- 22 Mar, 2022 40 commits
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Muchun Song authored
folio_copy() will copy the data from one page to the target page, then the target page will be mapped to the user space address, which might have an alias issue with the kernel address used to copy the data from the page to. There are 2 ways to fix this issue. 1) insert flush_dcache_page() after folio_copy(). 2) replace folio_copy() with copy_user_huge_page() which already considers the cache maintenance. We chose 2) way to fix the issue since architectures can optimize this situation. It is also make backports easier. Link: https://lkml.kernel.org/r/20220210123058.79206-5-songmuchun@bytedance.com Fixes: 8cc5fcbb ("mm, hugetlb: fix racy resv_huge_pages underflow on UFFDIO_COPY") Signed-off-by:Muchun Song <songmuchun@bytedance.com> Reviewed-by:
Mike Kravetz <mike.kravetz@oracle.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: David Rientjes <rientjes@google.com> Cc: Fam Zheng <fam.zheng@bytedance.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Lars Persson <lars.persson@axis.com> Cc: Peter Xu <peterx@redhat.com> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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Muchun Song authored
userfaultfd calls copy_huge_page_from_user() which does not do any cache flushing for the target page. Then the target page will be mapped to the user space with a different address (user address), which might have an alias issue with the kernel address used to copy the data from the user to. Fix this issue by flushing dcache in copy_huge_page_from_user(). Link: https://lkml.kernel.org/r/20220210123058.79206-4-songmuchun@bytedance.com Fixes: fa4d75c1 ("userfaultfd: hugetlbfs: add copy_huge_page_from_user for hugetlb userfaultfd support") Signed-off-by:
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Muchun Song authored
The D-cache maintenance inside move_to_new_page() only consider one page, there is still D-cache maintenance issue for tail pages of compound page (e.g. THP or HugeTLB). THP migration is only enabled on x86_64, ARM64 and powerpc, while powerpc and arm64 need to maintain the consistency between I-Cache and D-Cache, which depends on flush_dcache_page() to maintain the consistency between I-Cache and D-Cache. But there is no issues on arm64 and powerpc since they already considers the compound page cache flushing in their icache flush function. HugeTLB migration is enabled on arm, arm64, mips, parisc, powerpc, riscv, s390 and sh, while arm has handled the compound page cache flush in flush_dcache_page(), but most others do not. In theory, the issue exists on many architectures. Fix this by not using flush_dcache_folio() since it is not backportable. Link: https://lkml.kernel.org/r/20220210123058.79206-3-songmuchun@bytedance.com Fixes: 290408d4 ("hugetlb: hugepage migration core") Signed-off-by:
Zi Yan <ziy@nvidia.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: David Rientjes <rientjes@google.com> Cc: Fam Zheng <fam.zheng@bytedance.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Lars Persson <lars.persson@axis.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Peter Xu <peterx@redhat.com> Cc: Xiongchun Duan <duanxiongchun@bytedance.com> Signed-off-by:
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Muchun Song authored
Patch series "Fix some cache flush bugs", v5. This series focuses on fixing cache maintenance. This patch (of 7): The flush_cache_range() is supposed to be justified only if the page is already placed in process page table, and that is done right after flush_cache_range(). So using this interface is wrong. And there is no need to invalite cache since it was non-present before in remove_migration_pmd(). So just to remove it. Link: https://lkml.kernel.org/r/20220210123058.79206-1-songmuchun@bytedance.com Link: https://lkml.kernel.org/r/20220210123058.79206-2-songmuchun@bytedance.comSigned-off-by:
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Stafford Horne authored
Originally the mmu_gathers were removed in commit 1c395176 ("mm: now that all old mmu_gather code is gone, remove the storage"). However, the openrisc and hexagon architecture were merged around the same time and mmu_gathers was not removed. This patch removes them from openrisc, hexagon and nds32: Noticed while cleaning this warning: arch/openrisc/mm/init.c:41:1: warning: symbol 'mmu_gathers' was not declared. Should it be static? Link: https://lkml.kernel.org/r/20220205141956.3315419-1-shorne@gmail.comSigned-off-by:
Stafford Horne <shorne@gmail.com> Acked-by:
Mike Rapoport <rppt@linux.ibm.com> Cc: Brian Cain <bcain@codeaurora.org> Cc: Nick Hu <nickhu@andestech.com> Cc: Greentime Hu <green.hu@gmail.com> Cc: Vincent Chen <deanbo422@gmail.com> Cc: Jonas Bonn <jonas@southpole.se> Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi> Cc: Russell King <rmk+kernel@armlinux.org.uk> Cc: David Hildenbrand <david@redhat.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Signed-off-by:
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Anshuman Khandual authored
Each call into pte_mkhuge() is invariably followed by arch_make_huge_pte(). Instead arch_make_huge_pte() can accommodate pte_mkhuge() at the beginning. This updates generic fallback stub for arch_make_huge_pte() and available platforms definitions. This makes huge pte creation much cleaner and easier to follow. Link: https://lkml.kernel.org/r/1643860669-26307-1-git-send-email-anshuman.khandual@arm.comSigned-off-by:
Anshuman Khandual <anshuman.khandual@arm.com> Reviewed-by:
Christophe Leroy <christophe.leroy@csgroup.eu> Acked-by:
Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Paul Mackerras <paulus@samba.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by:
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Guillaume Tucker authored
The $(CC) variable used in Makefiles could contain several arguments such as "ccache gcc". These need to be passed as a single string to check_cc.sh, otherwise only the first argument will be used as the compiler command. Without quotes, the $(CC) variable is passed as distinct arguments which causes the script to fail to build trivial programs. Fix this by adding quotes around $(CC) when calling check_cc.sh to pass the whole string as a single argument to the script even if it has several words such as "ccache gcc". Link: https://lkml.kernel.org/r/d0d460d7be0107a69e3c52477761a6fe694c1840.1646991629.git.guillaume.tucker@collabora.com Fixes: e9886ace ("selftests, x86: Rework x86 target architecture detection") Signed-off-by:
Guillaume Tucker <guillaume.tucker@collabora.com> Tested-by:
"kernelci.org bot" <bot@kernelci.org> Reviewed-by:
Guenter Roeck <groeck@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Borislav Petkov <bp@suse.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by:
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Vasily Averin authored
At each login the user forces the kernel to create a new terminal and allocate up to ~1Kb memory for the tty-related structures. By default it's allowed to create up to 4096 ptys with 1024 reserve for initial mount namespace only and the settings are controlled by host admin. Though this default is not enough for hosters with thousands of containers per node. Host admin can be forced to increase it up to NR_UNIX98_PTY_MAX = 1<<20. By default container is restricted by pty mount_opt.max = 1024, but admin inside container can change it via remount. As a result, one container can consume almost all allowed ptys and allocate up to 1Gb of unaccounted memory. It is not enough per-se to trigger OOM on host, however anyway, it allows to significantly exceed the assigned memcg limit and leads to troubles on the over-committed node. It makes sense to account for them to restrict the host's memory consumption from inside the memcg-limited container. Link: https://lkml.kernel.org/r/5d4bca06-7d4f-a905-e518-12981ebca1b3@virtuozzo.comSigned-off-by:
Vasily Averin <vvs@virtuozzo.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jiri Slaby <jirislaby@kernel.org> Signed-off-by:
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Muchun Song authored
The memcg_cache_id() introduced by commit 2633d7a0 ("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 9855609b ("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.comSigned-off-by:
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Muchun Song authored
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.comSigned-off-by:
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Muchun Song authored
The idr_alloc() does not include @max ID. So in the current implementation, the maximum memcg ID is 65534 instead of 65535. It seems a bug. So fix this. Link: https://lkml.kernel.org/r/20220228122126.37293-15-songmuchun@bytedance.comSigned-off-by:
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Muchun Song authored
There are two idrs being used by memory cgroup, one is for kmem ID, another is for memory cgroup ID. The maximum ID of both is 64Ki. Both of them can limit the total number of memory cgroups. Actually, we can reuse memory cgroup ID for kmem ID to simplify the code. Link: https://lkml.kernel.org/r/20220228122126.37293-14-songmuchun@bytedance.comSigned-off-by:
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Muchun Song authored
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.comSigned-off-by:
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Muchun Song authored
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.comSigned-off-by:
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Muchun Song authored
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.comSigned-off-by:
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Muchun Song authored
It will simplify the code if moving memcg_online_kmem() to mem_cgroup_css_online() and do not need to set ->kmemcg_id to -1 to indicate the memcg is offline. In the next patch, ->kmemcg_id will be used to sync list lru reparenting which requires not to change ->kmemcg_id. Link: https://lkml.kernel.org/r/20220228122126.37293-10-songmuchun@bytedance.comSigned-off-by:
Roman Gushchin <roman.gushchin@linux.dev> 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: 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:
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Muchun Song authored
The workingset will add the xa_node to the shadow_nodes list. So the allocation of xa_node should be done by kmem_cache_alloc_lru(). Using xas_set_lru() to pass the list_lru which we want to insert xa_node into to set up the xa_node reclaim context correctly. Link: https://lkml.kernel.org/r/20220228122126.37293-9-songmuchun@bytedance.comSigned-off-by:
Johannes Weiner <hannes@cmpxchg.org> Acked-by:
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Muchun Song authored
Like inode cache, the dentry will also be added to its memcg list_lru. So replace kmem_cache_alloc() with kmem_cache_alloc_lru() to allocate dentry. Link: https://lkml.kernel.org/r/20220228122126.37293-8-songmuchun@bytedance.comSigned-off-by:
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Muchun Song authored
The inode allocation is supposed to use alloc_inode_sb(), so convert kmem_cache_alloc() to alloc_inode_sb(). Link: https://lkml.kernel.org/r/20220228122126.37293-6-songmuchun@bytedance.comSigned-off-by:
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Muchun Song authored
The inode allocation is supposed to use alloc_inode_sb(), so convert kmem_cache_alloc() of all filesystems to alloc_inode_sb(). Link: https://lkml.kernel.org/r/20220228122126.37293-5-songmuchun@bytedance.comSigned-off-by:
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Muchun Song authored
The allocated inode cache is supposed to be added to its memcg list_lru which should be allocated as well in advance. That can be done by kmem_cache_alloc_lru() which allocates object and list_lru. The file systems is main user of it. So introduce alloc_inode_sb() to allocate file system specific inodes and set up the inode reclaim context properly. The file system is supposed to use alloc_inode_sb() to allocate inodes. In later patches, we will convert all users to the new API. Link: https://lkml.kernel.org/r/20220228122126.37293-4-songmuchun@bytedance.comSigned-off-by:
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Muchun Song authored
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.comSigned-off-by:
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Muchun Song authored
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.comSigned-off-by: -
Sebastian Andrzej Siewior authored
Before the for-each-CPU loop, preemption is disabled so that so that drain_local_stock() can be invoked directly instead of scheduling a worker. Ensuring that drain_local_stock() completed on the local CPU is not correctness problem. It _could_ be that the charging path will be forced to reclaim memory because cached charges are still waiting for their draining. Disabling preemption before invoking drain_local_stock() is problematic on PREEMPT_RT due to the sleeping locks involved. To ensure that no CPU migrations happens across for_each_online_cpu() it is enouhg to use migrate_disable() which disables migration and keeps context preemptible to a sleeping lock can be acquired. A race with CPU hotplug is not a problem because pcp data is not going away. In the worst case we just schedule draining of an empty stock. Use migrate_disable() instead of get_cpu() around the for_each_online_cpu() loop. Link: https://lkml.kernel.org/r/20220226204144.1008339-7-bigeasy@linutronix.deSigned-off-by:
Sebastian Andrzej Siewior <bigeasy@linutronix.de> Acked-by:
Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: kernel test robot <oliver.sang@intel.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Michal Koutný <mkoutny@suse.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Shakeel Butt <shakeelb@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Waiman Long <longman@redhat.com> Signed-off-by:
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Sebastian Andrzej Siewior authored
The members of the per-CPU structure memcg_stock_pcp are protected by disabling interrupts. This is not working on PREEMPT_RT because it creates atomic context in which actions are performed which require preemptible context. One example is obj_cgroup_release(). The IRQ-disable sections can be replaced with local_lock_t which preserves the explicit disabling of interrupts while keeps the code preemptible on PREEMPT_RT. drain_obj_stock() drops a reference on obj_cgroup which leads to an invocat= ion of obj_cgroup_release() if it is the last object. This in turn leads to recursive locking of the local_lock_t. To avoid this, obj_cgroup_release() = is invoked outside of the locked section. obj_cgroup_uncharge_pages() can be invoked with the local_lock_t acquired a= nd without it. This will lead later to a recursion in refill_stock(). To avoid the locking recursion provide obj_cgroup_uncharge_pages_locked() which uses the locked version of refill_stock(). - Replace disabling interrupts for memcg_stock with a local_lock_t. - Let drain_obj_stock() return the old struct obj_cgroup which is passed to obj_cgroup_put() outside of the locked section. - Provide obj_cgroup_uncharge_pages_locked() which uses the locked version of refill_stock() to avoid recursive locking in drain_obj_stock(). Link: https://lkml.kernel.org/r/20220209014709.GA26885@xsang-OptiPlex-9020 Link: https://lkml.kernel.org/r/20220226204144.1008339-6-bigeasy@linutronix.deSigned-off-by:
kernel test robot <oliver.sang@intel.com> Acked-by:
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Johannes Weiner authored
Provide the inner part of refill_stock() as __refill_stock() without disabling interrupts. This eases the integration of local_lock_t where recursive locking must be avoided. Open code obj_cgroup_uncharge_pages() in drain_obj_stock() and use __refill_stock(). The caller of drain_obj_stock() already disables interrupts. [bigeasy@linutronix.de: patch body around Johannes' diff] Link: https://lkml.kernel.org/r/20220226204144.1008339-5-bigeasy@linutronix.deSigned-off-by:
Shakeel Butt <shakeelb@google.com> Reviewed-by:
Roman Gushchin <guro@fb.com> Acked-by:
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Sebastian Andrzej Siewior authored
The per-CPU counter are modified with the non-atomic modifier. The consistency is ensured by disabling interrupts for the update. On non PREEMPT_RT configuration this works because acquiring a spinlock_t typed lock with the _irq() suffix disables interrupts. On PREEMPT_RT configurations the RMW operation can be interrupted. Another problem is that mem_cgroup_swapout() expects to be invoked with disabled interrupts because the caller has to acquire a spinlock_t which is acquired with disabled interrupts. Since spinlock_t never disables interrupts on PREEMPT_RT the interrupts are never disabled at this point. The code is never called from in_irq() context on PREEMPT_RT therefore disabling preemption during the update is sufficient on PREEMPT_RT. The sections which explicitly disable interrupts can remain on PREEMPT_RT because the sections remain short and they don't involve sleeping locks (memcg_check_events() is doing nothing on PREEMPT_RT). Disable preemption during update of the per-CPU variables which do not explicitly disable interrupts. Link: https://lkml.kernel.org/r/20220226204144.1008339-4-bigeasy@linutronix.deSigned-off-by:
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Sebastian Andrzej Siewior authored
During the integration of PREEMPT_RT support, the code flow around memcg_check_events() resulted in `twisted code'. Moving the code around and avoiding then would then lead to an additional local-irq-save section within memcg_check_events(). While looking better, it adds a local-irq-save section to code flow which is usually within an local-irq-off block on non-PREEMPT_RT configurations. The threshold event handler is a deprecated memcg v1 feature. Instead of trying to get it to work under PREEMPT_RT just disable it. There should be no users on PREEMPT_RT. From that perspective it makes even less sense to get it to work under PREEMPT_RT while having zero users. Make memory.soft_limit_in_bytes and cgroup.event_control return -EOPNOTSUPP on PREEMPT_RT. Make an empty memcg_check_events() and memcg_write_event_control() which return only -EOPNOTSUPP on PREEMPT_RT. Document that the two knobs are disabled on PREEMPT_RT. Link: https://lkml.kernel.org/r/20220226204144.1008339-3-bigeasy@linutronix.deSuggested-by:
Michal Hocko <mhocko@kernel.org> Suggested-by:
Michal Koutný <mkoutny@suse.com> Signed-off-by:
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Michal Hocko authored
Patch series "mm/memcg: Address PREEMPT_RT problems instead of disabling it", v5. This series aims to address the memcg related problem on PREEMPT_RT. I tested them on CONFIG_PREEMPT and CONFIG_PREEMPT_RT with the tools/testing/selftests/cgroup/* tests and I haven't observed any regressions (other than the lockdep report that is already there). This patch (of 6): The optimisation is based on a micro benchmark where local_irq_save() is more expensive than a preempt_disable(). There is no evidence that it is visible in a real-world workload and there are CPUs where the opposite is true (local_irq_save() is cheaper than preempt_disable()). Based on micro benchmarks, the optimisation makes sense on PREEMPT_NONE where preempt_disable() is optimized away. There is no improvement with PREEMPT_DYNAMIC since the preemption counter is always available. The optimization makes also the PREEMPT_RT integration more complicated since most of the assumption are not true on PREEMPT_RT. Revert the optimisation since it complicates the PREEMPT_RT integration and the improvement is hardly visible. [bigeasy@linutronix.de: patch body around Michal's diff] Link: https://lkml.kernel.org/r/20220226204144.1008339-1-bigeasy@linutronix.de Link: https://lore.kernel.org/all/YgOGkXXCrD%2F1k+p4@dhcp22.suse.cz Link: https://lkml.kernel.org/r/YdX+INO9gQje6d0S@linutronix.de Link: https://lkml.kernel.org/r/20220226204144.1008339-2-bigeasy@linutronix.deSigned-off-by:
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Randy Dunlap authored
__setup() handlers should return 1 if the command line option is handled and 0 if not (or maybe never return 0; it just pollutes init's environment). The only reason that this particular __setup handler does not pollute init's environment is that the setup string contains a '.', as in "cgroup.memory". This causes init/main.c::unknown_boottoption() to consider it to be an "Unused module parameter" and ignore it. (This is for parsing of loadable module parameters any time after kernel init.) Otherwise the string "cgroup.memory=whatever" would be added to init's environment strings. Instead of relying on this '.' quirk, just return 1 to indicate that the boot option has been handled. Note that there is no warning message if someone enters: cgroup.memory=anything_invalid Link: https://lkml.kernel.org/r/20220222005811.10672-1-rdunlap@infradead.org Fixes: f7e1cb6e ("mm: memcontrol: account socket memory in unified hierarchy memory controller") Signed-off-by:
Randy Dunlap <rdunlap@infradead.org> Reported-by:
Igor Zhbanov <i.zhbanov@omprussia.ru> Link: lore.kernel.org/r/64644a2f-4a20-bab3-1e15-3b2cdd0defe3@omprussia.ru Reviewed-by:
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Shakeel Butt authored
The high limit is used to throttle the workload without invoking the oom-killer. Recently we tried to use the high limit to right size our internal workloads. More specifically dynamically adjusting the limits of the workload without letting the workload get oom-killed. However due to the limitation of the implementation of high limit enforcement, we observed the mechanism fails for some real workloads. The high limit is enforced on return-to-userspace i.e. the kernel let the usage goes over the limit and when the execution returns to userspace, the high reclaim is triggered and the process can get throttled as well. However this mechanism fails for workloads which do large allocations in a single kernel entry e.g. applications that mlock() a large chunk of memory in a single syscall. Such applications bypass the high limit and can trigger the oom-killer. To make high limit enforcement more robust, this patch makes the limit enforcement synchronous only if the accumulated overcharge becomes larger than MEMCG_CHARGE_BATCH. So, most of the allocations would still be throttled on the return-to-userspace path but only the extreme allocations which accumulates large amount of overcharge without returning to the userspace will be throttled synchronously. The value MEMCG_CHARGE_BATCH is a bit arbitrary but most of other places in the memcg codebase uses this constant therefore for now uses the same one. Link: https://lkml.kernel.org/r/20220211064917.2028469-5-shakeelb@google.comSigned-off-by:
Chris Down <chris@chrisdown.name> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by:
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Shakeel Butt authored
Test the enforcement of memory.high limit for large amount of memory allocation within a single kernel entry. There are valid use-cases where the application can trigger large amount of memory allocation within a single syscall e.g. mlock() or mmap(MAP_POPULATE). Make sure memory.high limit enforcement works for such use-cases. Link: https://lkml.kernel.org/r/20220211064917.2028469-4-shakeelb@google.comSigned-off-by:
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Shakeel Butt authored
Currently the kernel force charges the allocations which have __GFP_HIGH flag without triggering the memory reclaim. __GFP_HIGH indicates that the caller is high priority and since commit 869712fd ("mm: memcontrol: fix network errors from failing __GFP_ATOMIC charges") the kernel lets such allocations do force charging. Please note that __GFP_ATOMIC has been replaced by __GFP_HIGH. __GFP_HIGH does not tell if the caller can block or can trigger reclaim. There are separate checks to determine that. So, there is no need to skip reclaiming for __GFP_HIGH allocations. So, handle __GFP_HIGH together with __GFP_NOFAIL which also does force charging. Please note that this is a noop change as there are no __GFP_HIGH allocators in the kernel which also have __GFP_ACCOUNT (or SLAB_ACCOUNT) and does not allow reclaim for now. Link: https://lkml.kernel.org/r/20220211064917.2028469-3-shakeelb@google.comSigned-off-by:
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Shakeel Butt authored
Patch series "memcg: robust enforcement of memory.high", v2. Due to the semantics of memory.high enforcement i.e. throttle the workload without oom-kill, we are trying to use it for right sizing the workloads in our production environment. However we observed the mechanism fails for some specific applications which does big chunck of allocations in a single syscall. The reason behind this failure is due to the limitation of the memory.high enforcement's current implementation. This patch series solves this issue by enforcing the memory.high synchronously if the current process has accumulated a large amount of high overcharge. This patch (of 4): The function mem_cgroup_oom returns enum which has four possible values but the caller does not care about such values and only cares if the return value is OOM_SUCCESS or not. So, remove the enum altogether and make mem_cgroup_oom returns a simple bool. Link: https://lkml.kernel.org/r/20220211064917.2028469-1-shakeelb@google.com Link: https://lkml.kernel.org/r/20220211064917.2028469-2-shakeelb@google.comSigned-off-by:
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Wei Yang authored
The parent we get from page_counter is correct, while this is two different hierarchy. Let's retrieve the parent memcg from css.parent just like parent_cs(), blkcg_parent(), etc. Link: https://lkml.kernel.org/r/20220201004643.8391-2-richard.weiyang@gmail.comSigned-off-by:
Wei Yang <richard.weiyang@gmail.com> Reviewed-by:
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Wei Yang authored
kzalloc_node() would set data to 0, so it's not necessary to set it again. Link: https://lkml.kernel.org/r/20220201004643.8391-1-richard.weiyang@gmail.comSigned-off-by:
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Yosry Ahmed authored
Currently memcg stats show several types of kernel memory: kernel stack, page tables, sock, vmalloc, and slab. However, there are other allocations with __GFP_ACCOUNT (or supersets such as GFP_KERNEL_ACCOUNT) that are not accounted in any of those stats, a few examples are: - various kvm allocations (e.g. allocated pages to create vcpus) - io_uring - tmp_page in pipes during pipe_write() - bpf ringbuffers - unix sockets Keeping track of the total kernel memory is essential for the ease of migration from cgroup v1 to v2 as there are large discrepancies between v1's kmem.usage_in_bytes and the sum of the available kernel memory stats in v2. Adding separate memcg stats for all __GFP_ACCOUNT kernel allocations is an impractical maintenance burden as there a lot of those all over the kernel code, with more use cases likely to show up in the future. Therefore, add a "kernel" memcg stat that is analogous to kmem page counter, with added benefits such as using rstat infrastructure which aggregates stats more efficiently. Additionally, this provides a lighter alternative in case the legacy kmem is deprecated in the future [yosryahmed@google.com: v2] Link: https://lkml.kernel.org/r/20220203193856.972500-1-yosryahmed@google.com Link: https://lkml.kernel.org/r/20220201200823.3283171-1-yosryahmed@google.comSigned-off-by:
Yosry Ahmed <yosryahmed@google.com> Acked-by:
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Shakeel Butt authored
Replace the deprecated in_interrupt() with !in_task() because in_interrupt() returns true for BH disabled even if the call happens in the task context. in_task() is the right interface to differentiate task context from NMI, hard IRQ and softirq contexts. Link: https://lkml.kernel.org/r/20220127162636.3461256-1-shakeelb@google.comSigned-off-by:
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Miaohe Lin authored
Use helper macro __ATTR_RW to define shmem_enabled_attr to make code more clear. Minor readability improvement. Link: https://lkml.kernel.org/r/20220312082252.55586-1-linmiaohe@huawei.comSigned-off-by:
Miaohe Lin <linmiaohe@huawei.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by:
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Hugh Dickins authored
Mikulas asked in "Do we still need commit a0ee5ec5 ('tmpfs: allocate on read when stacked')?" in [1] Lukas noticed this unusual behavior of loop device backed by tmpfs in [2]. Normally, shmem_file_read_iter() copies the ZERO_PAGE when reading holes; but if it looks like it might be a read for "a stacking filesystem", it allocates actual pages to the page cache, and even marks them as dirty. And reads from the loop device do satisfy the test that is used. This oddity was added for an old version of unionfs, to help to limit its usage to the limited size of the tmpfs mount involved; but about the same time as the tmpfs mod went in (2.6.25), unionfs was reworked to proceed differently; and the mod kept just in case others needed it. Do we still need it? I cannot answer with more certainty than "Probably not". It's nasty enough that we really should try to delete it; but if a regression is reported somewhere, then we might have to revert later. It's not quite as simple as just removing the test (as Mikulas did): xfstests generic/013 hung because splice from tmpfs failed on page not up-to-date and page mapping unset. That can be fixed just by marking the ZERO_PAGE as Uptodate, which of course it is: do so in pagecache_init() - it might be useful to others than tmpfs. My intention, though, was to stop using the ZERO_PAGE here altogether: surely iov_iter_zero() is better for this case? Sadly not: it relies on clear_user(), and the x86 clear_user() is slower than its copy_user() [3]. But while we are still using the ZERO_PAGE, let's stop dirtying its struct page cacheline with unnecessary get_page() and put_page(). Link: https://lore.kernel.org/linux-mm/alpine.LRH.2.02.2007210510230.6959@file01.intranet.prod.int.rdu2.redhat.com/ [1] Link: https://lore.kernel.org/linux-mm/20211126075100.gd64odg2bcptiqeb@work/ [2] Link: https://lore.kernel.org/lkml/2f5ca5e4-e250-a41c-11fb-a7f4ebc7e1c9@google.com/ [3] Link: https://lkml.kernel.org/r/90bc5e69-9984-b5fa-a685-be55f2b64b@google.comSigned-off-by:
Hugh Dickins <hughd@google.com> Reported-by:
Mikulas Patocka <mpatocka@redhat.com> Reported-by:
Lukas Czerner <lczerner@redhat.com> Acked-by:
Darrick J. Wong <djwong@kernel.org> Reviewed-by:
Christoph Hellwig <hch@lst.de> Cc: Zdenek Kabelac <zkabelac@redhat.com> Cc: "Darrick J. Wong" <djwong@kernel.org> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: Borislav Petkov <bp@suse.de> Signed-off-by:
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