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authorNick Piggin <npiggin@suse.de>2008-02-08 19:15:19 -0500
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-08 21:57:39 -0500
commitb1d0e4f535e10775cffde922208b49629169aeaa (patch)
treec5fa68fb25ffd2485da5de236fcf2b67d9df3dfd
parent6a306e8b4c81a1c1f538e390d92bfe80d04b254c (diff)
mm: special mapping nopage
Convert special mapping install from nopage to fault. Because the "vm_file" is NULL for the special mapping, the generic VM code has messed up "vm_pgoff" thinking that it's an anonymous mapping and the offset does't matter. For that reason, we need to undo the vm_pgoff offset that got added into vmf->pgoff. [ We _really_ should clean that up - either by making this whole special mapping code just use a real file entry rather than that ugly array of "struct page" pointers, or by just making the VM code realize that even if vm_file is NULL it may not be a regular anonymous mmap. - Linus ] Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/mmap.c25
1 files changed, 16 insertions, 9 deletions
diff --git a/mm/mmap.c b/mm/mmap.c
index ad6e4eaf34f8..a32d28ce31cd 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2165,24 +2165,31 @@ int may_expand_vm(struct mm_struct *mm, unsigned long npages)
2165} 2165}
2166 2166
2167 2167
2168static struct page *special_mapping_nopage(struct vm_area_struct *vma, 2168static int special_mapping_fault(struct vm_area_struct *vma,
2169 unsigned long address, int *type) 2169 struct vm_fault *vmf)
2170{ 2170{
2171 pgoff_t pgoff;
2171 struct page **pages; 2172 struct page **pages;
2172 2173
2173 BUG_ON(address < vma->vm_start || address >= vma->vm_end); 2174 /*
2175 * special mappings have no vm_file, and in that case, the mm
2176 * uses vm_pgoff internally. So we have to subtract it from here.
2177 * We are allowed to do this because we are the mm; do not copy
2178 * this code into drivers!
2179 */
2180 pgoff = vmf->pgoff - vma->vm_pgoff;
2174 2181
2175 address -= vma->vm_start; 2182 for (pages = vma->vm_private_data; pgoff && *pages; ++pages)
2176 for (pages = vma->vm_private_data; address > 0 && *pages; ++pages) 2183 pgoff--;
2177 address -= PAGE_SIZE;
2178 2184
2179 if (*pages) { 2185 if (*pages) {
2180 struct page *page = *pages; 2186 struct page *page = *pages;
2181 get_page(page); 2187 get_page(page);
2182 return page; 2188 vmf->page = page;
2189 return 0;
2183 } 2190 }
2184 2191
2185 return NOPAGE_SIGBUS; 2192 return VM_FAULT_SIGBUS;
2186} 2193}
2187 2194
2188/* 2195/*
@@ -2194,7 +2201,7 @@ static void special_mapping_close(struct vm_area_struct *vma)
2194 2201
2195static struct vm_operations_struct special_mapping_vmops = { 2202static struct vm_operations_struct special_mapping_vmops = {
2196 .close = special_mapping_close, 2203 .close = special_mapping_close,
2197 .nopage = special_mapping_nopage, 2204 .fault = special_mapping_fault,
2198}; 2205};
2199 2206
2200/* 2207/*