"

* tag 'for-linus-20181102' of git://git.kernel.dk/linux-block:
  nvme-pci: fix conflicting p2p resource adds
  nvme-fc: fix request private initialization
  blkcg: revert blkcg cleanups series
  block: brd: associate with queue until adding disk
  block: call rq_qos_exit() after queue is frozen
  mtip32xx: clean an indentation issue, remove extraneous tabs
  block: fix the DISCARD request merge
</pre>
</div>
</content>
</entry>
<entry>
<title>blkcg: revert blkcg cleanups series</title>
<updated>2018-11-02T01:59:53+00:00</updated>
<author>
<name>Dennis Zhou</name>
<email>dennis@kernel.org</email>
</author>
<published>2018-11-01T21:24:10+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=b5f2954d30c77649bce9c27e7a0a94299d9cfdf8'/>
<id>b5f2954d30c77649bce9c27e7a0a94299d9cfdf8</id>
<content type='text'>
This reverts a series committed earlier due to null pointer exception
bug report in [1]. It seems there are edge case interactions that I did
not consider and will need some time to understand what causes the
adverse interactions.

The original series can be found in [2] with a follow up series in [3].

[1] https://www.spinics.net/lists/cgroups/msg20719.html
[2] https://lore.kernel.org/lkml/20180911184137.35897-1-dennisszhou@gmail.com/
[3] https://lore.kernel.org/lkml/20181020185612.51587-1-dennis@kernel.org/

This reverts the following commits:
d459d853c2ed, b2c3fa546705, 101246ec02b5, b3b9f24f5fcc, e2b0989954ae,
f0fcb3ec89f3, c839e7a03f92, bdc2491708c4, 74b7c02a9bc1, 5bf9a1f3b4ef,
a7b39b4e961c, 07b05bcc3213, 49f4c2dc2b50, 27e6fa996c53

Signed-off-by: Dennis Zhou &lt;dennis@kernel.org&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This reverts a series committed earlier due to null pointer exception
bug report in [1]. It seems there are edge case interactions that I did
not consider and will need some time to understand what causes the
adverse interactions.

The original series can be found in [2] with a follow up series in [3].

[1] https://www.spinics.net/lists/cgroups/msg20719.html
[2] https://lore.kernel.org/lkml/20180911184137.35897-1-dennisszhou@gmail.com/
[3] https://lore.kernel.org/lkml/20181020185612.51587-1-dennis@kernel.org/

This reverts the following commits:
d459d853c2ed, b2c3fa546705, 101246ec02b5, b3b9f24f5fcc, e2b0989954ae,
f0fcb3ec89f3, c839e7a03f92, bdc2491708c4, 74b7c02a9bc1, 5bf9a1f3b4ef,
a7b39b4e961c, 07b05bcc3213, 49f4c2dc2b50, 27e6fa996c53

Signed-off-by: Dennis Zhou &lt;dennis@kernel.org&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'xarray' of git://git.infradead.org/users/willy/linux-dax</title>
<updated>2018-10-28T18:35:40+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2018-10-28T18:35:40+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=dad4f140edaa3f6bb452b6913d41af1ffd672e45'/>
<id>dad4f140edaa3f6bb452b6913d41af1ffd672e45</id>
<content type='text'>
Pull XArray conversion from Matthew Wilcox:
 "The XArray provides an improved interface to the radix tree data
  structure, providing locking as part of the API, specifying GFP flags
  at allocation time, eliminating preloading, less re-walking the tree,
  more efficient iterations and not exposing RCU-protected pointers to
  its users.

  This patch set

   1. Introduces the XArray implementation

   2. Converts the pagecache to use it

   3. Converts memremap to use it

  The page cache is the most complex and important user of the radix
  tree, so converting it was most important. Converting the memremap
  code removes the only other user of the multiorder code, which allows
  us to remove the radix tree code that supported it.

  I have 40+ followup patches to convert many other users of the radix
  tree over to the XArray, but I'd like to get this part in first. The
  other conversions haven't been in linux-next and aren't suitable for
  applying yet, but you can see them in the xarray-conv branch if you're
  interested"

* 'xarray' of git://git.infradead.org/users/willy/linux-dax: (90 commits)
  radix tree: Remove multiorder support
  radix tree test: Convert multiorder tests to XArray
  radix tree tests: Convert item_delete_rcu to XArray
  radix tree tests: Convert item_kill_tree to XArray
  radix tree tests: Move item_insert_order
  radix tree test suite: Remove multiorder benchmarking
  radix tree test suite: Remove __item_insert
  memremap: Convert to XArray
  xarray: Add range store functionality
  xarray: Move multiorder_check to in-kernel tests
  xarray: Move multiorder_shrink to kernel tests
  xarray: Move multiorder account test in-kernel
  radix tree test suite: Convert iteration test to XArray
  radix tree test suite: Convert tag_tagged_items to XArray
  radix tree: Remove radix_tree_clear_tags
  radix tree: Remove radix_tree_maybe_preload_order
  radix tree: Remove split/join code
  radix tree: Remove radix_tree_update_node_t
  page cache: Finish XArray conversion
  dax: Convert page fault handlers to XArray
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull XArray conversion from Matthew Wilcox:
 "The XArray provides an improved interface to the radix tree data
  structure, providing locking as part of the API, specifying GFP flags
  at allocation time, eliminating preloading, less re-walking the tree,
  more efficient iterations and not exposing RCU-protected pointers to
  its users.

  This patch set

   1. Introduces the XArray implementation

   2. Converts the pagecache to use it

   3. Converts memremap to use it

  The page cache is the most complex and important user of the radix
  tree, so converting it was most important. Converting the memremap
  code removes the only other user of the multiorder code, which allows
  us to remove the radix tree code that supported it.

  I have 40+ followup patches to convert many other users of the radix
  tree over to the XArray, but I'd like to get this part in first. The
  other conversions haven't been in linux-next and aren't suitable for
  applying yet, but you can see them in the xarray-conv branch if you're
  interested"

* 'xarray' of git://git.infradead.org/users/willy/linux-dax: (90 commits)
  radix tree: Remove multiorder support
  radix tree test: Convert multiorder tests to XArray
  radix tree tests: Convert item_delete_rcu to XArray
  radix tree tests: Convert item_kill_tree to XArray
  radix tree tests: Move item_insert_order
  radix tree test suite: Remove multiorder benchmarking
  radix tree test suite: Remove __item_insert
  memremap: Convert to XArray
  xarray: Add range store functionality
  xarray: Move multiorder_check to in-kernel tests
  xarray: Move multiorder_shrink to kernel tests
  xarray: Move multiorder account test in-kernel
  radix tree test suite: Convert iteration test to XArray
  radix tree test suite: Convert tag_tagged_items to XArray
  radix tree: Remove radix_tree_clear_tags
  radix tree: Remove radix_tree_maybe_preload_order
  radix tree: Remove split/join code
  radix tree: Remove radix_tree_update_node_t
  page cache: Finish XArray conversion
  dax: Convert page fault handlers to XArray
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>fs: Convert buffer to XArray</title>
<updated>2018-10-21T14:46:41+00:00</updated>
<author>
<name>Matthew Wilcox</name>
<email>willy@infradead.org</email>
</author>
<published>2017-12-04T15:40:41+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=ec82e1c1c89ce02d7703b841e6ee7d429feed609'/>
<id>ec82e1c1c89ce02d7703b841e6ee7d429feed609</id>
<content type='text'>
Mostly comment fixes, but one use of __xa_set_mark.

Signed-off-by: Matthew Wilcox &lt;willy@infradead.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Mostly comment fixes, but one use of __xa_set_mark.

Signed-off-by: Matthew Wilcox &lt;willy@infradead.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>blkcg: associate writeback bios with a blkg</title>
<updated>2018-09-22T02:29:11+00:00</updated>
<author>
<name>Dennis Zhou (Facebook)</name>
<email>dennisszhou@gmail.com</email>
</author>
<published>2018-09-11T18:41:32+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=bdc2491708c47601603918a9a20acddef6e1d814'/>
<id>bdc2491708c47601603918a9a20acddef6e1d814</id>
<content type='text'>
One of the goals of this series is to remove a separate reference to
the css of the bio. This can and should be accessed via bio_blkcg. In
this patch, the wbc_init_bio call is changed such that it must be called
after a queue has been associated with the bio.

Signed-off-by: Dennis Zhou &lt;dennisszhou@gmail.com&gt;
Reviewed-by: Josef Bacik &lt;josef@toxicpanda.com&gt;
Acked-by: Tejun Heo &lt;tj@kernel.org&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
One of the goals of this series is to remove a separate reference to
the css of the bio. This can and should be accessed via bio_blkcg. In
this patch, the wbc_init_bio call is changed such that it must be called
after a queue has been associated with the bio.

Signed-off-by: Dennis Zhou &lt;dennisszhou@gmail.com&gt;
Reviewed-by: Josef Bacik &lt;josef@toxicpanda.com&gt;
Acked-by: Tejun Heo &lt;tj@kernel.org&gt;
Signed-off-by: Jens Axboe &lt;axboe@kernel.dk&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>notifier: Remove notifier header file wherever not used</title>
<updated>2018-08-30T10:56:40+00:00</updated>
<author>
<name>Mukesh Ojha</name>
<email>mojha@codeaurora.org</email>
</author>
<published>2018-08-24T12:33:53+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=13ba17bee18e321b073b49a88dcab10881f757da'/>
<id>13ba17bee18e321b073b49a88dcab10881f757da</id>
<content type='text'>
The conversion of the hotplug notifiers to a state machine left the
notifier.h includes around in some places. Remove them.

Signed-off-by: Mukesh Ojha &lt;mojha@codeaurora.org&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Link: https://lkml.kernel.org/r/1535114033-4605-1-git-send-email-mojha@codeaurora.org

</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The conversion of the hotplug notifiers to a state machine left the
notifier.h includes around in some places. Remove them.

Signed-off-by: Mukesh Ojha &lt;mojha@codeaurora.org&gt;
Signed-off-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Link: https://lkml.kernel.org/r/1535114033-4605-1-git-send-email-mojha@codeaurora.org

</pre>
</div>
</content>
</entry>
<entry>
<title>fs, mm: account buffer_head to kmemcg</title>
<updated>2018-08-17T23:20:30+00:00</updated>
<author>
<name>Shakeel Butt</name>
<email>shakeelb@google.com</email>
</author>
<published>2018-08-17T22:46:44+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=f745c6f5fe75734f3b35d9d4e6ebe2a7d010ddda'/>
<id>f745c6f5fe75734f3b35d9d4e6ebe2a7d010ddda</id>
<content type='text'>
The buffer_head can consume a significant amount of system memory and is
directly related to the amount of page cache.  In our production
environment we have observed that a lot of machines are spending a
significant amount of memory as buffer_head and can not be left as
system memory overhead.

Charging buffer_head is not as simple as adding __GFP_ACCOUNT to the
allocation.  The buffer_heads can be allocated in a memcg different from
the memcg of the page for which buffer_heads are being allocated.  One
concrete example is memory reclaim.  The reclaim can trigger I/O of
pages of any memcg on the system.  So, the right way to charge
buffer_head is to extract the memcg from the page for which buffer_heads
are being allocated and then use targeted memcg charging API.

[shakeelb@google.com: use __GFP_ACCOUNT for directed memcg charging]
  Link: http://lkml.kernel.org/r/20180702220208.213380-1-shakeelb@google.com
Link: http://lkml.kernel.org/r/20180627191250.209150-3-shakeelb@google.com
Signed-off-by: Shakeel Butt &lt;shakeelb@google.com&gt;
Acked-by: Johannes Weiner &lt;hannes@cmpxchg.org&gt;
Cc: Michal Hocko &lt;mhocko@kernel.org&gt;
Cc: Jan Kara &lt;jack@suse.cz&gt;
Cc: Amir Goldstein &lt;amir73il@gmail.com&gt;
Cc: Greg Thelen &lt;gthelen@google.com&gt;
Cc: Vladimir Davydov &lt;vdavydov.dev@gmail.com&gt;
Cc: Roman Gushchin &lt;guro@fb.com&gt;
Cc: Alexander Viro &lt;viro@zeniv.linux.org.uk&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The buffer_head can consume a significant amount of system memory and is
directly related to the amount of page cache.  In our production
environment we have observed that a lot of machines are spending a
significant amount of memory as buffer_head and can not be left as
system memory overhead.

Charging buffer_head is not as simple as adding __GFP_ACCOUNT to the
allocation.  The buffer_heads can be allocated in a memcg different from
the memcg of the page for which buffer_heads are being allocated.  One
concrete example is memory reclaim.  The reclaim can trigger I/O of
pages of any memcg on the system.  So, the right way to charge
buffer_head is to extract the memcg from the page for which buffer_heads
are being allocated and then use targeted memcg charging API.

[shakeelb@google.com: use __GFP_ACCOUNT for directed memcg charging]
  Link: http://lkml.kernel.org/r/20180702220208.213380-1-shakeelb@google.com
Link: http://lkml.kernel.org/r/20180627191250.209150-3-shakeelb@google.com
Signed-off-by: Shakeel Butt &lt;shakeelb@google.com&gt;
Acked-by: Johannes Weiner &lt;hannes@cmpxchg.org&gt;
Cc: Michal Hocko &lt;mhocko@kernel.org&gt;
Cc: Jan Kara &lt;jack@suse.cz&gt;
Cc: Amir Goldstein &lt;amir73il@gmail.com&gt;
Cc: Greg Thelen &lt;gthelen@google.com&gt;
Cc: Vladimir Davydov &lt;vdavydov.dev@gmail.com&gt;
Cc: Roman Gushchin &lt;guro@fb.com&gt;
Cc: Alexander Viro &lt;viro@zeniv.linux.org.uk&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
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