From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8F5784FD27C for ; Thu, 17 Sep 2026 21:25:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789680308; cv=none; b=kG/rjov0WTMjR39rnEt/uBHlsuwMXO/Nn7yZFKD0xbJxBtbHDZko5NGPZwtc5ZqQONt0PjwYYgsAB4d8iR7xhSvUNMVS9wj+xKMxbJMycEAoxD9e9hPbna8szrCMCHVkmXo6KcNVasXgCMnYWuNyr72Vu0jneYN+l/iS4bdDpd4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789680308; c=relaxed/simple; bh=9HDxL91Yz9mdPJLFOjl6SeANTug4jnN2X+Sz9deDkfA=; h=Date:To:From:Subject:Message-Id; b=D8PKX9nSD3DQdvgRL/M3sMONaDdWlF1+FCPxGJ7BL8L2aRO80mO2klavUjAH7yjhcL7vezKW4R2GnL61Yd2N2vaz4UujfRySCLaeqthntrL6u2Jezftq+UfjKMPpq842oPLQkVBpbwzmQdInYDjEVgTIwuR1203hBBk+WiO4DS4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=HxfjtoZD; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="HxfjtoZD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 53BB81F00893; Thu, 17 Sep 2026 21:25:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1789680305; bh=ncKlMFiExD6XpeJ7NkPKLnge+vYEo3doJ7aGOC6Nzv8=; h=Date:To:From:Subject; b=HxfjtoZDuWpurJ9s9b6cVjZy6u1Y4uRVvTFy02sYfnB5qYd4Jxd/l8GRkGyAiZ+UI 92Q1D+7vgooUXeWuxD4w2z8OVOJkD3Xfa0aXrXFl4g7XKOh3Piil3n4caoXTeN0a2z 5PF57eRFClqn0aBm0F3FwqAplk0z4xe6hj6KrVSQ= Date: Thu, 17 Sep 2026 14:25:04 -0700 To: mm-commits@vger.kernel.org,ljs@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: + scsi-sg-convert-mmap-hook-to-mmap_prepare-and-rework.patch added to mm-unstable branch Message-Id: <20260917212505.53BB81F00893@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: scsi: sg: convert mmap hook to mmap_prepare and rework has been added to the -mm mm-unstable branch. Its filename is scsi-sg-convert-mmap-hook-to-mmap_prepare-and-rework.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/scsi-sg-convert-mmap-hook-to-mmap_prepare-and-rework.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: "Lorenzo Stoakes (ARM)" Subject: scsi: sg: convert mmap hook to mmap_prepare and rework Date: Thu, 17 Sep 2026 17:22:27 +0100 Move from the deprecated mmap hook to the new mmap_prepare hook. We are mapping kernel pages here, so use the discontiguous kernel mapping mmap action to do so. Unwind the rather confusing loop and instead map as many pages as we can at one time. Note that we do not need to pay attention to rsv_schp->k_use_sg here, as the pages are populated for the length of the buffer at rsv_schp->page_order granularity as compound pages. The discontiguous kernel page mapping logic handles the compound pages for us. sfp->mmap_called keeps the buffer stable for us. As before it is never cleared, so a failed mmap also leaves it set. We also remove some useless vma, vma->vm_file NULL checks - these will always be non-NULL if you reached the mmap hook logic. We retain log output for consistency, but change what's output on page mapping to indicate that sg_discontig_get() does the work now. Note that we drop the VMA_IO_BIT flag for the VMA here. It was never necessary as we invoke alloc_pages() which gives us refcounted folios that are fine for GUP to access (VMA_IO_BIT would prevent that). Link: https://lore.kernel.org/20260917-b4-mmap-prepare-vma-flag-sanify-v3-18-4583d8a23bca@kernel.org Signed-off-by: Lorenzo Stoakes (ARM) Signed-off-by: Andrew Morton Cc: Albert Ou Cc: Alexander Gordeev Cc: Alexei Starovoitov Cc: Alistair Popple Cc: Al Viro Cc: Andreas Larsson Cc: Andrii Nakryiko Cc: "Aneesh Kumar K.V" Cc: Anup Patel Cc: Arnaldo Carvalho de Melo Cc: Arnd Bergmann Cc: Axel Rasmussen Cc: Baolin Wang Cc: Baoquan He Cc: Barry Song Cc: "Borislav Petkov (AMD)" Cc: Byungchul Park Cc: Catalin Marinas Cc: Chengming Zhou Cc: Chris Li Cc: Christian Borntraeger Cc: Christian Brauner Cc: Claudio Imbrenda Cc: Dave Airlie Cc: Dave Hansen Cc: David Hildenbrand Cc: David S. Miller Cc: Dennis Dalessandro Cc: Dev Jain Cc: Doug Gilbert Cc: Eduard Zingerman Cc: Emil Tsalapatis Cc: Gerald Schaefer Cc: Greg Kroah-Hartman Cc: Gregory Price Cc: Harry Yoo Cc: Heiko Carstens Cc: Helge Deller Cc: "Huang, Ying" Cc: Ingo Molnar Cc: James Bottomley Cc: Jan Kara Cc: Jann Horn Cc: Janosch Frank Cc: Jaroslav Kysela Cc: Jason Gunthorpe Cc: Jaya Kumar Cc: Johannes Weiner Cc: John Hubbard Cc: Jonathan Corbet Cc: Joshua Hahn Cc: Juri Lelli Cc: Kairui Song Cc: Kemeng Shi Cc: Kiryl Shutsemau Cc: Kumar Kartikeya Dwivedi Cc: Lance Yang Cc: Leon Romanovsky Cc: Liam R. Howlett Cc: Maarten Lankhorst Cc: Madhavan Srinivasan Cc: Marc Rutland Cc: Marc Zyngier Cc: "Masami Hiramatsu (Google)" Cc: Matthew Brost Cc: Matthew Wilcox (Oracle) Cc: Maxime Ripard Cc: Michal Hocko Cc: Michal Hocko Cc: Mike Rapoport Cc: Miklos Szeredi Cc: Muchun Song Cc: Namhyung kim Cc: Nhat Pham Cc: Nicholas Piggin Cc: Oleg Nesterov Cc: Oscar Salvador Cc: Palmer Dabbelt Cc: Paul Moore Cc: Pedro Falcato Cc: Peter Xu Cc: Peter Zijlstra Cc: Rakie Kim Cc: Rik van Riel Cc: Ryan Roberts Cc: Sebastian Reichel Cc: Shakeel Butt Cc: Stephen Smalley Cc: Suren Baghdasaryan Cc: Takashi Iwai (SUSE) Cc: Takashi Iwai Cc: Thomas Zimemrmann Cc: Vasily Gorbik Cc: Vincent Guittot Cc: Vlastimil Babka Cc: Wei Xu Cc: Will Deacon Cc: Yuanchu Xie Cc: Zi Yan --- drivers/scsi/sg.c | 115 +++++++++++++++++++------------------------- 1 file changed, 51 insertions(+), 64 deletions(-) --- a/drivers/scsi/sg.c~scsi-sg-convert-mmap-hook-to-mmap_prepare-and-rework +++ a/drivers/scsi/sg.c @@ -1212,85 +1212,72 @@ sg_fasync(int fd, struct file *filp, int return fasync_helper(fd, filp, mode, &sfp->async_qp); } -static vm_fault_t -sg_vma_fault(struct vm_fault *vmf) +static int sg_discontig_init(void *vm_private_data, void **private) { - struct vm_area_struct *vma = vmf->vma; - Sg_fd *sfp; - unsigned long offset, len, sa; - Sg_scatter_hold *rsv_schp; - int k, length; - - if ((NULL == vma) || (!(sfp = (Sg_fd *) vma->vm_private_data))) - return VM_FAULT_SIGBUS; - rsv_schp = &sfp->reserve; - offset = vmf->pgoff << PAGE_SHIFT; - if (offset >= rsv_schp->bufflen) - return VM_FAULT_SIGBUS; - SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sfp->parentdp, - "sg_vma_fault: offset=%lu, scatg=%d\n", - offset, rsv_schp->k_use_sg)); - sa = vma->vm_start; - length = 1 << (PAGE_SHIFT + rsv_schp->page_order); - for (k = 0; k < rsv_schp->k_use_sg && sa < vma->vm_end; k++) { - len = vma->vm_end - sa; - len = (len < length) ? len : length; - if (offset < len) { - struct page *page = rsv_schp->pages[k] + (offset >> PAGE_SHIFT); - get_page(page); /* increment page count */ - vmf->page = page; - return 0; /* success */ - } - sa += len; - offset -= len; + const unsigned long req_sz = (unsigned long)*private; + Sg_fd *sfp = vm_private_data; + Sg_scatter_hold *rsv_schp = &sfp->reserve; + int err = 0; + + mutex_lock(&sfp->f_mutex); + if (req_sz > rsv_schp->bufflen) { + err = -ENOMEM; /* cannot map more than reserved buffer */ + goto out; + } + sfp->mmap_called = 1; /* Prevents changes to buffer size. */ +out: + mutex_unlock(&sfp->f_mutex); + return err; +} + +static int +sg_discontig_get(struct discontig_kernel_page_state *state) +{ + Sg_fd *sfp = state->vm_private_data; + Sg_scatter_hold *rsv_schp = &sfp->reserve; + const unsigned int order = rsv_schp->page_order; + const pgoff_t nr_pages = state->nr_pages_mapped; + + if (nr_pages >= (rsv_schp->bufflen >> PAGE_SHIFT)) { + discontig_kernel_map_abort(state); + return 0; } - return VM_FAULT_SIGBUS; + SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sfp->parentdp, + "%s: offset=%lu, scatg=%d\n", __func__, + nr_pages << PAGE_SHIFT, rsv_schp->k_use_sg)); + + discontig_kernel_map_page(state, rsv_schp->pages[nr_pages >> order]); + return 0; } -static const struct vm_operations_struct sg_mmap_vm_ops = { - .fault = sg_vma_fault, +static const struct discontig_kernel_page_ops sg_discontig_ops = { + .init = sg_discontig_init, + .get = sg_discontig_get, }; static int -sg_mmap(struct file *filp, struct vm_area_struct *vma) +sg_mmap_prepare(struct vm_area_desc *desc) { - Sg_fd *sfp; - unsigned long req_sz, len, sa; - Sg_scatter_hold *rsv_schp; - int k, length; - int ret = 0; + Sg_fd *sfp = desc->file->private_data; + const unsigned long req_sz = vma_desc_size(desc); - if ((!filp) || (!vma) || (!(sfp = (Sg_fd *) filp->private_data))) + if (!sfp) return -ENXIO; - req_sz = vma->vm_end - vma->vm_start; + SCSI_LOG_TIMEOUT(3, sg_printk(KERN_INFO, sfp->parentdp, "sg_mmap starting, vm_start=%p, len=%d\n", - (void *) vma->vm_start, (int) req_sz)); - if (vma->vm_pgoff) + (void *) desc->start, (int) req_sz)); + + if (desc->pgoff) return -EINVAL; /* want no offset */ - rsv_schp = &sfp->reserve; - mutex_lock(&sfp->f_mutex); - if (req_sz > rsv_schp->bufflen) { - ret = -ENOMEM; /* cannot map more than reserved buffer */ - goto out; - } - sa = vma->vm_start; - length = 1 << (PAGE_SHIFT + rsv_schp->page_order); - for (k = 0; k < rsv_schp->k_use_sg && sa < vma->vm_end; k++) { - len = vma->vm_end - sa; - len = (len < length) ? len : length; - sa += len; - } + vma_desc_set_flags(desc, VMA_DONTEXPAND_BIT, VMA_DONTDUMP_BIT); + desc->private_data = sfp; - sfp->mmap_called = 1; - vm_flags_set(vma, VM_IO | VM_DONTEXPAND | VM_DONTDUMP); - vma->vm_private_data = sfp; - vma->vm_ops = &sg_mmap_vm_ops; -out: - mutex_unlock(&sfp->f_mutex); - return ret; + mmap_action_map_discontig_kernel_pages(desc, (void *)req_sz, + &sg_discontig_ops); + return 0; } static void @@ -1415,7 +1402,7 @@ static const struct file_operations sg_f .unlocked_ioctl = sg_ioctl, .compat_ioctl = compat_ptr_ioctl, .open = sg_open, - .mmap = sg_mmap, + .mmap_prepare = sg_mmap_prepare, .release = sg_release, .fasync = sg_fasync, }; _ Patches currently in -mm which might be from ljs@kernel.org are mm-vmpressure-remove-window-size-todo.patch tools-testing-selftests-mm-add-missing-gitignore-entries.patch mm-move-drivers-char-memc-to-mm-char-memc.patch mm-implement-file_is_dev_zero-to-uniquely-identify-dev-zero.patch mm-vma-only-permit-map_private-dev-zero-to-be-mapped-anonymous.patch mm-vma-make-map_private-mapped-dev-zero-mappings-truly-anonymous.patch tools-testing-vma-add-test-to-assert-map_private-dev-zero-is-anon.patch tools-testing-selftests-mm-add-map_private-dev-zero-merge-tests.patch mm-madvise-swap-in-cowd-map_private-file-mappings-on-madv_willneed.patch mm-huge_memory-zap-deposited-page-tables-after-an-rcu-grace-period.patch mm-enable-mmu_gather_rcu_table_free-for-most-2-level-architectures.patch mm-enable-mmu_gather_rcu_table_free-for-mmu-riscv.patch mm-enable-mmu_gather_rcu_table_free-for-mmu-arm.patch mm-enable-mmu_gather_rcu_table_free-for-arc-microblaze-xtensa.patch mm-enable-mmu_gather_rcu_table_free-for-sparc64.patch mm-enable-mmu_gather_rcu_table_free-for-m68k-coldfire.patch mm-enable-mmu_gather_rcu_table_free-for-sh-x2.patch mm-enable-mmu_gather_rcu_table_free-for-m68k-motorola.patch mm-enable-mmu_gather_rcu_table_free-for-sparc32.patch mm-make-userland-page-table-freeing-rcu-safe.patch mm-change-the-contract-for-free_pgtables-update-docs.patch mm-vma-fix-mmap_prepare-file-handling-remove-file_doesnt_need_get.patch mm-vma-predicate-setting-mmap_prepare-vma-fields-on-new-vma-alloc.patch mm-vma-introduce-and-use-vma_can_merge.patch mm-consistently-validate-vma-state-after-mmap-hooks.patch mm-vma-ensure-mmap_prepare-doesnt-set-actions-on-a-mergeable-vma.patch mm-make-map_kernel_pages_-internal-and-unexported.patch mm-vma-tidy-up-map-kernel-pages-enum-values.patch mm-add-mmap-action-for-discontiguous-kernel-page-mapping.patch docs-filesystems-update-mmap_prepare-docs-for-discontig-kernel-pgs.patch drivers-usb-mon-update-to-use-mmap_prepare-map-kernel-pages.patch infiniband-update-hfi1-to-use-remap_vmalloc_range.patch selinux-reject-writable-opens-of-policy-file-drop-mmap-shared-write-check.patch alsa-pcm-use-vm_insert_page-to-map-pcm-status-page.patch bpf-arena-mark-arena_map_mmap-mappings-vm_mixedmap.patch mm-vma-add-vma_is_kernel_owned-predicates.patch mm-vma-only-allow-mmap-to-clear-vma_maywrite_bit-if-kernel-owned.patch mm-vma-add-and-use-vma__is_fixed_mapping.patch scsi-sg-convert-mmap-hook-to-mmap_prepare-and-rework.patch fbdev-defio-assert-fbinfo_virtfb-drop-vm_io-add-vm_mixedmap.patch hsi-cmt_speech-convert-mmap-hook-to-mmap_prepare-refactor.patch mm-gup-error-out-early-on-vma_mayread_bit-vmas.patch uprobes-remove-vm_io-set-vm_mixedmap-for-mapped-kernel-pages.patch mm-mlock-clear-vma_locked_mask-over-mmap-callback.patch mm-mlock-eliminate-weird-vma_io_bit-abuse-and-simplify.patch mm-vma-enforce-that-only-kernel-owned-mappings-may-set-vma_io_bit.patch mm-remove-vma_io_bit-check-in-vma_is_kernel_owned.patch mm-remove-hugetlb_inlineh.patch mm-rename-is_vm_hugetlb_page-to-vma_is_hugetlb.patch mm-drop-some-redundant-checks-around-hugetlb-vmas.patch mm-madvise-update-is_valid_guard_vma-to-use-vma_can_merge.patch mm-vma-introduce-vma_is_persistent.patch mm-uffd-use-predicates-for-userfaultfd-checks.patch mm-madvise-use-predicates-for-madvise-madv_dofork.patch mm-eliminate-vma_special_flags-usage-when-hugetlb-explicitly-tested.patch mm-eliminate-vma_special_flags-check-in-lru_gen_look_around.patch mm-avoid-use-of-vma_special_flags-in-migrate_vma_setup.patch mm-eliminate-vm_special-vma_special_flags.patch fuse-dax-do-not-set-vm_mixedmap.patch mm-huge_memory-remove-vma_is_special_huge.patch mm-vma-introduce-and-use-vma_can_gup.patch mm-vma-const-ify-vma_assert_stabilised-and-associated-functions.patch mm-implement-and-use-vma_has_anon_rmap-silence-kcsan.patch mm-update-comments-to-refer-to-anon-rmap-rather-than-anon_vma.patch