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| author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2016-09-19 14:44:07 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-09-19 15:36:16 -0700 |
| commit | 4d35427ad7641cba08ea0deffae1a78147ad41c0 (patch) | |
| tree | 832a652ea61f198004cd27bfa8cc56a24087d422 /mm | |
| parent | 982785c6b05a82c01e90687b7e25ee87c8970b2e (diff) | |
| download | linux-0-day-4d35427ad7641cba08ea0deffae1a78147ad41c0.tar.gz linux-0-day-4d35427ad7641cba08ea0deffae1a78147ad41c0.tar.xz | |
mm: avoid endless recursion in dump_page()
dump_page() uses page_mapcount() to get mapcount of the page.
page_mapcount() has VM_BUG_ON_PAGE(PageSlab(page)) as mapcount doesn't
make sense for slab pages and the field in struct page used for other
information.
It leads to recursion if dump_page() called for slub page and DEBUG_VM
is enabled:
dump_page() -> page_mapcount() -> VM_BUG_ON_PAGE() -> dump_page -> ...
Let's avoid calling page_mapcount() for slab pages in dump_page().
Link: http://lkml.kernel.org/r/20160908082137.131076-1-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/debug.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/mm/debug.c b/mm/debug.c index 8865bfb41b0b6..74c7cae4f6837 100644 --- a/mm/debug.c +++ b/mm/debug.c @@ -42,9 +42,11 @@ const struct trace_print_flags vmaflag_names[] = { void __dump_page(struct page *page, const char *reason) { + int mapcount = PageSlab(page) ? 0 : page_mapcount(page); + pr_emerg("page:%p count:%d mapcount:%d mapping:%p index:%#lx", - page, page_ref_count(page), page_mapcount(page), - page->mapping, page->index); + page, page_ref_count(page), mapcount, + page->mapping, page_to_pgoff(page)); if (PageCompound(page)) pr_cont(" compound_mapcount: %d", compound_mapcount(page)); pr_cont("\n"); |