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![Andrey Vagin](/assets/img/avatar_default.png)
If the system had a few memory groups and all of them were destroyed, memcg_limited_groups_array_size has non-zero value, but all new caches are created without memcg_params, because memcg_kmem_enabled() returns false. We try to enumirate child caches in a few places and all of them are potentially dangerous. For example my kernel is compiled with CONFIG_SLAB and it crashed when I tryed to mount a NFS share after a few experiments with kmemcg. BUG: unable to handle kernel NULL pointer dereference at 0000000000000008 IP: [<ffffffff8118166a>] do_tune_cpucache+0x8a/0xd0 PGD b942a067 PUD b999f067 PMD 0 Oops: 0000 [#1] SMP Modules linked in: fscache(+) ip6table_filter ip6_tables iptable_filter ip_tables i2c_piix4 pcspkr virtio_net virtio_balloon i2c_core floppy CPU: 0 PID: 357 Comm: modprobe Not tainted 3.11.0-rc7+ #59 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 task: ffff8800b9f98240 ti: ffff8800ba32e000 task.ti: ffff8800ba32e000 RIP: 0010:[<ffffffff8118166a>] [<ffffffff8118166a>] do_tune_cpucache+0x8a/0xd0 RSP: 0018:ffff8800ba32fb70 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000006 RDX: 0000000000000000 RSI: ffff8800b9f98910 RDI: 0000000000000246 RBP: ffff8800ba32fba0 R08: 0000000000000002 R09: 0000000000000004 R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000010 R13: 0000000000000008 R14: 00000000000000d0 R15: ffff8800375d0200 FS: 00007f55f1378740(0000) GS:ffff8800bfa00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00007f24feba57a0 CR3: 0000000037b51000 CR4: 00000000000006f0 Call Trace: enable_cpucache+0x49/0x100 setup_cpu_cache+0x215/0x280 __kmem_cache_create+0x2fa/0x450 kmem_cache_create_memcg+0x214/0x350 kmem_cache_create+0x2b/0x30 fscache_init+0x19b/0x230 [fscache] do_one_initcall+0xfa/0x1b0 load_module+0x1c41/0x26d0 SyS_finit_module+0x86/0xb0 system_call_fastpath+0x16/0x1b Signed-off-by: Andrey Vagin <avagin@openvz.org> Cc: Pekka Enberg <penberg@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Glauber Costa <glommer@openvz.org> Cc: Joonsoo Kim <js1304@gmail.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
278 lines
7.4 KiB
C
278 lines
7.4 KiB
C
#ifndef MM_SLAB_H
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#define MM_SLAB_H
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/*
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* Internal slab definitions
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*/
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/*
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* State of the slab allocator.
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*
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* This is used to describe the states of the allocator during bootup.
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* Allocators use this to gradually bootstrap themselves. Most allocators
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* have the problem that the structures used for managing slab caches are
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* allocated from slab caches themselves.
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*/
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enum slab_state {
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DOWN, /* No slab functionality yet */
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PARTIAL, /* SLUB: kmem_cache_node available */
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PARTIAL_ARRAYCACHE, /* SLAB: kmalloc size for arraycache available */
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PARTIAL_NODE, /* SLAB: kmalloc size for node struct available */
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UP, /* Slab caches usable but not all extras yet */
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FULL /* Everything is working */
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};
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extern enum slab_state slab_state;
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/* The slab cache mutex protects the management structures during changes */
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extern struct mutex slab_mutex;
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/* The list of all slab caches on the system */
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extern struct list_head slab_caches;
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/* The slab cache that manages slab cache information */
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extern struct kmem_cache *kmem_cache;
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unsigned long calculate_alignment(unsigned long flags,
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unsigned long align, unsigned long size);
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#ifndef CONFIG_SLOB
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/* Kmalloc array related functions */
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void create_kmalloc_caches(unsigned long);
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/* Find the kmalloc slab corresponding for a certain size */
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struct kmem_cache *kmalloc_slab(size_t, gfp_t);
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#endif
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/* Functions provided by the slab allocators */
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extern int __kmem_cache_create(struct kmem_cache *, unsigned long flags);
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extern struct kmem_cache *create_kmalloc_cache(const char *name, size_t size,
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unsigned long flags);
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extern void create_boot_cache(struct kmem_cache *, const char *name,
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size_t size, unsigned long flags);
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struct mem_cgroup;
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#ifdef CONFIG_SLUB
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struct kmem_cache *
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__kmem_cache_alias(struct mem_cgroup *memcg, const char *name, size_t size,
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size_t align, unsigned long flags, void (*ctor)(void *));
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#else
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static inline struct kmem_cache *
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__kmem_cache_alias(struct mem_cgroup *memcg, const char *name, size_t size,
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size_t align, unsigned long flags, void (*ctor)(void *))
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{ return NULL; }
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#endif
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/* Legal flag mask for kmem_cache_create(), for various configurations */
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#define SLAB_CORE_FLAGS (SLAB_HWCACHE_ALIGN | SLAB_CACHE_DMA | SLAB_PANIC | \
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SLAB_DESTROY_BY_RCU | SLAB_DEBUG_OBJECTS )
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#if defined(CONFIG_DEBUG_SLAB)
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#define SLAB_DEBUG_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER)
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#elif defined(CONFIG_SLUB_DEBUG)
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#define SLAB_DEBUG_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
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SLAB_TRACE | SLAB_DEBUG_FREE)
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#else
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#define SLAB_DEBUG_FLAGS (0)
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#endif
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#if defined(CONFIG_SLAB)
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#define SLAB_CACHE_FLAGS (SLAB_MEM_SPREAD | SLAB_NOLEAKTRACE | \
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SLAB_RECLAIM_ACCOUNT | SLAB_TEMPORARY | SLAB_NOTRACK)
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#elif defined(CONFIG_SLUB)
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#define SLAB_CACHE_FLAGS (SLAB_NOLEAKTRACE | SLAB_RECLAIM_ACCOUNT | \
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SLAB_TEMPORARY | SLAB_NOTRACK)
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#else
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#define SLAB_CACHE_FLAGS (0)
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#endif
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#define CACHE_CREATE_MASK (SLAB_CORE_FLAGS | SLAB_DEBUG_FLAGS | SLAB_CACHE_FLAGS)
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int __kmem_cache_shutdown(struct kmem_cache *);
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struct seq_file;
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struct file;
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struct slabinfo {
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unsigned long active_objs;
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unsigned long num_objs;
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unsigned long active_slabs;
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unsigned long num_slabs;
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unsigned long shared_avail;
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unsigned int limit;
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unsigned int batchcount;
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unsigned int shared;
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unsigned int objects_per_slab;
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unsigned int cache_order;
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};
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void get_slabinfo(struct kmem_cache *s, struct slabinfo *sinfo);
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void slabinfo_show_stats(struct seq_file *m, struct kmem_cache *s);
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ssize_t slabinfo_write(struct file *file, const char __user *buffer,
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size_t count, loff_t *ppos);
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#ifdef CONFIG_MEMCG_KMEM
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static inline bool is_root_cache(struct kmem_cache *s)
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{
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return !s->memcg_params || s->memcg_params->is_root_cache;
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}
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static inline bool cache_match_memcg(struct kmem_cache *cachep,
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struct mem_cgroup *memcg)
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{
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return (is_root_cache(cachep) && !memcg) ||
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(cachep->memcg_params->memcg == memcg);
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}
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static inline void memcg_bind_pages(struct kmem_cache *s, int order)
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{
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if (!is_root_cache(s))
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atomic_add(1 << order, &s->memcg_params->nr_pages);
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}
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static inline void memcg_release_pages(struct kmem_cache *s, int order)
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{
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if (is_root_cache(s))
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return;
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if (atomic_sub_and_test((1 << order), &s->memcg_params->nr_pages))
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mem_cgroup_destroy_cache(s);
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}
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static inline bool slab_equal_or_root(struct kmem_cache *s,
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struct kmem_cache *p)
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{
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return (p == s) ||
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(s->memcg_params && (p == s->memcg_params->root_cache));
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}
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/*
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* We use suffixes to the name in memcg because we can't have caches
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* created in the system with the same name. But when we print them
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* locally, better refer to them with the base name
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*/
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static inline const char *cache_name(struct kmem_cache *s)
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{
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if (!is_root_cache(s))
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return s->memcg_params->root_cache->name;
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return s->name;
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}
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static inline struct kmem_cache *cache_from_memcg(struct kmem_cache *s, int idx)
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{
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if (!s->memcg_params)
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return NULL;
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return s->memcg_params->memcg_caches[idx];
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}
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static inline struct kmem_cache *memcg_root_cache(struct kmem_cache *s)
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{
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if (is_root_cache(s))
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return s;
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return s->memcg_params->root_cache;
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}
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#else
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static inline bool is_root_cache(struct kmem_cache *s)
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{
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return true;
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}
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static inline bool cache_match_memcg(struct kmem_cache *cachep,
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struct mem_cgroup *memcg)
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{
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return true;
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}
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static inline void memcg_bind_pages(struct kmem_cache *s, int order)
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{
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}
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static inline void memcg_release_pages(struct kmem_cache *s, int order)
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{
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}
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static inline bool slab_equal_or_root(struct kmem_cache *s,
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struct kmem_cache *p)
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{
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return true;
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}
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static inline const char *cache_name(struct kmem_cache *s)
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{
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return s->name;
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}
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static inline struct kmem_cache *cache_from_memcg(struct kmem_cache *s, int idx)
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{
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return NULL;
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}
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static inline struct kmem_cache *memcg_root_cache(struct kmem_cache *s)
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{
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return s;
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}
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#endif
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static inline struct kmem_cache *cache_from_obj(struct kmem_cache *s, void *x)
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{
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struct kmem_cache *cachep;
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struct page *page;
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/*
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* When kmemcg is not being used, both assignments should return the
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* same value. but we don't want to pay the assignment price in that
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* case. If it is not compiled in, the compiler should be smart enough
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* to not do even the assignment. In that case, slab_equal_or_root
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* will also be a constant.
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*/
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if (!memcg_kmem_enabled() && !unlikely(s->flags & SLAB_DEBUG_FREE))
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return s;
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page = virt_to_head_page(x);
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cachep = page->slab_cache;
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if (slab_equal_or_root(cachep, s))
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return cachep;
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pr_err("%s: Wrong slab cache. %s but object is from %s\n",
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__FUNCTION__, cachep->name, s->name);
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WARN_ON_ONCE(1);
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return s;
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}
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#endif
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/*
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* The slab lists for all objects.
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*/
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struct kmem_cache_node {
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spinlock_t list_lock;
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#ifdef CONFIG_SLAB
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struct list_head slabs_partial; /* partial list first, better asm code */
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struct list_head slabs_full;
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struct list_head slabs_free;
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unsigned long free_objects;
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unsigned int free_limit;
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unsigned int colour_next; /* Per-node cache coloring */
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struct array_cache *shared; /* shared per node */
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struct array_cache **alien; /* on other nodes */
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unsigned long next_reap; /* updated without locking */
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int free_touched; /* updated without locking */
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#endif
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#ifdef CONFIG_SLUB
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unsigned long nr_partial;
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struct list_head partial;
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#ifdef CONFIG_SLUB_DEBUG
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atomic_long_t nr_slabs;
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atomic_long_t total_objects;
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struct list_head full;
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#endif
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#endif
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};
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void *slab_next(struct seq_file *m, void *p, loff_t *pos);
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void slab_stop(struct seq_file *m, void *p);
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