mm: add printf attribute to shrinker_debugfs_name_alloc

This fixes a compiler warning when compiling an allyesconfig with W=1:

mm/internal.h:1235:9: error: function might be a candidate for `gnu_pr

mm: add printf attribute to shrinker_debugfs_name_alloc

This fixes a compiler warning when compiling an allyesconfig with W=1:

mm/internal.h:1235:9: error: function might be a candidate for `gnu_printf'
format attribute [-Werror=suggest-attribute=format]

[[email protected]: fix shrinker_alloc() as welll per Qi Zheng]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/ZSBue-3kM6gI6jCr@mainframe
Fixes: c42d50aefd17 ("mm: shrinker: add infrastructure for dynamically allocating shrinker")
Signed-off-by: Lucy Mielke <[email protected]>
Cc: Qi Zheng <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm: shrinker: make global slab shrink lockless

The shrinker_rwsem is a global read-write lock in shrinkers subsystem,
which protects most operations such as slab shrink, registration and
unregistrat

mm: shrinker: make global slab shrink lockless

The shrinker_rwsem is a global read-write lock in shrinkers subsystem,
which protects most operations such as slab shrink, registration and
unregistration of shrinkers, etc. This can easily cause problems in the
following cases.

1) When the memory pressure is high and there are many filesystems
mounted or unmounted at the same time, slab shrink will be affected
(down_read_trylock() failed).

Such as the real workload mentioned by Kirill Tkhai:

```
One of the real workloads from my experience is start
of an overcommitted node containing many starting
containers after node crash (or many resuming containers
after reboot for kernel update). In these cases memory
pressure is huge, and the node goes round in long reclaim.
```

2) If a shrinker is blocked (such as the case mentioned
in [1]) and a writer comes in (such as mount a fs),
then this writer will be blocked and cause all
subsequent shrinker-related operations to be blocked.

Even if there is no competitor when shrinking slab, there may still be a
problem. The down_read_trylock() may become a perf hotspot with frequent
calls to shrink_slab(). Because of the poor multicore scalability of
atomic operations, this can lead to a significant drop in IPC
(instructions per cycle).

We used to implement the lockless slab shrink with SRCU [2], but then
kernel test robot reported -88.8% regression in
stress-ng.ramfs.ops_per_sec test case [3], so we reverted it [4].

This commit uses the refcount+RCU method [5] proposed by Dave Chinner
to re-implement the lockless global slab shrink. The memcg slab shrink is
handled in the subsequent patch.

For now, all shrinker instances are converted to dynamically allocated and
will be freed by call_rcu(). So we can use rcu_read_{lock,unlock}() to
ensure that the shrinker instance is valid.

And the shrinker instance will not be run again after unregistration. So
the structure that records the pointer of shrinker instance can be safely
freed without waiting for the RCU read-side critical section.

In this way, while we implement the lockless slab shrink, we don't need to
be blocked in unregister_shrinker().

The following are the test results:

stress-ng --timeout 60 --times --verify --metrics-brief --ramfs 9 &

1) Before applying this patchset:

setting to a 60 second run per stressor
dispatching hogs: 9 ramfs
stressor bogo ops real time usr time sys time bogo ops/s bogo ops/s
(secs) (secs) (secs) (real time) (usr+sys time)
ramfs 473062 60.00 8.00 279.13 7884.12 1647.59
for a 60.01s run time:
1440.34s available CPU time
7.99s user time ( 0.55%)
279.13s system time ( 19.38%)
287.12s total time ( 19.93%)
load average: 7.12 2.99 1.15
successful run completed in 60.01s (1 min, 0.01 secs)

2) After applying this patchset:

setting to a 60 second run per stressor
dispatching hogs: 9 ramfs
stressor bogo ops real time usr time sys time bogo ops/s bogo ops/s
(secs) (secs) (secs) (real time) (usr+sys time)
ramfs 477165 60.00 8.13 281.34 7952.55 1648.40
for a 60.01s run time:
1440.33s available CPU time
8.12s user time ( 0.56%)
281.34s system time ( 19.53%)
289.46s total time ( 20.10%)
load average: 6.98 3.03 1.19
successful run completed in 60.01s (1 min, 0.01 secs)

We can see that the ops/s has hardly changed.

[1]. https://lore.kernel.org/lkml/[email protected]/
[2]. https://lore.kernel.org/lkml/[email protected]/
[3]. https://lore.kernel.org/lkml/[email protected]/
[4]. https://lore.kernel.org/all/[email protected]/
[5]. https://lore.kernel.org/lkml/[email protected]/

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Qi Zheng <[email protected]>
Cc: Abhinav Kumar <[email protected]>
Cc: Alasdair Kergon <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Alyssa Rosenzweig <[email protected]>
Cc: Andreas Dilger <[email protected]>
Cc: Andreas Gruenbacher <[email protected]>
Cc: Anna Schumaker <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Bob Peterson <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Carlos Llamas <[email protected]>
Cc: Chandan Babu R <[email protected]>
Cc: Chao Yu <[email protected]>
Cc: Chris Mason <[email protected]>
Cc: Christian Brauner <[email protected]>
Cc: Christian Koenig <[email protected]>
Cc: Chuck Lever <[email protected]>
Cc: Coly Li <[email protected]>
Cc: Dai Ngo <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: "Darrick J. Wong" <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David Airlie <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: David Sterba <[email protected]>
Cc: Dmitry Baryshkov <[email protected]>
Cc: Gao Xiang <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Huang Rui <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jaegeuk Kim <[email protected]>
Cc: Jani Nikula <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jason Wang <[email protected]>
Cc: Jeff Layton <[email protected]>
Cc: Jeffle Xu <[email protected]>
Cc: Joel Fernandes (Google) <[email protected]>
Cc: Joonas Lahtinen <[email protected]>
Cc: Josef Bacik <[email protected]>
Cc: Juergen Gross <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Kirill Tkhai <[email protected]>
Cc: Marijn Suijten <[email protected]>
Cc: "Michael S. Tsirkin" <[email protected]>
Cc: Mike Snitzer <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: Nadav Amit <[email protected]>
Cc: Neil Brown <[email protected]>
Cc: Oleksandr Tyshchenko <[email protected]>
Cc: Olga Kornievskaia <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Richard Weinberger <[email protected]>
Cc: Rob Clark <[email protected]>
Cc: Rob Herring <[email protected]>
Cc: Rodrigo Vivi <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Sean Paul <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Cc: Song Liu <[email protected]>
Cc: Stefano Stabellini <[email protected]>
Cc: Steven Price <[email protected]>
Cc: "Theodore Ts'o" <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Tomeu Vizoso <[email protected]>
Cc: Tom Talpey <[email protected]>
Cc: Trond Myklebust <[email protected]>
Cc: Tvrtko Ursulin <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Xuan Zhuo <[email protected]>
Cc: Yue Hu <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm: shrinker: add a secondary array for shrinker_info::{map, nr_deferred}

Currently, we maintain two linear arrays per node per memcg, which are
shrinker_info::map and shrinker_info::nr_deferred. An

mm: shrinker: add a secondary array for shrinker_info::{map, nr_deferred}

Currently, we maintain two linear arrays per node per memcg, which are
shrinker_info::map and shrinker_info::nr_deferred. And we need to resize
them when the shrinker_nr_max is exceeded, that is, allocate a new array,
and then copy the old array to the new array, and finally free the old
array by RCU.

For shrinker_info::map, we do set_bit() under the RCU lock, so we may set
the value into the old map which is about to be freed. This may cause the
value set to be lost. The current solution is not to copy the old map when
resizing, but to set all the corresponding bits in the new map to 1. This
solves the data loss problem, but bring the overhead of more pointless
loops while doing memcg slab shrink.

For shrinker_info::nr_deferred, we will only modify it under the read lock
of shrinker_rwsem, so it will not run concurrently with the resizing. But
after we make memcg slab shrink lockless, there will be the same data loss
problem as shrinker_info::map, and we can't work around it like the map.

For such resizable arrays, the most straightforward idea is to change it
to xarray, like we did for list_lru [1]. We need to do xa_store() in the
list_lru_add()-->set_shrinker_bit(), but this will cause memory
allocation, and the list_lru_add() doesn't accept failure. A possible
solution is to pre-allocate, but the location of pre-allocation is not
well determined (such as deferred_split_shrinker case).

Therefore, this commit chooses to introduce the following secondary array
for shrinker_info::{map, nr_deferred}:

+---------------+--------+--------+-----+
| shrinker_info | unit 0 | unit 1 | ... | (secondary array)
+---------------+--------+--------+-----+
|
v
+---------------+-----+
| nr_deferred[] | map | (leaf array)
+---------------+-----+
(shrinker_info_unit)

The leaf array is never freed unless the memcg is destroyed. The secondary
array will be resized every time the shrinker id exceeds shrinker_nr_max.
So the shrinker_info_unit can be indexed from both the old and the new
shrinker_info->unit[x]. Then even if we get the old secondary array under
the RCU lock, the found map and nr_deferred are also true, so the updated
nr_deferred and map will not be lost.

[1]. https://lore.kernel.org/all/[email protected]/

[[email protected]: unlock the &shrinker_rwsem before the call to free_shrinker_info()]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Qi Zheng <[email protected]>
Reviewed-by: Muchun Song <[email protected]>
Cc: Abhinav Kumar <[email protected]>
Cc: Alasdair Kergon <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Alyssa Rosenzweig <[email protected]>
Cc: Andreas Dilger <[email protected]>
Cc: Andreas Gruenbacher <[email protected]>
Cc: Anna Schumaker <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Bob Peterson <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Carlos Llamas <[email protected]>
Cc: Chandan Babu R <[email protected]>
Cc: Chao Yu <[email protected]>
Cc: Chris Mason <[email protected]>
Cc: Christian Brauner <[email protected]>
Cc: Christian Koenig <[email protected]>
Cc: Chuck Lever <[email protected]>
Cc: Coly Li <[email protected]>
Cc: Dai Ngo <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: "Darrick J. Wong" <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David Airlie <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: David Sterba <[email protected]>
Cc: Dmitry Baryshkov <[email protected]>
Cc: Gao Xiang <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Huang Rui <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jaegeuk Kim <[email protected]>
Cc: Jani Nikula <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jason Wang <[email protected]>
Cc: Jeff Layton <[email protected]>
Cc: Jeffle Xu <[email protected]>
Cc: Joel Fernandes (Google) <[email protected]>
Cc: Joonas Lahtinen <[email protected]>
Cc: Josef Bacik <[email protected]>
Cc: Juergen Gross <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Kirill Tkhai <[email protected]>
Cc: Marijn Suijten <[email protected]>
Cc: "Michael S. Tsirkin" <[email protected]>
Cc: Mike Snitzer <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: Nadav Amit <[email protected]>
Cc: Neil Brown <[email protected]>
Cc: Oleksandr Tyshchenko <[email protected]>
Cc: Olga Kornievskaia <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Richard Weinberger <[email protected]>
Cc: Rob Clark <[email protected]>
Cc: Rob Herring <[email protected]>
Cc: Rodrigo Vivi <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Sean Paul <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Cc: Song Liu <[email protected]>
Cc: Stefano Stabellini <[email protected]>
Cc: Steven Price <[email protected]>
Cc: "Theodore Ts'o" <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Tomeu Vizoso <[email protected]>
Cc: Tom Talpey <[email protected]>
Cc: Trond Myklebust <[email protected]>
Cc: Tvrtko Ursulin <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Xuan Zhuo <[email protected]>
Cc: Yue Hu <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm: shrinker: remove old APIs

Now no users are using the old APIs, just remove them.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Qi Zheng <zhen

mm: shrinker: remove old APIs

Now no users are using the old APIs, just remove them.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Qi Zheng <[email protected]>
Reviewed-by: Muchun Song <[email protected]>
Cc: Abhinav Kumar <[email protected]>
Cc: Alasdair Kergon <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Alyssa Rosenzweig <[email protected]>
Cc: Andreas Dilger <[email protected]>
Cc: Andreas Gruenbacher <[email protected]>
Cc: Anna Schumaker <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Bob Peterson <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Carlos Llamas <[email protected]>
Cc: Chandan Babu R <[email protected]>
Cc: Chao Yu <[email protected]>
Cc: Chris Mason <[email protected]>
Cc: Christian Brauner <[email protected]>
Cc: Christian Koenig <[email protected]>
Cc: Chuck Lever <[email protected]>
Cc: Coly Li <[email protected]>
Cc: Dai Ngo <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: "Darrick J. Wong" <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David Airlie <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: David Sterba <[email protected]>
Cc: Dmitry Baryshkov <[email protected]>
Cc: Gao Xiang <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Huang Rui <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jaegeuk Kim <[email protected]>
Cc: Jani Nikula <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jason Wang <[email protected]>
Cc: Jeff Layton <[email protected]>
Cc: Jeffle Xu <[email protected]>
Cc: Joel Fernandes (Google) <[email protected]>
Cc: Joonas Lahtinen <[email protected]>
Cc: Josef Bacik <[email protected]>
Cc: Juergen Gross <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Kirill Tkhai <[email protected]>
Cc: Marijn Suijten <[email protected]>
Cc: "Michael S. Tsirkin" <[email protected]>
Cc: Mike Snitzer <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: Nadav Amit <[email protected]>
Cc: Neil Brown <[email protected]>
Cc: Oleksandr Tyshchenko <[email protected]>
Cc: Olga Kornievskaia <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Richard Weinberger <[email protected]>
Cc: Rob Clark <[email protected]>
Cc: Rob Herring <[email protected]>
Cc: Rodrigo Vivi <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Sean Paul <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Cc: Song Liu <[email protected]>
Cc: Stefano Stabellini <[email protected]>
Cc: Steven Price <[email protected]>
Cc: "Theodore Ts'o" <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Tomeu Vizoso <[email protected]>
Cc: Tom Talpey <[email protected]>
Cc: Trond Myklebust <[email protected]>
Cc: Tvrtko Ursulin <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Xuan Zhuo <[email protected]>
Cc: Yue Hu <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm: shrinker: add infrastructure for dynamically allocating shrinker

Patch series "use refcount+RCU method to implement lockless slab shrink",
v6.

1. Background
=============

We used to implement

mm: shrinker: add infrastructure for dynamically allocating shrinker

Patch series "use refcount+RCU method to implement lockless slab shrink",
v6.

1. Background
=============

We used to implement the lockless slab shrink with SRCU [1], but then kernel
test robot reported -88.8% regression in stress-ng.ramfs.ops_per_sec test
case [2], so we reverted it [3].

This patch series aims to re-implement the lockless slab shrink using the
refcount+RCU method proposed by Dave Chinner [4].

[1]. https://lore.kernel.org/lkml/[email protected]/
[2]. https://lore.kernel.org/lkml/[email protected]/
[3]. https://lore.kernel.org/all/[email protected]/
[4]. https://lore.kernel.org/lkml/[email protected]/

2. Implementation
=================

Currently, the shrinker instances can be divided into the following three types:

a) global shrinker instance statically defined in the kernel, such as
workingset_shadow_shrinker.

b) global shrinker instance statically defined in the kernel modules, such as
mmu_shrinker in x86.

c) shrinker instance embedded in other structures.

For case a, the memory of shrinker instance is never freed. For case b, the
memory of shrinker instance will be freed after synchronize_rcu() when the
module is unloaded. For case c, the memory of shrinker instance will be freed
along with the structure it is embedded in.

In preparation for implementing lockless slab shrink, we need to dynamically
allocate those shrinker instances in case c, then the memory can be dynamically
freed alone by calling kfree_rcu().

This patchset adds the following new APIs for dynamically allocating shrinker,
and add a private_data field to struct shrinker to record and get the original
embedded structure.

1. shrinker_alloc()
2. shrinker_register()
3. shrinker_free()

In order to simplify shrinker-related APIs and make shrinker more independent of
other kernel mechanisms, this patchset uses the above APIs to convert all
shrinkers (including case a and b) to dynamically allocated, and then remove all
existing APIs. This will also have another advantage mentioned by Dave Chinner:

```
The other advantage of this is that it will break all the existing out of tree
code and third party modules using the old API and will no longer work with a
kernel using lockless slab shrinkers. They need to break (both at the source and
binary levels) to stop bad things from happening due to using uncoverted
shrinkers in the new setup.
```

Then we free the shrinker by calling call_rcu(), and use rcu_read_{lock,unlock}()
to ensure that the shrinker instance is valid. And the shrinker::refcount
mechanism ensures that the shrinker instance will not be run again after
unregistration. So the structure that records the pointer of shrinker instance
can be safely freed without waiting for the RCU read-side critical section.

In this way, while we implement the lockless slab shrink, we don't need to be
blocked in unregister_shrinker() to wait RCU read-side critical section.

PATCH 1: introduce new APIs
PATCH 2~38: convert all shrinnkers to use new APIs
PATCH 39: remove old APIs
PATCH 40~41: some cleanups and preparations
PATCH 42-43: implement the lockless slab shrink
PATCH 44~45: convert shrinker_rwsem to mutex

3. Testing
==========

3.1 slab shrink stress test
---------------------------

We can reproduce the down_read_trylock() hotspot through the following script:

```

DIR="/root/shrinker/memcg/mnt"

do_create()
{
mkdir -p /sys/fs/cgroup/memory/test
echo 4G > /sys/fs/cgroup/memory/test/memory.limit_in_bytes
for i in `seq 0 $1`;
do
mkdir -p /sys/fs/cgroup/memory/test/$i;
echo $$ > /sys/fs/cgroup/memory/test/$i/cgroup.procs;
mkdir -p $DIR/$i;
done
}

do_mount()
{
for i in `seq $1 $2`;
do
mount -t tmpfs $i $DIR/$i;
done
}

do_touch()
{
for i in `seq $1 $2`;
do
echo $$ > /sys/fs/cgroup/memory/test/$i/cgroup.procs;
dd if=/dev/zero of=$DIR/$i/file$i bs=1M count=1 &
done
}

case "$1" in
touch)
do_touch $2 $3
;;
test)
do_create 4000
do_mount 0 4000
do_touch 0 3000
;;
*)
exit 1
;;
esac
```

Save the above script, then run test and touch commands. Then we can use the
following perf command to view hotspots:

perf top -U -F 999

1) Before applying this patchset:

33.15% [kernel] [k] down_read_trylock
25.38% [kernel] [k] shrink_slab
21.75% [kernel] [k] up_read
4.45% [kernel] [k] _find_next_bit
2.27% [kernel] [k] do_shrink_slab
1.80% [kernel] [k] intel_idle_irq
1.79% [kernel] [k] shrink_lruvec
0.67% [kernel] [k] xas_descend
0.41% [kernel] [k] mem_cgroup_iter
0.40% [kernel] [k] shrink_node
0.38% [kernel] [k] list_lru_count_one

2) After applying this patchset:

64.56% [kernel] [k] shrink_slab
12.18% [kernel] [k] do_shrink_slab
3.30% [kernel] [k] __rcu_read_unlock
2.61% [kernel] [k] shrink_lruvec
2.49% [kernel] [k] __rcu_read_lock
1.93% [kernel] [k] intel_idle_irq
0.89% [kernel] [k] shrink_node
0.81% [kernel] [k] mem_cgroup_iter
0.77% [kernel] [k] mem_cgroup_calculate_protection
0.66% [kernel] [k] list_lru_count_one

We can see that the first perf hotspot becomes shrink_slab, which is what we
expect.

3.2 registration and unregistration stress test
-----------------------------------------------

Run the command below to test:

stress-ng --timeout 60 --times --verify --metrics-brief --ramfs 9 &

1) Before applying this patchset:

setting to a 60 second run per stressor
dispatching hogs: 9 ramfs
stressor bogo ops real time usr time sys time bogo ops/s bogo ops/s
(secs) (secs) (secs) (real time) (usr+sys time)
ramfs 473062 60.00 8.00 279.13 7884.12 1647.59
for a 60.01s run time:
1440.34s available CPU time
7.99s user time ( 0.55%)
279.13s system time ( 19.38%)
287.12s total time ( 19.93%)
load average: 7.12 2.99 1.15
successful run completed in 60.01s (1 min, 0.01 secs)

2) After applying this patchset:

setting to a 60 second run per stressor
dispatching hogs: 9 ramfs
stressor bogo ops real time usr time sys time bogo ops/s bogo ops/s
(secs) (secs) (secs) (real time) (usr+sys time)
ramfs 477165 60.00 8.13 281.34 7952.55 1648.40
for a 60.01s run time:
1440.33s available CPU time
8.12s user time ( 0.56%)
281.34s system time ( 19.53%)
289.46s total time ( 20.10%)
load average: 6.98 3.03 1.19
successful run completed in 60.01s (1 min, 0.01 secs)

We can see that the ops/s has hardly changed.


This patch (of 45):

Currently, the shrinker instances can be divided into the following three
types:

a) global shrinker instance statically defined in the kernel, such as
workingset_shadow_shrinker.

b) global shrinker instance statically defined in the kernel modules, such
as mmu_shrinker in x86.

c) shrinker instance embedded in other structures.

For case a, the memory of shrinker instance is never freed. For case b,
the memory of shrinker instance will be freed after synchronize_rcu() when
the module is unloaded. For case c, the memory of shrinker instance will
be freed along with the structure it is embedded in.

In preparation for implementing lockless slab shrink, we need to
dynamically allocate those shrinker instances in case c, then the memory
can be dynamically freed alone by calling kfree_rcu().

So this commit adds the following new APIs for dynamically allocating
shrinker, and add a private_data field to struct shrinker to record and
get the original embedded structure.

1. shrinker_alloc()

Used to allocate shrinker instance itself and related memory, it will
return a pointer to the shrinker instance on success and NULL on failure.

2. shrinker_register()

Used to register the shrinker instance, which is same as the current
register_shrinker_prepared().

3. shrinker_free()

Used to unregister (if needed) and free the shrinker instance.

In order to simplify shrinker-related APIs and make shrinker more
independent of other kernel mechanisms, subsequent submissions will use
the above API to convert all shrinkers (including case a and b) to
dynamically allocated, and then remove all existing APIs.

This will also have another advantage mentioned by Dave Chinner:

```
The other advantage of this is that it will break all the existing
out of tree code and third party modules using the old API and will
no longer work with a kernel using lockless slab shrinkers. They
need to break (both at the source and binary levels) to stop bad
things from happening due to using unconverted shrinkers in the new
setup.
```

[[email protected]: mm: shrinker: some cleanup]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Qi Zheng <[email protected]>
Reviewed-by: Muchun Song <[email protected]>
Cc: Christian Brauner <[email protected]>
Cc: Chuck Lever <[email protected]>
Cc: Darrick J. Wong <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Kirill Tkhai <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Cc: Steven Price <[email protected]>
Cc: Theodore Ts'o <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Abhinav Kumar <[email protected]>
Cc: Alasdair Kergon <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Alyssa Rosenzweig <[email protected]>
Cc: Andreas Dilger <[email protected]>
Cc: Andreas Gruenbacher <[email protected]>
Cc: Anna Schumaker <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Bob Peterson <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Carlos Llamas <[email protected]>
Cc: Chandan Babu R <[email protected]>
Cc: Chao Yu <[email protected]>
Cc: Chris Mason <[email protected]>
Cc: Christian Koenig <[email protected]>
Cc: Coly Li <[email protected]>
Cc: Dai Ngo <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David Airlie <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: David Sterba <[email protected]>
Cc: Dmitry Baryshkov <[email protected]>
Cc: Gao Xiang <[email protected]>
Cc: Huang Rui <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jaegeuk Kim <[email protected]>
Cc: Jani Nikula <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jason Wang <[email protected]>
Cc: Jeff Layton <[email protected]>
Cc: Jeffle Xu <[email protected]>
Cc: Joel Fernandes (Google) <[email protected]>
Cc: Joonas Lahtinen <[email protected]>
Cc: Josef Bacik <[email protected]>
Cc: Juergen Gross <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Marijn Suijten <[email protected]>
Cc: "Michael S. Tsirkin" <[email protected]>
Cc: Mike Snitzer <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Nadav Amit <[email protected]>
Cc: Neil Brown <[email protected]>
Cc: Oleksandr Tyshchenko <[email protected]>
Cc: Olga Kornievskaia <[email protected]>
Cc: Richard Weinberger <[email protected]>
Cc: Rob Clark <[email protected]>
Cc: Rob Herring <[email protected]>
Cc: Rodrigo Vivi <[email protected]>
Cc: Sean Paul <[email protected]>
Cc: Song Liu <[email protected]>
Cc: Stefano Stabellini <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Tomeu Vizoso <[email protected]>
Cc: Tom Talpey <[email protected]>
Cc: Trond Myklebust <[email protected]>
Cc: Tvrtko Ursulin <[email protected]>
Cc: Xuan Zhuo <[email protected]>
Cc: Yue Hu <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

drm/ttm: introduce pool_shrink_rwsem

Currently, synchronize_shrinkers() is only used by TTM pool. It only
requires that no shrinkers run in parallel.

After we use RCU+refcount method to implement

drm/ttm: introduce pool_shrink_rwsem

Currently, synchronize_shrinkers() is only used by TTM pool. It only
requires that no shrinkers run in parallel.

After we use RCU+refcount method to implement the lockless slab shrink, we
can not use shrinker_rwsem or synchronize_rcu() to guarantee that all
shrinker invocations have seen an update before freeing memory.

So we introduce a new pool_shrink_rwsem to implement a private
ttm_pool_synchronize_shrinkers(), so as to achieve the same purpose.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Qi Zheng <[email protected]>
Reviewed-by: Muchun Song <[email protected]>
Reviewed-by: Christian König <[email protected]>
Acked-by: Daniel Vetter <[email protected]>
Cc: Christian Brauner <[email protected]>
Cc: Chuck Lever <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Darrick J. Wong <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Joel Fernandes <[email protected]>
Cc: Kirill Tkhai <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Cc: Steven Price <[email protected]>
Cc: Theodore Ts'o <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Abhinav Kumar <[email protected]>
Cc: Alasdair Kergon <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Alyssa Rosenzweig <[email protected]>
Cc: Andreas Dilger <[email protected]>
Cc: Andreas Gruenbacher <[email protected]>
Cc: Anna Schumaker <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Bob Peterson <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Carlos Llamas <[email protected]>
Cc: Chandan Babu R <[email protected]>
Cc: Chao Yu <[email protected]>
Cc: Chris Mason <[email protected]>
Cc: Coly Li <[email protected]>
Cc: Dai Ngo <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David Airlie <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: David Sterba <[email protected]>
Cc: Dmitry Baryshkov <[email protected]>
Cc: Gao Xiang <[email protected]>
Cc: Huang Rui <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jaegeuk Kim <[email protected]>
Cc: Jani Nikula <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jason Wang <[email protected]>
Cc: Jeff Layton <[email protected]>
Cc: Jeffle Xu <[email protected]>
Cc: Joonas Lahtinen <[email protected]>
Cc: Josef Bacik <[email protected]>
Cc: Juergen Gross <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Marijn Suijten <[email protected]>
Cc: "Michael S. Tsirkin" <[email protected]>
Cc: Mike Snitzer <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: Nadav Amit <[email protected]>
Cc: Neil Brown <[email protected]>
Cc: Oleksandr Tyshchenko <[email protected]>
Cc: Olga Kornievskaia <[email protected]>
Cc: Richard Weinberger <[email protected]>
Cc: Rob Clark <[email protected]>
Cc: Rob Herring <[email protected]>
Cc: Rodrigo Vivi <[email protected]>
Cc: Sean Paul <[email protected]>
Cc: Song Liu <[email protected]>
Cc: Stefano Stabellini <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Tomeu Vizoso <[email protected]>
Cc: Tom Talpey <[email protected]>
Cc: Trond Myklebust <[email protected]>
Cc: Tvrtko Ursulin <[email protected]>
Cc: Xuan Zhuo <[email protected]>
Cc: Yue Hu <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm: move some shrinker-related function declarations to mm/internal.h

Patch series "cleanups for lockless slab shrink", v4.

This series is some cleanups for lockless slab shrink.


This patch (of 4

mm: move some shrinker-related function declarations to mm/internal.h

Patch series "cleanups for lockless slab shrink", v4.

This series is some cleanups for lockless slab shrink.


This patch (of 4):

The following functions are only used inside the mm subsystem, so it's
better to move their declarations to the mm/internal.h file.

1. shrinker_debugfs_add()
2. shrinker_debugfs_detach()
3. shrinker_debugfs_remove()

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Qi Zheng <[email protected]>
Reviewed-by: Muchun Song <[email protected]>
Cc: Christian Brauner <[email protected]>
Cc: Christian König <[email protected]>
Cc: Chuck Lever <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Darrick J. Wong <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Joel Fernandes <[email protected]>
Cc: Kirill Tkhai <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Cc: Steven Price <[email protected]>
Cc: Theodore Ts'o <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Abhinav Kumar <[email protected]>
Cc: Alasdair Kergon <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Alyssa Rosenzweig <[email protected]>
Cc: Andreas Dilger <[email protected]>
Cc: Andreas Gruenbacher <[email protected]>
Cc: Anna Schumaker <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Bob Peterson <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Carlos Llamas <[email protected]>
Cc: Chandan Babu R <[email protected]>
Cc: Chao Yu <[email protected]>
Cc: Chris Mason <[email protected]>
Cc: Coly Li <[email protected]>
Cc: Dai Ngo <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David Airlie <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: David Sterba <[email protected]>
Cc: Dmitry Baryshkov <[email protected]>
Cc: Gao Xiang <[email protected]>
Cc: Huang Rui <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jaegeuk Kim <[email protected]>
Cc: Jani Nikula <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jason Wang <[email protected]>
Cc: Jeff Layton <[email protected]>
Cc: Jeffle Xu <[email protected]>
Cc: Joonas Lahtinen <[email protected]>
Cc: Josef Bacik <[email protected]>
Cc: Juergen Gross <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Marijn Suijten <[email protected]>
Cc: "Michael S. Tsirkin" <[email protected]>
Cc: Mike Snitzer <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: Nadav Amit <[email protected]>
Cc: Neil Brown <[email protected]>
Cc: Oleksandr Tyshchenko <[email protected]>
Cc: Olga Kornievskaia <[email protected]>
Cc: Richard Weinberger <[email protected]>
Cc: Rob Clark <[email protected]>
Cc: Rob Herring <[email protected]>
Cc: Rodrigo Vivi <[email protected]>
Cc: Sean Paul <[email protected]>
Cc: Song Liu <[email protected]>
Cc: Stefano Stabellini <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Tomeu Vizoso <[email protected]>
Cc: Tom Talpey <[email protected]>
Cc: Trond Myklebust <[email protected]>
Cc: Tvrtko Ursulin <[email protected]>
Cc: Xuan Zhuo <[email protected]>
Cc: Yue Hu <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm: shrinkers: fix race condition on debugfs cleanup

When something registers and unregisters many shrinkers, such as:
for x in $(seq 10000); do unshare -Ui true; done

Sometimes the following e

mm: shrinkers: fix race condition on debugfs cleanup

When something registers and unregisters many shrinkers, such as:
for x in $(seq 10000); do unshare -Ui true; done

Sometimes the following error is printed to the kernel log:
debugfs: Directory '...' with parent 'shrinker' already present!

This occurs since commit badc28d4924b ("mm: shrinkers: fix deadlock in
shrinker debugfs") / v6.2: Since the call to `debugfs_remove_recursive`
was moved outside the `shrinker_rwsem`/`shrinker_mutex` lock, but the call
to `ida_free` stayed inside, a newly registered shrinker can be
re-assigned that ID and attempt to create the debugfs directory before the
directory from the previous shrinker has been removed.

The locking changes in commit f95bdb700bc6 ("mm: vmscan: make global slab
shrink lockless") made the race condition more likely, though it existed
before then.

Commit badc28d4924b ("mm: shrinkers: fix deadlock in shrinker debugfs")
could be reverted since the issue is addressed should no longer occur
since the count and scan operations are lockless since commit 20cd1892fcc3
("mm: shrinkers: make count and scan in shrinker debugfs lockless").
However, since this is a contended lock, prefer instead moving `ida_free`
outside the lock to avoid the race.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: badc28d4924b ("mm: shrinkers: fix deadlock in shrinker debugfs")
Signed-off-by: Joan Bruguera Micó <[email protected]>
Cc: Qi Zheng <[email protected]>
Cc: Roman Gushchin <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm: shrinkers: fix deadlock in shrinker debugfs

The debugfs_remove_recursive() is invoked by unregister_shrinker(), which
is holding the write lock of shrinker_rwsem. It will waits for the
handler

mm: shrinkers: fix deadlock in shrinker debugfs

The debugfs_remove_recursive() is invoked by unregister_shrinker(), which
is holding the write lock of shrinker_rwsem. It will waits for the
handler of debugfs file complete. The handler also needs to hold the read
lock of shrinker_rwsem to do something. So it may cause the following
deadlock:

CPU0 CPU1

debugfs_file_get()
shrinker_debugfs_count_show()/shrinker_debugfs_scan_write()

unregister_shrinker()
--> down_write(&shrinker_rwsem);
debugfs_remove_recursive()
// wait for (A)
--> wait_for_completion();

// wait for (B)
--> down_read_killable(&shrinker_rwsem)
debugfs_file_put() -- (A)

up_write() -- (B)

The down_read_killable() can be killed, so that the above deadlock can be
recovered. But it still requires an extra kill action, otherwise it will
block all subsequent shrinker-related operations, so it's better to fix
it.

[[email protected]: fix CONFIG_SHRINKER_DEBUG=n stub]
Link: https://lkml.kernel.org/r/[email protected]
Fixes: 5035ebc644ae ("mm: shrinkers: introduce debugfs interface for memory shrinkers")
Signed-off-by: Qi Zheng <[email protected]>
Reviewed-by: Roman Gushchin <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm: shrinkers: add missing includes for undeclared types

The shrinker.h header depends on a user including other headers before it
for types used by shrinker.h. Fix this by including the appropriat

mm: shrinkers: add missing includes for undeclared types

The shrinker.h header depends on a user including other headers before it
for types used by shrinker.h. Fix this by including the appropriate
headers in shrinker.h.

./include/linux/shrinker.h:13:9: error: unknown type name `gfp_t'
13 | gfp_t gfp_mask;
| ^~~~~
./include/linux/shrinker.h:71:26: error: field `list' has incomplete type
71 | struct list_head list;
| ^~~~
./include/linux/shrinker.h:82:9: error: unknown type name `atomic_long_t'
82 | atomic_long_t *nr_deferred;
|

Link: https://lkml.kernel.org/r/[email protected]
Fixes: 83aeeada7c69 ("vmscan: use atomic-long for shrinker batching")
Fixes: b0d40c92adaf ("superblock: introduce per-sb cache shrinker infrastructure")
Signed-off-by: T.J. Mercier <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: Konstantin Khlebnikov <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm: shrinkers: provide shrinkers with names

Currently shrinkers are anonymous objects. For debugging purposes they
can be identified by count/scan function names, but it's not always
useful: e.g.

mm: shrinkers: provide shrinkers with names

Currently shrinkers are anonymous objects. For debugging purposes they
can be identified by count/scan function names, but it's not always
useful: e.g. for superblock's shrinkers it's nice to have at least an
idea of to which superblock the shrinker belongs.

This commit adds names to shrinkers. register_shrinker() and
prealloc_shrinker() functions are extended to take a format and arguments
to master a name.

In some cases it's not possible to determine a good name at the time when
a shrinker is allocated. For such cases shrinker_debugfs_rename() is
provided.

The expected format is:
<subsystem>-<shrinker_type>[:<instance>]-<id>
For some shrinkers an instance can be encoded as (MAJOR:MINOR) pair.

After this change the shrinker debugfs directory looks like:
$ cd /sys/kernel/debug/shrinker/
$ ls
dquota-cache-16 sb-devpts-28 sb-proc-47 sb-tmpfs-42
mm-shadow-18 sb-devtmpfs-5 sb-proc-48 sb-tmpfs-43
mm-zspool:zram0-34 sb-hugetlbfs-17 sb-pstore-31 sb-tmpfs-44
rcu-kfree-0 sb-hugetlbfs-33 sb-rootfs-2 sb-tmpfs-49
sb-aio-20 sb-iomem-12 sb-securityfs-6 sb-tracefs-13
sb-anon_inodefs-15 sb-mqueue-21 sb-selinuxfs-22 sb-xfs:vda1-36
sb-bdev-3 sb-nsfs-4 sb-sockfs-8 sb-zsmalloc-19
sb-bpf-32 sb-pipefs-14 sb-sysfs-26 thp-deferred_split-10
sb-btrfs:vda2-24 sb-proc-25 sb-tmpfs-1 thp-zero-9
sb-cgroup2-30 sb-proc-39 sb-tmpfs-27 xfs-buf:vda1-37
sb-configfs-23 sb-proc-41 sb-tmpfs-29 xfs-inodegc:vda1-38
sb-dax-11 sb-proc-45 sb-tmpfs-35
sb-debugfs-7 sb-proc-46 sb-tmpfs-40

[[email protected]: fix build warnings]
Link: https://lkml.kernel.org/r/Yr+ZTnLb9lJk6fJO@castle
Reported-by: kernel test robot <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Roman Gushchin <[email protected]>
Cc: Christophe JAILLET <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: Hillf Danton <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Muchun Song <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm: shrinkers: introduce debugfs interface for memory shrinkers

This commit introduces the /sys/kernel/debug/shrinker debugfs interface
which provides an ability to observe the state of individual k

mm: shrinkers: introduce debugfs interface for memory shrinkers

This commit introduces the /sys/kernel/debug/shrinker debugfs interface
which provides an ability to observe the state of individual kernel memory
shrinkers.

Because the feature adds some memory overhead (which shouldn't be large
unless there is a huge amount of registered shrinkers), it's guarded by a
config option (enabled by default).

This commit introduces the "count" interface for each shrinker registered
in the system.

The output is in the following format:
<cgroup inode id> <nr of objects on node 0> <nr of objects on node 1>...
<cgroup inode id> <nr of objects on node 0> <nr of objects on node 1>...
...

To reduce the size of output on machines with many thousands cgroups, if
the total number of objects on all nodes is 0, the line is omitted.

If the shrinker is not memcg-aware or CONFIG_MEMCG is off, 0 is printed as
cgroup inode id. If the shrinker is not numa-aware, 0's are printed for
all nodes except the first one.

This commit gives debugfs entries simple numeric names, which are not very
convenient. The following commit in the series will provide shrinkers
with more meaningful names.

[[email protected]: remove WARN_ON_ONCE(), per Roman]
Reported-by: [email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Roman Gushchin <[email protected]>
Reviewed-by: Kent Overstreet <[email protected]>
Acked-by: Muchun Song <[email protected]>
Cc: Christophe JAILLET <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: Hillf Danton <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm/vmscan: add sync_shrinkers function v3

While unplugging a device the TTM shrinker implementation
needs a barrier to make sure that all concurrent shrink
operations are done and no other CPU is re

mm/vmscan: add sync_shrinkers function v3

While unplugging a device the TTM shrinker implementation
needs a barrier to make sure that all concurrent shrink
operations are done and no other CPU is referring to a
device specific pool any more.

Taking and releasing the shrinker semaphore on the write
side after unmapping and freeing all pages from the device
pool should make sure that no shrinker is running in
paralell.

This allows us to avoid the contented mutex in the TTM pool
implementation for every alloc/free operation.

v2: rework the commit message to make clear why we need this
v3: rename the function and add more doc as suggested by Daniel

Signed-off-by: Christian König <[email protected]>
Acked-by: Huang Rui <[email protected]>
Acked-by: Andrew Morton <[email protected]>
Reviewed-by: Daniel Vetter <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

show more ...

mm: fix spelling mistakes in header files

Fix some spelling mistakes in comments:
successfull ==> successful
potentialy ==> potentially
alloced ==> allocated
indicies ==> indices
wont ==> won't
resp

mm: fix spelling mistakes in header files

Fix some spelling mistakes in comments:
successfull ==> successful
potentialy ==> potentially
alloced ==> allocated
indicies ==> indices
wont ==> won't
resposible ==> responsible
dirtyness ==> dirtiness
droppped ==> dropped
alread ==> already
occured ==> occurred
interupts ==> interrupts
extention ==> extension
slighly ==> slightly
Dont't ==> Don't

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Zhen Lei <[email protected]>
Cc: Jerome Glisse <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Dennis Zhou <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Christoph Lameter <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

mm: vmscan: use a new flag to indicate shrinker is registered

Currently registered shrinker is indicated by non-NULL
shrinker->nr_deferred. This approach is fine with nr_deferred at the
shrinker le

mm: vmscan: use a new flag to indicate shrinker is registered

Currently registered shrinker is indicated by non-NULL
shrinker->nr_deferred. This approach is fine with nr_deferred at the
shrinker level, but the following patches will move MEMCG_AWARE
shrinkers' nr_deferred to memcg level, so their shrinker->nr_deferred
would always be NULL. This would prevent the shrinkers from
unregistering correctly.

Remove SHRINKER_REGISTERING since we could check if shrinker is
registered successfully by the new flag.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Yang Shi <[email protected]>
Acked-by: Kirill Tkhai <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Acked-by: Roman Gushchin <[email protected]>
Reviewed-by: Shakeel Butt <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Michal Hocko <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

mm: shrinker: make shrinker not depend on memcg kmem

Currently shrinker is just allocated and can work when memcg kmem is
enabled. But, THP deferred split shrinker is not slab shrinker, it
doesn't

mm: shrinker: make shrinker not depend on memcg kmem

Currently shrinker is just allocated and can work when memcg kmem is
enabled. But, THP deferred split shrinker is not slab shrinker, it
doesn't make too much sense to have such shrinker depend on memcg kmem.
It should be able to reclaim THP even though memcg kmem is disabled.

Introduce a new shrinker flag, SHRINKER_NONSLAB, for non-slab shrinker.
When memcg kmem is disabled, just such shrinkers can be called in
shrinking memcg slab.

[[email protected]: add comment]
Link: http://lkml.kernel.org/r/[email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Yang Shi <[email protected]>
Acked-by: Kirill A. Shutemov <[email protected]>
Reviewed-by: Kirill Tkhai <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: "Kirill A . Shutemov" <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Shakeel Butt <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Qian Cai <[email protected]>
Cc: Vladimir Davydov <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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mm: struct shrinker: make flags of unsigned type

Currently, there are two flags only, so unsigned is more then enough.
Also, move int seeks to keep these fields together.

Link: http://lkml.kernel.o

mm: struct shrinker: make flags of unsigned type

Currently, there are two flags only, so unsigned is more then enough.
Also, move int seeks to keep these fields together.

Link: http://lkml.kernel.org/r/153199748720.21131.6476256940113102483.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Cc: Vladimir Davydov <[email protected]>
Cc: Tetsuo Handa <[email protected]>
Cc: Chris Wilson <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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mm: struct shrink_control: keep int fields together

Patch series "Reorderings in struct shrinker and struct shrink_control".

These structures are intensively used during reclaim and, displace other

mm: struct shrink_control: keep int fields together

Patch series "Reorderings in struct shrinker and struct shrink_control".

These structures are intensively used during reclaim and, displace other
data in cache, so there is no a reason they have int fields not grouped
together.

This patch (of 2):

gfp_t is of unsigned type, so let's move nid to keep them together.

Link: http://lkml.kernel.org/r/153199747930.21131.861043607301997810.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Cc: Vladimir Davydov <[email protected]>
Cc: Tetsuo Handa <[email protected]>
Cc: Chris Wilson <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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mm: add SHRINK_EMPTY shrinker methods return value

We need to distinguish the situations when shrinker has very small
amount of objects (see vfs_pressure_ratio() called from
super_cache_count()), an

mm: add SHRINK_EMPTY shrinker methods return value

We need to distinguish the situations when shrinker has very small
amount of objects (see vfs_pressure_ratio() called from
super_cache_count()), and when it has no objects at all. Currently, in
the both of these cases, shrinker::count_objects() returns 0.

The patch introduces new SHRINK_EMPTY return value, which will be used
for "no objects at all" case. It's is a refactoring mostly, as
SHRINK_EMPTY is replaced by 0 by all callers of do_shrink_slab() in this
patch, and all the magic will happen in further.

Link: http://lkml.kernel.org/r/153063069574.1818.11037751256699341813.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <[email protected]>
Acked-by: Vladimir Davydov <[email protected]>
Tested-by: Shakeel Butt <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Andrey Ryabinin <[email protected]>
Cc: Chris Wilson <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Guenter Roeck <[email protected]>
Cc: "Huang, Ying" <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Josef Bacik <[email protected]>
Cc: Li RongQing <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Matthias Kaehlcke <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Philippe Ombredanne <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Sahitya Tummala <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Tetsuo Handa <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Waiman Long <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

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mm: assign id to every memcg-aware shrinker

Introduce shrinker::id number, which is used to enumerate memcg-aware
shrinkers. The number start from 0, and the code tries to maintain it
as small as p

mm: assign id to every memcg-aware shrinker

Introduce shrinker::id number, which is used to enumerate memcg-aware
shrinkers. The number start from 0, and the code tries to maintain it
as small as possible.

This will be used to represent a memcg-aware shrinkers in memcg
shrinkers map.

Since all memcg-aware shrinkers are based on list_lru, which is
per-memcg in case of !CONFIG_MEMCG_KMEM only, the new functionality will
be under this config option.

[[email protected]: v9]
Link: http://lkml.kernel.org/r/153112546435.4097.10607140323811756557.stgit@localhost.localdomain
Link: http://lkml.kernel.org/r/153063054586.1818.6041047871606697364.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <[email protected]>
Acked-by: Vladimir Davydov <[email protected]>
Tested-by: Shakeel Butt <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Andrey Ryabinin <[email protected]>
Cc: Chris Wilson <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Guenter Roeck <[email protected]>
Cc: "Huang, Ying" <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Josef Bacik <[email protected]>
Cc: Li RongQing <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Matthias Kaehlcke <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Philippe Ombredanne <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Sahitya Tummala <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Tetsuo Handa <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Waiman Long <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

mm,vmscan: Allow preallocating memory for register_shrinker().

syzbot is catching so many bugs triggered by commit 9ee332d99e4d5a97
("sget(): handle failures of register_shrinker()"). That commit ex

mm,vmscan: Allow preallocating memory for register_shrinker().

syzbot is catching so many bugs triggered by commit 9ee332d99e4d5a97
("sget(): handle failures of register_shrinker()"). That commit expected
that calling kill_sb() from deactivate_locked_super() without successful
fill_super() is safe, but the reality was different; some callers assign
attributes which are needed for kill_sb() after sget() succeeds.

For example, [1] is a report where sb->s_mode (which seems to be either
FMODE_READ | FMODE_EXCL | FMODE_WRITE or FMODE_READ | FMODE_EXCL) is not
assigned unless sget() succeeds. But it does not worth complicate sget()
so that register_shrinker() failure path can safely call
kill_block_super() via kill_sb(). Making alloc_super() fail if memory
allocation for register_shrinker() failed is much simpler. Let's avoid
calling deactivate_locked_super() from sget_userns() by preallocating
memory for the shrinker and making register_shrinker() in sget_userns()
never fail.

[1] https://syzkaller.appspot.com/bug?id=588996a25a2587be2e3a54e8646728fb9cae44e7

Signed-off-by: Tetsuo Handa <[email protected]>
Reported-by: syzbot <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Michal Hocko <[email protected]>
Signed-off-by: Al Viro <[email protected]>

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License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.

For non */uapi/* files that summary was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139

and resulted in the first patch in this series.

If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930

and resulted in the second patch in this series.

- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:

SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1

and that resulted in the third patch in this series.

- when the two scanners agreed on the detected license(s), that became
the concluded license(s).

- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.

- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).

- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.

- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct

This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <[email protected]>
Reviewed-by: Philippe Ombredanne <[email protected]>
Reviewed-by: Thomas Gleixner <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

show more ...

mm: track actual nr_scanned during shrink_slab()

Some shrinkers may only be able to free a bunch of objects at a time,
and so free more than the requested nr_to_scan in one pass.

Whilst other shrin

mm: track actual nr_scanned during shrink_slab()

Some shrinkers may only be able to free a bunch of objects at a time,
and so free more than the requested nr_to_scan in one pass.

Whilst other shrinkers may find themselves even unable to scan as many
objects as they counted, and so underreport. Account for the extra
freed/scanned objects against the total number of objects we intend to
scan, otherwise we may end up penalising the slab far more than
intended. Similarly, we want to add the underperforming scan to the
deferred pass so that we try harder and harder in future passes.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Chris Wilson <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Hillf Danton <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Shaohua Li <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: Pekka Enberg <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Joonas Lahtinen <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

vmscan: per memory cgroup slab shrinkers

This patch adds SHRINKER_MEMCG_AWARE flag. If a shrinker has this flag
set, it will be called per memory cgroup. The memory cgroup to scan
objects from is

vmscan: per memory cgroup slab shrinkers

This patch adds SHRINKER_MEMCG_AWARE flag. If a shrinker has this flag
set, it will be called per memory cgroup. The memory cgroup to scan
objects from is passed in shrink_control->memcg. If the memory cgroup
is NULL, a memcg aware shrinker is supposed to scan objects from the
global list. Unaware shrinkers are only called on global pressure with
memcg=NULL.

Signed-off-by: Vladimir Davydov <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Greg Thelen <[email protected]>
Cc: Glauber Costa <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: Pekka Enberg <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Tejun Heo <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

mm: vmscan: invoke slab shrinkers from shrink_zone()

The slab shrinkers are currently invoked from the zonelist walkers in
kswapd, direct reclaim, and zone reclaim, all of which roughly gauge the
el

mm: vmscan: invoke slab shrinkers from shrink_zone()

The slab shrinkers are currently invoked from the zonelist walkers in
kswapd, direct reclaim, and zone reclaim, all of which roughly gauge the
eligible LRU pages and assemble a nodemask to pass to NUMA-aware
shrinkers, which then again have to walk over the nodemask. This is
redundant code, extra runtime work, and fairly inaccurate when it comes to
the estimation of actually scannable LRU pages. The code duplication will
only get worse when making the shrinkers cgroup-aware and requiring them
to have out-of-band cgroup hierarchy walks as well.

Instead, invoke the shrinkers from shrink_zone(), which is where all
reclaimers end up, to avoid this duplication.

Take the count for eligible LRU pages out of get_scan_count(), which
considers many more factors than just the availability of swap space, like
zone_reclaimable_pages() currently does. Accumulate the number over all
visited lruvecs to get the per-zone value.

Some nodes have multiple zones due to memory addressing restrictions. To
avoid putting too much pressure on the shrinkers, only invoke them once
for each such node, using the class zone of the allocation as the pivot
zone.

For now, this integrates the slab shrinking better into the reclaim logic
and gets rid of duplicative invocations from kswapd, direct reclaim, and
zone reclaim. It also prepares for cgroup-awareness, allowing
memcg-capable shrinkers to be added at the lruvec level without much
duplication of both code and runtime work.

This changes kswapd behavior, which used to invoke the shrinkers for each
zone, but with scan ratios gathered from the entire node, resulting in
meaningless pressure quantities on multi-zone nodes.

Zone reclaim behavior also changes. It used to shrink slabs until the
same amount of pages were shrunk as were reclaimed from the LRUs. Now it
merely invokes the shrinkers once with the zone's scan ratio, which makes
the shrinkers go easier on caches that implement aging and would prefer
feeding back pressure from recently used slab objects to unused LRU pages.

[[email protected]: assure class zone is populated]
Signed-off-by: Johannes Weiner <[email protected]>
Cc: Dave Chinner <[email protected]>
Signed-off-by: Vladimir Davydov <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...