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@xxxxxxxxxx>
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@xxxxxxxxxx
Signed-off-by: James Houghton <jthoughton@xxxxxxxxxx>
Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Reviewed-by: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
Tested-by: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
Reviewed-by: Yang Shi <shy828301@xxxxxxxxx>
Cc: Axel Rasmussen <axelrasmussen@xxxxxxxxxx>
Cc: James Houghton <jthoughton@xxxxxxxxxx>
Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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@xxxxxxxxxx are
