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mm/hugetlb.c: undo change to page mapcount in fault handler 

Page mapcount should be updated only if we are sure that the page ends
up in the page table otherwise we would leak if we couldn't COW due to
reservations or if idx is out of bounds.

Signed-off-by: Hillf Danton <dhillf@gmail.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Hillf Danton 2012-01-20 14:34:13 -08:00 committed by Linus Torvalds
parent 6568d4a9c9
commit 409eb8c261
1 changed files with 6 additions and 3 deletions
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9
mm/hugetlb.c
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@ -2508,6 +2508,7 @@ static int hugetlb_no_page(struct mm_struct *mm, struct vm_area_struct *vma,
{ {
struct hstate *h = hstate_vma(vma); struct hstate *h = hstate_vma(vma);
int ret = VM_FAULT_SIGBUS; int ret = VM_FAULT_SIGBUS;
int anon_rmap = 0;
pgoff_t idx; pgoff_t idx;
unsigned long size; unsigned long size;
struct page *page; struct page *page;
@ -2562,14 +2563,13 @@ retry:
spin_lock(&inode->i_lock); spin_lock(&inode->i_lock);
inode->i_blocks += blocks_per_huge_page(h); inode->i_blocks += blocks_per_huge_page(h);
spin_unlock(&inode->i_lock); spin_unlock(&inode->i_lock);
page_dup_rmap(page);
} else { } else {
lock_page(page); lock_page(page);
if (unlikely(anon_vma_prepare(vma))) { if (unlikely(anon_vma_prepare(vma))) {
ret = VM_FAULT_OOM; ret = VM_FAULT_OOM;
goto backout_unlocked; goto backout_unlocked;
} }
hugepage_add_new_anon_rmap(page, vma, address); anon_rmap = 1;
} }
} else { } else {
/* /*
@ -2582,7 +2582,6 @@ retry:
VM_FAULT_SET_HINDEX(h - hstates); VM_FAULT_SET_HINDEX(h - hstates);
goto backout_unlocked; goto backout_unlocked;
} }
page_dup_rmap(page);
} }
/* /*
@ -2606,6 +2605,10 @@ retry:
if (!huge_pte_none(huge_ptep_get(ptep))) if (!huge_pte_none(huge_ptep_get(ptep)))
goto backout; goto backout;
if (anon_rmap)
hugepage_add_new_anon_rmap(page, vma, address);
else
page_dup_rmap(page);
new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE) new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
&& (vma->vm_flags & VM_SHARED))); && (vma->vm_flags & VM_SHARED)));
set_huge_pte_at(mm, address, ptep, new_pte); set_huge_pte_at(mm, address, ptep, new_pte);