From: Johannes Weiner <jweiner@redhat.com> Date: Wed, 1 Dec 2010 15:08:06 -0500 Subject: [mm] add guard page for stacks that grow upwards Message-id: <1291216086-10898-1-git-send-email-jweiner@redhat.com> Patchwork-id: 29762 O-Subject: [RHEL5.6 PATCH] mm: guard page for stacks that grow upwards Bugzilla: 630563 RH-Acked-by: Rik van Riel <riel@redhat.com> bz: 630563 brew: 2923460 commit 8ca3eb08097f6839b2206e2242db4179aee3cfb3 Author: Luck, Tony <tony.luck@intel.com> Date: Tue Aug 24 11:44:18 2010 -0700 guard page for stacks that grow upwards pa-risc and ia64 have stacks that grow upwards. Check that they do not run into other mappings. By making VM_GROWSUP 0x0 on architectures that do not ever use it, we can avoid some unpleasant #ifdefs in check_stack_guard_page(). Signed-off-by: Tony Luck <tony.luck@intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Johannes Weiner <jweiner@redhat.com> diff --git a/include/linux/mm.h b/include/linux/mm.h index 896e124..d31424f 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -147,7 +147,11 @@ extern unsigned int kobjsize(const void *objp); #define VM_MAYSHARE 0x00000080 #define VM_GROWSDOWN 0x00000100 /* general info on the segment */ +#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64) #define VM_GROWSUP 0x00000200 +#else +#define VM_GROWSUP 0x00000000 +#endif #define VM_PFNMAP 0x00000400 /* Page-ranges managed without "struct page", just pure PFN */ #define VM_DENYWRITE 0x00000800 /* ETXTBSY on write attempts.. */ @@ -1131,8 +1135,10 @@ unsigned long max_sane_readahead(unsigned long nr); /* Do stack extension */ extern int expand_stack(struct vm_area_struct *vma, unsigned long address); -#ifdef CONFIG_IA64 +#if VM_GROWSUP extern int expand_upwards(struct vm_area_struct *vma, unsigned long address); +#else + #define expand_upwards(vma, address) do { } while (0) #endif extern int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address); diff --git a/mm/memory.c b/mm/memory.c index ef2f14f..4d6a646 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2353,11 +2353,9 @@ out_nomap: } /* - * This is like a special single-page "expand_downwards()", - * except we must first make sure that 'address-PAGE_SIZE' + * This is like a special single-page "expand_{down|up}wards()", + * except we must first make sure that 'address{-|+}PAGE_SIZE' * doesn't hit another vma. - * - * The "find_vma()" will do the right thing even if we wrap */ static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address) { @@ -2378,6 +2376,15 @@ static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned lo expand_stack(vma, address - PAGE_SIZE); } + if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) { + struct vm_area_struct *next = vma->vm_next; + + /* As VM_GROWSDOWN but s/below/above/ */ + if (next && next->vm_start == address + PAGE_SIZE) + return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM; + + expand_upwards(vma, address + PAGE_SIZE); + } return 0; } diff --git a/mm/mmap.c b/mm/mmap.c index 4b7dd25..9bb8262 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1639,9 +1639,6 @@ static int acct_stack_growth(struct vm_area_struct * vma, unsigned long size, un * PA-RISC uses this for its stack; IA64 for its Register Backing Store. * vma is the last one with address > vma->vm_end. Have to extend vma. */ -#ifndef CONFIG_IA64 -static inline -#endif int expand_upwards(struct vm_area_struct *vma, unsigned long address) { int error;