projects/linux·commit a7d6e4ec

thp: prevent hugepages during args/env copying into the user stack

a7d6e4ec · Andrea Arcangeli <[email protected]> · 2011-02-15 19:02:45 +01:00

Transparent hugepages can only be created if rmap is fully
functional. So we must prevent hugepages to be created while
is_vma_temporary_stack() is true.

This also optmizes away some harmless but unnecessary setting of
khugepaged_scan.address and it switches some BUG_ON to VM_BUG_ON.

Signed-off-by: Andrea Arcangeli <[email protected]>
Acked-by: Rik van Riel <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Commit
a7d6e4ecdb7648478ddec76d30d87d03d6e22b31
Parents
09f586b3

Changes

2 files changed · +18 −20

FileStatusAddDelContent
include/linux/huge_mm.hmodified+2−1View file
mm/huge_memory.cmodified+16−19View file

include/linux/huge_mm.h

View file
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 8e6c8c4..df29c8f 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -57,7 +57,8 @@ extern pmd_t *page_check_address_pmd(struct page *page,
(transparent_hugepage_flags & \
(1<<TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG) && \
((__vma)->vm_flags & VM_HUGEPAGE))) && \
- !((__vma)->vm_flags & VM_NOHUGEPAGE))
+ !((__vma)->vm_flags & VM_NOHUGEPAGE) && \
+ !is_vma_temporary_stack(__vma))
#define transparent_hugepage_defrag(__vma) \
((transparent_hugepage_flags & \
(1<<TRANSPARENT_HUGEPAGE_DEFRAG_FLAG)) || \

mm/huge_memory.c

View file
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index e62ddb8..3e29781 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1811,6 +1811,8 @@ static void collapse_huge_page(struct mm_struct *mm,
/* VM_PFNMAP vmas may have vm_ops null but vm_file set */
if (!vma->anon_vma || vma->vm_ops || vma->vm_file)
goto out;
+ if (is_vma_temporary_stack(vma))
+ goto out;
VM_BUG_ON(is_linear_pfn_mapping(vma) || is_pfn_mapping(vma));
pgd = pgd_offset(mm, address);
@@ -2032,32 +2034,27 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
if ((!(vma->vm_flags & VM_HUGEPAGE) &&
!khugepaged_always()) ||
(vma->vm_flags & VM_NOHUGEPAGE)) {
+ skip:
progress++;
continue;
}
-
/* VM_PFNMAP vmas may have vm_ops null but vm_file set */
- if (!vma->anon_vma || vma->vm_ops || vma->vm_file) {
- khugepaged_scan.address = vma->vm_end;
- progress++;
- continue;
- }
+ if (!vma->anon_vma || vma->vm_ops || vma->vm_file)
+ goto skip;
+ if (is_vma_temporary_stack(vma))
+ goto skip;
+
VM_BUG_ON(is_linear_pfn_mapping(vma) || is_pfn_mapping(vma));
hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
hend = vma->vm_end & HPAGE_PMD_MASK;
- if (hstart >= hend) {
- progress++;
- continue;
- }
+ if (hstart >= hend)
+ goto skip;
+ if (khugepaged_scan.address > hend)
+ goto skip;
if (khugepaged_scan.address < hstart)
khugepaged_scan.address = hstart;
- if (khugepaged_scan.address > hend) {
- khugepaged_scan.address = hend + HPAGE_PMD_SIZE;
- progress++;
- continue;
- }
- BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK);
+ VM_BUG_ON(khugepaged_scan.address & ~HPAGE_PMD_MASK);
while (khugepaged_scan.address < hend) {
int ret;
@@ -2086,7 +2083,7 @@ breakouterloop:
breakouterloop_mmap_sem:
spin_lock(&khugepaged_mm_lock);
- BUG_ON(khugepaged_scan.mm_slot != mm_slot);
+ VM_BUG_ON(khugepaged_scan.mm_slot != mm_slot);
/*
* Release the current mm_slot if this mm is about to die, or
* if we scanned all vmas of this mm.
@@ -2241,9 +2238,9 @@ static int khugepaged(void *none)
for (;;) {
mutex_unlock(&khugepaged_mutex);
- BUG_ON(khugepaged_thread != current);
+ VM_BUG_ON(khugepaged_thread != current);
khugepaged_loop();
- BUG_ON(khugepaged_thread != current);
+ VM_BUG_ON(khugepaged_thread != current);
mutex_lock(&khugepaged_mutex);
if (!khugepaged_enabled())