From 83e9b7e929d1323b9a155d186f77aa8c06155cc3 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Mon, 21 Nov 2005 21:32:12 -0800 Subject: [PATCH] [PATCH] unpaged: private write VM_RESERVED The PageReserved removal in 2.6.15-rc1 issued a "deprecated" message when you tried to mmap or mprotect MAP_PRIVATE PROT_WRITE a VM_RESERVED, and failed with -EACCES: because do_wp_page lacks the refinement to COW pages in those areas, nor do we expect to find anonymous pages in them; and it seemed just bloat to add code for handling such a peculiar case. But immediately it caused vbetool and ddcprobe (using lrmi) to fail. So revert the "deprecated" messages, letting mmap and mprotect succeed. But leave do_wp_page's BUG_ON(vma->vm_flags & VM_RESERVED) in place until we've added the code to do it right: so this particular patch is only good if the app doesn't really need to write to that private area. Signed-off-by: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/mmap.c | 11 ----------- mm/mprotect.c | 8 -------- 2 files changed, 19 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 4f8def03428..11ca5927d5f 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1076,17 +1076,6 @@ munmap_back: error = file->f_op->mmap(file, vma); if (error) goto unmap_and_free_vma; - if ((vma->vm_flags & (VM_SHARED | VM_WRITE | VM_RESERVED)) - == (VM_WRITE | VM_RESERVED)) { - printk(KERN_WARNING "program %s is using MAP_PRIVATE, " - "PROT_WRITE mmap of VM_RESERVED memory, which " - "is deprecated. Please report this to " - "linux-kernel@vger.kernel.org\n",current->comm); - if (vma->vm_ops && vma->vm_ops->close) - vma->vm_ops->close(vma); - error = -EACCES; - goto unmap_and_free_vma; - } } else if (vm_flags & VM_SHARED) { error = shmem_zero_setup(vma); if (error) diff --git a/mm/mprotect.c b/mm/mprotect.c index 17a2b52b753..653b8571c1e 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -124,14 +124,6 @@ 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_RESERVED) { - BUG_ON(oldflags & VM_WRITE); - printk(KERN_WARNING "program %s is using MAP_PRIVATE, " - "PROT_WRITE mprotect of VM_RESERVED memory, " - "which is deprecated. Please report this to " - "linux-kernel@vger.kernel.org\n",current->comm); - return -EACCES; - } if (!(oldflags & (VM_ACCOUNT|VM_WRITE|VM_SHARED|VM_HUGETLB))) { charged = nrpages; if (security_vm_enough_memory(charged)) -- 2.20.1