Commit a7d6e4ec authored by Andrea Arcangeli's avatar Andrea Arcangeli Committed by Linus Torvalds
Browse files

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



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: default avatarAndrea Arcangeli <aarcange@redhat.com>
Acked-by: default avatarRik van Riel <riel@redhat.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 09f586b3
......@@ -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)) || \
......
......@@ -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())
......
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