Jes Sorensen wrote: > Kirill Korotaev wrote: > >>>>>>>>"akpm" == akpm <akpm@xxxxxxxx> writes: >>> >>>akpm> From: Kirill Korotaev <dev@xxxxxxxxxx> It does not return NULL >>>akpm> when arg is NULL. >>> >>>Shouldn't the real fix be to track down who calls virt_to_page() with >>>a NULL pointer? IMHO it is bogus to do so. >> >>what do you propose? to insert BUG_ON(!kaddr) into virt_to_page()? >>in this case caller in question should be still fixed. > > > If you hit this, yes I'd insert the BUG_ON in your test kernel and fix > the code. Maybe add the BUG_ON in upstream for CONFIG_DEBUG or > something. I guess then all the platforms should be analyzed/patched carefully or all the callers of virt_to_page(). Care to create debug patch? > 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. 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
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