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SubjectRe: [PATCH] mm acct accounting fix
>>Sorry, forgot to write that all these patches are against 2.6.12-rc4...
>>
>>This patch fixes mm->total_vm and mm->locked_vm acctounting in case
>>when move_page_tables() fails inside move_vma().
>>
>>Signed-Off-By: Kirill Korotaev <dev@sw.ru>
>>
>>--- ./mm/mremap.c.mmacct 2005-05-10 16:10:40.000000000 +0400
>>+++ ./mm/mremap.c 2005-05-10 18:12:13.000000000 +0400
>>@@ -213,6 +213,7 @@ static unsigned long move_vma(struct vm_
>> old_len = new_len;
>> old_addr = new_addr;
>> new_addr = -ENOMEM;
>>+ new_len = 0;
>> }
>>
>> /* Conceal VM_ACCOUNT so old reservation is not undone */
>
>
> Are you sure?
>
> The way it's supposed to work is that the do_munmap(,,old_len) which
> follows, which normally unmaps the area moved from, when unsuccessful
> unmaps the area moved to: which will "mistakenly" decrement total_vm etc.
> by old_len, which needs to be bumped back up by that amount before leaving.

Yup, I was wrong. Sorry for taking your time.
It would be nice to accept this small patch with a comment.

Kirill

--- ./mm/mremap.c.mmacct 2005-05-10 16:10:40.000000000 +0400
+++ ./mm/mremap.c 2005-05-12 11:56:17.000000000 +0400
@@ -224,6 +224,12 @@ static unsigned long move_vma(struct vm_
split = 1;
}

+ /*
+ * if we failed to move page tables we still do total_vm increment
+ * since do_munmap() will decrement it by old_len == new_len
+ */
+ mm->total_vm += new_len >> PAGE_SHIFT;
+
if (do_munmap(mm, old_addr, old_len) < 0) {
/* OOM: unable to split vma, just get accounts right */
vm_unacct_memory(excess >> PAGE_SHIFT);
@@ -237,7 +243,6 @@ static unsigned long move_vma(struct vm_
vma->vm_next->vm_flags |= VM_ACCOUNT;
}

- mm->total_vm += new_len >> PAGE_SHIFT;
__vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT);
if (vm_flags & VM_LOCKED) {
mm->locked_vm += new_len >> PAGE_SHIFT;
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