From 8f860591ffb29738cf5539b6fbf27f50dcdeb380 Mon Sep 17 00:00:00 2001 From: "Zhang, Yanmin" Date: Wed, 22 Mar 2006 00:08:50 -0800 Subject: [PATCH] Enable mprotect on huge pages 2.6.16-rc3 uses hugetlb on-demand paging, but it doesn_t support hugetlb mprotect. From: David Gibson Remove a test from the mprotect() path which checks that the mprotect()ed range on a hugepage VMA is hugepage aligned (yes, really, the sense of is_aligned_hugepage_range() is the opposite of what you'd guess :-/). In fact, we don't need this test. If the given addresses match the beginning/end of a hugepage VMA they must already be suitably aligned. If they don't, then mprotect_fixup() will attempt to split the VMA. The very first test in split_vma() will check for a badly aligned address on a hugepage VMA and return -EINVAL if necessary. From: "Chen, Kenneth W" On i386 and x86-64, pte flag _PAGE_PSE collides with _PAGE_PROTNONE. The identify of hugetlb pte is lost when changing page protection via mprotect. A page fault occurs later will trigger a bug check in huge_pte_alloc(). The fix is to always make new pte a hugetlb pte and also to clean up legacy code where _PAGE_PRESENT is forced on in the pre-faulting day. Signed-off-by: Zhang Yanmin Cc: David Gibson Cc: "David S. Miller" Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: William Lee Irwin III Signed-off-by: Ken Chen Signed-off-by: Nishanth Aravamudan Cc: Andi Kleen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/mprotect.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) (limited to 'mm/mprotect.c') diff --git a/mm/mprotect.c b/mm/mprotect.c index 653b8571c1ed..4c14d4289b61 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -124,7 +124,7 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev, * a MAP_NORESERVE private mapping to writable will now reserve. */ if (newflags & VM_WRITE) { - if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_SHARED|VM_HUGETLB))) { + if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_SHARED))) { charged = nrpages; if (security_vm_enough_memory(charged)) return -ENOMEM; @@ -166,7 +166,10 @@ success: */ vma->vm_flags = newflags; vma->vm_page_prot = newprot; - change_protection(vma, start, end, newprot); + if (is_vm_hugetlb_page(vma)) + hugetlb_change_protection(vma, start, end, newprot); + else + change_protection(vma, start, end, newprot); vm_stat_account(mm, oldflags, vma->vm_file, -nrpages); vm_stat_account(mm, newflags, vma->vm_file, nrpages); return 0; @@ -240,11 +243,6 @@ sys_mprotect(unsigned long start, size_t len, unsigned long prot) /* Here we know that vma->vm_start <= nstart < vma->vm_end. */ - if (is_vm_hugetlb_page(vma)) { - error = -EACCES; - goto out; - } - newflags = vm_flags | (vma->vm_flags & ~(VM_READ | VM_WRITE | VM_EXEC)); /* newflags >> 4 shift VM_MAY% in place of VM_% */ -- cgit v1.2.3-59-g8ed1b