Merge tag 'mm-hotfixes-stable-2022-06-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull hotfixes from Andrew Morton:
 "Minor things, mainly - mailmap updates, MAINTAINERS updates, etc.

  Fixes for this merge window:

   - fix for a damon boot hang, from SeongJae

   - fix for a kfence warning splat, from Jason Donenfeld

   - fix for zero-pfn pinning, from Alex Williamson

   - fix for fallocate hole punch clearing, from Mike Kravetz

  Fixes for previous releases:

   - fix for a performance regression, from Marcelo

   - fix for a hwpoisining BUG from zhenwei pi"

* tag 'mm-hotfixes-stable-2022-06-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
  mailmap: add entry for Christian Marangi
  mm/memory-failure: disable unpoison once hw error happens
  hugetlbfs: zero partial pages during fallocate hole punch
  mm: memcontrol: reference to tools/cgroup/memcg_slabinfo.py
  mm: re-allow pinning of zero pfns
  mm/kfence: select random number before taking raw lock
  MAINTAINERS: add maillist information for LoongArch
  MAINTAINERS: update MM tree references
  MAINTAINERS: update Abel Vesa's email
  MAINTAINERS: add MEMORY HOT(UN)PLUG section and add David as reviewer
  MAINTAINERS: add Miaohe Lin as a memory-failure reviewer
  mailmap: add alias for jarkko@profian.com
  mm/damon/reclaim: schedule 'damon_reclaim_timer' only after 'system_wq' is initialized
  kthread: make it clear that kthread_create_on_node() might be terminated by any fatal signal
  mm: lru_cache_disable: use synchronize_rcu_expedited
  mm/page_isolation.c: fix one kernel-doc comment

1 files changed, 53 insertions, 15 deletions

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 62408047e8d7..02eb72351b15 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -600,41 +600,79 @@ static void hugetlb_vmtruncate(struct inode *inode, loff_t offset)
 	remove_inode_hugepages(inode, offset, LLONG_MAX);
 }
 
+static void hugetlbfs_zero_partial_page(struct hstate *h,
+					struct address_space *mapping,
+					loff_t start,
+					loff_t end)
+{
+	pgoff_t idx = start >> huge_page_shift(h);
+	struct folio *folio;
+
+	folio = filemap_lock_folio(mapping, idx);
+	if (!folio)
+		return;
+
+	start = start & ~huge_page_mask(h);
+	end = end & ~huge_page_mask(h);
+	if (!end)
+		end = huge_page_size(h);
+
+	folio_zero_segment(folio, (size_t)start, (size_t)end);
+
+	folio_unlock(folio);
+	folio_put(folio);
+}
+
 static long hugetlbfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
 {
+	struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
+	struct address_space *mapping = inode->i_mapping;
 	struct hstate *h = hstate_inode(inode);
 	loff_t hpage_size = huge_page_size(h);
 	loff_t hole_start, hole_end;
 
 	/*
-	 * For hole punch round up the beginning offset of the hole and
-	 * round down the end.
+	 * hole_start and hole_end indicate the full pages within the hole.
 	 */
 	hole_start = round_up(offset, hpage_size);
 	hole_end = round_down(offset + len, hpage_size);
 
-	if (hole_end > hole_start) {
-		struct address_space *mapping = inode->i_mapping;
-		struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
+	inode_lock(inode);
 
-		inode_lock(inode);
+	/* protected by i_rwsem */
+	if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE)) {
+		inode_unlock(inode);
+		return -EPERM;
+	}
 
-		/* protected by i_rwsem */
-		if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE)) {
-			inode_unlock(inode);
-			return -EPERM;
-		}
+	i_mmap_lock_write(mapping);
+
+	/* If range starts before first full page, zero partial page. */
+	if (offset < hole_start)
+		hugetlbfs_zero_partial_page(h, mapping,
+				offset, min(offset + len, hole_start));
 
-		i_mmap_lock_write(mapping);
+	/* Unmap users of full pages in the hole. */
+	if (hole_end > hole_start) {
 		if (!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root))
 			hugetlb_vmdelete_list(&mapping->i_mmap,
 					      hole_start >> PAGE_SHIFT,
 					      hole_end >> PAGE_SHIFT, 0);
-		i_mmap_unlock_write(mapping);
-		remove_inode_hugepages(inode, hole_start, hole_end);
-		inode_unlock(inode);
 	}
 
+	/* If range extends beyond last full page, zero partial page. */
+	if ((offset + len) > hole_end && (offset + len) > hole_start)
+		hugetlbfs_zero_partial_page(h, mapping,
+				hole_end, offset + len);
+
+	i_mmap_unlock_write(mapping);
+
+	/* Remove full pages from the file. */
+	if (hole_end > hole_start)
+		remove_inode_hugepages(inode, hole_start, hole_end);
+
+	inode_unlock(inode);
+
 	return 0;
 }