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 > recently... > > 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? Ralf
