From f165b378bbdf6c8afd950060fc3cbc935bb890c6 Mon Sep 17 00:00:00 2001 From: Pavel Tatashin Date: Thu, 5 Apr 2018 16:22:47 -0700 Subject: [PATCH] mm: uninitialized struct page poisoning sanity checking During boot we poison struct page memory in order to ensure that no one is accessing this memory until the struct pages are initialized in __init_single_page(). This patch adds more scrutiny to this checking by making sure that flags do not equal the poison pattern when they are accessed. The pattern is all ones. Since node id is also stored in struct page, and may be accessed quite early, we add this enforcement into page_to_nid() function as well. Note, this is applicable only when NODE_NOT_IN_PAGE_FLAGS=n [pasha.tatashin@oracle.com: v4] Link: http://lkml.kernel.org/r/20180215165920.8570-4-pasha.tatashin@oracle.com Link: http://lkml.kernel.org/r/20180213193159.14606-4-pasha.tatashin@oracle.com Signed-off-by: Pavel Tatashin Reviewed-by: Ingo Molnar Acked-by: Michal Hocko Cc: Baoquan He Cc: Bharata B Rao Cc: Daniel Jordan Cc: Dan Williams Cc: Greg Kroah-Hartman Cc: "H. Peter Anvin" Cc: Kirill A. Shutemov Cc: Mel Gorman Cc: Steven Sistare Cc: Thomas Gleixner Cc: Vlastimil Babka Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mm.h | 4 +++- include/linux/page-flags.h | 22 +++++++++++++++++----- mm/memblock.c | 2 +- 3 files changed, 21 insertions(+), 7 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index f945dff34925..2e40a44a1fae 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -903,7 +903,9 @@ extern int page_to_nid(const struct page *page); #else static inline int page_to_nid(const struct page *page) { - return (page->flags >> NODES_PGSHIFT) & NODES_MASK; + struct page *p = (struct page *)page; + + return (PF_POISONED_CHECK(p)->flags >> NODES_PGSHIFT) & NODES_MASK; } #endif diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 50c2b8786831..e34a27727b9a 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -156,9 +156,18 @@ static __always_inline int PageCompound(struct page *page) return test_bit(PG_head, &page->flags) || PageTail(page); } +#define PAGE_POISON_PATTERN -1l +static inline int PagePoisoned(const struct page *page) +{ + return page->flags == PAGE_POISON_PATTERN; +} + /* * Page flags policies wrt compound pages * + * PF_POISONED_CHECK + * check if this struct page poisoned/uninitialized + * * PF_ANY: * the page flag is relevant for small, head and tail pages. * @@ -176,17 +185,20 @@ static __always_inline int PageCompound(struct page *page) * PF_NO_COMPOUND: * the page flag is not relevant for compound pages. */ -#define PF_ANY(page, enforce) page -#define PF_HEAD(page, enforce) compound_head(page) +#define PF_POISONED_CHECK(page) ({ \ + VM_BUG_ON_PGFLAGS(PagePoisoned(page), page); \ + page; }) +#define PF_ANY(page, enforce) PF_POISONED_CHECK(page) +#define PF_HEAD(page, enforce) PF_POISONED_CHECK(compound_head(page)) #define PF_ONLY_HEAD(page, enforce) ({ \ VM_BUG_ON_PGFLAGS(PageTail(page), page); \ - page;}) + PF_POISONED_CHECK(page); }) #define PF_NO_TAIL(page, enforce) ({ \ VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page); \ - compound_head(page);}) + PF_POISONED_CHECK(compound_head(page)); }) #define PF_NO_COMPOUND(page, enforce) ({ \ VM_BUG_ON_PGFLAGS(enforce && PageCompound(page), page); \ - page;}) + PF_POISONED_CHECK(page); }) /* * Macros to create function definitions for page flags diff --git a/mm/memblock.c b/mm/memblock.c index f7f76513a0c5..c2fed302c2f8 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -1345,7 +1345,7 @@ void * __init memblock_virt_alloc_try_nid_raw( min_addr, max_addr, nid); #ifdef CONFIG_DEBUG_VM if (ptr && size > 0) - memset(ptr, 0xff, size); + memset(ptr, PAGE_POISON_PATTERN, size); #endif return ptr; } -- 2.30.2