On 11/14/22 11:33, gregkh@linuxfoundation.org wrote:

The patch below does not apply to the 6.0-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

Below is backport for 6.0-stable. Only minor conflicts in code that is being removed by this patch. Tested with simple program to access hugetlb pagecache page after poisoning.

From 5dcd97ae1a0848c1b9a1ec5f4ab623b1ab478892 Mon Sep 17 00:00:00 2001 From: James Houghton jthoughton@google.com Date: Tue, 18 Oct 2022 20:01:25 +0000 Subject: [PATCH] hugetlbfs: don't delete error page from pagecache

commit 8625147cafaa9ba74713d682f5185eb62cb2aedb upstream.

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 Signed-off-by: Mike Kravetz mike.kravetz@oracle.com --- fs/hugetlbfs/inode.c | 13 ++++++------- mm/hugetlb.c | 4 ++++ mm/memory-failure.c | 5 ++++- 3 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index f7a5b5124d8a..398f8702c34f 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -328,6 +328,12 @@ static ssize_t hugetlbfs_read_iter(struct kiocb *iocb, struct iov_iter *to) } else { unlock_page(page);

+ if (PageHWPoison(page)) { + put_page(page); + retval = -EIO; + break; + } + /* * We have the page, copy it to user space buffer. */ @@ -991,13 +997,6 @@ static int hugetlbfs_migrate_folio(struct address_space *mapping, static int hugetlbfs_error_remove_page(struct address_space *mapping, struct page *page) { - struct inode *inode = mapping->host; - pgoff_t index = page->index; - - remove_huge_page(page); - if (unlikely(hugetlb_unreserve_pages(inode, index, index + 1, 1))) - hugetlb_fix_reserve_counts(inode); - return 0; }

diff --git a/mm/hugetlb.c b/mm/hugetlb.c index ecc197d24efb..590ba2bf033d 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -6021,6 +6021,10 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, ptl = huge_pte_lockptr(h, dst_mm, dst_pte); spin_lock(ptl);

+ ret = -EIO; + if (PageHWPoison(page)) + goto out_release_unlock; + /* * Recheck the i_size after holding PT lock to make sure not * to leave any page mapped (as page_mapped()) beyond the end diff --git a/mm/memory-failure.c b/mm/memory-failure.c index e7ac570dda75..4d302f6b02fc 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1079,6 +1079,7 @@ static int me_huge_page(struct page_state *ps, struct page *p) int res; struct page *hpage = compound_head(p); struct address_space *mapping; + bool extra_pins = false;

if (!PageHuge(hpage)) return MF_DELAYED; @@ -1086,6 +1087,8 @@ static int me_huge_page(struct page_state *ps, struct page *p) 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); @@ -1103,7 +1106,7 @@ static int me_huge_page(struct page_state *ps, struct page *p) } }

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

return res;