Currently mem_cgroup_from_obj() is not working properly with objects
allocated using vmalloc(). It creates problems in some cases, when it's
called for static objects belonging to modules or generally allocated
using vmalloc().
This patch makes mem_cgroup_from_obj() safe to be called on objects
allocated using vmalloc().
It also introduces mem_cgroup_from_slab_obj(), which is a faster version
to use in places when we know the object is either a slab object or a
generic slab page (e.g. when adding an object to a lru list).
Link: https://lkml.kernel.org/r/20220610180310.1725111-1-roman.gushchin@linux.dev
Suggested-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Roman Gushchin <roman.gushchin@linux.dev>
Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>
Acked-by: Shakeel Butt <shakeelb@google.com>
Tested-by: Vasily Averin <vvs@openvz.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Muchun Song <songmuchun@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Naresh Kamboju <naresh.kamboju@linaro.org>
Cc: Qian Cai <quic_qiancai@quicinc.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Florian Westphal <fw@strlen.de>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Commit 405cc51fc1 ("mm/list_lru: optimize memcg_reparent_list_lru_node()")
has subtle races which are proving ugly to fix. Revert the original
optimization. If quantitative testing indicates that we have a
significant problem here then other implementations can be looked at.
Fixes: 405cc51fc1 ("mm/list_lru: optimize memcg_reparent_list_lru_node()")
Acked-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since commit 2c80cd57c7 ("mm/list_lru.c: fix list_lru_count_node() to
be race free"), we are tracking the total number of lru entries in a
list_lru_node in its nr_items field.
In the case of memcg_reparent_list_lru_node(), there is nothing to be
done if nr_items is 0. We don't even need to take the nlru->lock as no
new lru entry could be added by a racing list_lru_add() to the draining
src_idx memcg at this point.
On systems that serve a lot of containers, it is possible that there can
be thousands of list_lru's present due to the fact that each container
may mount its own container specific filesystems. As a typical
container uses only a few cpus, it is likely that only the list_lru_node
that contains those cpus will be utilized while the rests may be empty.
In other words, there can be a lot of list_lru_node with 0 nr_items.
By skipping a lock/unlock operation and loading a cacheline from
memcg_lrus, a sizeable number of cpu cycles can be saved. That can be
substantial if we are talking about thousands of list_lru_node's with 0
nr_items.
Link: https://lkml.kernel.org/r/20220309144000.1470138-1-longman@redhat.com
Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The memcg_cache_id() introduced by commit 2633d7a028 ("slab/slub:
consider a memcg parameter in kmem_create_cache") is used to index in the
kmem_cache->memcg_params->memcg_caches array. Since
kmem_cache->memcg_params.memcg_caches has been removed by commit
9855609bde ("mm: memcg/slab: use a single set of kmem_caches for all
accounted allocations"). So the name does not need to reflect cache
related. Just rename it to memcg_kmem_id. And it can reflect kmem
related.
Link: https://lkml.kernel.org/r/20220228122126.37293-17-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Cc: Alex Shi <alexs@kernel.org>
Cc: Anna Schumaker <Anna.Schumaker@Netapp.com>
Cc: Chao Yu <chao@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Fam Zheng <fam.zheng@bytedance.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kari Argillander <kari.argillander@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The name of list_lru_memcg was occupied before and became free since
last commit. Rename list_lru_per_memcg to list_lru_memcg since the name
is brief.
Link: https://lkml.kernel.org/r/20220228122126.37293-16-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Cc: Alex Shi <alexs@kernel.org>
Cc: Anna Schumaker <Anna.Schumaker@Netapp.com>
Cc: Chao Yu <chao@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Fam Zheng <fam.zheng@bytedance.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kari Argillander <kari.argillander@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If we run 10k containers in the system, the size of the
list_lru_memcg->lrus can be ~96KB per list_lru. When we decrease the
number containers, the size of the array will not be shrinked. It is
not scalable. The xarray is a good choice for this case. We can save a
lot of memory when there are tens of thousands continers in the system.
If we use xarray, we also can remove the logic code of resizing array,
which can simplify the code.
[akpm@linux-foundation.org: remove unused local]
Link: https://lkml.kernel.org/r/20220228122126.37293-13-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Cc: Alex Shi <alexs@kernel.org>
Cc: Anna Schumaker <Anna.Schumaker@Netapp.com>
Cc: Chao Yu <chao@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Fam Zheng <fam.zheng@bytedance.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kari Argillander <kari.argillander@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The purpose of the memcg_drain_all_list_lrus() is list_lrus reparenting.
It is very similar to memcg_reparent_objcgs(). Rename it to
memcg_reparent_list_lrus() so that the name can more consistent with
memcg_reparent_objcgs().
Link: https://lkml.kernel.org/r/20220228122126.37293-12-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Cc: Alex Shi <alexs@kernel.org>
Cc: Anna Schumaker <Anna.Schumaker@Netapp.com>
Cc: Chao Yu <chao@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Fam Zheng <fam.zheng@bytedance.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kari Argillander <kari.argillander@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In our server, we found a suspected memory leak problem. The kmalloc-32
consumes more than 6GB of memory. Other kmem_caches consume less than
2GB memory.
After our in-depth analysis, the memory consumption of kmalloc-32 slab
cache is the cause of list_lru_one allocation.
crash> p memcg_nr_cache_ids
memcg_nr_cache_ids = $2 = 24574
memcg_nr_cache_ids is very large and memory consumption of each list_lru
can be calculated with the following formula.
num_numa_node * memcg_nr_cache_ids * 32 (kmalloc-32)
There are 4 numa nodes in our system, so each list_lru consumes ~3MB.
crash> list super_blocks | wc -l
952
Every mount will register 2 list lrus, one is for inode, another is for
dentry. There are 952 super_blocks. So the total memory is 952 * 2 * 3
MB (~5.6GB). But the number of memory cgroup is less than 500. So I
guess more than 12286 containers have been deployed on this machine (I do
not know why there are so many containers, it may be a user's bug or the
user really want to do that). And memcg_nr_cache_ids has not been reduced
to a suitable value. This can waste a lot of memory.
Now the infrastructure for dynamic list_lru_one allocation is ready, so
remove statically allocated memory code to save memory.
Link: https://lkml.kernel.org/r/20220228122126.37293-11-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Cc: Alex Shi <alexs@kernel.org>
Cc: Anna Schumaker <Anna.Schumaker@Netapp.com>
Cc: Chao Yu <chao@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Fam Zheng <fam.zheng@bytedance.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kari Argillander <kari.argillander@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We currently allocate scope for every memcg to be able to tracked on
every superblock instantiated in the system, regardless of whether that
superblock is even accessible to that memcg.
These huge memcg counts come from container hosts where memcgs are
confined to just a small subset of the total number of superblocks that
instantiated at any given point in time.
For these systems with huge container counts, list_lru does not need the
capability of tracking every memcg on every superblock. What it comes
down to is that adding the memcg to the list_lru at the first insert.
So introduce kmem_cache_alloc_lru to allocate objects and its list_lru.
In the later patch, we will convert all inode and dentry allocation from
kmem_cache_alloc to kmem_cache_alloc_lru.
Link: https://lkml.kernel.org/r/20220228122126.37293-3-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Cc: Alex Shi <alexs@kernel.org>
Cc: Anna Schumaker <Anna.Schumaker@Netapp.com>
Cc: Chao Yu <chao@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Fam Zheng <fam.zheng@bytedance.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kari Argillander <kari.argillander@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Optimize list lru memory consumption", v6.
In our server, we found a suspected memory leak problem. The kmalloc-32
consumes more than 6GB of memory. Other kmem_caches consume less than
2GB memory.
After our in-depth analysis, the memory consumption of kmalloc-32 slab
cache is the cause of list_lru_one allocation.
crash> p
memcg_nr_cache_ids memcg_nr_cache_ids = $2 = 24574
memcg_nr_cache_ids is very large and memory consumption of each list_lru
can be calculated with the following formula.
num_numa_node * memcg_nr_cache_ids * 32 (kmalloc-32)
There are 4 numa nodes in our system, so each list_lru consumes ~3MB.
crash> list super_blocks | wc -l
952
Every mount will register 2 list lrus, one is for inode, another is for
dentry. There are 952 super_blocks. So the total memory is 952 * 2 * 3
MB (~5.6GB). But now the number of memory cgroups is less than 500. So
I guess more than 12286 memory cgroups have been created on this machine
(I do not know why there are so many cgroups, it may be a user's bug or
the user really want to do that). Because memcg_nr_cache_ids has not
been reduced to a suitable value. It leads to waste a lot of memory.
If we want to reduce memcg_nr_cache_ids, we have to *reboot* the server.
This is not what we want.
In order to reduce memcg_nr_cache_ids, I had posted a patchset [1] to do
this. But this did not fundamentally solve the problem.
We currently allocate scope for every memcg to be able to tracked on
every superblock instantiated in the system, regardless of whether that
superblock is even accessible to that memcg.
These huge memcg counts come from container hosts where memcgs are
confined to just a small subset of the total number of superblocks that
instantiated at any given point in time.
For these systems with huge container counts, list_lru does not need the
capability of tracking every memcg on every superblock.
What it comes down to is that the list_lru is only needed for a given
memcg if that memcg is instatiating and freeing objects on a given
list_lru.
As Dave said, "Which makes me think we should be moving more towards 'add
the memcg to the list_lru at the first insert' model rather than
'instantiate all at memcg init time just in case'."
This patchset aims to optimize the list lru memory consumption from
different aspects.
I had done a easy test to show the optimization. I create 10k memory
cgroups and mount 10k filesystems in the systems. We use free command to
show how many memory does the systems comsumes after this operation (There
are 2 numa nodes in the system).
+-----------------------+------------------------+
| condition | memory consumption |
+-----------------------+------------------------+
| without this patchset | 24464 MB |
+-----------------------+------------------------+
| after patch 1 | 21957 MB | <--------+
+-----------------------+------------------------+ |
| after patch 10 | 6895 MB | |
+-----------------------+------------------------+ |
| after patch 12 | 4367 MB | |
+-----------------------+------------------------+ |
|
The more the number of nodes, the more obvious the effect---+
BTW, there was a recent discussion [2] on the same issue.
[1] https://lore.kernel.org/all/20210428094949.43579-1-songmuchun@bytedance.com/
[2] https://lore.kernel.org/all/20210405054848.GA1077931@in.ibm.com/
This series not only optimizes the memory usage of list_lru but also
simplifies the code.
This patch (of 16):
The current scheme of maintaining per-node per-memcg lru lists looks like:
struct list_lru {
struct list_lru_node *node; (for each node)
struct list_lru_memcg *memcg_lrus;
struct list_lru_one *lru[]; (for each memcg)
}
By effectively transposing the two-dimension array of list_lru_one's structures
(per-node per-memcg => per-memcg per-node) it's possible to save some memory
and simplify alloc/dealloc paths. The new scheme looks like:
struct list_lru {
struct list_lru_memcg *mlrus;
struct list_lru_per_memcg *mlru[]; (for each memcg)
struct list_lru_one node[0]; (for each node)
}
Memory savings are coming from not only 'struct rcu_head' but also some
pointer arrays used to store the pointer to 'struct list_lru_one'. The
array is per node and its size is 8 (a pointer) * num_memcgs. So the
total size of the arrays is 8 * num_nodes * memcg_nr_cache_ids. After
this patch, the size becomes 8 * memcg_nr_cache_ids.
Link: https://lkml.kernel.org/r/20220228122126.37293-1-songmuchun@bytedance.com
Link: https://lkml.kernel.org/r/20220228122126.37293-2-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Alex Shi <alexs@kernel.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Anna Schumaker <Anna.Schumaker@Netapp.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Chao Yu <chao@kernel.org>
Cc: Kari Argillander <kari.argillander@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Xiongchun Duan <duanxiongchun@bytedance.com>
Cc: Fam Zheng <fam.zheng@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The non-memcg-aware lru is always skiped when traversing the global lru
list, which is not efficient. We can only add the memcg-aware lru to
the global lru list instead to make traversing more efficient.
Link: https://lkml.kernel.org/r/20211025124353.55781-1-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since commit 2788cf0c40 ("memcg: reparent list_lrus and free kmemcg_id
on css offline"), ->nr_items can be negative during memory cgroup
reparenting. In this case, list_lru_count_one() will return an unusual
and huge value, which can surprise users. At least for now it hasn't
affected any users. But it is better to let list_lru_count_ont()
returns zero when ->nr_items is negative.
Link: https://lkml.kernel.org/r/20211025124910.56433-1-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since commit e5bc3af773 ("rcu: Consolidate PREEMPT and !PREEMPT
synchronize_rcu()"), the critical section of spin lock can serve as an
RCU read-side critical section which already allows readers that hold
nlru->lock to avoid taking rcu lock. So just remove holding lock.
Link: https://lkml.kernel.org/r/20211025124534.56345-1-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
As noted in the "Deprecated Interfaces, Language Features, Attributes,
and Conventions" documentation [1], size calculations (especially
multiplication) should not be performed in memory allocator (or similar)
function arguments due to the risk of them overflowing.
This could lead to values wrapping around and a smaller allocation being
made than the caller was expecting. Using those allocations could lead
to linear overflows of heap memory and other misbehaviors.
So, use the struct_size() helper to do the arithmetic instead of the
argument "size + count * size" in the kvmalloc() functions.
Also, take the opportunity to refactor the memcpy() call to use the
flex_array_size() helper.
This code was detected with the help of Coccinelle and audited and fixed
manually.
[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments
Link: https://lkml.kernel.org/r/20211017105929.9284-1-len.baker@gmx.com
Signed-off-by: Len Baker <len.baker@gmx.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The shrinker map management is not purely memcg specific, it is at the
intersection between memory cgroup and shrinkers. It's allocation and
assignment of a structure, and the only memcg bit is the map is being
stored in a memcg structure. So move the shrinker_maps handling code
into vmscan.c for tighter integration with shrinker code, and remove the
"memcg_" prefix. There is no functional change.
Link: https://lkml.kernel.org/r/20210311190845.9708-3-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The list_lru file used to have local kvfree_rcu() which was renamed by
commit e0feed08ab ("mm/list_lru.c: Rename kvfree_rcu() to local
variant") to introduce the globally visible kvfree_rcu().
Now we have global kvfree_rcu(), so remove the local kvfree_rcu_local()
and just use the global one.
Link: https://lkml.kernel.org/r/20210207152148.1285842-1-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Uladzislau Rezki <urezki@gmail.com>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When investigating a slab cache bloat problem, significant amount of
negative dentry cache was seen, but confusingly they neither got shrunk
by reclaimer (the host has very tight memory) nor be shrunk by dropping
cache. The vmcore shows there are over 14M negative dentry objects on
lru, but tracing result shows they were even not scanned at all.
Further investigation shows the memcg's vfs shrinker_map bit is not set.
So the reclaimer or dropping cache just skip calling vfs shrinker. So
we have to reboot the hosts to get the memory back.
I didn't manage to come up with a reproducer in test environment, and
the problem can't be reproduced after rebooting. But it seems there is
race between shrinker map bit clear and reparenting by code inspection.
The hypothesis is elaborated as below.
The memcg hierarchy on our production environment looks like:
root
/ \
system user
The main workloads are running under user slice's children, and it
creates and removes memcg frequently. So reparenting happens very often
under user slice, but no task is under user slice directly.
So with the frequent reparenting and tight memory pressure, the below
hypothetical race condition may happen:
CPU A CPU B
reparent
dst->nr_items == 0
shrinker:
total_objects == 0
add src->nr_items to dst
set_bit
return SHRINK_EMPTY
clear_bit
child memcg offline
replace child's kmemcg_id with
parent's (in memcg_offline_kmem())
list_lru_del() between shrinker runs
see parent's kmemcg_id
dec dst->nr_items
reparent again
dst->nr_items may go negative
due to concurrent list_lru_del()
The second run of shrinker:
read nr_items without any
synchronization, so it may
see intermediate negative
nr_items then total_objects
may return 0 coincidently
keep the bit cleared
dst->nr_items != 0
skip set_bit
add scr->nr_item to dst
After this point dst->nr_item may never go zero, so reparenting will not
set shrinker_map bit anymore. And since there is no task under user
slice directly, so no new object will be added to its lru to set the
shrinker map bit either. That bit is kept cleared forever.
How does list_lru_del() race with reparenting? It is because reparenting
replaces children's kmemcg_id to parent's without protecting from
nlru->lock, so list_lru_del() may see parent's kmemcg_id but actually
deleting items from child's lru, but dec'ing parent's nr_items, so the
parent's nr_items may go negative as commit 2788cf0c40 ("memcg:
reparent list_lrus and free kmemcg_id on css offline") says.
Since it is impossible that dst->nr_items goes negative and
src->nr_items goes zero at the same time, so it seems we could set the
shrinker map bit iff src->nr_items != 0. We could synchronize
list_lru_count_one() and reparenting with nlru->lock, but it seems
checking src->nr_items in reparenting is the simplest and avoids lock
contention.
Fixes: fae91d6d8b ("mm/list_lru.c: set bit in memcg shrinker bitmap on first list_lru item appearance")
Suggested-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: <stable@vger.kernel.org> [4.19]
Link: https://lkml.kernel.org/r/20201202171749.264354-1-shy828301@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
struct list_lru_one l.nr_items could be accessed concurrently as noticed
by KCSAN,
BUG: KCSAN: data-race in list_lru_count_one / list_lru_isolate_move
write to 0xffffa102789c4510 of 8 bytes by task 823 on cpu 39:
list_lru_isolate_move+0xf9/0x130
list_lru_isolate_move at mm/list_lru.c:180
inode_lru_isolate+0x12b/0x2a0
__list_lru_walk_one+0x122/0x3d0
list_lru_walk_one+0x75/0xa0
prune_icache_sb+0x8b/0xc0
super_cache_scan+0x1b8/0x250
do_shrink_slab+0x256/0x6d0
shrink_slab+0x41b/0x4a0
shrink_node+0x35c/0xd80
balance_pgdat+0x652/0xd90
kswapd+0x396/0x8d0
kthread+0x1e0/0x200
ret_from_fork+0x27/0x50
read to 0xffffa102789c4510 of 8 bytes by task 6345 on cpu 56:
list_lru_count_one+0x116/0x2f0
list_lru_count_one at mm/list_lru.c:193
super_cache_count+0xe8/0x170
do_shrink_slab+0x95/0x6d0
shrink_slab+0x41b/0x4a0
shrink_node+0x35c/0xd80
do_try_to_free_pages+0x1f7/0xa10
try_to_free_pages+0x26c/0x5e0
__alloc_pages_slowpath+0x458/0x1290
__alloc_pages_nodemask+0x3bb/0x450
alloc_pages_vma+0x8a/0x2c0
do_anonymous_page+0x170/0x700
__handle_mm_fault+0xc9f/0xd00
handle_mm_fault+0xfc/0x2f0
do_page_fault+0x263/0x6f9
page_fault+0x34/0x40
Reported by Kernel Concurrency Sanitizer on:
CPU: 56 PID: 6345 Comm: oom01 Tainted: G W L 5.5.0-next-20200205+ #4
Hardware name: HPE ProLiant DL385 Gen10/ProLiant DL385 Gen10, BIOS A40 07/10/2019
A shattered l.nr_items could affect the shrinker behaviour due to a data
race. Fix it by adding READ_ONCE() for the read. Since the writes are
aligned and up to word-size, assume those are safe from data races to
avoid readability issues of writing WRITE_ONCE(var, var + val).
Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Marco Elver <elver@google.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Link: http://lkml.kernel.org/r/1581114679-5488-1-git-send-email-cai@lca.pw
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Rename kvfree_rcu() function to the kvfree_rcu_local() one.
The purpose is to prevent a conflict of two same function
declarations. The kvfree_rcu() will be globally visible
what would lead to a build error. No functional change.
Cc: linux-mm@kvack.org
Cc: rcu@vger.kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
There is a typo in comment, fix it.
Signed-off-by: Ethon Paul <ethp@qq.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
Link: http://lkml.kernel.org/r/20200411071041.16161-1-ethp@qq.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Sometimes we need to get a memcg pointer from a charged kernel object.
The right way to get it depends on whether it's a proper slab object or
it's backed by raw pages (e.g. it's a vmalloc alloction). In the first
case the kmem_cache->memcg_params.memcg indirection should be used; in
other cases it's just page->mem_cgroup.
To simplify this task and hide the implementation details let's use the
mem_cgroup_from_obj() helper, which takes a pointer to any kernel object
and returns a valid memcg pointer or NULL.
Passing a kernel address rather than a pointer to a page will allow to use
this helper for per-object (rather than per-page) tracked objects in the
future.
The caller is still responsible to ensure that the returned memcg isn't
going away underneath: take the rcu read lock, cgroup mutex etc; depending
on the context.
mem_cgroup_from_kmem() defined in mm/list_lru.c is now obsolete and can be
removed.
Signed-off-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Link: http://lkml.kernel.org/r/20200117203609.3146239-1-guro@fb.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Every slab page charged to a non-root memory cgroup has a pointer to the
memory cgroup and holds a reference to it, which protects a non-empty
memory cgroup from being released. At the same time the page has a
pointer to the corresponding kmem_cache, and also hold a reference to the
kmem_cache. And kmem_cache by itself holds a reference to the cgroup.
So there is clearly some redundancy, which allows to stop setting the
page->mem_cgroup pointer and rely on getting memcg pointer indirectly via
kmem_cache. Further it will allow to change this pointer easier, without
a need to go over all charged pages.
So let's stop setting page->mem_cgroup pointer for slab pages, and stop
using the css refcounter directly for protecting the memory cgroup from
going away. Instead rely on kmem_cache as an intermediate object.
Make sure that vmstats and shrinker lists are working as previously, as
well as /proc/kpagecgroup interface.
Link: http://lkml.kernel.org/r/20190611231813.3148843-10-guro@fb.com
Signed-off-by: Roman Gushchin <guro@fb.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Waiman Long <longman@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Andrei Vagin <avagin@gmail.com>
Cc: Qian Cai <cai@lca.pw>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We have a single node system with node 0 disabled:
Scanning NUMA topology in Northbridge 24
Number of physical nodes 2
Skipping disabled node 0
Node 1 MemBase 0000000000000000 Limit 00000000fbff0000
NODE_DATA(1) allocated [mem 0xfbfda000-0xfbfeffff]
This causes crashes in memcg when system boots:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
#PF error: [normal kernel read fault]
...
RIP: 0010:list_lru_add+0x94/0x170
...
Call Trace:
d_lru_add+0x44/0x50
dput.part.34+0xfc/0x110
__fput+0x108/0x230
task_work_run+0x9f/0xc0
exit_to_usermode_loop+0xf5/0x100
It is reproducible as far as 4.12. I did not try older kernels. You have
to have a new enough systemd, e.g. 241 (the reason is unknown -- was not
investigated). Cannot be reproduced with systemd 234.
The system crashes because the size of lru array is never updated in
memcg_update_all_list_lrus and the reads are past the zero-sized array,
causing dereferences of random memory.
The root cause are list_lru_memcg_aware checks in the list_lru code. The
test in list_lru_memcg_aware is broken: it assumes node 0 is always
present, but it is not true on some systems as can be seen above.
So fix this by avoiding checks on node 0. Remember the memcg-awareness by
a bool flag in struct list_lru.
Link: http://lkml.kernel.org/r/20190522091940.3615-1-jslaby@suse.cz
Fixes: 60d3fd32a7 ("list_lru: introduce per-memcg lists")
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Suggested-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add SPDX license identifiers to all files which:
- Have no license information of any form
- Have EXPORT_.*_SYMBOL_GPL inside which was used in the
initial scan/conversion to ignore the file
These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:
GPL-2.0-only
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Provide list_lru_shrink_walk_irq() and let it behave like
list_lru_walk_one() except that it locks the spinlock with
spin_lock_irq(). This is used by scan_shadow_nodes() because its lock
nests within the i_pages lock which is acquired with IRQ. This change
allows to use proper locking promitives instead hand crafted
lock_irq_disable() plus spin_lock().
There is no EXPORT_SYMBOL provided because the current user is in-kernel
only.
Add list_lru_shrink_walk_irq() which acquires the spinlock with the
proper locking primitives.
Link: http://lkml.kernel.org/r/20180716111921.5365-5-bigeasy@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__list_lru_walk_one() is invoked with struct list_lru *lru, int nid as
the first two argument. Those two are only used to retrieve struct
list_lru_node. Since this is already done by the caller of the function
for the locking, we can pass struct list_lru_node* directly and avoid
the dance around it.
Link: http://lkml.kernel.org/r/20180716111921.5365-4-bigeasy@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Move the locking inside __list_lru_walk_one() to its caller. This is a
preparation step in order to introduce list_lru_walk_one_irq() which
does spin_lock_irq() instead of spin_lock() for the locking.
Link: http://lkml.kernel.org/r/20180716111921.5365-3-bigeasy@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "mm/list_lru: Add list_lru_shrink_walk_irq() and a user".
This series removes the local_irq_disable() around
list_lru_shrink_walk() (as used by mm/workingset) by adding
list_lru_shrink_walk_irq().
Vladimir Davydov preferred this over `irq' argument which I added to
struct list_lru.
The initial post (of this series) received a Reviewed-by tag by Vladimir
Davydov which I added to each patch of the series. The series applies
on top of akpm's tree which has Kirill's shrink_slab series and does not
clash with it (akpm asked me to wait a week or so and repost it then).
I tested the code paths by triggering the OOM-killer via memory over
commit and lockdep did not complain (nor did I see any warnings).
This patch (of 4):
list_lru_walk_node() invokes __list_lru_walk_one() with -1 as the
memcg_idx parameter. The same can be achieved by list_lru_walk_one() and
passing NULL as memcg argument which then gets converted into -1. This is
a preparation step when the spin_lock() function is lifted to the caller
of __list_lru_walk_one(). Invoke list_lru_walk_one() instead
__list_lru_walk_one() when possible.
Link: http://lkml.kernel.org/r/20180716111921.5365-2-bigeasy@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Introduce set_shrinker_bit() function to set shrinker-related bit in
memcg shrinker bitmap, and set the bit after the first item is added and
in case of reparenting destroyed memcg's items.
This will allow next patch to make shrinkers be called only, in case of
they have charged objects at the moment, and to improve shrink_slab()
performance.
[ktkhai@virtuozzo.com: v9]
Link: http://lkml.kernel.org/r/153112557572.4097.17315791419810749985.stgit@localhost.localdomain
Link: http://lkml.kernel.org/r/153063065671.1818.15914674956134687268.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Tested-by: Shakeel Butt <shakeelb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Li RongQing <lirongqing@baidu.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Sahitya Tummala <stummala@codeaurora.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is just refactoring to allow next patches to have lru pointer in
memcg_drain_list_lru_node().
Link: http://lkml.kernel.org/r/153063063164.1818.55009531386089350.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Tested-by: Shakeel Butt <shakeelb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Li RongQing <lirongqing@baidu.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Sahitya Tummala <stummala@codeaurora.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is just refactoring to allow the next patches to have dst_memcg
pointer in memcg_drain_list_lru_node().
Link: http://lkml.kernel.org/r/153063062118.1818.2761273817739499749.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Tested-by: Shakeel Butt <shakeelb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Li RongQing <lirongqing@baidu.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Sahitya Tummala <stummala@codeaurora.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is just refactoring to allow the next patches to have memcg pointer
in list_lru_from_kmem().
Link: http://lkml.kernel.org/r/153063060664.1818.9541345386733498582.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Tested-by: Shakeel Butt <shakeelb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Li RongQing <lirongqing@baidu.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Sahitya Tummala <stummala@codeaurora.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add list_lru::shrinker_id field and populate it by registered shrinker
id.
This will be used to set correct bit in memcg shrinkers map by lru code
in next patches, after there appeared the first related to memcg element
in list_lru.
Link: http://lkml.kernel.org/r/153063059758.1818.14866596416857717800.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Tested-by: Shakeel Butt <shakeelb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Li RongQing <lirongqing@baidu.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Sahitya Tummala <stummala@codeaurora.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Introduce new config option, which is used to replace repeating
CONFIG_MEMCG && !CONFIG_SLOB pattern. Next patches add a little more
memcg+kmem related code, so let's keep the defines more clearly.
Link: http://lkml.kernel.org/r/153063053670.1818.15013136946600481138.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Tested-by: Shakeel Butt <shakeelb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Li RongQing <lirongqing@baidu.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Sahitya Tummala <stummala@codeaurora.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Improve shrink_slab() scalability (old complexity was O(n^2), new is O(n))", v8.
This patcheset solves the problem with slow shrink_slab() occuring on
the machines having many shrinkers and memory cgroups (i.e., with many
containers). The problem is complexity of shrink_slab() is O(n^2) and
it grows too fast with the growth of containers numbers.
Let us have 200 containers, and every container has 10 mounts and 10
cgroups. All container tasks are isolated, and they don't touch foreign
containers mounts.
In case of global reclaim, a task has to iterate all over the memcgs and
to call all the memcg-aware shrinkers for all of them. This means, the
task has to visit 200 * 10 = 2000 shrinkers for every memcg, and since
there are 2000 memcgs, the total calls of do_shrink_slab() are 2000 *
2000 = 4000000.
4 million calls are not a number operations, which can takes 1 cpu
cycle. E.g., super_cache_count() accesses at least two lists, and makes
arifmetical calculations. Even, if there are no charged objects, we do
these calculations, and replaces cpu caches by read memory. I observed
nodes spending almost 100% time in kernel, in case of intensive writing
and global reclaim. The writer consumes pages fast, but it's need to
shrink_slab() before the reclaimer reached shrink pages function (and
frees SWAP_CLUSTER_MAX pages). Even if there is no writing, the
iterations just waste the time, and slows reclaim down.
Let's see the small test below:
$echo 1 > /sys/fs/cgroup/memory/memory.use_hierarchy
$mkdir /sys/fs/cgroup/memory/ct
$echo 4000M > /sys/fs/cgroup/memory/ct/memory.kmem.limit_in_bytes
$for i in `seq 0 4000`;
do mkdir /sys/fs/cgroup/memory/ct/$i;
echo $$ > /sys/fs/cgroup/memory/ct/$i/cgroup.procs;
mkdir -p s/$i; mount -t tmpfs $i s/$i; touch s/$i/file;
done
Then, let's see drop caches time (5 sequential calls):
$time echo 3 > /proc/sys/vm/drop_caches
0.00user 13.78system 0:13.78elapsed 99%CPU
0.00user 5.59system 0:05.60elapsed 99%CPU
0.00user 5.48system 0:05.48elapsed 99%CPU
0.00user 8.35system 0:08.35elapsed 99%CPU
0.00user 8.34system 0:08.35elapsed 99%CPU
The last four calls don't actually shrink anything. So, the iterations
over slab shrinkers take 5.48 seconds. Not so good for scalability.
The patchset solves the problem by making shrink_slab() of O(n)
complexity. There are following functional actions:
1) Assign id to every registered memcg-aware shrinker.
2) Maintain per-memcgroup bitmap of memcg-aware shrinkers, and set a
shrinker-related bit after the first element is added to lru list
(also, when removed child memcg elements are reparanted).
3) Split memcg-aware shrinkers and !memcg-aware shrinkers, and call a
shrinker if its bit is set in memcg's shrinker bitmap. (Also, there is
a functionality to clear the bit, after last element is shrinked).
This gives significant performance increase. The result after patchset
is applied:
$time echo 3 > /proc/sys/vm/drop_caches
0.00user 1.10system 0:01.10elapsed 99%CPU
0.00user 0.00system 0:00.01elapsed 64%CPU
0.00user 0.01system 0:00.01elapsed 82%CPU
0.00user 0.00system 0:00.01elapsed 64%CPU
0.00user 0.01system 0:00.01elapsed 82%CPU
The results show the performance increases at least in 548 times.
So, the patchset makes shrink_slab() of less complexity and improves the
performance in such types of load I pointed. This will give a profit in
case of !global reclaim case, since there also will be less
do_shrink_slab() calls.
This patch (of 17):
These two pairs of blocks of code are under the same #ifdef #else
#endif.
Link: http://lkml.kernel.org/r/153063052519.1818.9393587113056959488.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Tested-by: Shakeel Butt <shakeelb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Sahitya Tummala <stummala@codeaurora.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Roman Gushchin <guro@fb.com>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Waiman Long <longman@redhat.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Li RongQing <lirongqing@baidu.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__list_lru_count_one() has a single callsite.
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
During the reclaiming slab of a memcg, shrink_slab iterates over all
registered shrinkers in the system, and tries to count and consume
objects related to the cgroup. In case of memory pressure, this behaves
bad: I observe high system time and time spent in list_lru_count_one()
for many processes on RHEL7 kernel.
This patch makes list_lru_node::memcg_lrus rcu protected, that allows to
skip taking spinlock in list_lru_count_one().
Shakeel Butt with the patch observes significant perf graph change. He
says:
========================================================================
Setup: running a fork-bomb in a memcg of 200MiB on a 8GiB and 4 vcpu
VM and recording the trace with 'perf record -g -a'.
The trace without the patch:
+ 34.19% fb.sh [kernel.kallsyms] [k] queued_spin_lock_slowpath
+ 30.77% fb.sh [kernel.kallsyms] [k] _raw_spin_lock
+ 3.53% fb.sh [kernel.kallsyms] [k] list_lru_count_one
+ 2.26% fb.sh [kernel.kallsyms] [k] super_cache_count
+ 1.68% fb.sh [kernel.kallsyms] [k] shrink_slab
+ 0.59% fb.sh [kernel.kallsyms] [k] down_read_trylock
+ 0.48% fb.sh [kernel.kallsyms] [k] _raw_spin_unlock_irqrestore
+ 0.38% fb.sh [kernel.kallsyms] [k] shrink_node_memcg
+ 0.32% fb.sh [kernel.kallsyms] [k] queue_work_on
+ 0.26% fb.sh [kernel.kallsyms] [k] count_shadow_nodes
With the patch:
+ 0.16% swapper [kernel.kallsyms] [k] default_idle
+ 0.13% oom_reaper [kernel.kallsyms] [k] mutex_spin_on_owner
+ 0.05% perf [kernel.kallsyms] [k] copy_user_generic_string
+ 0.05% init.real [kernel.kallsyms] [k] wait_consider_task
+ 0.05% kworker/0:0 [kernel.kallsyms] [k] finish_task_switch
+ 0.04% kworker/2:1 [kernel.kallsyms] [k] finish_task_switch
+ 0.04% kworker/3:1 [kernel.kallsyms] [k] finish_task_switch
+ 0.04% kworker/1:0 [kernel.kallsyms] [k] finish_task_switch
+ 0.03% binary [kernel.kallsyms] [k] copy_page
========================================================================
Thanks Shakeel for the testing.
[ktkhai@virtuozzo.com: v2]
Link: http://lkml.kernel.org/r/151203869520.3915.2587549826865799173.stgit@localhost.localdomain
Link: http://lkml.kernel.org/r/150583358557.26700.8490036563698102569.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Tested-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In preparation for enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.
Link: http://lkml.kernel.org/r/20171020190754.GA24332@embeddedor.com
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
For quick per-memcg indexing, slab caches and list_lru structures
maintain linear arrays of descriptors. As the number of concurrent
memory cgroups in the system goes up, this requires large contiguous
allocations (8k cgroups = order-5, 16k cgroups = order-6 etc.) for every
existing slab cache and list_lru, which can easily fail on loaded
systems. E.g.:
mkdir: page allocation failure: order:5, mode:0x14040c0(GFP_KERNEL|__GFP_COMP), nodemask=(null)
CPU: 1 PID: 6399 Comm: mkdir Not tainted 4.13.0-mm1-00065-g720bbe532b7c-dirty #481
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-20170228_101828-anatol 04/01/2014
Call Trace:
? __alloc_pages_direct_compact+0x4c/0x110
__alloc_pages_nodemask+0xf50/0x1430
alloc_pages_current+0x60/0xc0
kmalloc_order_trace+0x29/0x1b0
__kmalloc+0x1f4/0x320
memcg_update_all_list_lrus+0xca/0x2e0
mem_cgroup_css_alloc+0x612/0x670
cgroup_apply_control_enable+0x19e/0x360
cgroup_mkdir+0x322/0x490
kernfs_iop_mkdir+0x55/0x80
vfs_mkdir+0xd0/0x120
SyS_mkdirat+0x6c/0xe0
SyS_mkdir+0x14/0x20
entry_SYSCALL_64_fastpath+0x18/0xad
Mem-Info:
active_anon:2965 inactive_anon:19 isolated_anon:0
active_file:100270 inactive_file:98846 isolated_file:0
unevictable:0 dirty:0 writeback:0 unstable:0
slab_reclaimable:7328 slab_unreclaimable:16402
mapped:771 shmem:52 pagetables:278 bounce:0
free:13718 free_pcp:0 free_cma:0
This output is from an artificial reproducer, but we have repeatedly
observed order-7 failures in production in the Facebook fleet. These
systems become useless as they cannot run more jobs, even though there
is plenty of memory to allocate 128 individual pages.
Use kvmalloc and kvzalloc to fall back to vmalloc space if these arrays
prove too large for allocating them physically contiguous.
Link: http://lkml.kernel.org/r/20170918184919.20644-1-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
list_lru_count_node() iterates over all memcgs to get the total number of
entries on the node but it can race with memcg_drain_all_list_lrus(),
which migrates the entries from a dead cgroup to another. This can return
incorrect number of entries from list_lru_count_node().
Fix this by keeping track of entries per node and simply return it in
list_lru_count_node().
Link: http://lkml.kernel.org/r/1498707555-30525-1-git-send-email-stummala@codeaurora.org
Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Alexander Polakov <apolyakov@beget.ru>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
As described in https://bugzilla.kernel.org/show_bug.cgi?id=177821:
After some analysis it seems to be that the problem is in alloc_super().
In case list_lru_init_memcg() fails it goes into destroy_super(), which
calls list_lru_destroy().
And in list_lru_init() we see that in case memcg_init_list_lru() fails,
lru->node is freed, but not set NULL, which then leads list_lru_destroy()
to believe it is initialized and call memcg_destroy_list_lru().
memcg_destroy_list_lru() in turn can access lru->node[i].memcg_lrus,
which is NULL.
[akpm@linux-foundation.org: add comment]
Signed-off-by: Alexander Polakov <apolyakov@beget.ru>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The cgroup2 memory controller will account important in-kernel memory
consumers per default. Move all necessary components to CONFIG_MEMCG.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Before the previous patch ("memcg: unify slab and other kmem pages
charging"), __mem_cgroup_from_kmem had to handle two types of kmem - slab
pages and pages allocated with alloc_kmem_pages - memcg in the page
struct. Now we can unify it. Since after it, this function becomes tiny
we can fold it into mem_cgroup_from_kmem.
[hughd@google.com: move mem_cgroup_from_kmem into list_lru.c]
Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The functions used in the patch are in slowpath, which gets called
whenever alloc_super is called during mounts.
Though this should not make difference for the architectures with
sequential numa node ids, for the powerpc which can potentially have
sparse node ids (for e.g., 4 node system having numa ids, 0,1,16,17 is
common), this patch saves some unnecessary allocations for non existing
numa nodes.
Even without that saving, perhaps patch makes code more readable.
[vdavydov@parallels.com: take memcg_aware check outside for_each loop]
Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Anton Blanchard <anton@samba.org>
Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>
Cc: Greg Kurz <gkurz@linux.vnet.ibm.com>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If the list_head is empty then we'll have called list_lru_from_kmem for
nothing. Move that call inside of the list_empty if block.
Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
Reviewed-by: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now, the only reason to keep kmemcg_id till css free is list_lru, which
uses it to distribute elements between per-memcg lists. However, it can
be easily sorted out - we only need to change kmemcg_id of an offline
cgroup to its parent's id, making further list_lru_add()'s add elements to
the parent's list, and then move all elements from the offline cgroup's
list to the one of its parent. It will work, because a racing
list_lru_del() does not need to know the list it is deleting the element
from. It can decrement the wrong nr_items counter though, but the ongoing
reparenting will fix it. After list_lru reparenting is done we are free
to release kmemcg_id saving a valuable slot in a per-memcg array for new
cgroups.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Dave Chinner <david@fromorbit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, the isolate callback passed to the list_lru_walk family of
functions is supposed to just delete an item from the list upon returning
LRU_REMOVED or LRU_REMOVED_RETRY, while nr_items counter is fixed by
__list_lru_walk_one after the callback returns. Since the callback is
allowed to drop the lock after removing an item (it has to return
LRU_REMOVED_RETRY then), the nr_items can be less than the actual number
of elements on the list even if we check them under the lock. This makes
it difficult to move items from one list_lru_one to another, which is
required for per-memcg list_lru reparenting - we can't just splice the
lists, we have to move entries one by one.
This patch therefore introduces helpers that must be used by callback
functions to isolate items instead of raw list_del/list_move. These are
list_lru_isolate and list_lru_isolate_move. They not only remove the
entry from the list, but also fix the nr_items counter, making sure
nr_items always reflects the actual number of elements on the list if
checked under the appropriate lock.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Dave Chinner <david@fromorbit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
