Xin,
I'm attaching a patch that we've been using since late May/early June to
address an "Eeek" issues. Since we applied the patch, we haven't seen the
issue. As this was some time ago, I cannot recall if this is the same
problem that you're seeing now. The patch wasn't submitted, as it isn't
particularly clean. It's one of the many "some day soon" patches that we
need to get resubmitted after a bit more work. I attach it here, not
because
I believe that it is "the answer", but as a data point for you.
-b
On 8/1/06, Keir Fraser <Keir.Fraser@xxxxxxxxxxxx> wrote:
On 1 Aug 2006, at 11:39, Li, Xin B wrote:
>> Do you mind creating a patch to do this? I can send you more
>> details if you like.
>
> Sure, pls send more info on this.
1. Add an 'int has_foreign_mappings' to mmu_context structure
2. Ensure the field is initialised in init_new_context() (e.g.,
memset-zero the whole structure; already done on x86/64)
3. Set the field in direct_remap_pfn_range()
4. Check the field in _arch_exit_mmap() to avoid calling mm_unpin().
That's it. Just needs testing.
-- Keir
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------------------------------------------------------------------------
# HG changeset patch
# User lively@dlively2
# Node ID 2d63622421e93895f9f5c99d900e80e78943b0c6
# Parent 0b79b3c194b17dcf4d7916e33628feb321cc1e05
Robert's workaround for the infamous Eeek! page_mapcount(page) went negative!
bug.
[Bug id:] 3914
[Reviewed By:] Ben & Dave L
diff -r 0b79b3c194b1 -r 2d63622421e9
linux-2.6-xen-sparse/drivers/xen/privcmd/privcmd.c
--- a/linux-2.6-xen-sparse/drivers/xen/privcmd/privcmd.c Sat Jun 10
13:23:11 2006 -0400
+++ b/linux-2.6-xen-sparse/drivers/xen/privcmd/privcmd.c Tue Jun 13
11:05:44 2006 -0400
@@ -244,7 +244,7 @@ static int privcmd_mmap(struct file * fi
static int privcmd_mmap(struct file * file, struct vm_area_struct * vma)
{
/* DONTCOPY is essential for Xen as copy_page_range is broken. */
- vma->vm_flags |= VM_RESERVED | VM_IO | VM_DONTCOPY;
+ vma->vm_flags |= VM_RESERVED | VM_IO | VM_DONTCOPY | VM_PRIVCMD;
return 0;
}
diff -r 0b79b3c194b1 -r 2d63622421e9 linux-2.6-xen-sparse/include/linux/mm.h
--- a/linux-2.6-xen-sparse/include/linux/mm.h Sat Jun 10 13:23:11 2006 -0400
+++ b/linux-2.6-xen-sparse/include/linux/mm.h Tue Jun 13 11:05:44 2006 -0400
@@ -169,6 +169,7 @@ extern unsigned int kobjsize(const void
#ifdef CONFIG_XEN
#define VM_FOREIGN 0x04000000 /* Has pages belonging to another VM */
#endif
+#define VM_PRIVCMD 0x08000000 /* Pages belong to privcmd mmap */
#ifndef VM_STACK_DEFAULT_FLAGS /* arch can override this */
#define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS
diff -r 0b79b3c194b1 -r 2d63622421e9 linux-2.6-xen-sparse/mm/memory.c
--- a/linux-2.6-xen-sparse/mm/memory.c Sat Jun 10 13:23:11 2006 -0400
+++ b/linux-2.6-xen-sparse/mm/memory.c Tue Jun 13 11:05:44 2006 -0400
@@ -409,6 +409,10 @@ struct page *vm_normal_page(struct vm_ar
print_bad_pte(vma, pte, addr);
return NULL;
}
+
+ /* This vma points to foreign pages */
+ if (vma->vm_flags & VM_PRIVCMD)
+ return NULL;
/*
* NOTE! We still have PageReserved() pages in the page
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