linux-kernel - Re: [PATCH 5/7] mm/x86: Make pud_leaf() only cares about PSE bit

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Date: Fri, 21 Jun 2024 07:32:09 -0700
From: Dave Hansen <dave.hansen@...el.com>
To: Peter Xu <peterx@...hat.com>, linux-kernel@...r.kernel.org,
 linux-mm@...ck.org
Cc: x86@...nel.org, Borislav Petkov <bp@...en8.de>,
 Dave Jiang <dave.jiang@...el.com>, "Kirill A . Shutemov"
 <kirill@...temov.name>, Ingo Molnar <mingo@...hat.com>,
 Oscar Salvador <osalvador@...e.de>, Matthew Wilcox <willy@...radead.org>,
 Vlastimil Babka <vbabka@...e.cz>, Dan Williams <dan.j.williams@...el.com>,
 Andrew Morton <akpm@...ux-foundation.org>, Hugh Dickins <hughd@...gle.com>,
 Michael Ellerman <mpe@...erman.id.au>,
 Dave Hansen <dave.hansen@...ux.intel.com>,
 Thomas Gleixner <tglx@...utronix.de>, linuxppc-dev@...ts.ozlabs.org,
 Christophe Leroy <christophe.leroy@...roup.eu>,
 Rik van Riel <riel@...riel.com>, Mel Gorman <mgorman@...hsingularity.net>,
 "Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>,
 Nicholas Piggin <npiggin@...il.com>, Huang Ying <ying.huang@...el.com>
Subject: Re: [PATCH 5/7] mm/x86: Make pud_leaf() only cares about PSE bit

On 6/21/24 07:25, Peter Xu wrote:
> An entry should be reported as PUD leaf even if it's PROT_NONE, in which
> case PRESENT bit isn't there. I hit bad pud without this when testing dax
> 1G on zapping a PROT_NONE PUD.

Yeah, looks like pmd_leaf() got fixed up because of its involvement in
THP, but PUDs got missed.  This patch also realigns pmd_leaf() and
pud_leaf() behavior, which is important.

Acked-by: Dave Hansen <dave.hansen@...ux.intel.com>