From b9d02f1bdd98f38e6e5ecacc9786a8f58f3f8b2c Mon Sep 17 00:00:00 2001 From: Yang Shi Date: Fri, 5 Nov 2021 13:41:10 -0700 Subject: mm: shmem: don't truncate page if memory failure happens The current behavior of memory failure is to truncate the page cache regardless of dirty or clean. If the page is dirty the later access will get the obsolete data from disk without any notification to the users. This may cause silent data loss. It is even worse for shmem since shmem is in-memory filesystem, truncating page cache means discarding data blocks. The later read would return all zero. The right approach is to keep the corrupted page in page cache, any later access would return error for syscalls or SIGBUS for page fault, until the file is truncated, hole punched or removed. The regular storage backed filesystems would be more complicated so this patch is focused on shmem. This also unblock the support for soft offlining shmem THP. [arnd@arndb.de: fix uninitialized variable use in me_pagecache_clean()] Link: https://lkml.kernel.org/r/20211022064748.4173718-1-arnd@kernel.org Link: https://lkml.kernel.org/r/20211020210755.23964-6-shy828301@gmail.com Signed-off-by: Yang Shi Signed-off-by: Arnd Bergmann Cc: Hugh Dickins Cc: Kirill A. Shutemov Cc: Matthew Wilcox Cc: Naoya Horiguchi Cc: Oscar Salvador Cc: Peter Xu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/userfaultfd.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'mm/userfaultfd.c') diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index caf6dfff2a60..77fce86371a9 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -232,6 +232,11 @@ static int mcontinue_atomic_pte(struct mm_struct *dst_mm, goto out; } + if (PageHWPoison(page)) { + ret = -EIO; + goto out_release; + } + ret = mfill_atomic_install_pte(dst_mm, dst_pmd, dst_vma, dst_addr, page, false, wp_copy); if (ret) -- cgit v1.2.3