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Date: Sun, 09 Sep 2012 10:01:33 -0700 From: "H. Peter Anvin" <hpa@...or.com> To: Linus Torvalds <torvalds@...ux-foundation.org> CC: suresh.b.siddha@...el.com, Sasha Levin <levinsasha928@...il.com>, Andrew Morton <akpm@...ux-foundation.org>, dwmw2@...radead.org, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, linux-mtd@...ts.infradead.org, linux-mm <linux-mm@...ck.org>, Dave Jones <davej@...hat.com> Subject: Re: mtd: kernel BUG at arch/x86/mm/pat.c:279! On 09/09/2012 08:31 AM, Linus Torvalds wrote: > On Sun, Sep 9, 2012 at 7:56 AM, Suresh Siddha <suresh.b.siddha@...el.com> wrote: >> >> yes but that is not a valid range I think because of the supported >> physical address bit limits of the processor and also the max >> architecture limit of 52 address bits. > > But how could the caller possibly know that? None of those internal > PAT limits are exposed anywhere. > > So doing the BUG_ON() is wrong. I'd suggest changing it to an EINVAL. > > In fact, BUG_ON() is *always* wrong, unless it's a "my internal data > structures are so messed up that I cannot continue". > I suspect the right answer is doing something like: u64 max_phys = 1ULL << boot_cpu_data.x86_phys_bits; if (start >= max_phys || end > max_phys || start >= end) return -EINVAL; ... although max_phys perhaps should be precalculated and stored in struct cpuinfo_x86 instead of being generated de novo. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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