+ fs-hugetlbfs-cleanup-folio-in-adjust_range_hwpoison.patch added to mm-new branch

+ fs-hugetlbfs-cleanup-folio-in-adjust_range_hwpoison.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: fs: hugetlbfs: cleanup folio in adjust_range_hwpoison()
has been added to the -mm mm-new branch.  Its filename is
     fs-hugetlbfs-cleanup-folio-in-adjust_range_hwpoison.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/fs-hugetlbfs-cleanup-folio-in-adjust_range_hwpoison.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

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
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

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------------------------------------------------------
From: David Hildenbrand <david@redhat.com>
Subject: fs: hugetlbfs: cleanup folio in adjust_range_hwpoison()
Date: Mon, 1 Sep 2025 17:03:37 +0200

Let's cleanup and simplify the function a bit.

Link: https://lkml.kernel.org/r/20250901150359.867252-17-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/hugetlbfs/inode.c |   34 +++++++++++-----------------------
 1 file changed, 11 insertions(+), 23 deletions(-)

--- a/fs/hugetlbfs/inode.c~fs-hugetlbfs-cleanup-folio-in-adjust_range_hwpoison
+++ a/fs/hugetlbfs/inode.c
@@ -192,37 +192,25 @@ hugetlb_get_unmapped_area(struct file *f
  * Someone wants to read @bytes from a HWPOISON hugetlb @folio from @offset.
  * Returns the maximum number of bytes one can read without touching the 1st raw
  * HWPOISON page.
- *
- * The implementation borrows the iteration logic from copy_page_to_iter*.
  */
 static size_t adjust_range_hwpoison(struct folio *folio, size_t offset,
 		size_t bytes)
 {
-	struct page *page;
-	size_t n = 0;
-	size_t res = 0;
+	struct page *page = folio_page(folio, offset / PAGE_SIZE);
+	size_t safe_bytes;
 
-	/* First page to start the loop. */
-	page = folio_page(folio, offset / PAGE_SIZE);
-	offset %= PAGE_SIZE;
-	while (1) {
-		if (is_raw_hwpoison_page_in_hugepage(page))
-			break;
+	if (is_raw_hwpoison_page_in_hugepage(page))
+		return 0;
+	/* Safe to read the remaining bytes in this page. */
+	safe_bytes = PAGE_SIZE - (offset % PAGE_SIZE);
+	page++;
 
-		/* Safe to read n bytes without touching HWPOISON subpage. */
-		n = min(bytes, (size_t)PAGE_SIZE - offset);
-		res += n;
-		bytes -= n;
-		if (!bytes || !n)
+	/* Check each remaining page as long as we are not done yet. */
+	for (; safe_bytes < bytes; safe_bytes += PAGE_SIZE, page++)
+		if (is_raw_hwpoison_page_in_hugepage(page))
 			break;
-		offset += n;
-		if (offset == PAGE_SIZE) {
-			page++;
-			offset = 0;
-		}
-	}
 
-	return res;
+	return min(safe_bytes, bytes);
 }
 
 /*
_

Patches currently in -mm which might be from david@redhat.com are

mm-migrate-remove-migratepage_unmap.patch
mm-migrate-remove-migratepage_unmap-fix.patch
treewide-remove-migratepage_success.patch
mm-huge_memory-move-more-common-code-into-insert_pmd.patch
mm-huge_memory-move-more-common-code-into-insert_pud.patch
mm-huge_memory-support-huge-zero-folio-in-vmf_insert_folio_pmd.patch
fs-dax-use-vmf_insert_folio_pmd-to-insert-the-huge-zero-folio.patch
mm-huge_memory-mark-pmd-mappings-of-the-huge-zero-folio-special.patch
powerpc-ptdump-rename-struct-pgtable_level-to-struct-ptdump_pglevel.patch
mm-rmap-convert-enum-rmap_level-to-enum-pgtable_level.patch
mm-memory-convert-print_bad_pte-to-print_bad_page_map.patch
mm-memory-convert-print_bad_pte-to-print_bad_page_map-fix.patch
mm-memory-factor-out-common-code-from-vm_normal_page_.patch
mm-introduce-and-use-vm_normal_page_pud.patch
mm-rename-vm_ops-find_special_page-to-vm_ops-find_normal_page.patch
prctl-extend-pr_set_thp_disable-to-optionally-exclude-vm_hugepage.patch
mm-huge_memory-convert-tva_flags-to-enum-tva_type.patch
mm-huge_memory-respect-madv_collapse-with-pr_thp_disable_except_advised.patch
mm-stop-making-sparsemem_vmemmap-user-selectable.patch
arm64-kconfig-drop-superfluous-select-sparsemem_vmemmap.patch
s390-kconfig-drop-superfluous-select-sparsemem_vmemmap.patch
x86-kconfig-drop-superfluous-select-sparsemem_vmemmap.patch
wireguard-selftests-remove-config_sparsemem_vmemmap=y-from-qemu-kernel-config.patch
mm-page_alloc-reject-unreasonable-folio-compound-page-sizes-in-alloc_contig_range_noprof.patch
mm-memremap-reject-unreasonable-folio-compound-page-sizes-in-memremap_pages.patch
mm-hugetlb-check-for-unreasonable-folio-sizes-when-registering-hstate.patch
mm-mm_init-make-memmap_init_compound-look-more-like-prep_compound_page.patch
mm-sanity-check-maximum-folio-size-in-folio_set_order.patch
mm-limit-folio-compound-page-sizes-in-problematic-kernel-configs.patch
mm-simplify-folio_page-and-folio_page_idx.patch
mm-hugetlb-cleanup-hugetlb_folio_init_tail_vmemmap.patch
mm-mm-percpu-km-drop-nth_page-usage-within-single-allocation.patch
fs-hugetlbfs-remove-nth_page-usage-within-folio-in-adjust_range_hwpoison.patch
fs-hugetlbfs-cleanup-folio-in-adjust_range_hwpoison.patch
mm-pagewalk-drop-nth_page-usage-within-folio-in-folio_walk_start.patch
mm-gup-drop-nth_page-usage-within-folio-when-recording-subpages.patch
mm-gup-remove-record_subpages.patch
io_uring-zcrx-remove-nth_page-usage-within-folio.patch
mips-mm-convert-__flush_dcache_pages-to-__flush_dcache_folio_pages.patch
mm-cma-refuse-handing-out-non-contiguous-page-ranges.patch
dma-remap-drop-nth_page-in-dma_common_contiguous_remap.patch
scatterlist-disallow-non-contigous-page-ranges-in-a-single-sg-entry.patch
ata-libata-sff-drop-nth_page-usage-within-sg-entry.patch
drm-i915-gem-drop-nth_page-usage-within-sg-entry.patch
mspro_block-drop-nth_page-usage-within-sg-entry.patch
memstick-drop-nth_page-usage-within-sg-entry.patch
mmc-drop-nth_page-usage-within-sg-entry.patch
scsi-scsi_lib-drop-nth_page-usage-within-sg-entry.patch
scsi-sg-drop-nth_page-usage-within-sg-entry.patch
vfio-pci-drop-nth_page-usage-within-sg-entry.patch
crypto-remove-nth_page-usage-within-sg-entry.patch
mm-gup-drop-nth_page-usage-in-unpin_user_page_range_dirty_lock.patch
kfence-drop-nth_page-usage.patch
block-update-comment-of-struct-bio_vec-regarding-nth_page.patch
mm-remove-nth_page.patch