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authorYang Shi <shy828301@gmail.com>2022-01-14 14:05:19 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2022-01-15 16:30:26 +0200
commita7605426666196c5a460dd3de6f8dac1d3c21f00 (patch)
treea03128c8a2439699d133141206464b0399fef82f
parent28b0ee3fb35047bd2bac57cc5a051b26bbd9b194 (diff)
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. [akpm@linux-foundation.org: coding style fixes] [arnd@arndb.de: fix uninitialized variable use in me_pagecache_clean()] Link: https://lkml.kernel.org/r/20211022064748.4173718-1-arnd@kernel.org [Fix invalid pointer dereference in shmem_read_mapping_page_gfp() with a slight different implementation from what Ajay Garg <ajaygargnsit@gmail.com> and Muchun Song <songmuchun@bytedance.com> proposed and reworked the error handling of shmem_write_begin() suggested by Linus] Link: https://lore.kernel.org/linux-mm/20211111084617.6746-1-ajaygargnsit@gmail.com/ Link: https://lkml.kernel.org/r/20211020210755.23964-6-shy828301@gmail.com Link: https://lkml.kernel.org/r/20211116193247.21102-1-shy828301@gmail.com Signed-off-by: Yang Shi <shy828301@gmail.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Hugh Dickins <hughd@google.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Peter Xu <peterx@redhat.com> Cc: Ajay Garg <ajaygargnsit@gmail.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Andy Lavr <andy.lavr@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/memory-failure.c14
-rw-r--r--mm/shmem.c51
-rw-r--r--mm/userfaultfd.c5
3 files changed, 61 insertions, 9 deletions
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 3a274468f193..5f8ad5527506 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -58,6 +58,7 @@
#include <linux/ratelimit.h>
#include <linux/page-isolation.h>
#include <linux/pagewalk.h>
+#include <linux/shmem_fs.h>
#include "internal.h"
#include "ras/ras_event.h"
@@ -867,6 +868,7 @@ static int me_pagecache_clean(struct page_state *ps, struct page *p)
{
int ret;
struct address_space *mapping;
+ bool extra_pins;
delete_from_lru_cache(p);
@@ -896,17 +898,23 @@ static int me_pagecache_clean(struct page_state *ps, struct page *p)
}
/*
+ * The shmem page is kept in page cache instead of truncating
+ * so is expected to have an extra refcount after error-handling.
+ */
+ extra_pins = shmem_mapping(mapping);
+
+ /*
* Truncation is a bit tricky. Enable it per file system for now.
*
* Open: to take i_rwsem or not for this? Right now we don't.
*/
ret = truncate_error_page(p, page_to_pfn(p), mapping);
+ if (has_extra_refcount(ps, p, extra_pins))
+ ret = MF_FAILED;
+
out:
unlock_page(p);
- if (has_extra_refcount(ps, p, false))
- ret = MF_FAILED;
-
return ret;
}
diff --git a/mm/shmem.c b/mm/shmem.c
index 18f93c2d68f1..fb5152369926 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2457,6 +2457,7 @@ shmem_write_begin(struct file *file, struct address_space *mapping,
struct inode *inode = mapping->host;
struct shmem_inode_info *info = SHMEM_I(inode);
pgoff_t index = pos >> PAGE_SHIFT;
+ int ret = 0;
/* i_rwsem is held by caller */
if (unlikely(info->seals & (F_SEAL_GROW |
@@ -2467,7 +2468,19 @@ shmem_write_begin(struct file *file, struct address_space *mapping,
return -EPERM;
}
- return shmem_getpage(inode, index, pagep, SGP_WRITE);
+ ret = shmem_getpage(inode, index, pagep, SGP_WRITE);
+
+ if (ret)
+ return ret;
+
+ if (PageHWPoison(*pagep)) {
+ unlock_page(*pagep);
+ put_page(*pagep);
+ *pagep = NULL;
+ return -EIO;
+ }
+
+ return 0;
}
static int
@@ -2554,6 +2567,12 @@ static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
if (sgp == SGP_CACHE)
set_page_dirty(page);
unlock_page(page);
+
+ if (PageHWPoison(page)) {
+ put_page(page);
+ error = -EIO;
+ break;
+ }
}
/*
@@ -3093,7 +3112,8 @@ static const char *shmem_get_link(struct dentry *dentry,
page = find_get_page(inode->i_mapping, 0);
if (!page)
return ERR_PTR(-ECHILD);
- if (!PageUptodate(page)) {
+ if (PageHWPoison(page) ||
+ !PageUptodate(page)) {
put_page(page);
return ERR_PTR(-ECHILD);
}
@@ -3101,6 +3121,13 @@ static const char *shmem_get_link(struct dentry *dentry,
error = shmem_getpage(inode, 0, &page, SGP_READ);
if (error)
return ERR_PTR(error);
+ if (!page)
+ return ERR_PTR(-ECHILD);
+ if (PageHWPoison(page)) {
+ unlock_page(page);
+ put_page(page);
+ return ERR_PTR(-ECHILD);
+ }
unlock_page(page);
}
set_delayed_call(done, shmem_put_link, page);
@@ -3751,6 +3778,13 @@ static void shmem_destroy_inodecache(void)
kmem_cache_destroy(shmem_inode_cachep);
}
+/* Keep the page in page cache instead of truncating it */
+static int shmem_error_remove_page(struct address_space *mapping,
+ struct page *page)
+{
+ return 0;
+}
+
const struct address_space_operations shmem_aops = {
.writepage = shmem_writepage,
.set_page_dirty = __set_page_dirty_no_writeback,
@@ -3761,7 +3795,7 @@ const struct address_space_operations shmem_aops = {
#ifdef CONFIG_MIGRATION
.migratepage = migrate_page,
#endif
- .error_remove_page = generic_error_remove_page,
+ .error_remove_page = shmem_error_remove_page,
};
EXPORT_SYMBOL(shmem_aops);
@@ -4169,9 +4203,14 @@ struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE,
gfp, NULL, NULL, NULL);
if (error)
- page = ERR_PTR(error);
- else
- unlock_page(page);
+ return ERR_PTR(error);
+
+ unlock_page(page);
+ if (PageHWPoison(page)) {
+ put_page(page);
+ return ERR_PTR(-EIO);
+ }
+
return page;
#else
/*
diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index ac6f036298cd..0780c2a57ff1 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)