On Thu, Dec 27, 2001 at 10:55:18AM +0900, Atsushi Nemoto wrote:
> >> In somewhere between 2.4.6 and 2.4.9, the call to flush_cache_all()
> >> disappered from vmalloc_area_pages(). I have a data corruption
> >> problem in vmalloc()ed area without this call. I think we still
> >> need this call.
> ralf> Have you ever resolved this problem? I've just doublechecked
> ralf> the vmalloc code and it seems as if it should be entirely safe
> ralf> without these two calls. The tlb is flushed on vfree so no
> ralf> stale entries for a vmalloc address can ever be in the tlb at
> ralf> vmalloc time, so this flush_tlb_all() is just an expensive nop.
> ralf> And the same it true for flush_cache_all() no matter if caches
> ralf> are physically or virtually indexed.
> I am still using the patch and have not tried without the two calls
> When I found this problem, I suppose that vmalloc called after
> free_pages causes the data corruption. vmalloc can re-use pages freed
> by free_pages and it seems free_pages does not flush cache. If
> vmalloc is to use a page which is associated with dirty cache and has
> different "color", virtual aliasing happens and data may be corrupt.
> Is this wrong?
Yes, you're right as for the cache. But there is no reason for the
TLB flush, right?