Commit 8625147c authored by James Houghton's avatar James Houghton Committed by Andrew Morton
Browse files

hugetlbfs: don't delete error page from pagecache 

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 a7605426 ("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: default avatarJames Houghton <jthoughton@google.com>
Reviewed-by: default avatarMike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: default avatarNaoya Horiguchi <naoya.horiguchi@nec.com>
Tested-by: default avatarNaoya Horiguchi <naoya.horiguchi@nec.com>
Reviewed-by: default avatarYang 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: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 120b1162

fs/hugetlbfs/inode.c

+6 −7
Original line number Diff line number Diff line
@@ -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.

			 */
@@ -1111,13 +1117,6 @@ 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;



	hugetlb_delete_from_page_cache(page);

	if (unlikely(hugetlb_unreserve_pages(inode, index, index + 1, 1)))

		hugetlb_fix_reserve_counts(inode);



	return 0;

}

mm/hugetlb.c

+4 −0
Original line number Diff line number Diff line
@@ -6111,6 +6111,10 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, 


	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

mm/memory-failure.c

+4 −1
Original line number Diff line number Diff line
@@ -1080,6 +1080,7 @@ 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;
@@ -1087,6 +1088,8 @@ 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);
@@ -1104,7 +1107,7 @@ 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;