Messages in this thread | | | Date | Thu, 28 Dec 2017 12:51:14 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [lkp-robot] [x86/cpu_entry_area] 10043e02db: kernel_BUG_at_arch/x86/mm/physaddr.c |
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On Wed, 27 Dec 2017, Dmitry Vyukov wrote: > On Wed, Dec 27, 2017 at 7:05 PM, Thomas Gleixner <tglx@linutronix.de> wrote: > > So this dies simply because kasan_populate_shadow() runs out of memory and > > has no sanity check whatsoever. > > > > static __init void *early_alloc(size_t size, int nid) > > { > > return memblock_virt_alloc_try_nid_nopanic(size, size, > > __pa(MAX_DMA_ADDRESS), BOOTMEM_ALLOC_ACCESSIBLE, nid); > > } > > > > kasan_populate_pmd() > > { > > ..... > > > > p = early_alloc(PAGE_SIZE, nid); > > entry = pfn_pte(PFN_DOWN(__pa(p)), PAGE_KERNEL); > > > > I've instrumented the whole thing and early_alloc() returns NULL at some > > point and then __pa(NULL) dies in the VIRTUAL_DEBUG code. Well, it would > > die with VIRTUAL_DEBUG=n as well at some other place. > > > > Not really a problem caused by the patch above, it's merily exposing a code > > path which relies blindly on "enough memory available" assumptions. > > > > Throwing more memory at the VM makes the problem go away... > > Hi Thomas, > > We just need a check inside of early_alloc() to properly diagnose such > situation, right?
At least you want to panic with a proper out of memory message. But letting the thing die at a random place is a bad idea.
Thanks,
tglx
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