lkml.org 
[lkml]   [2001]   [Jul]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: msync() bug
Chris Wedgwood wrote:
>
> (cc' list snipped)
>
> This stuff is gold.
>
> Anyone clueful want to comment things so this will end up in the
> documentation when you do a make docbook or something?
>

One can but try.

Linus included the test for non-null page->mapping
as well. I wonder why.

Also, the change means that the TLB flush is not performed
for invalid or reserved pages. Is this correct? (Why is there
a TLB flush there in the first place?)

There's a flush_tlb_range() down in filemap_sync() as well, so
we appear to end up flushing the affected TLBs twice?


--- linux-2.4.7-pre5/mm/memory.c Tue Jul 10 22:32:53 2001
+++ linux-akpm/mm/memory.c Tue Jul 10 23:37:45 2001
@@ -766,6 +766,8 @@ int zeromap_page_range(unsigned long add
* maps a range of physical memory into the requested pages. the old
* mappings are removed. any references to nonexistent pages results
* in null mappings (currently treated as "copy-on-access")
+ * We forbid mapping of valid, unreserved pages because that would
+ * allow corruption of their reference counts via this additional mapping.
*/
static inline void remap_pte_range(pte_t * pte, unsigned long address, unsigned long size,
unsigned long phys_addr, pgprot_t prot)
--- linux-2.4.7-pre5/mm/filemap.c Tue Jul 10 22:32:53 2001
+++ linux-akpm/mm/filemap.c Tue Jul 10 23:45:28 2001
@@ -1643,6 +1643,8 @@ page_not_uptodate:

/* Called with mm->page_table_lock held to protect against other
* threads/the swapper from ripping pte's out from under us.
+ * Mappings from remap_pte_range() can cover invalid or reserved
+ * pages, so we must check for that here.
*/
static inline int filemap_sync_pte(pte_t * ptep, struct vm_area_struct *vma,
unsigned long address, unsigned int flags)
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
\
 
 \ /
  Last update: 2005-03-22 12:56    [W:0.064 / U:5.852 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site