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 7446D36E46C for ; Sat, 10 Oct 2026 22:02:11 +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=1791669733; cv=none; b=MTwXt4JuFwemRYByXdi7F4Dmkfkr8hQ+6z2EmGz/jBmbD7swo2BrRIJYp5WYIfVl0an1rtn1BZMqoxYOdGBbJFVCKRaJFUrcx0HzzAI9cgtwLA//0mTczR4qJtmDsLAEehFexzez71ZB+uPKfrj8u3k0baNo4Yp0JvDKDJhgqEU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791669733; c=relaxed/simple; bh=QjAXGef0YcwyZRLs7O5/YQl79P5ibVYeg+CQ8mOj4Hs=; h=Date:To:From:Subject:Message-Id; b=C3wJZsj7tuTMmo6yFRMsiYqsRDuPKb811WfdkP24/s8gbqerkPpK1nnv+/hsA2m5WOuWl5rj19JqPaDsw5gdvMzkpwI8y2gmxMrJ3kBaunQ7m5Mdo2e63LND05iTpI9RCmGJr8T6bRFp/NMqV2iBhtcn8lkYrXk3NGpiorrHAEQ= 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=iJ90x7Bt; 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="iJ90x7Bt" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3F6EF1F000FF; Sat, 10 Oct 2026 22:02:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=korg; t=1791669731; bh=hkIZOaU7WLO6wsSavyJGev33pHqOl7zBrCJxvI3Bqwc=; h=Date:To:From:Subject; b=iJ90x7BtvRUXR64MZPDRqWNEFPWGPMX6Tk2KpbuqAUeNKA4dFe+D4jaP53CjsY3IF eQWvNGSw5CuttWK2gBBl0rKQYDfpK6K2pAFfabWNk9dk/HEaIgRI0Fo0vebavcIUvc wO/UIKEULcTuo6jMtd5aA+Scvg+NteztKlWVIfJ0= Date: Sat, 10 Oct 2026 15:02:10 -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: <20261010220211.3F6EF1F000FF@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: Fri, 09 Oct 2026 19:04:11 +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/20261009-b4-mmap-prepare-vma-flag-sanify-v5-17-923b70125b1e@kernel.org Signed-off-by: Lorenzo Stoakes (ARM) Signed-off-by: Andrew Morton Reviewed-by: Suren Baghdasaryan Cc: Liam R. Howlett Cc: Vlastimil Babka Cc: Jann Horn Cc: Pedro Falcato Cc: David Hildenbrand Cc: Mike Rapoport Cc: Michal Hocko Cc: Jonathan Corbet Cc: Greg Kroah-Hartman Cc: Dennis Dalessandro Cc: Jason Gunthorpe Cc: Leon Romanovsky Cc: Paul Moore Cc: Stephen Smalley Cc: Jaroslav Kysela Cc: Takashi Iwai Cc: Alexei Starovoitov Cc: Daniel Borkmann Cc: Andrii Nakryiko Cc: Eduard Zingerman Cc: Kumar Kartikeya Dwivedi Cc: Zi Yan Cc: Baolin Wang Cc: Nico Pache Cc: Ryan Roberts Cc: Dev Jain Cc: Barry Song Cc: Lance Yang Cc: Usama Arif Cc: Kiryl Shutsemau Cc: Doug Gilbert Cc: James Bottomley Cc: Martin K. Petersen Cc: Simona Vetter Cc: Helge Deller Cc: Sebastian Reichel Cc: John Hubbard Cc: Peter Xu Cc: Masami Hiramatsu Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: Arnaldo Carvalho de Melo Cc: Namhyung Kim Cc: Mark Rutland Cc: Rik van Riel Cc: Harry Yoo Cc: Juri Lelli Cc: Vincent Guittot Cc: Maarten Lankhorst Cc: Maxime Ripard Cc: Thomas Zimmermann Cc: David Airlie Cc: Will Deacon Cc: Aneesh Kumar K.V Cc: Nicholas Piggin Cc: Arnd Bergmann Cc: Muchun Song Cc: Oscar Salvador Cc: Matthew Wilcox (Oracle) Cc: Jan Kara Cc: Marc Zyngier Cc: Oliver Upton Cc: Catalin Marinas Cc: Madhavan Srinivasan Cc: Anup Patel Cc: Paul Walmsley Cc: Palmer Dabbelt Cc: Albert Ou Cc: Christian Borntraeger Cc: Janosch Frank Cc: Claudio Imbrenda Cc: Alexander Gordeev Cc: Gerald Schaefer Cc: Heiko Carstens Cc: Vasily Gorbik Cc: David S. Miller Cc: Andreas Larsson Cc: Al Viro Cc: Christian Brauner Cc: Matthew Brost Cc: Joshua Hahn Cc: Rakie Kim Cc: Byungchul Park Cc: Gregory Price Cc: Ying Huang Cc: Alistair Popple Cc: Chris Li Cc: Kairui Song Cc: Kemeng Shi Cc: Nhat Pham Cc: Baoquan He Cc: Youngjun Park Cc: Johannes Weiner Cc: Qi Zheng Cc: Shakeel Butt Cc: Axel Rasmussen Cc: Yuanchu Xie Cc: Wei Xu Cc: Chengming Zhou Cc: Michal Hocko Cc: Miklos Szeredi Cc: Xu Xin Cc: Ihor Solodrai Cc: Bert Karwatzki --- 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-vma-fix-mmap_prepare-file-handling-remove-file_doesnt_need_get.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_mm_managed-predicates.patch mm-vma-only-allow-mmap-to-clear-vma_maywrite_bit-if-not-mm-managed.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-mm-managed-mappings-may-not-set-vma_io_bit.patch mm-remove-vma_io_bit-check-in-vma_is_mm_managed.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_mm_backed.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-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 mm-vma-dont-remove-vma-from-rmap-if-pgoff-unchanged.patch