On Thu, 2008-06-26 at 10:55 +0100, Andy Whitcroft wrote: > The implementation of huge_ptep_set_wrprotect() directly calls > ptep_set_wrprotect() to mark a hugepte write protected. However this > call is not appropriate on ppc64 kernels as this is a small page only > implementation. This can lead to the hash not being flushed correctly > when a mapping is being converted to COW, allowing processes to continue > using the original copy. > > Currently huge_ptep_set_wrprotect() unconditionally calls > ptep_set_wrprotect(). This is fine on ppc32 kernels as this call is > generic. On 64 bit this is implemented as: > > pte_update(mm, addr, ptep, _PAGE_RW, 0); > > On ppc64 this last parameter is the page size and is passed directly on > to hpte_need_flush(): > > hpte_need_flush(mm, addr, ptep, old, huge); > > And this directly affects the page size we pass to flush_hash_page(): > > flush_hash_page(vaddr, rpte, psize, ssize, 0); > > As this changes the way the hash is calculated we will flush the wrong > pages, potentially leaving live hashes to the original page. > > Move the definition of huge_ptep_set_wrprotect() to the 32/64 bit specific > headers. > > Signed-off-by: Andy Whitcroft <[EMAIL PROTECTED]>
Acked-by: Benjamin Herrenschmidt <[EMAIL PROTECTED]> Good catch btw ! Cheers, Ben. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
