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b=Ei438QZPhoA/j4TNX5sKSZg5DC94anuXDfwoCs3yZ2nJ1Oo93Z8QUJh0hP+z8jZfx mvDvVMgJYsQ8OLdhMamWwAEZDxoj7gyp4EdbNObTpzy9Bg8USo+npPQAQuMCrN/RRx 58Vb14FKQ+pq8lMWh+GJn5EmAzsQrh7qEucJJNxVf3Rq9Q7MAf/oi7JVeOJtdxjOEV QGnVdcagw3jrjs8gqu7q4xY4E5RkSpPAS2vNOoRYOcqHrN8lM4/EMdx5XhG48/rkwa vrY1+iC3yvCIF7sDeFCS3a17J0J76nGjnXB+FGLpElE1FKSfCksjfAo8RNZq/teTMr UAgmKCVERFOAQ== Date: Mon, 27 Jul 2026 17:30:51 +0100 From: "Lorenzo Stoakes (ARM)" To: Hongfu Li Cc: akpm@linux-foundation.org, david@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Hongfu Li Subject: Re: [PATCH v2 2/2] mm: Extract non-swap page handling to do_non_swap_page() Message-ID: References: <20260723030752.16979-1-hongfu.li@linux.dev> <20260723030752.16979-3-hongfu.li@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260723030752.16979-3-hongfu.li@linux.dev> X-Rspam-User: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 7DA9D40003 X-Stat-Signature: zng4qpgoqyu6ybct86ka9e7uyt5ud9q5 X-HE-Tag: 1785169868-282903 X-HE-Meta: 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 e78SfB2R B5lAOfj1dxXg5dL/iPrCref2AYriCgzfNZjqlJl3QGZ8qBopD8I0YNCC0OmTZWDQpsLizUpPNGcQdmdsIx5tV3xIFN5zErhUzdpSaNGcoVV5U8ByUMtl3yYIGp6+Tr00B70FwRGNLaioV/AiPgP5T020sMi+tJ3d6f2h8K6GZPcuYXNpXQ0geE9+9eyIKuCPr67Zct1E6uRc2ekrOU1pqB01xQbv/UenDNwQn0GiYS1kDyrN0eiD3/JiCJG0vxSRQY7tcmmFuwnX4ze/PoxUmNQmRUqKfDs9upXLg6VBnxIUkbtk= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Jul 23, 2026 at 11:07:52AM +0800, Hongfu Li wrote: > From: Hongfu Li > > Factor non-swap entry logic out of bloated do_swap_page() to simplify > the main swap fault flow and improve readability. > > The new do_non_swap_page() handles migration, device private/exclusive, > hwpoison, marker and bad PTE entries. > > Signed-off-by: Hongfu Li We've already gone over this elsewhere in the thread, we don't want a do_non_swap_page() (HELL no). But in general I want to finish what I started with softleaves, which still has some work to do with swap entries so maybe could you just drop this patch so I can follow up with that later? That way you can do a respin of just the 1/2 as a v3. Thanks, Lorenzo > --- > mm/memory.c | 120 ++++++++++++++++++++++++++++++---------------------- > 1 file changed, 69 insertions(+), 51 deletions(-) > > diff --git a/mm/memory.c b/mm/memory.c > index ae521baa8c84..50d8e92aef91 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -4815,6 +4815,74 @@ static void check_swap_exclusive(struct folio *folio, swp_entry_t entry, > } while (--nr_pages); > } > > +static vm_fault_t do_non_swap_page(struct vm_fault *vmf) > +{ > + struct vm_area_struct *vma = vmf->vma; > + struct folio *folio; > + softleaf_t entry; > + vm_fault_t ret = 0; > + > + entry = softleaf_from_pte(vmf->orig_pte); > + if (softleaf_is_migration(entry)) { > + migration_entry_wait(vma->vm_mm, vmf->pmd, > + vmf->address); > + } else if (softleaf_is_device_exclusive(entry)) { > + vmf->page = softleaf_to_page(entry); > + ret = remove_device_exclusive_entry(vmf); > + } else if (softleaf_is_device_private(entry)) { > + > + if (vmf->flags & FAULT_FLAG_VMA_LOCK) { > + /* > + * migrate_to_ram is not yet ready to operate > + * under VMA lock. > + */ > + vma_end_read(vma); > + return VM_FAULT_RETRY; > + } > + > + vmf->page = softleaf_to_page(entry); > + vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, > + vmf->address, &vmf->ptl); > + if (unlikely(!vmf->pte || > + !pte_same(ptep_get(vmf->pte), > + vmf->orig_pte))) > + goto unlock; > + > + /* > + * Get a folio reference while we know the folio can't be > + * freed. > + */ > + folio = page_folio(vmf->page); > + if (folio_trylock(folio)) { > + struct dev_pagemap *pgmap; > + > + folio_get(folio); > + pte_unmap_unlock(vmf->pte, vmf->ptl); > + pgmap = page_pgmap(vmf->page); > + ret = pgmap->ops->migrate_to_ram(vmf); > + folio_unlock(folio); > + folio_put(folio); > + } else { > + pte_unmap(vmf->pte); > + softleaf_entry_wait_on_locked(entry, vmf->ptl); > + } > + } else if (softleaf_is_hwpoison(entry)) { > + ret = VM_FAULT_HWPOISON; > + } else if (softleaf_is_marker(entry)) { > + ret = handle_pte_marker(vmf); > + } else { > + print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL); > + ret = VM_FAULT_SIGBUS; > + } > + > + return ret; > + > +unlock: > + if (vmf->pte) > + pte_unmap_unlock(vmf->pte, vmf->ptl); > + return ret; > +} > + > /* > * We enter with either the VMA lock or the mmap_lock held (see > * FAULT_FLAG_VMA_LOCK), and pte mapped but not yet locked. > @@ -4845,57 +4913,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) > > entry = softleaf_from_pte(vmf->orig_pte); > if (unlikely(!softleaf_is_swap(entry))) { > - if (softleaf_is_migration(entry)) { > - migration_entry_wait(vma->vm_mm, vmf->pmd, > - vmf->address); > - } else if (softleaf_is_device_exclusive(entry)) { > - vmf->page = softleaf_to_page(entry); > - ret = remove_device_exclusive_entry(vmf); > - } else if (softleaf_is_device_private(entry)) { > - if (vmf->flags & FAULT_FLAG_VMA_LOCK) { > - /* > - * migrate_to_ram is not yet ready to operate > - * under VMA lock. > - */ > - vma_end_read(vma); > - ret = VM_FAULT_RETRY; > - goto out; > - } > - > - vmf->page = softleaf_to_page(entry); > - vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, > - vmf->address, &vmf->ptl); > - if (unlikely(!vmf->pte || > - !pte_same(ptep_get(vmf->pte), > - vmf->orig_pte))) > - goto unlock; > - > - /* > - * Get a folio reference while we know the folio can't be > - * freed. > - */ > - folio = page_folio(vmf->page); > - if (folio_trylock(folio)) { > - struct dev_pagemap *pgmap; > - > - folio_get(folio); > - pte_unmap_unlock(vmf->pte, vmf->ptl); > - pgmap = page_pgmap(vmf->page); > - ret = pgmap->ops->migrate_to_ram(vmf); > - folio_unlock(folio); > - folio_put(folio); > - } else { > - pte_unmap(vmf->pte); > - softleaf_entry_wait_on_locked(entry, vmf->ptl); > - } > - } else if (softleaf_is_hwpoison(entry)) { > - ret = VM_FAULT_HWPOISON; > - } else if (softleaf_is_marker(entry)) { > - ret = handle_pte_marker(vmf); > - } else { > - print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL); > - ret = VM_FAULT_SIGBUS; > - } > + ret = do_non_swap_page(vmf); > goto out; > } > > -- > 2.54.0 >