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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

63
mm/mmap.c
View File

@@ -1220,24 +1220,6 @@ none:
return NULL;
}
#ifdef CONFIG_PROC_FS
void vm_stat_account(struct mm_struct *mm, unsigned long flags,
struct file *file, long pages)
{
const unsigned long stack_flags
= VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN);
mm->total_vm += pages;
if (file) {
mm->shared_vm += pages;
if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC)
mm->exec_vm += pages;
} else if (flags & stack_flags)
mm->stack_vm += pages;
}
#endif /* CONFIG_PROC_FS */
/*
* If a hint addr is less than mmap_min_addr change hint to be as
* low as possible but still greater than mmap_min_addr
@@ -1556,7 +1538,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
unsigned long charged = 0;
/* Check against address space limit. */
if (!may_expand_vm(mm, len >> PAGE_SHIFT)) {
if (!may_expand_vm(mm, vm_flags, len >> PAGE_SHIFT)) {
unsigned long nr_pages;
/*
@@ -1565,7 +1547,8 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
*/
nr_pages = count_vma_pages_range(mm, addr, addr + len);
if (!may_expand_vm(mm, (len >> PAGE_SHIFT) - nr_pages))
if (!may_expand_vm(mm, vm_flags,
(len >> PAGE_SHIFT) - nr_pages))
return -ENOMEM;
}
@@ -1664,7 +1647,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
out:
perf_event_mmap(vma);
vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
vm_stat_account(mm, vm_flags, len >> PAGE_SHIFT);
if (vm_flags & VM_LOCKED) {
if (!((vm_flags & VM_SPECIAL) || is_vm_hugetlb_page(vma) ||
vma == get_gate_vma(current->mm)))
@@ -2111,7 +2094,7 @@ static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, uns
unsigned long new_start, actual_size;
/* address space limit tests */
if (!may_expand_vm(mm, grow))
if (!may_expand_vm(mm, vma->vm_flags, grow))
return -ENOMEM;
/* Stack limit test */
@@ -2208,8 +2191,7 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
spin_lock(&mm->page_table_lock);
if (vma->vm_flags & VM_LOCKED)
mm->locked_vm += grow;
vm_stat_account(mm, vma->vm_flags,
vma->vm_file, grow);
vm_stat_account(mm, vma->vm_flags, grow);
anon_vma_interval_tree_pre_update_vma(vma);
vma->vm_end = address;
anon_vma_interval_tree_post_update_vma(vma);
@@ -2284,8 +2266,7 @@ int expand_downwards(struct vm_area_struct *vma,
spin_lock(&mm->page_table_lock);
if (vma->vm_flags & VM_LOCKED)
mm->locked_vm += grow;
vm_stat_account(mm, vma->vm_flags,
vma->vm_file, grow);
vm_stat_account(mm, vma->vm_flags, grow);
anon_vma_interval_tree_pre_update_vma(vma);
vma->vm_start = address;
vma->vm_pgoff -= grow;
@@ -2399,7 +2380,7 @@ static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma)
if (vma->vm_flags & VM_ACCOUNT)
nr_accounted += nrpages;
vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages);
vm_stat_account(mm, vma->vm_flags, -nrpages);
vma = remove_vma(vma);
} while (vma);
vm_unacct_memory(nr_accounted);
@@ -2769,7 +2750,7 @@ static unsigned long do_brk(unsigned long addr, unsigned long len)
}
/* Check against address space limits *after* clearing old maps... */
if (!may_expand_vm(mm, len >> PAGE_SHIFT))
if (!may_expand_vm(mm, flags, len >> PAGE_SHIFT))
return -ENOMEM;
if (mm->map_count > sysctl_max_map_count)
@@ -2804,6 +2785,7 @@ static unsigned long do_brk(unsigned long addr, unsigned long len)
out:
perf_event_mmap(vma);
mm->total_vm += len >> PAGE_SHIFT;
mm->data_vm += len >> PAGE_SHIFT;
if (flags & VM_LOCKED)
mm->locked_vm += (len >> PAGE_SHIFT);
vma->vm_flags |= VM_SOFTDIRTY;
@@ -2995,9 +2977,28 @@ out:
* Return true if the calling process may expand its vm space by the passed
* number of pages
*/
int may_expand_vm(struct mm_struct *mm, unsigned long npages)
bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages)
{
return mm->total_vm + npages <= rlimit(RLIMIT_AS) >> PAGE_SHIFT;
if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT)
return false;
if ((flags & (VM_WRITE | VM_SHARED | (VM_STACK_FLAGS &
(VM_GROWSUP | VM_GROWSDOWN)))) == VM_WRITE)
return mm->data_vm + npages <= rlimit(RLIMIT_DATA);
return true;
}
void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages)
{
mm->total_vm += npages;
if ((flags & (VM_EXEC | VM_WRITE)) == VM_EXEC)
mm->exec_vm += npages;
else if (flags & (VM_STACK_FLAGS & (VM_GROWSUP | VM_GROWSDOWN)))
mm->stack_vm += npages;
else if ((flags & (VM_WRITE | VM_SHARED)) == VM_WRITE)
mm->data_vm += npages;
}
static int special_mapping_fault(struct vm_area_struct *vma,
@@ -3079,7 +3080,7 @@ static struct vm_area_struct *__install_special_mapping(
if (ret)
goto out;
mm->total_vm += len >> PAGE_SHIFT;
vm_stat_account(mm, vma->vm_flags, len >> PAGE_SHIFT);
perf_event_mmap(vma);