Jes, > Well you suggested a patch which just hides the problem. I suggest you > change it to have the BUG_ON(). IMHO you are wrong. the suggested patch *fixes* one particular place, which can be triggered on mainstream IA64 by a standard user and is actually a *SECURITY* bug which can be potentially exploited (when OOM killer is enabled). It doesn't hide anything, It just doesn't help to catch other places. >>>Which callers did you see cause this? If it was a common problem I would >>>expect a lot of data corruption or crashes on ia64 systems which I >>>haven't heard of. >> >>from the patch: >>pte_alloc_one() calls pgtable_quicklist_alloc() which can return NULL in >>case of allocation failure. >> >>It was hit on OpenVZ where kernel memory is accounted and limited on >>per-container basis (it is possible to DoS using page tables allocations). >>In mainstream the bug can be hit if OOM killer >>kills the process and __get_free_page() returns NULL which is rare, but still possible. > > > I see, since you have it tracked down, it would be good to fix it > and push a patch upstream. Unless of course Andrew or Linus thinks this > is the wrong approach. Maybe the fact that I came without an exploit to crash IA64 makes you think it should not be commited, ok, you can leave it as is then. NOTE: I don't mind against the debug you proposed. It is quite a good idea. Thanks, Kirill - To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
|