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[96.255.20.138]) by smtp.gmail.com with ESMTPSA id af79cd13be357-89eadc0ab82sm58312485a.53.2025.10.24.10.32.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 24 Oct 2025 10:32:31 -0700 (PDT) Date: Fri, 24 Oct 2025 13:32:29 -0400 From: Gregory Price To: Lorenzo Stoakes Cc: Andrew Morton , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , David Hildenbrand , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Sven Schnelle , Zi Yan , Baolin Wang , "Liam R . Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Kemeng Shi , Kairui Song , Nhat Pham , Baoquan He , Chris Li , Peter Xu , Matthew Wilcox , Jason Gunthorpe , Leon Romanovsky , Muchun Song , Oscar Salvador , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Ying Huang , Alistair Popple , Pedro Falcato , Pasha Tatashin , Rik van Riel , Harry Yoo , kvm@vger.kernel.org, linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC PATCH 05/12] fs/proc/task_mmu: refactor pagemap_pmd_range() Message-ID: References: <2ce1da8c64bf2f831938d711b047b2eba0fa9f32.1761288179.git.lorenzo.stoakes@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2ce1da8c64bf2f831938d711b047b2eba0fa9f32.1761288179.git.lorenzo.stoakes@oracle.com> X-Rspamd-Queue-Id: A94DE4001B X-Rspamd-Server: rspam11 X-Rspam-User: X-Stat-Signature: py3k5opok8t8cnkix33xmo7kyx3knmg9 X-HE-Tag: 1761327153-747384 X-HE-Meta: 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 DMGAynBm VvqH1sN+/9D409Up3kDoIgeh5mzxJMmtPKWJoEoC01ED65N8jex3gkMAtgwUyVqES3hNcvlN5io+/a4RPISKw8sSFrPz18iMtU8LjvXQ5mmXiQ4g48XP12r/VyF9IZX4s2yvJMNtWp5GdNdnryXrRj+Jcv7POMe9YrBFLgqnJu2Q3cd5MrZ+UBxoXS8i7rxWAiz2utrW5ANOd/p2N1GrP5ap9xI9TeO3I3/ivu3OiAB0x3xoef6ZXZExLrjyAhGFwteTl00X+G7BadV2TEynotDucQV5JI9SqHZvFwbr0MC8XSflI/okxQ9DksWQjxQyZaCnQ/b3f1AMcCUE0vCistoSB/E5Go+kDM5IwfHPLiIZlFnxuu8k/J4GYpUTq3wppWj7MsLT24g5WnUbqfdCZLNXMpwmgDT/9IdY+B7AE1wFiMBfr1f0Bl7qQ2vm8u66VROXFqoPjJfvwmj2m9Uv4qKMw8w== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Oct 24, 2025 at 08:41:21AM +0100, Lorenzo Stoakes wrote: > Separate out THP logic so we can drop an indentation level and reduce the > amount of noise in this function. > > We add pagemap_pmd_range_thp() for this purpose. > > While we're here, convert the VM_BUG_ON() to a VM_WARN_ON_ONCE() at the > same time. > > Signed-off-by: Lorenzo Stoakes ... >8 > +static int pagemap_pmd_range(pmd_t *pmdp, unsigned long addr, unsigned long end, > + struct mm_walk *walk) > +{ > + struct vm_area_struct *vma = walk->vma; > + struct pagemapread *pm = walk->private; > + spinlock_t *ptl; > + pte_t *pte, *orig_pte; > + int err = 0; > + > +#ifdef CONFIG_TRANSPARENT_HUGEPAGE > + ptl = pmd_trans_huge_lock(pmdp, vma); > + if (ptl) > + return pagemap_pmd_range_thp(pmdp, addr, end, vma, pm, ptl); > +#endif Maybe something like... #ifdef CONFIG_TRANSPARENT_HUGEPAGE ptl = pmd_trans_huge_lock(pmdp, vma); if (ptl) { err = pagemap_pmd_range_thp(pmdp, addr, end, vma, pm, ptl); spin_unlock(ptl); return err; } #endif and drop the spin_unlock(ptl) calls from pagemap_pmd_range_thp? Makes it easier to understand the locking semantics. Might be worth adding a comment to pagemap_pmd_range_thp that callers must hold the ptl lock. ~Gregory P.S. This patch set made my day, the whole non-swap-swap thing has always broken my brain. <3