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Message-Id: <20081229151731.2a2c5a02.akpm@linux-foundation.org> Date: Mon, 29 Dec 2008 15:17:31 -0800 From: Andrew Morton <akpm@...ux-foundation.org> To: Nick Piggin <npiggin@...e.de> Cc: ebiederm@...ssion.com, linux-kernel@...r.kernel.org, tglx@...utronix.de, mingo@...e.hu, ijc@...lion.org.uk Subject: Re: early fixmap causes kmap breakage On Thu, 18 Dec 2008 22:15:43 +0100 Nick Piggin <npiggin@...e.de> wrote: > Hi, > > I've debugged a problem where i386+pae systems with more than a few CPUs > blow up at boot in the kmap_atomic code. ping? > The problem is that the kmap_atomic pte pages all need to be contiguous > memory because the pte is calculated via the first kmap pte page + an > offset (so as not to have to walk the page tables every time). > > The fixmap setup code crudely allocates contiguous pte pages, which is fine, > but if it finds an already populated pmd entry, then it will not switch it > to a new, contiguous pte page. So the early fixmap introduces a discontig > page table right in the middle of the kmap atomic fixmaps. > > Commenting out the eaarly fixmap setup in head_32.S gets everything working > properly. What would be the best way to fix this? Could we put the early > fixmap page table in initdata, and then have the fixmap setup proper first > clear its corresponding pmd entry? How come users/testers aren't reporting this? -- 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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