Messages in this thread | | | From | Dmitry Vyukov <> | Date | Thu, 28 Dec 2017 12:54:32 +0100 | Subject | Re: [lkp-robot] [x86/cpu_entry_area] 10043e02db: kernel_BUG_at_arch/x86/mm/physaddr.c |
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On Thu, Dec 28, 2017 at 12:51 PM, Thomas Gleixner <tglx@linutronix.de> wrote: > 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. I will cook a patch (if Andrey won't beat me to it).
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