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Bottomley" , Helge Deller , Juergen Gross , Stefano Stabellini , Muchun Song , Oscar Salvador , Andrew Morton , "Liam R. Howlett" , Lorenzo Stoakes , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Peter Zijlstra , Andrey Ryabinin , David Hildenbrand , Pasha Tatashin , Chris Li , Kairui Song , Uladzislau Rezki , Steven Rostedt , Masami Hiramatsu , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Eduard Zingerman , Kumar Kartikeya Dwivedi , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , SJ Park , "Matthew Wilcox (Oracle)" , Jan Kara , Jason Gunthorpe , Leon Romanovsky , Miaohe Lin , Dennis Zhou , Tejun Heo , Christoph Lameter , Mike Rapoport , Johannes Weiner , ziy@nvidia.com, pfalcato@suse.de, ryan.roberts@arm.com, linux-kernel@vger.kernel.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-parisc@vger.kernel.org, xen-devel@lists.xenproject.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, kasan-dev@googlegroups.com, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org, linux-perf-users@vger.kernel.org, damon@lists.linux.dev Subject: Re: [PATCH 6/9] mm: convert PTE table entry to pte Message-ID: References: <20260806083926.1807279-1-usama.anjum@arm.com> <20260806083926.1807279-7-usama.anjum@arm.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260806083926.1807279-7-usama.anjum@arm.com> X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Info: AW1haW4tMjYwODA3MDA0OSBTYWx0ZWRfX3Npn1dSDlp+R fqhR9MpXZOAAKnyVJ8e3VxdJ3uPpsfM7vsZzpddpvCei+hGCUgHlBFVERXxX+W23gcpS04A1TAu ZsTRXf6ZMD17BVZmsTCM0lUCa3PumjU= X-Authority-Analysis: v=2.4 cv=VPTtWdPX c=1 sm=1 tr=0 ts=6a758218 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=kj9zAlcOel0A:10 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VwQbUJbxAAAA:8 a=7CQSdrXTAAAA:8 a=VnNF1IyMAAAA:8 a=MkxDnzPc83ckttyupOUA:9 a=CjuIK1q_8ugA:10 a=a-qgeE7W1pNrGK8U0ZQC:22 X-Proofpoint-ORIG-GUID: 9g22-5Yiq-VIyR9utDe_g8M8U8wsuEOd X-Proofpoint-GUID: 9g22-5Yiq-VIyR9utDe_g8M8U8wsuEOd X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODA3MDA0OSBTYWx0ZWRfX4qeGdjjX3Iob oR2d/W90tNYt47jYoawp2wnB7y1FcZkNxxg7/PT57hDZR5feFluugIlRZ22mBQ/td/U5spNK5Sw r8fBBZDJMOMHDyBDHn28hS5vFD1IBzJcw9uh6xxZ9XoecZCsQnhJUSSf9noMzRB2RMvDZxhPIkf XMKQ1X4w4JsUHL/vsYXt9nxlaz1I/q7ljQgCtXwMvAVt1kijbs35mMQ7c76oGi39I1XSIpxXjmb kIMcLde1EyTpmQmaPbN+E3LbUk4M/lkkgjjjvsZIBgTXWy3e0GMD7NaUrStoYwo4ESb8Z4Wsdqh +581CUAUBwBVUa2TokmdsZzGbrL67tdrfft71SfQsy0ZlWFNR+iL1PR2Oez6zshpb+e7rynA9dG f8FbSxO38FmGhTq0nvrdQcjHK2fKXR2vKx64CE0UHGLhgbh7cUWWpBSkiNUoiKjHZV0BphvCO4H jlupay2/A2mIbK8uZUQ== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-07_01,2026-08-06_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 malwarescore=0 bulkscore=0 spamscore=0 clxscore=1015 priorityscore=1501 phishscore=0 impostorscore=0 adultscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608070049 On Thu, Aug 06, 2026 at 09:38:44AM +0100, Muhammad Usama Anjum wrote: > The non-MMU stub receives hw_pte_t but returns a logical pte_t > value. Convert the stored entry through __pte_from_hw() before > returning. > > Signed-off-by: Muhammad Usama Anjum > --- > include/linux/hugetlb.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h > index bc0b9c65aa1d0..9e8b391aa4bc9 100644 > --- a/include/linux/hugetlb.h > +++ b/include/linux/hugetlb.h > @@ -1283,7 +1283,7 @@ static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma, > #ifdef CONFIG_MMU > return ptep_get(ptep); > #else > - return *ptep; > + return __pte_from_hw(*ptep); But this is a direct dereferencing, which breaks the whole point, isn't it? What about introducing something like pte_t ptep_get_sw(hw_pte_t *ptep) to be used in exactly situations like this? With that the semantics of hw_pte_t pointers becomes straightforward and closes the still ongoing "storage vs lifetime" discussion: hw_pte_t* points to HW-formatted page table entries ptep_get() is used to obtain HW-linked/attached entries, and may wire extra code like [1] or [2] ptep_get_sw() is used to obtain HW-unlinked/unattached entries and in most cases is just a direct dereference The caller should always know whether the entry is attached or not, so confusions like [3] are avoided. 1. https://lore.kernel.org/linux-mm/20260526-kpkeys-v8-21-eaaacdacc67c@arm.com/ 2. https://lore.kernel.org/linux-s390/650903a4-0dd9-4e6b-9d4b-3c32c5657236-agordeev@linux.ibm.com/ 3. https://lore.kernel.org/linux-s390/b44e071d-7c9d-4e7e-a84d-4af3499a5a05@arm.com/ > #endif > } > > -- > 2.47.3 >