Re: [parisc-linux] Re: Problems with kernel mmap (failing tst-mmap-eofsync in glibc on parisc)

[James Bottomley <James.Bottomley@steeleye.com>]

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On Sat, 2003-08-23 at 02:22, Hugh Dickins wrote:
> Good idea.  It's VM_MAYSHARE you need to check for.

OK, to get all this to work, there's a corner case in do_mremap() that I
need to be fixed:

When choosing the flags for the new area, it keys off VM_SHARED to
determine whether MAP_SHARED is passed to the mapping.  It has to key of
VM_MAYSHARE to preserve VM_MAYSHARE on the new mapping.

Patch below.

James



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===== mremap.c 1.32 vs edited =====
--- 1.32/mm/mremap.c	Thu Aug  7 12:29:10 2003
+++ edited/mremap.c	Sat Aug 23 10:54:21 2003
@@ -420,7 +420,7 @@
 	if (flags & MREMAP_MAYMOVE) {
 		if (!(flags & MREMAP_FIXED)) {
 			unsigned long map_flags = 0;
-			if (vma->vm_flags & VM_SHARED)
+			if (vma->vm_flags & VM_MAYSHARE)
 				map_flags |= MAP_SHARED;
 
 			new_addr = get_unmapped_area(vma->vm_file, 0, new_len,