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Miller" , Andreas Larsson , Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Peter Zijlstra , sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 3/3] mm: cleanup clear_not_present_full_ptes() and rename to clear_non_present_ptes() Message-ID: References: <20260611-clear_not_present_full_ptes-v1-0-49865fc82629@kernel.org> <20260611-clear_not_present_full_ptes-v1-3-49865fc82629@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 68453160002 X-Stat-Signature: exxipx158atr6fcg49qujexrfty41yfs X-HE-Tag: 1781260623-242578 X-HE-Meta: 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 I0olCcui bisr4zykLlL3HqjNU8S9ZAGrkoIu40p2hmS2cJyCL9KORNwreTC3o5aPqCT3Ny4SW0GEPF4ynumohWsE+IU9HN55Y7aSei4rKPRwv5NdtiOOBt4Jz0VSNL87SqMVG+GoMW3EOCZWD/H/8z1nPrnTYN6fICPkKgZnJeaWwCsFbJUv0n7dDz6mF6Y2/1pGYpEVT0cypSbfqF9sQ3OPOTPSi+ixsM+POhCZREiwtZU6smhgz9Ra5AR+W7nPmIOBMRx/D3zqzTUnuimkIzzw= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Jun 11, 2026 at 06:14:34PM +0200, David Hildenbrand (Arm) wrote: > Usually, you want to get access and dirty bits, and that requires get_and_clear > semantics. I suspect there are some more details to the low-level helpers. > > > > > I guess that such a renaming would have to first audit that all current > > users obey that? Othen than that, is there anything else stopping us > > from doing so? > > When I last skimmed over some users, they were all dealing with non-present > entries. (mremap.c, rmap.c, mpreotect.c, memory.c, madvise.c) > > But yes, we would have to audit and make sure that's the case. So, I quickly checked some users. As you mentioned, users from rmap.c, mremap.c, memory.c and madvise.c deal with non-present ptes. Hugetlb via huge_pte_clear does it for uffd markers or explicit !pte_present, so that is fine as well. That is wrt. generic code. Now, moving to arch-specific code, things look a bit funny. E.g: bpf: arena_free_pages()-> apply_range_clear_cb() apply_range_clear_cb() only calls pte_clear for present ptes. Then, e.g: remove_pagetable() from powerpc and and x86 end up calling pte_clear (for present ptes), but that is fine because we are just nuking it. And s390 has the same in modify_pte_table() -- Oscar Salvador SUSE Labs