mm: Allocate the mm_cpumask (mm->cpu_bitmap[]) dynamically based on nr_cpu_ids
The mm_struct always contains a cpumask bitmap, regardless of CONFIG_CPUMASK_OFFSTACK. That means the first step can be to simplify things, and simply have one bitmask at the end of the mm_struct for the mm_cpumask. This does necessitate moving everything else in mm_struct into an anonymous sub-structure, which can be randomized when struct randomization is enabled. The second step is to determine the correct size for the mm_struct slab object from the size of the mm_struct (excluding the CPU bitmap) and the size the cpumask. For init_mm we can simply allocate the maximum size this kernel is compiled for, since we only have one init_mm in the system, anyway. Pointer magic by Mike Galbraith, to evade -Wstringop-overflow getting confused by the dynamically sized array. Tested-by: Song Liu <songliubraving@fb.com> Signed-off-by: Rik van Riel <riel@surriel.com> Signed-off-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Rik van Riel <riel@surriel.com> Acked-by: Dave Hansen <dave.hansen@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: kernel-team@fb.com Cc: luto@kernel.org Link: http://lkml.kernel.org/r/20180716190337.26133-2-riel@surriel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Rik van Riel
Ingo Molnar
parent
37c45b2354
commit
c1a2f7f0c0
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@ -82,6 +82,7 @@ struct mm_struct efi_mm = {
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.mmap_sem = __RWSEM_INITIALIZER(efi_mm.mmap_sem),
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.page_table_lock = __SPIN_LOCK_UNLOCKED(efi_mm.page_table_lock),
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.mmlist = LIST_HEAD_INIT(efi_mm.mmlist),
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.cpu_bitmap = { [BITS_TO_LONGS(NR_CPUS)] = 0},
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};
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static bool disable_runtime;
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@ -335,176 +335,183 @@ struct core_state {
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struct kioctx_table;
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struct mm_struct {
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struct vm_area_struct *mmap; /* list of VMAs */
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struct rb_root mm_rb;
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u32 vmacache_seqnum; /* per-thread vmacache */
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struct {
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struct vm_area_struct *mmap; /* list of VMAs */
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struct rb_root mm_rb;
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u32 vmacache_seqnum; /* per-thread vmacache */
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#ifdef CONFIG_MMU
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unsigned long (*get_unmapped_area) (struct file *filp,
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unsigned long (*get_unmapped_area) (struct file *filp,
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unsigned long addr, unsigned long len,
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unsigned long pgoff, unsigned long flags);
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#endif
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unsigned long mmap_base; /* base of mmap area */
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unsigned long mmap_legacy_base; /* base of mmap area in bottom-up allocations */
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unsigned long mmap_base; /* base of mmap area */
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unsigned long mmap_legacy_base; /* base of mmap area in bottom-up allocations */
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#ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES
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/* Base adresses for compatible mmap() */
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unsigned long mmap_compat_base;
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unsigned long mmap_compat_legacy_base;
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/* Base adresses for compatible mmap() */
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unsigned long mmap_compat_base;
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unsigned long mmap_compat_legacy_base;
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#endif
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unsigned long task_size; /* size of task vm space */
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unsigned long highest_vm_end; /* highest vma end address */
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pgd_t * pgd;
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unsigned long task_size; /* size of task vm space */
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unsigned long highest_vm_end; /* highest vma end address */
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pgd_t * pgd;
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/**
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* @mm_users: The number of users including userspace.
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*
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* Use mmget()/mmget_not_zero()/mmput() to modify. When this drops
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* to 0 (i.e. when the task exits and there are no other temporary
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* reference holders), we also release a reference on @mm_count
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* (which may then free the &struct mm_struct if @mm_count also
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* drops to 0).
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*/
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atomic_t mm_users;
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/**
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* @mm_users: The number of users including userspace.
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*
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* Use mmget()/mmget_not_zero()/mmput() to modify. When this
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* drops to 0 (i.e. when the task exits and there are no other
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* temporary reference holders), we also release a reference on
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* @mm_count (which may then free the &struct mm_struct if
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* @mm_count also drops to 0).
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*/
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atomic_t mm_users;
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/**
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* @mm_count: The number of references to &struct mm_struct
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* (@mm_users count as 1).
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*
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* Use mmgrab()/mmdrop() to modify. When this drops to 0, the
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* &struct mm_struct is freed.
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*/
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atomic_t mm_count;
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/**
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* @mm_count: The number of references to &struct mm_struct
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* (@mm_users count as 1).
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*
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* Use mmgrab()/mmdrop() to modify. When this drops to 0, the
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* &struct mm_struct is freed.
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*/
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atomic_t mm_count;
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#ifdef CONFIG_MMU
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atomic_long_t pgtables_bytes; /* PTE page table pages */
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atomic_long_t pgtables_bytes; /* PTE page table pages */
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#endif
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int map_count; /* number of VMAs */
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int map_count; /* number of VMAs */
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spinlock_t page_table_lock; /* Protects page tables and some counters */
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struct rw_semaphore mmap_sem;
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spinlock_t page_table_lock; /* Protects page tables and some
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* counters
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*/
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struct rw_semaphore mmap_sem;
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struct list_head mmlist; /* List of maybe swapped mm's. These are globally strung
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* together off init_mm.mmlist, and are protected
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* by mmlist_lock
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*/
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struct list_head mmlist; /* List of maybe swapped mm's. These
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* are globally strung together off
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* init_mm.mmlist, and are protected
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* by mmlist_lock
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*/
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unsigned long hiwater_rss; /* High-watermark of RSS usage */
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unsigned long hiwater_vm; /* High-water virtual memory usage */
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unsigned long hiwater_rss; /* High-watermark of RSS usage */
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unsigned long hiwater_vm; /* High-water virtual memory usage */
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unsigned long total_vm; /* Total pages mapped */
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unsigned long locked_vm; /* Pages that have PG_mlocked set */
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unsigned long pinned_vm; /* Refcount permanently increased */
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unsigned long data_vm; /* VM_WRITE & ~VM_SHARED & ~VM_STACK */
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unsigned long exec_vm; /* VM_EXEC & ~VM_WRITE & ~VM_STACK */
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unsigned long stack_vm; /* VM_STACK */
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unsigned long def_flags;
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unsigned long total_vm; /* Total pages mapped */
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unsigned long locked_vm; /* Pages that have PG_mlocked set */
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unsigned long pinned_vm; /* Refcount permanently increased */
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unsigned long data_vm; /* VM_WRITE & ~VM_SHARED & ~VM_STACK */
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unsigned long exec_vm; /* VM_EXEC & ~VM_WRITE & ~VM_STACK */
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unsigned long stack_vm; /* VM_STACK */
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unsigned long def_flags;
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spinlock_t arg_lock; /* protect the below fields */
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unsigned long start_code, end_code, start_data, end_data;
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unsigned long start_brk, brk, start_stack;
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unsigned long arg_start, arg_end, env_start, env_end;
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spinlock_t arg_lock; /* protect the below fields */
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unsigned long start_code, end_code, start_data, end_data;
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unsigned long start_brk, brk, start_stack;
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unsigned long arg_start, arg_end, env_start, env_end;
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unsigned long saved_auxv[AT_VECTOR_SIZE]; /* for /proc/PID/auxv */
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unsigned long saved_auxv[AT_VECTOR_SIZE]; /* for /proc/PID/auxv */
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/*
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* Special counters, in some configurations protected by the
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* page_table_lock, in other configurations by being atomic.
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*/
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struct mm_rss_stat rss_stat;
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/*
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* Special counters, in some configurations protected by the
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* page_table_lock, in other configurations by being atomic.
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*/
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struct mm_rss_stat rss_stat;
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struct linux_binfmt *binfmt;
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struct linux_binfmt *binfmt;
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cpumask_var_t cpu_vm_mask_var;
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/* Architecture-specific MM context */
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mm_context_t context;
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/* Architecture-specific MM context */
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mm_context_t context;
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unsigned long flags; /* Must use atomic bitops to access */
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unsigned long flags; /* Must use atomic bitops to access the bits */
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struct core_state *core_state; /* coredumping support */
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struct core_state *core_state; /* coredumping support */
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#ifdef CONFIG_MEMBARRIER
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atomic_t membarrier_state;
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atomic_t membarrier_state;
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#endif
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#ifdef CONFIG_AIO
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spinlock_t ioctx_lock;
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struct kioctx_table __rcu *ioctx_table;
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spinlock_t ioctx_lock;
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struct kioctx_table __rcu *ioctx_table;
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#endif
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#ifdef CONFIG_MEMCG
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/*
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* "owner" points to a task that is regarded as the canonical
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* user/owner of this mm. All of the following must be true in
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* order for it to be changed:
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*
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* current == mm->owner
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* current->mm != mm
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* new_owner->mm == mm
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* new_owner->alloc_lock is held
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*/
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struct task_struct __rcu *owner;
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/*
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* "owner" points to a task that is regarded as the canonical
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* user/owner of this mm. All of the following must be true in
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* order for it to be changed:
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*
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* current == mm->owner
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* current->mm != mm
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* new_owner->mm == mm
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* new_owner->alloc_lock is held
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*/
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struct task_struct __rcu *owner;
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#endif
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struct user_namespace *user_ns;
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struct user_namespace *user_ns;
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/* store ref to file /proc/<pid>/exe symlink points to */
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struct file __rcu *exe_file;
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/* store ref to file /proc/<pid>/exe symlink points to */
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struct file __rcu *exe_file;
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#ifdef CONFIG_MMU_NOTIFIER
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struct mmu_notifier_mm *mmu_notifier_mm;
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struct mmu_notifier_mm *mmu_notifier_mm;
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#endif
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#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
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pgtable_t pmd_huge_pte; /* protected by page_table_lock */
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#endif
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#ifdef CONFIG_CPUMASK_OFFSTACK
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struct cpumask cpumask_allocation;
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pgtable_t pmd_huge_pte; /* protected by page_table_lock */
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#endif
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#ifdef CONFIG_NUMA_BALANCING
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/*
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* numa_next_scan is the next time that the PTEs will be marked
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* pte_numa. NUMA hinting faults will gather statistics and migrate
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* pages to new nodes if necessary.
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*/
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unsigned long numa_next_scan;
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/*
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* numa_next_scan is the next time that the PTEs will be marked
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* pte_numa. NUMA hinting faults will gather statistics and
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* migrate pages to new nodes if necessary.
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*/
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unsigned long numa_next_scan;
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/* Restart point for scanning and setting pte_numa */
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unsigned long numa_scan_offset;
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/* Restart point for scanning and setting pte_numa */
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unsigned long numa_scan_offset;
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/* numa_scan_seq prevents two threads setting pte_numa */
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int numa_scan_seq;
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/* numa_scan_seq prevents two threads setting pte_numa */
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int numa_scan_seq;
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#endif
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/*
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* An operation with batched TLB flushing is going on. Anything that
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* can move process memory needs to flush the TLB when moving a
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* PROT_NONE or PROT_NUMA mapped page.
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*/
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atomic_t tlb_flush_pending;
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/*
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* An operation with batched TLB flushing is going on. Anything
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* that can move process memory needs to flush the TLB when
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* moving a PROT_NONE or PROT_NUMA mapped page.
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*/
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atomic_t tlb_flush_pending;
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#ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
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/* See flush_tlb_batched_pending() */
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bool tlb_flush_batched;
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/* See flush_tlb_batched_pending() */
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bool tlb_flush_batched;
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#endif
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struct uprobes_state uprobes_state;
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struct uprobes_state uprobes_state;
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#ifdef CONFIG_HUGETLB_PAGE
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atomic_long_t hugetlb_usage;
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atomic_long_t hugetlb_usage;
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#endif
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struct work_struct async_put_work;
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struct work_struct async_put_work;
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#if IS_ENABLED(CONFIG_HMM)
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/* HMM needs to track a few things per mm */
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struct hmm *hmm;
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/* HMM needs to track a few things per mm */
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struct hmm *hmm;
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#endif
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} __randomize_layout;
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} __randomize_layout;
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/*
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* The mm_cpumask needs to be at the end of mm_struct, because it
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* is dynamically sized based on nr_cpu_ids.
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*/
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unsigned long cpu_bitmap[];
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};
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extern struct mm_struct init_mm;
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/* Pointer magic because the dynamic array size confuses some compilers. */
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static inline void mm_init_cpumask(struct mm_struct *mm)
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{
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#ifdef CONFIG_CPUMASK_OFFSTACK
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mm->cpu_vm_mask_var = &mm->cpumask_allocation;
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#endif
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cpumask_clear(mm->cpu_vm_mask_var);
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unsigned long cpu_bitmap = (unsigned long)mm;
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cpu_bitmap += offsetof(struct mm_struct, cpu_bitmap);
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cpumask_clear((struct cpumask *)cpu_bitmap);
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}
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/* Future-safe accessor for struct mm_struct's cpu_vm_mask. */
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static inline cpumask_t *mm_cpumask(struct mm_struct *mm)
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{
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return mm->cpu_vm_mask_var;
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return (struct cpumask *)&mm->cpu_bitmap;
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}
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struct mmu_gather;
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@ -2253,6 +2253,8 @@ static void sighand_ctor(void *data)
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void __init proc_caches_init(void)
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{
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unsigned int mm_size;
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sighand_cachep = kmem_cache_create("sighand_cache",
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sizeof(struct sighand_struct), 0,
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SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_TYPESAFE_BY_RCU|
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@ -2269,15 +2271,16 @@ void __init proc_caches_init(void)
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sizeof(struct fs_struct), 0,
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SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
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NULL);
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/*
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* FIXME! The "sizeof(struct mm_struct)" currently includes the
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* whole struct cpumask for the OFFSTACK case. We could change
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* this to *only* allocate as much of it as required by the
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* maximum number of CPU's we can ever have. The cpumask_allocation
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* is at the end of the structure, exactly for that reason.
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* The mm_cpumask is located at the end of mm_struct, and is
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* dynamically sized based on the maximum CPU number this system
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* can have, taking hotplug into account (nr_cpu_ids).
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*/
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mm_size = sizeof(struct mm_struct) + cpumask_size();
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mm_cachep = kmem_cache_create_usercopy("mm_struct",
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sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN,
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mm_size, ARCH_MIN_MMSTRUCT_ALIGN,
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SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
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offsetof(struct mm_struct, saved_auxv),
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sizeof_field(struct mm_struct, saved_auxv),
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11
mm/init-mm.c
11
mm/init-mm.c
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@ -15,6 +15,16 @@
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#define INIT_MM_CONTEXT(name)
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#endif
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/*
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* For dynamically allocated mm_structs, there is a dynamically sized cpumask
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* at the end of the structure, the size of which depends on the maximum CPU
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* number the system can see. That way we allocate only as much memory for
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* mm_cpumask() as needed for the hundreds, or thousands of processes that
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* a system typically runs.
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*
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* Since there is only one init_mm in the entire system, keep it simple
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* and size this cpu_bitmask to NR_CPUS.
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*/
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struct mm_struct init_mm = {
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.mm_rb = RB_ROOT,
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.pgd = swapper_pg_dir,
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@ -25,5 +35,6 @@ struct mm_struct init_mm = {
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.arg_lock = __SPIN_LOCK_UNLOCKED(init_mm.arg_lock),
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.mmlist = LIST_HEAD_INIT(init_mm.mmlist),
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.user_ns = &init_user_ns,
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.cpu_bitmap = { [BITS_TO_LONGS(NR_CPUS)] = 0},
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INIT_MM_CONTEXT(init_mm)
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};
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