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From: Yeoreum Yun <yeoreum.yun@arm.com>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Yeoreum Yun <yeoreum.yun@arm.com>,
	Russell King <linux@armlinux.org.uk>,
	Huacai Chen <chenhuacai@kernel.org>,
	WANG Xuerui <kernel@xen0n.name>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	Kairui Song <kasong@tencent.com>, Qi Zheng <qi.zheng@linux.dev>,
	Shakeel Butt <shakeel.butt@linux.dev>,
	Barry Song <baohua@kernel.org>,
	Axel Rasmussen <axelrasmussen@google.com>,
	Yuanchu Xie <yuanchu@google.com>, Wei Xu <weixugc@google.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	David Hildenbrand <david@kernel.org>,
	Michal Hocko <mhocko@kernel.org>,
	Lorenzo Stoakes <ljs@kernel.org>,
	Tianrui Zhao <zhaotianrui@loongson.cn>,
	Bibo Mao <maobibo@loongson.cn>, Anup Patel <anup@brainfault.org>,
	Atish Patra <atish.patra@linux.dev>,
	Paul Walmsley <pjw@kernel.org>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Alexandre Ghiti <alex@ghiti.fr>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Andy Lutomirski <luto@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@kernel.org>, Ingo Molnar <mingo@redhat.com>,
	Borislav Petkov <bp@alien8.de>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	"Liam R. Howlett" <liam@infradead.org>,
	Vlastimil Babka <vbabka@kernel.org>,
	Mike Rapoport <rppt@kernel.org>,
	Suren Baghdasaryan <surenb@google.com>,
	Michal Hocko <mhocko@suse.com>, Jonas Bonn <jonas@southpole.se>,
	Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>,
	Stafford Horne <shorne@gmail.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, loongarch@lists.linux.dev,
	linux-mips@vger.kernel.org, linux-arch@vger.kernel.org,
	linux-mm@kvack.org, kvm@vger.kernel.org,
	kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org,
	linux-openrisc@vger.kernel.org
Subject: Re: [PATCH RFC v2 13/20] x86: mm: carve out the generic compile-time folded pgtable case in effective_prot()
Date: Wed, 22 Jul 2026 18:37:42 +0100	[thread overview]
Message-ID: <amD_5r04mzMoZ0-r@e129823.arm.com> (raw)
In-Reply-To: <d16a8412-acee-4c21-a126-f570d6306983@intel.com>

> On 7/22/26 08:30, Yeoreum Yun wrote:
> >  struct pg_state {
> >  	struct ptdump_state ptdump;
> > +	int first_level;
> >  	int level;
> >  	pgprotval_t current_prot;
> >  	pgprotval_t effective_prot;
> 
> There is zero reason on x86 to hold this value in a data structure. It
> is 100% determined at boot time or earlier. Pre-5-level-paging it's a
> compile-time constant.
> 
> On x86, it never varies per-mm.

However, mm_pXd_folded() requires to mm for other architecture like
s390. might save the mm instead of first_level and calls the
ptdump_pt_level_first() with static inline version would make the
constant comparison. So it requires to save *mm* structure in here.

[...]
-- 
Sincerely,
Yeoreum Yun

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  parent reply	other threads:[~2026-07-22 17:38 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-07-22 15:30 [PATCH RFC v2 00/20] mm: optimize unnecessary loads due to ptep_get() and friends out Yeoreum Yun
2026-07-22 15:30 ` [PATCH RFC v2 01/20] ARM: mm: make nommu pgd_t a scalar Yeoreum Yun
2026-07-22 15:30 ` [PATCH RFC v2 02/20] ARM: mm: make 2-level " Yeoreum Yun
2026-07-22 15:30 ` [PATCH RFC v2 03/20] ARM: mm: remove custom pgdp_get() Yeoreum Yun
2026-07-22 15:30 ` [PATCH RFC v2 04/20] LoongArch: mm: define pud_leaf() only when PUD exists Yeoreum Yun
2026-07-22 15:30 ` [PATCH RFC v2 05/20] MIPS: " Yeoreum Yun
2026-07-22 15:30 ` [PATCH RFC v2 06/20] mm/pgtable: define (pgd|p4d|pud)_leaf() for folded page tables Yeoreum Yun
2026-07-22 15:30 ` [PATCH RFC v2 07/20] mm/pgtable: define (pgd|p4d|pud)_offset_lockless() " Yeoreum Yun
2026-07-22 15:30 ` [PATCH RFC v2 08/20] mm: vmscan: remove stack copy address of pud pass in wallk_pud_range() Yeoreum Yun
2026-07-22 15:30 ` [PATCH RFC v2 09/20] loongarch: kvm: remove stack copy address of pXd in pXd_offset() Yeoreum Yun
2026-07-22 15:30 ` [PATCH RFC v2 10/20] riscv: " Yeoreum Yun
2026-07-22 15:30 ` [PATCH RFC v2 11/20] riscv: mm: use proper set_pXd() for generic compile-time folded patable in vmalloc_fault() Yeoreum Yun
2026-07-22 15:30 ` [PATCH RFC v2 12/20] x86: mm: define pudp_set_access_flags() when CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD is enabled only Yeoreum Yun
2026-07-22 16:02   ` Dave Hansen
2026-07-22 17:27     ` Yeoreum Yun
2026-07-22 15:30 ` [PATCH RFC v2 13/20] x86: mm: carve out the generic compile-time folded pgtable case in effective_prot() Yeoreum Yun
2026-07-22 16:11   ` Dave Hansen
2026-07-22 16:28     ` Yeoreum Yun
2026-07-22 17:37     ` Yeoreum Yun [this message]
2026-07-22 20:20       ` Dave Hansen
2026-07-22 21:00         ` Yeoreum Yun
2026-07-22 15:30 ` [PATCH RFC v2 14/20] x86: mm: skip pud setup when using generic compile-time folded pagetable Yeoreum Yun
2026-07-22 16:33   ` Dave Hansen
2026-07-22 17:18     ` Yeoreum Yun
2026-07-22 20:02       ` Dave Hansen
2026-07-22 20:18         ` Yeoreum Yun
2026-07-22 20:22           ` Dave Hansen
2026-07-22 20:28             ` H. Peter Anvin
2026-07-22 20:40               ` Yeoreum Yun
2026-07-22 15:30 ` [PATCH RFC v2 15/20] mm/pgtable: optimize pmdp_get() and friends for folded pagetable levels Yeoreum Yun
2026-07-22 15:30 ` [PATCH RFC v2 16/20] mm/pgtable: catch abuse of folded dummy pgd_t/p4d_t/pud_t Yeoreum Yun
2026-07-22 15:30 ` [PATCH RFC v2 17/20] mm/pgtable: disallow calling (pgd|p4d|pud)_page, pgd_page_vaddr() and (p4d|pud)_pgtable with dummy Yeoreum Yun
2026-07-22 15:30 ` [PATCH RFC v2 18/20] mm/pgtable: disallow calling folded set_pgd/set_p4d/set_pud " Yeoreum Yun
2026-07-22 15:30 ` [PATCH RFC v2 19/20] openrisc/pgtable: drop __pmd_offset() Yeoreum Yun
2026-07-22 15:30 ` [PATCH RFC v2 20/20] arm64: pgtable: convert pte_present() from macro to static inline Yeoreum Yun
2026-07-22 16:40 ` [PATCH RFC v2 00/20] mm: optimize unnecessary loads due to ptep_get() and friends out Dave Hansen
2026-07-22 17:30   ` Yeoreum Yun

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