The patch titled
Subject: mm/hugetlb.c: undo change to page mapcount in fault handler
has been added to the -mm tree. Its filename is
mm-hugetlb-undo-change-to-page-mapcount-in-fault-handler.patch
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From: Hillf Danton <dhillf@xxxxxxxxx>
Subject: 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@xxxxxxxxx>
Reviewed-by: Michal Hocko <mhocko@xxxxxxx>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/hugetlb.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff -puN mm/hugetlb.c~mm-hugetlb-undo-change-to-page-mapcount-in-fault-handler mm/hugetlb.c
--- a/mm/hugetlb.c~mm-hugetlb-undo-change-to-page-mapcount-in-fault-handler
+++ a/mm/hugetlb.c
@@ -2508,6 +2508,7 @@ static int hugetlb_no_page(struct mm_str
{
struct hstate *h = hstate_vma(vma);
int ret = VM_FAULT_SIGBUS;
+ int anon_rmap = 0;
pgoff_t idx;
unsigned long size;
struct page *page;
@@ -2562,14 +2563,13 @@ retry:
spin_lock(&inode->i_lock);
inode->i_blocks += blocks_per_huge_page(h);
spin_unlock(&inode->i_lock);
- page_dup_rmap(page);
} else {
lock_page(page);
if (unlikely(anon_vma_prepare(vma))) {
ret = VM_FAULT_OOM;
goto backout_unlocked;
}
- hugepage_add_new_anon_rmap(page, vma, address);
+ anon_rmap = 1;
}
} else {
/*
@@ -2582,7 +2582,6 @@ retry:
VM_FAULT_SET_HINDEX(h - hstates);
goto backout_unlocked;
}
- page_dup_rmap(page);
}
/*
@@ -2606,6 +2605,10 @@ retry:
if (!huge_pte_none(huge_ptep_get(ptep)))
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)
&& (vma->vm_flags & VM_SHARED)));
set_huge_pte_at(mm, address, ptep, new_pte);
_
Subject: Subject: mm/hugetlb.c: undo change to page mapcount in fault handler
Patches currently in -mm which might be from dhillf@xxxxxxxxx are
origin.patch
linux-next.patch
hugetlb-detect-race-upon-page-allocation-failure-during-cow.patch
hugetlb-clarify-hugetlb_instantiation_mutex-usage.patch
mm-compaction-push-isolate-search-base-of-compact-control-one-pfn-ahead.patch
mm-hugetlb-fix-pgoff-computation-when-unmapping-page-from-vma.patch
mm-hugetlb-fix-pgoff-computation-when-unmapping-page-from-vma-fix.patch
mm-hugetlb-avoid-bogus-counter-of-surplus-huge-page.patch
mm-vmscan-fix-typo-in-isolating-lru-pages.patch
mm-hugetlb-undo-change-to-page-mapcount-in-fault-handler.patch
mm-vmscanc-check-page-order-when-isolating-lru-pages.patch
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