<feed xmlns='http://www.w3.org/2005/Atom'>
<title>user/sven/linux.git/include, branch v4.14.231</title>
<subtitle>Linux Kernel
</subtitle>
<id>https://git.stealer.net/cgit.cgi/user/sven/linux.git/atom?h=v4.14.231</id>
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<updated>2021-04-16T09:57:51Z</updated>
<entry>
<title>net/ncsi: Add generic netlink family</title>
<updated>2021-04-16T09:57:51Z</updated>
<author>
<name>Samuel Mendoza-Jonas</name>
<email>sam@mendozajonas.com</email>
</author>
<published>2018-03-05T00:39:05Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=f4e7325060fe9d7f6b223fee7d2a28bf91ba8cb9'/>
<id>urn:sha1:f4e7325060fe9d7f6b223fee7d2a28bf91ba8cb9</id>
<content type='text'>
commit 955dc68cb9b23b42999cafe6df3684309bc686c6 upstream.

Add a generic netlink family for NCSI. This supports three commands;
NCSI_CMD_PKG_INFO which returns information on packages and their
associated channels, NCSI_CMD_SET_INTERFACE which allows a specific
package or package/channel combination to be set as the preferred
choice, and NCSI_CMD_CLEAR_INTERFACE which clears any preferred setting.

Signed-off-by: Samuel Mendoza-Jonas &lt;sam@mendozajonas.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Cc: Guenter Roeck &lt;linux@roeck-us.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>net/mlx5: Fix placement of log_max_flow_counter</title>
<updated>2021-04-16T09:57:50Z</updated>
<author>
<name>Raed Salem</name>
<email>raeds@nvidia.com</email>
</author>
<published>2021-01-21T14:01:37Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=9def0f437728cead6411e3c692b4d5a0d486e2ce'/>
<id>urn:sha1:9def0f437728cead6411e3c692b4d5a0d486e2ce</id>
<content type='text'>
[ Upstream commit a14587dfc5ad2312dabdd42a610d80ecd0dc8bea ]

The cited commit wrongly placed log_max_flow_counter field of
mlx5_ifc_flow_table_prop_layout_bits, align it to the HW spec intended
placement.

Fixes: 16f1c5bb3ed7 ("net/mlx5: Check device capability for maximum flow counters")
Signed-off-by: Raed Salem &lt;raeds@nvidia.com&gt;
Reviewed-by: Roi Dayan &lt;roid@nvidia.com&gt;
Signed-off-by: Saeed Mahameed &lt;saeedm@nvidia.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>sch_red: fix off-by-one checks in red_check_params()</title>
<updated>2021-04-16T09:57:49Z</updated>
<author>
<name>Eric Dumazet</name>
<email>edumazet@google.com</email>
</author>
<published>2021-03-25T18:14:53Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=a4173e6b7ba3b6cc712ed422bb16a1bd8773d8c4'/>
<id>urn:sha1:a4173e6b7ba3b6cc712ed422bb16a1bd8773d8c4</id>
<content type='text'>
[ Upstream commit 3a87571f0ffc51ba3bf3ecdb6032861d0154b164 ]

This fixes following syzbot report:

UBSAN: shift-out-of-bounds in ./include/net/red.h:237:23
shift exponent 32 is too large for 32-bit type 'unsigned int'
CPU: 1 PID: 8418 Comm: syz-executor170 Not tainted 5.12.0-rc4-next-20210324-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x141/0x1d7 lib/dump_stack.c:120
 ubsan_epilogue+0xb/0x5a lib/ubsan.c:148
 __ubsan_handle_shift_out_of_bounds.cold+0xb1/0x181 lib/ubsan.c:327
 red_set_parms include/net/red.h:237 [inline]
 choke_change.cold+0x3c/0xc8 net/sched/sch_choke.c:414
 qdisc_create+0x475/0x12f0 net/sched/sch_api.c:1247
 tc_modify_qdisc+0x4c8/0x1a50 net/sched/sch_api.c:1663
 rtnetlink_rcv_msg+0x44e/0xad0 net/core/rtnetlink.c:5553
 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2502
 netlink_unicast_kernel net/netlink/af_netlink.c:1312 [inline]
 netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1338
 netlink_sendmsg+0x856/0xd90 net/netlink/af_netlink.c:1927
 sock_sendmsg_nosec net/socket.c:654 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:674
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2350
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2404
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2433
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x43f039
Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 &lt;48&gt; 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffdfa725168 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000400488 RCX: 000000000043f039
RDX: 0000000000000000 RSI: 0000000020000040 RDI: 0000000000000004
RBP: 0000000000403020 R08: 0000000000400488 R09: 0000000000400488
R10: 0000000000400488 R11: 0000000000000246 R12: 00000000004030b0
R13: 0000000000000000 R14: 00000000004ac018 R15: 0000000000400488

Fixes: 8afa10cbe281 ("net_sched: red: Avoid illegal values")
Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Reported-by: syzbot &lt;syzkaller@googlegroups.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>net: ensure mac header is set in virtio_net_hdr_to_skb()</title>
<updated>2021-04-16T09:57:48Z</updated>
<author>
<name>Eric Dumazet</name>
<email>edumazet@google.com</email>
</author>
<published>2021-03-30T23:43:43Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=12ba6288b027b816459782fcd8d7b37ed8a16828'/>
<id>urn:sha1:12ba6288b027b816459782fcd8d7b37ed8a16828</id>
<content type='text'>
commit 61431a5907fc36d0738e9a547c7e1556349a03e9 upstream.

Commit 924a9bc362a5 ("net: check if protocol extracted by virtio_net_hdr_set_proto is correct")
added a call to dev_parse_header_protocol() but mac_header is not yet set.

This means that eth_hdr() reads complete garbage, and syzbot complained about it [1]

This patch resets mac_header earlier, to get more coverage about this change.

Audit of virtio_net_hdr_to_skb() callers shows that this change should be safe.

[1]

BUG: KASAN: use-after-free in eth_header_parse_protocol+0xdc/0xe0 net/ethernet/eth.c:282
Read of size 2 at addr ffff888017a6200b by task syz-executor313/8409

CPU: 1 PID: 8409 Comm: syz-executor313 Not tainted 5.12.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x141/0x1d7 lib/dump_stack.c:120
 print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:232
 __kasan_report mm/kasan/report.c:399 [inline]
 kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:416
 eth_header_parse_protocol+0xdc/0xe0 net/ethernet/eth.c:282
 dev_parse_header_protocol include/linux/netdevice.h:3177 [inline]
 virtio_net_hdr_to_skb.constprop.0+0x99d/0xcd0 include/linux/virtio_net.h:83
 packet_snd net/packet/af_packet.c:2994 [inline]
 packet_sendmsg+0x2325/0x52b0 net/packet/af_packet.c:3031
 sock_sendmsg_nosec net/socket.c:654 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:674
 sock_no_sendpage+0xf3/0x130 net/core/sock.c:2860
 kernel_sendpage.part.0+0x1ab/0x350 net/socket.c:3631
 kernel_sendpage net/socket.c:3628 [inline]
 sock_sendpage+0xe5/0x140 net/socket.c:947
 pipe_to_sendpage+0x2ad/0x380 fs/splice.c:364
 splice_from_pipe_feed fs/splice.c:418 [inline]
 __splice_from_pipe+0x43e/0x8a0 fs/splice.c:562
 splice_from_pipe fs/splice.c:597 [inline]
 generic_splice_sendpage+0xd4/0x140 fs/splice.c:746
 do_splice_from fs/splice.c:767 [inline]
 do_splice+0xb7e/0x1940 fs/splice.c:1079
 __do_splice+0x134/0x250 fs/splice.c:1144
 __do_sys_splice fs/splice.c:1350 [inline]
 __se_sys_splice fs/splice.c:1332 [inline]
 __x64_sys_splice+0x198/0x250 fs/splice.c:1332
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46

Fixes: 924a9bc362a5 ("net: check if protocol extracted by virtio_net_hdr_set_proto is correct")
Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Cc: Balazs Nemeth &lt;bnemeth@redhat.com&gt;
Cc: Willem de Bruijn &lt;willemb@google.com&gt;
Reported-by: syzbot &lt;syzkaller@googlegroups.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>extcon: Add stubs for extcon_register_notifier_all() functions</title>
<updated>2021-04-07T10:47:03Z</updated>
<author>
<name>Krzysztof Kozlowski</name>
<email>krzk@kernel.org</email>
</author>
<published>2020-12-31T08:52:52Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=8fb4f3e42f2087d5da7146a3b02bf28b0cdcfd43'/>
<id>urn:sha1:8fb4f3e42f2087d5da7146a3b02bf28b0cdcfd43</id>
<content type='text'>
[ Upstream commit c9570d4a5efd04479b3cd09c39b571eb031d94f4 ]

Add stubs for extcon_register_notifier_all() function for !CONFIG_EXTCON
case.  This is useful for compile testing and for drivers which use
EXTCON but do not require it (therefore do not depend on CONFIG_EXTCON).

Fixes: 815429b39d94 ("extcon: Add new extcon_register_notifier_all() to monitor all external connectors")
Reported-by: kernel test robot &lt;lkp@intel.com&gt;
Signed-off-by: Krzysztof Kozlowski &lt;krzk@kernel.org&gt;
Signed-off-by: Chanwoo Choi &lt;cw00.choi@samsung.com&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>mm: writeback: use exact memcg dirty counts</title>
<updated>2021-04-07T10:47:03Z</updated>
<author>
<name>Greg Thelen</name>
<email>gthelen@google.com</email>
</author>
<published>2021-03-30T18:19:10Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=f34769a0b8d6887103305374c4a02bcd295ef9c7'/>
<id>urn:sha1:f34769a0b8d6887103305374c4a02bcd295ef9c7</id>
<content type='text'>
commit 0b3d6e6f2dd0a7b697b1aa8c167265908940624b upstream.

Since commit a983b5ebee57 ("mm: memcontrol: fix excessive complexity in
memory.stat reporting") memcg dirty and writeback counters are managed
as:

 1) per-memcg per-cpu values in range of [-32..32]

 2) per-memcg atomic counter

When a per-cpu counter cannot fit in [-32..32] it's flushed to the
atomic.  Stat readers only check the atomic.  Thus readers such as
balance_dirty_pages() may see a nontrivial error margin: 32 pages per
cpu.

Assuming 100 cpus:
   4k x86 page_size:  13 MiB error per memcg
  64k ppc page_size: 200 MiB error per memcg

Considering that dirty+writeback are used together for some decisions the
errors double.

This inaccuracy can lead to undeserved oom kills.  One nasty case is
when all per-cpu counters hold positive values offsetting an atomic
negative value (i.e.  per_cpu[*]=32, atomic=n_cpu*-32).
balance_dirty_pages() only consults the atomic and does not consider
throttling the next n_cpu*32 dirty pages.  If the file_lru is in the
13..200 MiB range then there's absolutely no dirty throttling, which
burdens vmscan with only dirty+writeback pages thus resorting to oom
kill.

It could be argued that tiny containers are not supported, but it's more
subtle.  It's the amount the space available for file lru that matters.
If a container has memory.max-200MiB of non reclaimable memory, then it
will also suffer such oom kills on a 100 cpu machine.

The following test reliably ooms without this patch.  This patch avoids
oom kills.

  $ cat test
  mount -t cgroup2 none /dev/cgroup
  cd /dev/cgroup
  echo +io +memory &gt; cgroup.subtree_control
  mkdir test
  cd test
  echo 10M &gt; memory.max
  (echo $BASHPID &gt; cgroup.procs &amp;&amp; exec /memcg-writeback-stress /foo)
  (echo $BASHPID &gt; cgroup.procs &amp;&amp; exec dd if=/dev/zero of=/foo bs=2M count=100)

  $ cat memcg-writeback-stress.c
  /*
   * Dirty pages from all but one cpu.
   * Clean pages from the non dirtying cpu.
   * This is to stress per cpu counter imbalance.
   * On a 100 cpu machine:
   * - per memcg per cpu dirty count is 32 pages for each of 99 cpus
   * - per memcg atomic is -99*32 pages
   * - thus the complete dirty limit: sum of all counters 0
   * - balance_dirty_pages() only sees atomic count -99*32 pages, which
   *   it max()s to 0.
   * - So a workload can dirty -99*32 pages before balance_dirty_pages()
   *   cares.
   */
  #define _GNU_SOURCE
  #include &lt;err.h&gt;
  #include &lt;fcntl.h&gt;
  #include &lt;sched.h&gt;
  #include &lt;stdlib.h&gt;
  #include &lt;stdio.h&gt;
  #include &lt;sys/stat.h&gt;
  #include &lt;sys/sysinfo.h&gt;
  #include &lt;sys/types.h&gt;
  #include &lt;unistd.h&gt;

  static char *buf;
  static int bufSize;

  static void set_affinity(int cpu)
  {
  	cpu_set_t affinity;

  	CPU_ZERO(&amp;affinity);
  	CPU_SET(cpu, &amp;affinity);
  	if (sched_setaffinity(0, sizeof(affinity), &amp;affinity))
  		err(1, "sched_setaffinity");
  }

  static void dirty_on(int output_fd, int cpu)
  {
  	int i, wrote;

  	set_affinity(cpu);
  	for (i = 0; i &lt; 32; i++) {
  		for (wrote = 0; wrote &lt; bufSize; ) {
  			int ret = write(output_fd, buf+wrote, bufSize-wrote);
  			if (ret == -1)
  				err(1, "write");
  			wrote += ret;
  		}
  	}
  }

  int main(int argc, char **argv)
  {
  	int cpu, flush_cpu = 1, output_fd;
  	const char *output;

  	if (argc != 2)
  		errx(1, "usage: output_file");

  	output = argv[1];
  	bufSize = getpagesize();
  	buf = malloc(getpagesize());
  	if (buf == NULL)
  		errx(1, "malloc failed");

  	output_fd = open(output, O_CREAT|O_RDWR);
  	if (output_fd == -1)
  		err(1, "open(%s)", output);

  	for (cpu = 0; cpu &lt; get_nprocs(); cpu++) {
  		if (cpu != flush_cpu)
  			dirty_on(output_fd, cpu);
  	}

  	set_affinity(flush_cpu);
  	if (fsync(output_fd))
  		err(1, "fsync(%s)", output);
  	if (close(output_fd))
  		err(1, "close(%s)", output);
  	free(buf);
  }

Make balance_dirty_pages() and wb_over_bg_thresh() work harder to
collect exact per memcg counters.  This avoids the aforementioned oom
kills.

This does not affect the overhead of memory.stat, which still reads the
single atomic counter.

Why not use percpu_counter? memcg already handles cpus going offline, so
no need for that overhead from percpu_counter.  And the percpu_counter
spinlocks are more heavyweight than is required.

It probably also makes sense to use exact dirty and writeback counters
in memcg oom reports.  But that is saved for later.

Link: http://lkml.kernel.org/r/20190329174609.164344-1-gthelen@google.com
Signed-off-by: Greg Thelen &lt;gthelen@google.com&gt;
Reviewed-by: Roman Gushchin &lt;guro@fb.com&gt;
Acked-by: Johannes Weiner &lt;hannes@cmpxchg.org&gt;
Cc: Michal Hocko &lt;mhocko@kernel.org&gt;
Cc: Vladimir Davydov &lt;vdavydov.dev@gmail.com&gt;
Cc: Tejun Heo &lt;tj@kernel.org&gt;
Cc: &lt;stable@vger.kernel.org&gt;	[4.16+]
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>mm: fix oom_kill event handling</title>
<updated>2021-04-07T10:47:03Z</updated>
<author>
<name>Roman Gushchin</name>
<email>guro@fb.com</email>
</author>
<published>2021-03-30T18:19:09Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=6f599379fd3a9a9ea4eb10f4f8e7dc74cf2ec249'/>
<id>urn:sha1:6f599379fd3a9a9ea4eb10f4f8e7dc74cf2ec249</id>
<content type='text'>
commit fe6bdfc8e1e131720abbe77a2eb990c94c9024cb upstream.

Commit e27be240df53 ("mm: memcg: make sure memory.events is uptodate
when waking pollers") converted most of memcg event counters to
per-memcg atomics, which made them less confusing for a user.  The
"oom_kill" counter remained untouched, so now it behaves differently
than other counters (including "oom").  This adds nothing but confusion.

Let's fix this by adding the MEMCG_OOM_KILL event, and follow the
MEMCG_OOM approach.

This also removes a hack from count_memcg_event_mm(), introduced earlier
specially for the OOM_KILL counter.

[akpm@linux-foundation.org: fix for droppage of memcg-replace-mm-owner-with-mm-memcg.patch]
Link: http://lkml.kernel.org/r/20180508124637.29984-1-guro@fb.com
Signed-off-by: Roman Gushchin &lt;guro@fb.com&gt;
Acked-by: Konstantin Khlebnikov &lt;khlebnikov@yandex-team.ru&gt;
Acked-by: Johannes Weiner &lt;hannes@cmpxchg.org&gt;
Acked-by: Michal Hocko &lt;mhocko@suse.com&gt;
Cc: Vladimir Davydov &lt;vdavydov.dev@gmail.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
[fllinden@amazon.com: backport to 4.14, minor contextual changes]
Signed-off-by: Frank van der Linden &lt;fllinden@amazon.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>mem_cgroup: make sure moving_account, move_lock_task and stat_cpu in the same cacheline</title>
<updated>2021-04-07T10:47:03Z</updated>
<author>
<name>Aaron Lu</name>
<email>aaron.lu@intel.com</email>
</author>
<published>2021-03-30T18:19:08Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=ad6e2898e66e324ed6d386d6a29b0e9a9103670c'/>
<id>urn:sha1:ad6e2898e66e324ed6d386d6a29b0e9a9103670c</id>
<content type='text'>
commit e81bf9793b1861d74953ef041b4f6c7faecc2dbd upstream.

The LKP robot found a 27% will-it-scale/page_fault3 performance
regression regarding commit e27be240df53("mm: memcg: make sure
memory.events is uptodate when waking pollers").

What the test does is:
 1 mkstemp() a 128M file on a tmpfs;
 2 start $nr_cpu processes, each to loop the following:
   2.1 mmap() this file in shared write mode;
   2.2 write 0 to this file in a PAGE_SIZE step till the end of the file;
   2.3 unmap() this file and repeat this process.
 3 After 5 minutes, check how many loops they managed to complete, the
   higher the better.

The commit itself looks innocent enough as it merely changed some event
counting mechanism and this test didn't trigger those events at all.
Perf shows increased cycles spent on accessing root_mem_cgroup-&gt;stat_cpu
in count_memcg_event_mm()(called by handle_mm_fault()) and in
__mod_memcg_state() called by page_add_file_rmap().  So it's likely due
to the changed layout of 'struct mem_cgroup' that either make stat_cpu
falling into a constantly modifying cacheline or some hot fields stop
being in the same cacheline.

I verified this by moving memory_events[] back to where it was:

: --- a/include/linux/memcontrol.h
: +++ b/include/linux/memcontrol.h
: @@ -205,7 +205,6 @@ struct mem_cgroup {
:  	int		oom_kill_disable;
:
:  	/* memory.events */
: -	atomic_long_t memory_events[MEMCG_NR_MEMORY_EVENTS];
:  	struct cgroup_file events_file;
:
:  	/* protect arrays of thresholds */
: @@ -238,6 +237,7 @@ struct mem_cgroup {
:  	struct mem_cgroup_stat_cpu __percpu *stat_cpu;
:  	atomic_long_t		stat[MEMCG_NR_STAT];
:  	atomic_long_t		events[NR_VM_EVENT_ITEMS];
: +	atomic_long_t memory_events[MEMCG_NR_MEMORY_EVENTS];
:
:  	unsigned long		socket_pressure;

And performance restored.

Later investigation found that as long as the following 3 fields
moving_account, move_lock_task and stat_cpu are in the same cacheline,
performance will be good.  To avoid future performance surprise by other
commits changing the layout of 'struct mem_cgroup', this patch makes
sure the 3 fields stay in the same cacheline.

One concern of this approach is, moving_account and move_lock_task could
be modified when a process changes memory cgroup while stat_cpu is a
always read field, it might hurt to place them in the same cacheline.  I
assume it is rare for a process to change memory cgroup so this should
be OK.

Link: https://lkml.kernel.org/r/20180528114019.GF9904@yexl-desktop
Link: http://lkml.kernel.org/r/20180601071115.GA27302@intel.com
Signed-off-by: Aaron Lu &lt;aaron.lu@intel.com&gt;
Reported-by: kernel test robot &lt;xiaolong.ye@intel.com&gt;
Cc: Johannes Weiner &lt;hannes@cmpxchg.org&gt;
Cc: Michal Hocko &lt;mhocko@kernel.org&gt;
Cc: Tejun Heo &lt;tj@kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>mm: memcg: make sure memory.events is uptodate when waking pollers</title>
<updated>2021-04-07T10:47:03Z</updated>
<author>
<name>Johannes Weiner</name>
<email>hannes@cmpxchg.org</email>
</author>
<published>2021-03-30T18:19:07Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=09031a8b68be05a0cc05312f95b347d489d331eb'/>
<id>urn:sha1:09031a8b68be05a0cc05312f95b347d489d331eb</id>
<content type='text'>
commit e27be240df53f1a20c659168e722b5d9f16cc7f4 upstream.

Commit a983b5ebee57 ("mm: memcontrol: fix excessive complexity in
memory.stat reporting") added per-cpu drift to all memory cgroup stats
and events shown in memory.stat and memory.events.

For memory.stat this is acceptable.  But memory.events issues file
notifications, and somebody polling the file for changes will be
confused when the counters in it are unchanged after a wakeup.

Luckily, the events in memory.events - MEMCG_LOW, MEMCG_HIGH, MEMCG_MAX,
MEMCG_OOM - are sufficiently rare and high-level that we don't need
per-cpu buffering for them: MEMCG_HIGH and MEMCG_MAX would be the most
frequent, but they're counting invocations of reclaim, which is a
complex operation that touches many shared cachelines.

This splits memory.events from the generic VM events and tracks them in
their own, unbuffered atomic counters.  That's also cleaner, as it
eliminates the ugly enum nesting of VM and cgroup events.

[hannes@cmpxchg.org: "array subscript is above array bounds"]
  Link: http://lkml.kernel.org/r/20180406155441.GA20806@cmpxchg.org
Link: http://lkml.kernel.org/r/20180405175507.GA24817@cmpxchg.org
Fixes: a983b5ebee57 ("mm: memcontrol: fix excessive complexity in memory.stat reporting")
Signed-off-by: Johannes Weiner &lt;hannes@cmpxchg.org&gt;
Reported-by: Tejun Heo &lt;tj@kernel.org&gt;
Acked-by: Tejun Heo &lt;tj@kernel.org&gt;
Acked-by: Michal Hocko &lt;mhocko@suse.com&gt;
Cc: Vladimir Davydov &lt;vdavydov.dev@gmail.com&gt;
Cc: Roman Gushchin &lt;guro@fb.com&gt;
Cc: Rik van Riel &lt;riel@surriel.com&gt;
Cc: Stephen Rothwell &lt;sfr@canb.auug.org.au&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>mm: memcontrol: fix NR_WRITEBACK leak in memcg and system stats</title>
<updated>2021-04-07T10:47:03Z</updated>
<author>
<name>Johannes Weiner</name>
<email>hannes@cmpxchg.org</email>
</author>
<published>2021-03-30T18:19:06Z</published>
<link rel='alternate' type='text/html' href='https://git.stealer.net/cgit.cgi/user/sven/linux.git/commit/?id=cfc5a8f43e6e155262af9e05b105427126ab99dd'/>
<id>urn:sha1:cfc5a8f43e6e155262af9e05b105427126ab99dd</id>
<content type='text'>
commit c3cc39118c3610eb6ab4711bc624af7fc48a35fe upstream.

After commit a983b5ebee57 ("mm: memcontrol: fix excessive complexity in
memory.stat reporting"), we observed slowly upward creeping NR_WRITEBACK
counts over the course of several days, both the per-memcg stats as well
as the system counter in e.g.  /proc/meminfo.

The conversion from full per-cpu stat counts to per-cpu cached atomic
stat counts introduced an irq-unsafe RMW operation into the updates.

Most stat updates come from process context, but one notable exception
is the NR_WRITEBACK counter.  While writebacks are issued from process
context, they are retired from (soft)irq context.

When writeback completions interrupt the RMW counter updates of new
writebacks being issued, the decs from the completions are lost.

Since the global updates are routed through the joint lruvec API, both
the memcg counters as well as the system counters are affected.

This patch makes the joint stat and event API irq safe.

Link: http://lkml.kernel.org/r/20180203082353.17284-1-hannes@cmpxchg.org
Fixes: a983b5ebee57 ("mm: memcontrol: fix excessive complexity in memory.stat reporting")
Signed-off-by: Johannes Weiner &lt;hannes@cmpxchg.org&gt;
Debugged-by: Tejun Heo &lt;tj@kernel.org&gt;
Reviewed-by: Rik van Riel &lt;riel@surriel.com&gt;
Reviewed-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Cc: Vladimir Davydov &lt;vdavydov.dev@gmail.com&gt;
Cc: Michal Hocko &lt;mhocko@suse.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
</feed>
