The patch titled
Subject: mm: more checks on free_pages_prepare() for tail pages
has been added to the -mm tree. Its filename is
mm-more-checks-on-free_pages_prepare-for-tail-pages.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-more-checks-on-free_pages_prepare-for-tail-pages.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-more-checks-on-free_pages_prepare-for-tail-pages.patch
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From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Subject: mm: more checks on free_pages_prepare() for tail pages
Although it was not called, destroy_compound_page() did some potentially
useful checks. Let's re-introduce them in free_pages_prepare(), where
they can be acctually triggered.
compound_order() assert is already in free_pages_prepare(). We have few
checks for tail pages left.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 27 +++++++++++++++++++++++----
1 file changed, 23 insertions(+), 4 deletions(-)
diff -puN mm/page_alloc.c~mm-more-checks-on-free_pages_prepare-for-tail-pages mm/page_alloc.c
--- a/mm/page_alloc.c~mm-more-checks-on-free_pages_prepare-for-tail-pages
+++ a/mm/page_alloc.c
@@ -764,21 +764,40 @@ static void free_one_page(struct zone *z
spin_unlock(&zone->lock);
}
+static int free_tail_pages_check(struct page *head_page, struct page *page)
+{
+ if (!IS_ENABLED(CONFIG_DEBUG_VM))
+ return 0;
+ if (unlikely(!PageTail(page))) {
+ bad_page(page, "PageTail not set", 0);
+ return 1;
+ }
+ if (unlikely(page->first_page != head_page)) {
+ bad_page(page, "first_page not consistent", 0);
+ return 1;
+ }
+ return 0;
+}
+
static bool free_pages_prepare(struct page *page, unsigned int order)
{
- int i;
- int bad = 0;
+ bool compound = PageCompound(page);
+ int i, bad = 0;
VM_BUG_ON_PAGE(PageTail(page), page);
- VM_BUG_ON_PAGE(PageHead(page) && compound_order(page) != order, page);
+ VM_BUG_ON_PAGE(compound && compound_order(page) != order, page);
trace_mm_page_free(page, order);
kmemcheck_free_shadow(page, order);
if (PageAnon(page))
page->mapping = NULL;
- for (i = 0; i < (1 << order); i++)
+ bad += free_pages_check(page);
+ for (i = 1; i < (1 << order); i++) {
+ if (compound)
+ free_tail_pages_check(page, page + i);
bad += free_pages_check(page + i);
+ }
if (bad)
return false;
_
Patches currently in -mm which might be from kirill.shutemov@xxxxxxxxxxxxxxx are
mm-protect-set_page_dirty-from-ongoing-truncation.patch
mm-replace-remap_file_pages-syscall-with-emulation.patch
mm-drop-support-of-non-linear-mapping-from-unmap-zap-codepath.patch
mm-drop-support-of-non-linear-mapping-from-fault-codepath.patch
mm-drop-vm_ops-remap_pages-and-generic_file_remap_pages-stub.patch
proc-drop-handling-non-linear-mappings.patch
rmap-drop-support-of-non-linear-mappings.patch
mm-replace-vma-shareadlinear-with-vma-shared.patch
mm-remove-rest-usage-of-vm_nonlinear-and-pte_file.patch
asm-generic-drop-unused-pte_file-helpers.patch
alpha-drop-_page_file-and-pte_file-related-helpers.patch
arc-drop-_page_file-and-pte_file-related-helpers.patch
arc-drop-_page_file-and-pte_file-related-helpers-fix.patch
arm64-drop-pte_file-and-pte_file-related-helpers.patch
arm-drop-l_pte_file-and-pte_file-related-helpers.patch
avr32-drop-_page_file-and-pte_file-related-helpers.patch
blackfin-drop-pte_file.patch
c6x-drop-pte_file.patch
cris-drop-_page_file-and-pte_file-related-helpers.patch
frv-drop-_page_file-and-pte_file-related-helpers.patch
hexagon-drop-_page_file-and-pte_file-related-helpers.patch
ia64-drop-_page_file-and-pte_file-related-helpers.patch
m32r-drop-_page_file-and-pte_file-related-helpers.patch
m68k-drop-_page_file-and-pte_file-related-helpers.patch
metag-drop-_page_file-and-pte_file-related-helpers.patch
microblaze-drop-_page_file-and-pte_file-related-helpers.patch
mips-drop-_page_file-and-pte_file-related-helpers.patch
mn10300-drop-_page_file-and-pte_file-related-helpers.patch
nios2-drop-_page_file-and-pte_file-related-helpers.patch
openrisc-drop-_page_file-and-pte_file-related-helpers.patch
parisc-drop-_page_file-and-pte_file-related-helpers.patch
powerpc-drop-_page_file-and-pte_file-related-helpers.patch
s390-drop-pte_file-related-helpers.patch
score-drop-_page_file-and-pte_file-related-helpers.patch
sh-drop-_page_file-and-pte_file-related-helpers.patch
sparc-drop-pte_file-related-helpers.patch
tile-drop-pte_file-related-helpers.patch
um-drop-_page_file-and-pte_file-related-helpers.patch
unicore32-drop-pte_file-related-helpers.patch
x86-drop-_page_file-and-pte_file-related-helpers.patch
xtensa-drop-_page_file-and-pte_file-related-helpers.patch
mm-memory-remove-vm_file-check-on-shared-writable-vmas.patch
mm-memory-merge-shared-writable-dirtying-branches-in-do_wp_page.patch
mm-add-fields-for-compound-destructor-and-order-into-struct-page.patch
mm-add-vm_bug_on_page-for-page_mapcount.patch
mm-numa-do-not-dereference-pmd-outside-of-the-lock-during-numa-hinting-fault.patch
mm-add-p-protnone-helpers-for-use-by-numa-balancing.patch
mm-convert-p_numa-users-to-p_protnone_numa.patch
ppc64-add-paranoid-warnings-for-unexpected-dsisr_protfault.patch
mm-convert-p_mknonnuma-and-remaining-page-table-manipulations.patch
mm-remove-remaining-references-to-numa-hinting-bits-and-helpers.patch
mm-numa-do-not-trap-faults-on-the-huge-zero-page.patch
x86-mm-restore-original-pte_special-check.patch
mm-numa-add-paranoid-check-around-pte_protnone_numa.patch
mm-numa-avoid-unnecessary-tlb-flushes-when-setting-numa-hinting-entries.patch
mm-set-page-pfmemalloc-in-prep_new_page.patch
mm-page_alloc-reduce-number-of-alloc_pages-functions-parameters.patch
mm-reduce-try_to_compact_pages-parameters.patch
mm-microoptimize-zonelist-operations.patch
mm-page_allocc-drop-dead-destroy_compound_page.patch
mm-more-checks-on-free_pages_prepare-for-tail-pages.patch
mm-more-checks-on-free_pages_prepare-for-tail-pages-fix.patch
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