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Date: Fri, 22 Jan 2021 16:27:23 +0800 From: Miaohe Lin <linmiaohe@...wei.com> To: Andrew Morton <akpm@...ux-foundation.org> CC: <tglx@...utronix.de>, <dave.hansen@...el.com>, <jpoimboe@...hat.com>, <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>, Andi Kleen <ak@...ux.intel.com> Subject: Re: [PATCH] mm: Fix potential pte_unmap_unlock pte error Hi Andrew: On 2021/1/14 10:51, Miaohe Lin wrote: > Hi: > On 2021/1/11 1:14, Andi Kleen wrote: >> On Sat, Jan 09, 2021 at 03:01:18AM -0500, Miaohe Lin wrote: >>> Since commit 42e4089c7890 ("x86/speculation/l1tf: Disallow non privileged >>> high MMIO PROT_NONE mappings"), when the first pfn modify is not allowed, >>> we would break the loop with pte unchanged. Then the wrong pte - 1 would >>> be passed to pte_unmap_unlock. >> >> Thanks. >> >> While the fix is correct, I'm not sure if it actually is a real bug. Is there >> any architecture that would do something else than unlocking the underlying >> page? If it's just the underlying page then it should be always the same >> page, so no bug. >> > > It's just a theoretical issue via code inspection. Should I send a new one without Cc statle or just drop this patch? Thanks. > >> That said of course the change is the right thing for main line, but probably doesn't >> need to be backported. >> > > So it should not be backported. Should I resend a patch or Andrew would kindly do this? > >> -Andi >> . >> > > Many thanks for review and reply. >
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