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mm: rework virtual memory accounting

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When inspecting a vague code inside prctl(PR_SET_MM_MEM) call (which
testing the RLIMIT_DATA value to figure out if we're allowed to assign
new @start_brk, @brk, @start_data, @end_data from mm_struct) it's been
commited that RLIMIT_DATA in a form it's implemented now doesn't do
anything useful because most of user-space libraries use mmap() syscall
for dynamic memory allocations.

Linus suggested to convert RLIMIT_DATA rlimit into something suitable
for anonymous memory accounting.  But in this patch we go further, and
the changes are bundled together as:

 * keep vma counting if CONFIG_PROC_FS=n, will be used for limits
 * replace mm->shared_vm with better defined mm->data_vm
 * account anonymous executable areas as executable
 * account file-backed growsdown/up areas as stack
 * drop struct file* argument from vm_stat_account
 * enforce RLIMIT_DATA for size of data areas

This way code looks cleaner: now code/stack/data classification depends
only on vm_flags state:

 VM_EXEC & ~VM_WRITE            -> code  (VmExe + VmLib in proc)
 VM_GROWSUP | VM_GROWSDOWN      -> stack (VmStk)
 VM_WRITE & ~VM_SHARED & !stack -> data  (VmData)

The rest (VmSize - VmData - VmStk - VmExe - VmLib) could be called
"shared", but that might be strange beast like readonly-private or VM_IO
area.

 - RLIMIT_AS            limits whole address space "VmSize"
 - RLIMIT_STACK         limits stack "VmStk" (but each vma individually)
 - RLIMIT_DATA          now limits "VmData"

Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Willy Tarreau <w@1wt.eu>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Kees Cook <keescook@google.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Konstantin Khlebnikov
2016-01-14 15:22:07 -08:00
committed by Linus Torvalds
parent d30b5545bd
commit 8463833590
9 changed files with 54 additions and 58 deletions
Download Patch File Download Diff File Expand all files Collapse all files

13
include/linux/mm.h
View File

@@ -1929,7 +1929,9 @@ extern void mm_drop_all_locks(struct mm_struct *mm);
extern void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file);
extern struct file *get_mm_exe_file(struct mm_struct *mm);
extern int may_expand_vm(struct mm_struct *mm, unsigned long npages);
extern bool may_expand_vm(struct mm_struct *, vm_flags_t, unsigned long npages);
extern void vm_stat_account(struct mm_struct *, vm_flags_t, long npages);
extern struct vm_area_struct *_install_special_mapping(struct mm_struct *mm,
unsigned long addr, unsigned long len,
unsigned long flags,
@@ -2147,15 +2149,6 @@ typedef int (*pte_fn_t)(pte_t *pte, pgtable_t token, unsigned long addr,
extern int apply_to_page_range(struct mm_struct *mm, unsigned long address,
unsigned long size, pte_fn_t fn, void *data);
#ifdef CONFIG_PROC_FS
void vm_stat_account(struct mm_struct *, unsigned long, struct file *, long);
#else
static inline void vm_stat_account(struct mm_struct *mm,
unsigned long flags, struct file *file, long pages)
{
mm->total_vm += pages;
}
#endif /* CONFIG_PROC_FS */
#ifdef CONFIG_DEBUG_PAGEALLOC
extern bool _debug_pagealloc_enabled;

2
include/linux/mm_types.h
View File

@@ -427,7 +427,7 @@ struct mm_struct {
unsigned long total_vm; /* Total pages mapped */
unsigned long locked_vm; /* Pages that have PG_mlocked set */
unsigned long pinned_vm; /* Refcount permanently increased */
unsigned long shared_vm; /* Shared pages (files) */
unsigned long data_vm; /* VM_WRITE & ~VM_SHARED/GROWSDOWN */
unsigned long exec_vm; /* VM_EXEC & ~VM_WRITE */
unsigned long stack_vm; /* VM_GROWSUP/DOWN */
unsigned long def_flags;