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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

include/linux/huge_mm.h

+2 −1
Original line number Diff line number Diff line
@@ -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

+16 −19
Original line number Diff line number Diff line
@@ -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 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, 
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())