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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> Precedence: bulk X-Mailing-List: linux-s390@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: <2ce1da8c64bf2f831938d711b047b2eba0fa9f32.1761288179.git.lorenzo.stoakes@oracle.com> 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