The quilt patch titled Subject: hugetlbfs: don't delete error page from pagecache has been removed from the -mm tree. Its filename was hugetlbfs-dont-delete-error-page-from-pagecache.patch

This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------ From: James Houghton jthoughton@google.com Subject: hugetlbfs: don't delete error page from pagecache Date: Tue, 18 Oct 2022 20:01:25 +0000

This change is very similar to the change that was made for shmem [1], and it solves the same problem but for HugeTLBFS instead.

Currently, when poison is found in a HugeTLB page, the page is removed from the page cache. That means that attempting to map or read that hugepage in the future will result in a new hugepage being allocated instead of notifying the user that the page was poisoned. As [1] states, this is effectively memory corruption.

The fix is to leave the page in the page cache. If the user attempts to use a poisoned HugeTLB page with a syscall, the syscall will fail with EIO, the same error code that shmem uses. For attempts to map the page, the thread will get a BUS_MCEERR_AR SIGBUS.

[1]: commit a76054266661 ("mm: shmem: don't truncate page if memory failure happens")

Link: https://lkml.kernel.org/r/20221018200125.848471-1-jthoughton@google.com Signed-off-by: James Houghton jthoughton@google.com Reviewed-by: Mike Kravetz mike.kravetz@oracle.com Reviewed-by: Naoya Horiguchi naoya.horiguchi@nec.com Tested-by: Naoya Horiguchi naoya.horiguchi@nec.com Reviewed-by: Yang Shi shy828301@gmail.com Cc: Axel Rasmussen axelrasmussen@google.com Cc: James Houghton jthoughton@google.com Cc: Miaohe Lin linmiaohe@huawei.com Cc: Muchun Song songmuchun@bytedance.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

fs/hugetlbfs/inode.c | 13 ++++++------- mm/hugetlb.c | 4 ++++ mm/memory-failure.c | 5 ++++- 3 files changed, 14 insertions(+), 8 deletions(-)

--- a/fs/hugetlbfs/inode.c~hugetlbfs-dont-delete-error-page-from-pagecache +++ a/fs/hugetlbfs/inode.c @@ -328,6 +328,12 @@ static ssize_t hugetlbfs_read_iter(struc } else { unlock_page(page);

+ if (PageHWPoison(page)) { + put_page(page); + retval = -EIO; + break; + } + /* * We have the page, copy it to user space buffer. */ @@ -1111,13 +1117,6 @@ static int hugetlbfs_migrate_folio(struc static int hugetlbfs_error_remove_page(struct address_space *mapping, struct page *page) { - struct inode *inode = mapping->host; - pgoff_t index = page->index; - - hugetlb_delete_from_page_cache(page); - if (unlikely(hugetlb_unreserve_pages(inode, index, index + 1, 1))) - hugetlb_fix_reserve_counts(inode); - return 0; }

--- a/mm/hugetlb.c~hugetlbfs-dont-delete-error-page-from-pagecache +++ a/mm/hugetlb.c @@ -6111,6 +6111,10 @@ int hugetlb_mcopy_atomic_pte(struct mm_s

ptl = huge_pte_lock(h, dst_mm, dst_pte);

+ ret = -EIO; + if (PageHWPoison(page)) + goto out_release_unlock; + /* * We allow to overwrite a pte marker: consider when both MISSING|WP * registered, we firstly wr-protect a none pte which has no page cache --- a/mm/memory-failure.c~hugetlbfs-dont-delete-error-page-from-pagecache +++ a/mm/memory-failure.c @@ -1080,6 +1080,7 @@ static int me_huge_page(struct page_stat int res; struct page *hpage = compound_head(p); struct address_space *mapping; + bool extra_pins = false;

if (!PageHuge(hpage)) return MF_DELAYED; @@ -1087,6 +1088,8 @@ static int me_huge_page(struct page_stat mapping = page_mapping(hpage); if (mapping) { res = truncate_error_page(hpage, page_to_pfn(p), mapping); + /* The page is kept in page cache. */ + extra_pins = true; unlock_page(hpage); } else { unlock_page(hpage); @@ -1104,7 +1107,7 @@ static int me_huge_page(struct page_stat } }

- if (has_extra_refcount(ps, p, false)) + if (has_extra_refcount(ps, p, extra_pins)) res = MF_FAILED;

return res; _

Patches currently in -mm which might be from jthoughton@google.com are