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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 <[email protected]>
Signed-off-by: Cyrill Gorcunov <[email protected]>
Cc: Quentin Casasnovas <[email protected]>
Cc: Vegard Nossum <[email protected]>
Acked-by: Linus Torvalds <[email protected]>
Cc: Willy Tarreau <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Vladimir Davydov <[email protected]>
Cc: Pavel Emelyanov <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Konstantin Khlebnikov 2016-01-14 15:22:07 -08:00 • committed by Linus Torvalds
commit 8463833590
9 changed files with 54 additions and 58 deletions
Download patch file Download diff file Expand all files Collapse all files

7
mm/mremap.c
View file

@ -317,7 +317,7 @@ static unsigned long move_vma(struct vm_area_struct *vma,
* If this were a serious issue, we'd add a flag to do_munmap().
*/
hiwater_vm = mm->hiwater_vm;
vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT);
vm_stat_account(mm, vma->vm_flags, new_len >> PAGE_SHIFT);
/* Tell pfnmap has moved from this vma */
if (unlikely(vma->vm_flags & VM_PFNMAP))
@ -383,7 +383,8 @@ static struct vm_area_struct *vma_to_resize(unsigned long addr,
return ERR_PTR(-EAGAIN);
}
if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT))
if (!may_expand_vm(mm, vma->vm_flags,
(new_len - old_len) >> PAGE_SHIFT))
return ERR_PTR(-ENOMEM);
if (vma->vm_flags & VM_ACCOUNT) {
@ -545,7 +546,7 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
goto out;
}
vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages);
vm_stat_account(mm, vma->vm_flags, pages);
if (vma->vm_flags & VM_LOCKED) {
mm->locked_vm += pages;
locked = true;